摘要:

11 Chromium, molybdenum and tungsten H. Sloan Consulting Chemist, 40Wendan Road, Newbury, Berkshire, UK RG14 7AF 1 Introduction The first issue of Chemical Reviews was devoted1 to polyoxometalates, having fourteen articles including historical developments, nomenclature, many aspects of their inorganic, organic and physical chemistry, and applications particularly in catalysis. Reviews have appeared on seven-co-ordinate halogenocarbonyl complexes of molybdenum and tungsten,2 metal sulfides, metallacarbohedranes and nitrogenase,3 polyoxometalates in organic oxidation,4 asymmetric syntheses with Fischer carbene complexes, 5 alkene metathesis,6 reduction with [W(CO) 5 L]~· radicals,7 tungsten salicylate free acids,8 18- and 17-electron molybdenum compounds with only carbondonor ligands,9 oxygen atom transfer involving oxomolybdenum complexes,10 thiolato-bridged molybdenum compounds,11 [Cr(CO) 3 (g6-arene)] complexes,12 modelling of polyoxometalates,13 decatungstate photocatalysis14 and Group 6 organometallic complexes in zeolite voids.15 Volume 177 of Coordination Chemical Reviews is devoted to MLCT/LMCT e§ects and Group 6 elements are referred to particularly in articles on polymerisation,16 metal–CO photodissociation,17 photoreactivity,18 time-resolved IR spectroscopy of excited states,19 mechanistic roles of CT excited states20 and excited state properties of chiral complexes.21 Aspects of this group also appear in reviews on bent metallocenes, 22 metal–metal bonds,23 transition metals as components of molecular containers, 24 hydrogenation, hydrogenolysis and desulfurisation of thiophenes,25 complexes of amino acids and peptides,26 complexes of boron,27 transition metal–boryl compounds,28 vibrational spectroscopy of electronically excited complexes,29 crystal architecture,30 e§ects of media on charge transfer,31 exchange coupling in polyhydride and dihydrogen complexes,32 reactions of transition metal complexes with fullerenes,33 MLCT transitions relevant to oxidative addition,34 co-ordination modes of chelating and heteroaromatic ligands,35 tris(2-pyridyl) ligands,36 mixed nitrogenand sulfur-donor tridentate macrocycles,37 dinuclear paddlewheel compounds,38 the transition metal–oxygen bond in oxidic solids,39 allenylidene and cumulenylidene ligands,40 heterogeneous hydrogenation catalysts,41 nitrogen fixation,42 and conducting and magnetic molecular materials.43 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 1292 Metalates The hydrothermal reaction of Na 2 WO 4 ·2H 2 O, MoO, Mo, [NEt 4 ]Cl and water at 160 °C gave44 bluish purple crystals of the mixed valence tungstate [NEt 4 ] 3 - [WVWVIO 19 ]·0.5H 2 O. The same anion is formed from the analogous reaction of Na 2 WO 4 ·2H 2 O, V, en·2H 2 O and water giving brown crystals of [enH 2 ] 2 - [WVWVIO 19 ]Cl·en·8H 2 O.The presence of only one band in each of the regions attributable to l(W––O) and l(W–O–W) suggests the identical nature of the terminal W–Oand bridgingW–O–Wgroups. There is a slight shift of these two main IR bands of the anion compared with the unreduced species.X-Ray structural data support the similarity of the terminal and bridging groups of the Lindquist-type anion in both compounds. The compounds [H 2 imz] 6 [TeMo 6 O 24 ]·4H 2 O and [H 2 pyz] 6 [TeMo 6 O 24 ]· Te(OH) 6 are formed45 in aqueous solution by the reaction of MoO 3 and Te(OH) 6 in the presence of the base. The lower pH of the solution in forming the latter may cause inclusion in the crystal of Te(OH) 6 , which is not uncommon.The Anderson–Evans anion contains a central octahedral TeO 6 unit with octahedral MoO 6 units sharing edges around it. The imidazolium compound is less stable, being hydrolysed in water to MoO 4 2~ species. The reaction of sodium tungstate with hydrofluoric acid and cobalt acetate gave46 [NaCoW 11 O 43 FH 12 ]6~ isolated as the ammonium salt.The isomorphous nickel analogue was obtained similarly. The cobalt or nickel atom occupies an octahedral site normally occupied by tungsten and the sodium atom is in the central cavity. An equimolar mixture of ZnSO 4 and Co(O 2 CMe) 2 was added47 dropwise to aqueous Na 2 WO 4 at 55 °C and the mixture boiled, cooled, H 2 O 2 added followed by ammonium chloride to give [NH 4 ] 7 [CoZnW 11 O 40 H 2 ]·20H 2 O.Cobalt(III) occupies the octahedral site vacated by tungsten in this Keggin anion, the zinc atom being in the central tetrahedral cavity. This compound proved able to catalyse the splitting of water on irradiation with UV light. An aqueous solution of Na 2 WO 4 reacted48 with 48% HF, followed by dropwise addition of In 2 SO 4 and heating to 85 °C, to give [InW 17 O 56 F 6 NaH 4 ]8~, separated as the ammonium salt.This anion has a Dawson structure with an indium atom occupying the site vacated by the missing tungsten atom. The reaction of Na 2 WO 4 · 2H 2 O, [W(CO) 6 ] and GaCl 3 in propionic anhydride at 120 °C gave49 black crystals of Na 2 [MW 3 O 4 (O 2 CEt) 8NGa 2 ] in which the tungsten oxometalate units are connected by two bridging gallium atoms.The centrosymmetric eight-membered W 2 O 4 Ga 2 ring has a chair-like conformation. It is insoluble in water and common organic solvents and in aqueous acids. It is more stable than the molybdenum–aluminium analogue but decomposes in hot 2 MHCl to give a species containingW 3 O 4 units. Organophosphonic acids RPO(OH) 2 reacted50 in the presence of [NBu 4 ]Br with b-A-Na 8 [HPW 9 O 34 ]·24H 2 O to give a-A-[NBu 4 ] 3 Na 2 [PW 9 O 34 (RPO 2 )] (R\Et, Bu/, Bu5, allyl, Ph).The two RPO groups are bonded through the oxygen atoms of P–O–Wbridges on the a-A-PW 9 O 34 framework. The 31P magic-angle spinningNMR spectra of the pseudo-liquid phase of [H 3 PW 12 O 40 ]·nH 2 O (n\6) showed51 that the acidic protons on heteropolyanions could be distinguished from protons inH 3 O` and H 5 O 2 `.At 173 K, these protons were distributed over the polyanions with 0, 1, 2 or 3 protons attached to any one polyanion. The NMR peaks coalesced at 298 K, demon- Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 130strating the rapid migration of these protons between the heteropolyanions.In acidic solutions of MeCN or Me 2 CO, MoO 4 ~ reacted52 with EO 3 ~ (E\Se, Te) to form [Mo 15 O 45 (EO 3 ) 2 ]4~, which was converted into [Mo 12 O 36 (EO 3 ) 2 ]4~ on stirring for a few hours. The latter anion is also formed in the absence of the organic solvent but this must be present to obtain the Mo 15 intermediate. The polyanion of [NH 4 ] 2 [V 3 W 3 O 19 ]·12H 2 O has53 a structure similar to that of [W 6 O 19 ]5~.The vanadium and tungsten atoms are randomly distributed over the six possible positions in the otherwise centrosymmetric anion. Reduction of an acidified solution of Na 2 MoO 4 by iron powder54 or by SnCl 2 55 gave [Mo 176 O 496 (OH) 32 (H 2 O) 80 ]. The molecule is tyre-shaped with a cavity ca. 3nm in diameter. It consists of sixteen Mo 8 subunits connected by 48 MoO 6 octahedra. It is very soluble in water, ethanol and acetone. 3 Cubanes The cubanes [MoxW 4~xS 4 (H 2 O) 12 ]5` (x\1–3) and [MoW 3 Se 4 (H 2 O) 12 ]5` were obtained56 by the reaction of [Mo 2 Cl 8 ]4~ on the appropriate trinuclear incomplete cubane. In comparisons by cyclic voltammetry, including [Mo 4 E 4 (H 2 O) 12 ]5` (E\S, Se), more tungsten atoms result in a more strongly reducing e§ect. Oxidation of these products with [Fe(H 2 O) 6 ]3` gives the 6] anion followed by decomposition to a trinuclear cubane, always with loss of tungsten.In 2 M HCl, [Mo 3 S 4 (H 2 O) 9 ]4` reacted57 rapidly with AsO 2 ~ or HAsO 4 2~ in the presence of H 3 PO 2 as reductant to give the air-sensitive corner-shared double cubane [Mo 6 AsS 8 (H 2 O) 18 ]8`.The Mo–Mo distances are short (2.716Å average) compared with other cubanes and the Mo–As distances long (3.554Å). The classification of cubanes suggested here accords with that from Fenske–Hall MO calculations which indicate58 that incorporation of main group elements into Mo 3 MS 4 type cubanes involves oxidation of the heterometal and bonding through the sulfur atoms only; there is no Mo–M direct bonding.However, whenM is a transition metal atom, oxidation does not occur andM bonds directly to the Mo 3 triangle. The relatively high CO stretching frequencies in carbonyl compounds in this series are the result of competition between the CO ligands on M and the interaction with the Mo 3 group. The reaction of the solid polymeric [W 3 Se 7 Br 4 ] with H 3 PO 2 in aqueous HCl gave59 green [W 3 Se 4 (H 2 O) 9 ]4` which further reacted with SnCl 2 in aqueous HCl in the presence of [NH 2 Me 2 ]Cl and NaSCN giving brown [NH 2 Me 2 ] 6 - [W 3 (SnCl 3 )Se 4 (SCN) 9 ].The Sn–Se bond lengths in this compound are slightly longer than in the molybdenum analogue, suggesting weaker bonds. The elongated thermal ellipsoids obtained from the chlorine atoms in the crystal structural study suggest some rotational libration in the SnCl 3 moiety.Addition of SnCl 2 to[M 3 Se 4 (H 2 O) 9 ]4` (M\Mo, W) in 2Mp-toluenesulfonic acid gave60 [M 3 SnSe 4 (H 2 O) 12 ]6` and in 2M HCl gave[M 3 (SnCl 3 )Se 4 (H 2 O) 9 ]3`. The reaction of [Mo 3 S 4 (H 2 O) 9 ]4` with tin metal gave the corner-shared double cubane[Mo 6 SnSe 8 (H 2 O) 18 ]8`, characterized by X-ray crystallography as the p-toluenesulfonate. Reductive addition of [M 3 Se 4 (H 2 O) 9 ]4` and [M 3 S 4 (H 2 O) 9 ]4` (M\Mo, W) to [Mo 3 SnSe 4 (H 2 O) 12 ]6` using [BH 4 ]~ gave [Mo 3 M 3 SnSe 8 (H 2 O) 18 ]8` and [Mo 3 M 3 SnSe 4 S 4 (H 2 O) 18 ]8` respectively.Transfer of tin occurred from [M 3 SnE 8 (H 2 O) 12 ]6` (M\Mo, W, E\Se; M\W, E\S) to Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 131[Mo 3 (H 2 O) 9 ]4`. The order of a¶nities for tin uptake is Mo 3 S 4 4`[Mo 3 Se 4 4`[W 3 Se 4 4`[W 3 S 4 4`. The action of concentrated ammonia on [Mo 3 CuS 4 (H 2 O) 10 ]4` gave61 the centrosymmetric twin cubane [MMo 3 CuS 4 (H 2 O)(NH 3 ) 6 (OH)N2 (l-O) 2 ]Cl 4 ·8H 2 O where two cubane structures are connected by bridging oxo ligands between molybdenum atoms.The reaction of [Mo 3 S 4 (H 2 O) 9 ]4` with gallium in 0.5 M HCl gave62 [Mo 3 GaS 4 (H 2 O) 9 ]4`. Solution studies of the related cubanes and double cubanes (not Ga) of Group 13 elements showed the latter to be more sensitive to oxygen, more so in HCl than in p-toluenesulfonic acid. The single cubanes are only oxidised by acids at higher concentrations of about 4 M.The reaction of [W(CO) 6 ], Na 2 WO 4 ·2H 2 O and InCl 3 in propionic anhydride at 120 °C gave63 Na 2 [MW 3 O 4 (O 2 CEt) 8N2 In 2 ] in which each indium atom bridges the incomplete tungsten oxide cubane units across two of the ‘open’ oxygen corners. The anion is centrosymmetric. The compound is insoluble in water and organic solvents but is decomposed by 2 M HCl.Antimony metal reacted64 with [Mo 3 S 4 (H 2 O) 9 ]4` to give the corner-sharing double cubane [Mo 6 SbS 8 (H 2 O) 18 ]8` as the p-toluenesulfonate. The Mo–Sb distances (3.68Å) are much longer than the Mo–Mo distances (2.717Å). Mo� ssbauer and XPS spectra indicate an oxidation number of ]3 for antimony and mean oxidation number of ]3.5 for molybdenum. The reaction of [Mo 3 Te 7 I 4 ] or [WTe 2 ] with KCN at 450 °C followed by recrystallisation from water gave65 dark red-brown crystals of paramagnetic K 7 [Mo 4 Te 4 (CN) 12 ]·11H 2 O or diamagnetic K 6 [W 4 Te 4 (CN) 12 ]·5H 2 O.Crystal structural determinations confirmed the M 4 Te 4 cubane-like core in both compounds. There is some distortion of the metal tetrahedral arrangement, which is greater for the tungsten compound. 4 Quadruple metal–metal bonds The reaction of [NH 4 ] 5 [Mo 2 Cl 9 ] with etp in methanol gave66 [Mo 2 Cl 4 (j3P,P@,PA- etp)(MeOH)]. This reacts easily with PR 3 (R\Me, Et) in thf giving [Mo 2 Cl 4 (j3P,P@,PA-etp)(PR 3 )] which have the etp ligand chelating one molybdenum atom and bridging to the other. Refluxing the methanol complex with one equivalent of etp in methanol gave a-[Mo 2 Cl 4 (j2P,P@-etp) 2 ] with the etp chelating through the central and one terminal phosphorus atoms.Mercaptopurine reacted with [Mo 2 (OAc) 4 ] in dry methanol on warming to give67 [Mo 2 (mpH) 4 (H 2 O) 2 ]·2H 2 O or [Mo 2 (mp) 2 (H 2 O) 2 ] depending on stoichiometry. In the first complex, the deprotonated mercaptopurine ligands bridge the Mo–Mo quadruple bond, with opposite bridges linked N–S and S–N across the bond.This complex is dehydrated at 200 °C, losing four molecules of water. The second complex is polymeric and the four bridging ligands at each Mo–Mo quadruple bond have N–S and S–N opposite each other with linkage from the other two N–N pairs in the other positions (Fig. 1). The complexes [Mo 2 Cl 4 L 4 ] (L\S-chea, R-chea) were obtained68 by the reaction of L with [Mo 2 Cl 4 (PPh 3 ) 2 (MeOH) 2 ] in acetone.Crystal structural studies of both products showed disorder in the crystals with about 3% and 6% of a second disposition respectively. The two molecules occupying the same site in the unit cell have their Mo–Mo vectors at right angles to each other. Opposite configurations for the core Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 132Fig. 1 The proposed structure of [Mo 2 (mp) 2 (H 2 O) 2 ]. (Reproduced by permission from Inorg. Chim. Acta, 1998, 279, 136.) structures are present in solution compared to the crystal form. The CD spectra show temperature dependent equilibria between the conformers in solution. The complex [Mo 2 Cl 2 (darf) 6 ] (or its p-tolyl analogue) reacted69 with Na[BHEt 3 ] to give [MMo 2 Cl 2 (darf) 6N2 (l-H) 2 ].These have two Mo–Moquadruply bonded entities linked parallel to each other by two independent Mo–H–Mo bridges. They are resistant to hydrolysis by water. The complex [Mo 2 Cl 2 (darf) 6 ] reacted70 with Na[BHEt 3 ] and [NBu 4 ] 2 [C 2 O 4 ] in CH2 Cl 2 to give [MMo(darf) 3N2 (l4 -C 2 O 4 )] in which the oxalate group bridges all four molybdenum atoms such that the entire molybdenums–oxalate moiety is planar.The Mo–Mo quadruple bonds are retained. Each carboxylate group bridges one Mo–Mo quadruple bond. In the analogous complex with the O 2 CC 6 F 4 CO 2 bridge, the aromatic ring is rotated by 30.4° from the two coplanar Mo 2 O 2 C units. The reaction of cis-[Mo 2 (O 2 CMe) 2 (NCMe) 6 ][BF 4 ] with the potentially tetradentate ligand dpnapy in CH 2 Cl 2 at room temperature gave71 a mixture of the isomers cis-[Mo 2 (O 2 CMe) 2 (dpnapy-N,P) 2 ][BF 4 ] and trans-[Mo 2 (O 2 CMe) 2 (dpnapy-N,N@) 2 ]- [BF 4 ].Crystal structural analysis of both complexes showed short Mo–Mo distances (2.119, 2.099Å respectively) indicative of quadruple bonds. In the former product, the dpnapy ligands adopt a head-to-tail formation.TheMo–Ndistances for the nominally unbonded nitrogens of the dpnapy ligands are such that they may result from weak interactions with the axial orbitals of the molybdenum atoms; some deformation of the dpnapy ligands is in line with this possibility. Reduction of [MoIII 2 Cl 6 (thf) 3 ] during the reaction with diethylamine gave72 [MoII 2 Cl 4 (NHEt 2 ) 4 ] as well as by-products resulting from reaction of the chloride ions released with the starting materials.The main product has trans-MoCl 2 (NHEt 2 ) 2 units joined by a quadruple Mo–Mo bond. The by-products all proved resistant to reduction under these conditions. 5 Other metal–metal bonds The alcoholysis of [W 2 Cl 2 (NMe 2 ) 4 ] with tert-butyl alcohol gave73 the asymmetric Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 133W W O NMe2 Cl Cl CMe3 Me2N O O Cl CMe3 Me3C H H 1 Fig. 2 The structure of complex 1. (Reproduced by permission from Acta Crystallogr., Sect. C., 1998, 54, 225.) complex 1 (Fig. 2). TheW–Wdistance (2.3155Å) is close to that of the starting material (2.301Å). There is some steric interaction between ligands in an eclipsed configuration across the triple bond but none of the W–W–L angles is greer than 109°.TheW–N distances denote single bonds, in agreement with protonation of the amino ligands. The complex [W 2 H 2 (OPr*) 4 (dmpe) 2 ] reacted74 with CO, CO 2 and H 2 O to give [(Pr*O) 4 WW(j2P,P@-dmpe) 2 (CO)], [(j1O-HCO 2 )(Pr*O) 4 WW(j2P,P@-dmpe) 2 H] and [MH(j2P,P@-dmpe) 2 WWO 2N2 (l-O)] respectively.The product [(Pr*O) 4 WW(j2P,P@- dmpe) 2 H] reacted with water to give [M(j2P,P@-dmpe) 2 (CO)WWON2 (l-O)]. These all contain unsupported W–W bonds with the tungsten atoms in di§erent oxidation states. The chelating dmpe ligands in [(Pr*O) 4 WW(j2P,P@-dmpe) 2 (CO)] give rise to two enantiomeric forms in the disordered crystal state with about 50% of each enantiomer present (oxidation states 0 and ]4).TheW–Wdistance corresponds to a double bond. The product [M(j2P,P@-dmpe) 2 (CO)WWO 2N(l-O)] is centrosymmetric with the tungsten atom linked by the oxo bridge each bearing two terminal oxo ligands (oxidation states 0 and ]5). 6 Face- and edge-sharing bioctahedral complexes The addition of [NBnEt 3 ]Cl to (WCl 4 )x powder in CH 2 Cl 2 gave75 edge-sharing [W 2 Cl 9 ]~ and face-sharing [W 2 Cl 10 ]2~ with double bonds between the tungsten atoms (W–W\2.689, 2.792Å respectively).Addition of further [NBnEt 3 ]Cl at room temperature converts these to [W 2 Cl 9 ]2~, [WCl 6 ]~ and ultimately [WCl 6 ]2~. At [30 °C, [NBnEt 3 ][W 2 Cl 9 ] is converted into [NBnEt 3 ][W 2 Cl 10 ]. The racemate and the enantiomers ("-") or (*-*) of [MCr(chxn) 2N2 (l-OH) 2 ], together with meso compound 2 (Fig. 3), were formed76 by dehydration, simply by heating mixtures of enantiomeric forms of [Cr(OH)(chxn) 2 (H 2 O)] to 140 °C for 3 hours in the solid state. This indicates the presence of homochiral and heterochiral 3 pairs of molecules held together by hydrogen bonding in the starting material. This contrasts with the analogous ethylenediamine complex which gives only the meso product, suggesting the presence of only heterochiral pairs.The carboxylate complexes [Cr 2 (O 2 CR) 4 (H 2 O) 2 ] reacted77 easily with the tridentate ligand bispma in water giving [Cr 2 (l-OH)n(l- O 2 CR) 3~n(bispma) 2 ]Xm·yH 2 O (n\1, m\3, R\H, Me, Et, CH 2 Cl, CH 2 CH 2 Cl; n\1, m\4, R\CH 2 NH 3 , CH 2 CH 2 NH 3 , CHMeNH 2 ; n\2, m\3, R\H, Me).The crystal structure of [Cr 2 (l-OH) 2 (l-O 2 CR)(bispma) 2 ][ClO 4 ] is of edge-sharing octahedral form with the formate ligand bridging adjacent apical positions, the other apical positions being occupied by the amino nitrogen of bispma. Two complexes, with R\H and R\CH 2 Cl, exhibit magnetic properties alternating from antiferromag- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 134Fig. 3 Molecular models of the meso form and the bridged structure of [MCr(chxn) 2N2 (l-OH) 2 ]. (Reproduced by permission from Inorg. Chim. Acta, 1998, 274, 210.) netic to ferromagnetic with a change of counter ion. The reduction of WCl 4 with Na–Hg in the presence of a thioether gave78 [(WCl 3 ) 2 (l-L) 3 ] (L\1,4-dithiane, 1,4- thioxane, pms) and Na[(WCl 3 ) 2 (l-L) 2 (l-Cl)].Both series of products are face-sharing bioctahedra. The thioether ligands bridge though a single sulfur atom only; the second sulfur atom or oxygen atom is not co-ordinated. All of the thioether ligands adopt a chair conformation with no disorder in their orientation. The neutral compounds gives C–S bond cleavage by reaction with [PPh 4 ][Stol] to give [PPh 4 ][(WCl 3 ) 2 (l-L) 2 (l- SCH 2 CH 2 ECH 2 CH 2 Stol)] (E\S, O, CH 2 ). 7 Cluster complexes The compounds [Mo 2 (OR) 6 ] (R\Pr*, CH 2 Bu5), KH or KHB(Bu4) 3 and 18-crown-6 reacted79 in thf to give [K(18-crown-6)][Mo 4 (l-H)(OR) 12 ]·2thf. These have an Mo 4 butterfly (Mo–Mo 2.50Å average) with the hydride ligand bridging the wingtips. Each edge of the butterfly is bridged by anORgroup and the two faces are capped by l3 -OR groups.Backbone MO atoms have one terminal OR and the wingtips bear two terminal OR ligands. Hydrogenation of the mixture from the reaction of [1,2- Mo 2 (tol) 2 (NMe 2 ) 4 ] and Bu5OH in hydrocarbons gave [Mo 4 (l-H) 3 (OBu5) 7 (HNMe 2 )]. This has a butterfly structure asymmetrically supported by alkoxide and hydride ligands.The hydride ligands appear to occur on one face of the butterfly (one face-capping and two edge bridging positions). The Mo–Mo distances for the outer edges of this face are shorter (2.38Å) than those for the alkoxide supported face (2.50Å). The NMR spectra reveal the hydride ligands; the clusters are static on the NMR timescale. The compound [NBu 4 ] 2 [Mo 6 Br 8 (CF 3 SO 3 ) 6 ] was obtained80 from the reaction of [NBu 4 ] 2 [Mo 6 Br 8 Br 6 ] with Ag[CF 3 SO 3 ] inCH 2 Cl 2 .The six terminal ligands are readily displaced by other anions to give [Mo 6 Br 8 X 6 ]2~ (X\CF 3 CO 2 , SCN, NCO, Cl, Br, I, Ph 3 PO). The reaction of NOBF 4 and [Mo 6 S 8 (PEt 3 ) 6 ] in CH 2 Cl 2 gave81 green [Mo 6 S 8 (NO)(PEt 3 ) 5 ] after 15 min. Stirring the same mixture for 2 days gave brown [Mo 12 S 16 (PEt 3 ) 10 ].For the green complex, the octahedral disposition of the six molybdenum atoms is distorted in that the metal atom bearing the NO ligand is further away from the others. Molecular orbital calculations indicate that such distortion enhances p-donation to the nitrosyl ligand. The open-triangular, nido cluster [Ru 3 (l3 -Se) 2 (CO) 7 (PPh 3 ) 2 ] reacted82 with [M(CO) 3 (NCMe) 3 ] (M\Mo, W) at ambient temperature in CH 2 Cl 2 to give [M 2 Ru 2 (l4 -Se) 2 (l-CO) 4 (CO) 6 (PPh 3 ) 2 ].The symmetrical square metal base has cap- Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 135ping selenium atoms on both sides, a carbonyl ligand bridges each side of the square and the phosphine ligands remain attached to the ruthenium atoms.This is an electron deficient closo structure. The magnetic susceptibility of [CrIII 2 MgO(O 2 CMe) 6 (py) 3 ] showed83 an exchange parameter J(M–M) considerably smaller (17 cm~1) than for the Cr 2 Co and Cr 2 Ni (27, 26 cm~1) analogues but larger than that for the Cr 3 analogue (11cm~1). 8 Hydride and dihydrogen complexes Di¶culties that may arise during single crystal X-ray di§raction analysis have given misleading structures as mentioned in this Section previously.These di¶culties are emphasised84 again in a study of the eight-co-ordinate hydride complexes [WH 2 X 2 (PMe 3 ) 4 ] (X\F, Cl, Br, I) and [WH 2 F(FHF)(PMe 3 ) 4 ]. All of these complexes have a trigonal dodecahedral form with a distorted tetrahedral array of phosphine ligands.Benzyl alcohol reacted85 with [WH 2 (PMe 3 ) 5 ] over 12 days at ambient temperatures to give [WH 3 (OCH 2 Ph)(PMe 3 ) 4 ]. Thermolysis of this compound at 80 °C gave [WH 2 (CO)(PMe 3 ) 4 ] and benzene. The conversion is slower in the presence of hydrogen. H/D exchange occurred with the hydride ligands and at the benzylic and ortho positions of the benzyloxide ligands.Thermolysis in the presence of free benzyl alcohol gave toluene, bibenzyl, [WH 4 (PMe 3 ) 4 ] and PMe 3 . Photolysis of [Cr(CO) 6 ] with dmpm·2BH 3 in toluene under vacuum gave86 the orange-yellow, air-sensitive [MCr(CO) 4N2 (g4-B 2 H 4 ·dmpm)]. Crystal structural analysis showed the five-membered B 2 P 2 C ring system bridging the two Cr(CO) 4 moieties through pairs of hydrogen bridges Cr–H–B so that each chromium atom has a distorted octahedral environment.The formation of the B–B bond is of particular interest. The one-electron oxidation of [MH 3 (dppe)Cp*] (M\Mo, W) by [FeCp 2 ][PF 6 ] gave87 paramagnetic [MH 3 (dppe)Cp*][PF 6 ]. Cyclic voltammetric studies show reversible oxidation of the neutral complexes ([0.75, [0.88 V vs. Fc–Fc` respectively).The molybdenum salt exhibits a triplet of quartets in the EPR spectrum consistent with coupling to three equivalent hydrides and two equivalent phosphorus ligands. Oxidation of [MD 3 (dppe)Cp*] shows a broad EPR triplet. IR spectra show the expected isotopic shift on deuteriation and a 10–20cm~1 blue shift upon oxidation. Simple theory indicates a correlation of bond energy with vibrational frequency, suggesting stronger M–H bonds in the oxidized material.However, the cation (M\Mo) decomposes rapidly at room temperature in solution by reductive elimination of dihydrogen to give the corresponding monohydrido cation. X-Ray di§raction of the salt (M\W) allowed the positions of the three hydride ligands to be located (W–H\1.67–1.71Å). The H–H distances are all large enough to discount bonding. 9 Carbon- and silicon-donor ligands The IR spectra of [Cr(CO) 4 (bipy)] and its 13CO isotopomers were used88 to calculate all stretching and interaction force constants and the normal coordinates of the CO stretching frequencies. Resonance Raman and Fourier transform Raman spectra were compared in assigning ring deformation vibrations.The resonance Raman spectra Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 136confirmed a localised Cr]bipy metal-to-ligand charge transfer character of the electronic transition responsible for the visible absorption band. MLCT excitation a§ects theCObond vibrations, being greater for the axial ligand. Reduction of samples of this complex with natural level and with 16 and 79% levels of 13CO enrichment to the radical anion [Cr(CO) 4 (bipy)]~ were studied89 by EPR and IR spectroscopies.There is considerable coupling of the unpaired electron with 13C which occurs in the axial ligands, i.e. cis to bipy. This indicates interaction between the singly occupied p* orbital of bipy and the r or r* orbitals of the axial C–Cr–C system. Changes in the stretching force constants on reduction show significant strengthening of the p-back donation to the equatorial CO ligands.Photolysis of [W(CO) 6 ] with benzene gave90 [W(CO) 3 (C 6 H 6 )] which is isomorphous with the chromium and molybdenum analogues. All of these complexes exhibit bond length alternation in the benzene ring which is staggered with respect to the carbonyl ligands.The reaction of the complexes [W(CR)Cl(CO)(PMe 3 ) 3 ] or [W(CR)Cl(CO)(py)(PMe 3 ) 2 ] with HCl gave91 [W(CHR)Cl 2 (CO)(PMe 3 ) 2 ] (R\Me, Et, Ph, tol). Protonation of [W(CR)X(CO)(CNR@)(PMe 3 ) 2 ] with CF 3 SO 3 H or HBF 4 gave [W(CHR)X(CO)(CNR@)(PMe 3 ) 2 ]Y (some combinations of R\Me, Ph; R@Bu5, 2,6-Me 2 C 6 H 3 , cyclohexyl; X\Cl, I; Y\CF 3 SO 3 , BF 4 ). The alkylidene ligands are easily deprotonated to alkylidynes by bases such as NEt 3 .Neutron di§raction and X-ray data indicate g2-co-ordination of the alkylidene ligand to tungsten with similar W–CR andW–H distances (1.857, 1.922Å respectively). Alkyne insertion into aMo–P bond occurs92 when [MoH(SC 6 H 2 R 3 -2,4,6) 3 (PMePh 2 )] (R\Me, Pr*) reacts with HCCR@ (R@\Ph, tol) in thf–MeOH giving diamagnetic [MoO(SC 6 H 2 R 3 -2,4,6) 2 (g2- CHCR@)(CR@CHPMePh 2 )], the oxo ligand probably being from adventitious water. The reaction of [MoH(SC 6 H 2 Pr* 3 -2,4,6) 3 (PMe 2 Ph)] with HCCPh under similar conditions gave [MoO(SC 6 H 2 Pr* 3 -2,4,6) 3 (–– CPhCH––CPhCH 2 PMe 2 Ph)] where successive insertion into Mo–P and Mo–C bonds has occurred.The alkynes PhCCPh and PhCCMe did not react with the latter hydride complex.The sequential reaction of [W(CO) 6 ] with Li[C 6 H 4 X-4] (X\Br, I) in Et 2 O and C 2 O 2 Cl 2 or C 2 O 2 Br 2 and 4-methylpyridine in CH 2 Cl 2 gave93 [WZ(CO) 2 (CC 6 H 4 X- 4)(pic) 2 ] (Z\I, X\Cl, Br; Z\Br, X\Cl). The chloro ligand in the iodobenzylidyne complex is readily replaced by iodine by treatment with NaI. Substitution of the methylpyridine ligands by tmen or dppe gave complexes which underwent palladium( II) catalysed cross-coupling reactions, e.g.with Me 3 SiCCH, followed by hydrolysis, to give the acetylide [WCl(CO) 2MCC 6 H 4 (CCH)-4N(tmen)]. The analogous 4- aminobenzylidene complexes [WZ(CO) 2 (CC 6 H 4 NH 2 -4)(pic) 2 ] (Z\Cl, Br) were similarly obtained94 from Li[C 6 H 4 N(SiMe 3 ) 2 ]. The methylpyridine ligands are easily replaced by tmen or dppe.The amino group undergoes typical functional group transformations. The reaction of [WI 2 (CO)(NCMe)(g2-MeC 2 Ph) 2 ] with dppm gave95 [WI 2 (CO)(NCMe)(dppm)(g2-MeC 2 Ph)]. This has a distorted octahedral structure with the phosphorus donors of dppm trans to an iodo and the alkyne ligand and the other iodo and carbonyl groups in the axial sites.TheW–I andW–P distance pairs are quite di§erent, reflecting trans e§ects on the bonding. Variable temperature 31PNMR spectra were used to estimate the activation energy for alkyne rotation at 48.1 kJ mol~1. A number of enantiomers of chromium arene tricarbonyl complexes have been separated96 by high pressure liquid chromatography on a Diacel column eluted with hexane–propan-2-ol mixtures.The elution order of these complexes can be Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 137Fig. 4 Structures of complexes 4 and 5. (Reproduced by permission from Chem. Lett., 1998, 149.) predicted by their CD spectra. Alkylation of [MCl 3 (NBu5)Cp@] (M\Mo, Cp@\Cp*; M\W, Cp@\Cp, Cp*) with stoichiometric amounts of LiMe or MeMgCl gave97 [MMe 2 Cl(NBu5)Cp@] and [MMe 3 (NBu5)Cp@].The 18-electron WMe 3 –Cp* complex reacts very slowly with 2,6-dimethylphenyl isocyanide giving the insertion product [WMe 2MC(Me)––N(2,6- Me 2 C 6 H 3 )N(NBu5)Cp*]. The reaction of cbdt with [MMoI 2 (NO)CpN2 ] in the presence of NEt 3 gave98 [NHEt 3 ][MoI(NO)(cbdt)Cp]. Use of MoCl 5 in thf gave diamagnetic [MMoO(cbdt)N2 (l-O) 2 ] with the carborane ligands on the same side of the Mo–Mo axis.Little conjugation between the sulfur atoms and the carbon atoms of the carborane cage occurs, the C–S bond length (1.785Å) being but slightly shorter than that for a single bond. Quadruply-bonded [Mo 2 (l-O 2 CMe) 4 ] reacted99 with KCp* in the presence of PMe 3 to give [MMoCp*(l-O 2 CMeN2 (l-PMe 2 )(l-Me)] the Mo–Mo distance of which is between those of single and double bonds.NMR spectroscopy supported this structure which results from cleavage of a P–Me bond. The bridging methyl group is pyramidal and symmetrically bonded to the two metal atoms. Treatment of [CrCl 3 (thf) 3 ] with Li(C 6 Cl 5 ) gave100 paramagnetic [Li(thf) 4 ][Cr(C 6 Cl 5 ) 4 ] in which the chromium(III) sits in a distorted octahedral environment provided by the four aryl groups and two cis-oriented Cr–Cl interactions of dissimilar length. The reaction of cis-[WMe(CO) 2 (NCMe)Cp*] with [ReH(CO) 2 (SiHMe 2 )Cp*] in toluene at ambient temperature gave101 [MCp*(CO) 2 WN(l-SiMe 2 )(l-H)MRe(CO) 2 Cp*N] 4 (Fig. 4), photolysis of which gave an isomeric mixture of 5 which reverts to 4 on standing. 10 Nitrogen-donor ligands The reaction of [CrN(salen)]·MeNO 2 in refluxing dme or MeOH–water with NaCN or [NMe 4 ]Cl gave102 products containing the [CrN(CN) 5 ]~ anion.The trans-cyano group is labile. Recrystallisation from water and addition of [PPh 4 ]Cl gave five-coordinate [PPh 4 ] 2 [CrN(CN) 4 ]. The salts of both anions are paramagnetic. The five-coordinate anion readily adds pyridine trans to the nitrido ligand.The complexes [MoCl 2 (NHNPhR)(NNPhR)(acac)] (R\Me, Ph) reacted103 in MeCN with NaTp (or in toluene with KTp@) to give [MoCl(NNPhR) 2 L] (L\Tp or Tp@)]. X-Ray structural data show a distorted octahedral complex with Mo–N–N nearly linear (169.4°) and shortMo–NandN–Nbonds (1.771, 1.308Årespectively) in the hydrazido ligands, indicating extensive p-electron delocalisation.The complex trans-[NBu 4 ]- [W(NCS)(N 2 )(dppe) 2 ] reacted104 with primary and secondary boranes in benzene to give boryldiazenido complexes. trans-[W(NCS)(N––NBHCMe 2 CHMe 2 )(dppe) 2 ] has Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 138Fig. 5 The structure of complex 6. (Reproduced by permission from Chem. Lett., 1998, 897.) an almost linear W–N–N moiety (176.1°) and the N–N–B angle is 133.6°.The N–N bond distance corresponds to a bond order of two (1.262Å) and theN–B bond is short (1.37Å) compared to the single bond of aminoboranes. Secondary boranes reacted more slowly and the N–N bond vibration is significantly di§erent from that of the primary borane product, consistent with electron-donating alkyl groups on boron reducing the double bond character of the N–N bond.The complex [W(N 2 ) 2 (dppe) 2 ] reacted similarly with 9-borabicyclo-[3.3.1]-nonyl trifluoromethanesulfonate to give trans-[W(O 3 SCF 3 )(N––NBC 8 H 14 )(dppe) 2 ] with an even higher N–N vibration. Crystal structural analysis of this complex showed an essentially linearW–N–N–B system. The complex cis-[W(N 2 ) 2 (PMe 2 Ph) 4 ] reacted105 with Ga 2 Cl 4 or GaX 3 (X\Cl, Br) to give 6 (Fig. 5). X-Ray structural studies of the chloro complex showed that the W 2 N 4 Ga 2 system is planar and the W–N–N linkage is almost linear (176°). Chromium( II) acetate reacted106 with HBF 4 in nitrile solutions to give blue, air-sensitive, paramagnetic [Cr(NCR) 4 ][BF 4 ] 2 (R\Me, Bu5, Ph). In the acetonitrile complex, X-ray data showed a square planar disposition around chromium.The magnetic susceptibility (k%&& \4.9 kB at 300 K) is characteristic of a d4 high-spin complex. The reaction of [Cr 2 (OAc) 4 (H 2 O) 2 ] with KTp in dme gave107 a red product, possibly [Cr 2 (OAc) 2 (H 2 O) 2 Tp 2 ] with a quadruple Cr–Cr bond, which reacted with Me 3 SiCl in CH 2 Cl 2 to give [CrCl 3 Tp][CrTp 2 ]. [Cr 2 (OAc) 4 (H 2 O) 2 ] reacted with Me 3 SiCl in thf followed by KTp to give [CrCl 2 (thf)Tp] which reacted with PMe 3 in CH 2 Cl 2 giving [PHMe 3 ][CrCl 3 Tp]. Ligand exchange of [Mo(NO) 2 (acac)] with salicaldehyde-2-mercaptoanil (H 2 L) gave108 [Mo(NO)LL@] having tripodal L and with L@, the cyclic oxidation product of L containing a C 2 NCS five-membered ring, co-ordinated through the nitrogen and oxygen atoms.The slightly distorted octahedral complex [pyH] 2 [MoCl 5 (py)] is unusual in that the pyridine ligand is oriented109 so that it is very nearly in the same plane as two of the cis-chloro ligands, being rotated just 5.1° from such a plane. The dehydration of CrCl 3 ·6H 2 O in dmf, followed by addition of ampy gave110 violet cis-[CrCl 2 (ampy) 2 ]Cl, the a form being obtained from treatment with hot aqueous oxalic acid and the b form by recrystallisation from HCl–HClO 4 .The a form has chloro ligands trans to the amino nitrogen of both of the ampy ligands whereas in the b form one of the ampy ligands has reversed co-ordination. The complexes trans-[M(N 2 )(NCR)(dppe) 2 ] (M\Mo, W; R\Ph, tol, C 6 H 4 OMe-p, Me) underwent111 double protonation at the nitrile carbon atom with loss of N 2 and change of oxidation state to ]4 on treatment with HCl, giving trans-[MCl(NCH 2 R)(dppe) 2 ]`.The crystal structure of trans-[WCl(NCH 2 R)(dppe) 2 ]- [PF 6 ]·CH 2 Cl 2 showed a shortW–Nbond (1.734Å), consistent with a triple bond, and Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 139almost linear W–N–C angle (172.8°). The complex trans-[M(N 2 ) 2 (dppe) 2 ] (M\Mo, W) reacted with benzoylacetonitrile, which has acidic CH hydrogen atoms, to give nitrogen, PhCOCH–– CH 2 and trans-[M(N 2 )(NCCHCOPh)(dppe) 2 ].This zwitterionic structure, where the anionic enolate ligand PhC(O~)––CHCN co-ordinates through nitrogen, was confirmed by spectral and X-ray analysis. An intermolecular C–H· · ·O is present. The complexes [Mo(CO) 3 L] (L\1,3,5-R 3 -1,3,5-triazacyclohexane, R\Me, Bu5) were obtained112 in refluxing mesitylene from the triazacyclohexane and [Mo(CO) 6 ], as for the chromium complexes.Tungsten gave only deep red-black solutions of unknown composition. Corresponding tungsten complexes resulted from the reaction of [W(CO) 6 ] with the triazacyclohexane on irradiation in benzene or thf.The molybdenum complex with R\CH 2 Ph was similarly obtained. These complexes are bright yellow. The trimethyl complexes are air-sensitive in the solid state, the benzyl complex slowly decomposes in air but the tributyl complexes are indefinitely stable in air. The crystal analyses of the tributyl complexes show less deviation from linearity in the M–C–O moieties compared to the chromium complex where the smaller metal atom involves greater steric crowding.The reaction of [M(CN) 4 O(H 2 O)] (M\Mo) with salicylaldehyde and methylamine gave113 [Mo(CN) 3 O(mesal)]. If a diamine is used in this reaction, only singly condensed Schi§ bases result, such as [M(CN) 3 O(ensal)] (M\Mo, W) and [Mo(CN) 3 O(tnsal)]. X-Ray analysis showed the free amino group unco-ordinated in these complexes.The electronic spectra show strong solvatochromic e§ects on the MLCT bands. Oxygen atom transfer to [WI(CO)(MCR)Tp@] (R\Me, Et, Ph) by pyridine N-oxide at 40 °C in MeCN–CH 2 Cl 2 gave114 [WI(CO)(NCOMe)Tp@]. These complexes are very stable and fail to react with phosphines in refluxing toluene. The iodo ligand of the acetylimido complex is replaced by reaction with NaSPh in refluxing thf to give [W(SPh)(CO)(NCOMe)Tp@].The reaction of sodium molybdate with 2-H 2 NC 6 H 4 CH 2 CMe 2 NH 2 in dme in the presence of NEt 3 and Me 3 SiCl gave115 [MoCl 2 (dme)(NCMe 2 CH 2 C 6 H 4 N)]. Cryoscopy and NMR spectra were consistent with a monomeric six-co-ordinated molybdenum compound having a chelating unsymmetric bis(imido) ligand.This chelate ring must be highly strained though the compound is very stable thermally. It is very soluble in common organic solvents other than aliphatic hydrocarbons. 11 Phosphorus-donor ligands The photolytic reaction of benzyldiphenylphosphine with [Cr(CO) 3 (C 6 H 6 )] occurs116 easily to form [Cr(CO) 2 (PPh 2 Bn)(C 6 H 6 )] which is highly stable to nucleophilic attack. The compounds trans-[Mo(C 2 H 4 ) 2MP(OR) 3N4 ] (R\Me, Et) were obtained117 by the direct reduction of [MoCl 4 (thf) 2 ] with Na–Hg under ethylene in the presence of the appropriate phosphite.Reaction of the products with CO gave trans,trans- [Mo(C 2 H 4 ) 2 (CO) 2MP(OR) 3N2 ]. The methyl derivative gave a similar trans,trans complex with CNPr*. Reaction with CO 2 gave [MoH(O 2 CCH––CH 2 )MP(OR) 3N4 ] with a four-membered carboxylate–molybdenum chelate ring.The methyl derivative gave [Mo(C 2 S 4 )(C 2 H 4 )MP(OMe) 3N3 ] (Fig. 6). The complexes fac-[W(CO) 3 (j2P,P@-L)(j1PL @)] (L\dppf, L@\dppm, dppe; L\dppm, L@\dppf, dppe; L\dppe, L@\dppf, dppm) were obtained118 by the reaction of fac-[W(CO) 3 (j2P,P@-L)(NCMe)] with the Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 140Fig. 6 The structure of [Mo(C 2 S 4 )(C 2 H 4 )MP(OMe) 3N3 ]. (Reproduced by permission from Inorg. Chim. Acta, 1998, 272, 125.) appropriate diphosphine in dichloromethane. The slow rearrangement to the mer form was monitored by NMR spectroscopy in CD 2 Cl 2 . It appears to involve a five-coordinate square-pyramidal intermediate in contrast to the fast acid-assisted rearrangement which has been ascribed to a mechanism involving a seven-co-ordinate hydrido intermediate.Organophosphorus boranes R 3 PBH 3 [R 3 \Ph 3 , Ph2 Me, PhMe(OMe), Ph(OMe)(o-anisyl) or R 3 P\3,4-dimethyl-2,5-diphenyl-1,3,2-oxazaphospholidine] gave119 ligand exchange in thf under argon, replacing the amine group in [W(CO) 5 (amine)] (amine\py, pip, bzc, pyz, pm, pipz) to give [W(CO) 5 (PR 3 )].In these reactions the configuration about the phosphorus atom for chiral phosphorus –boron compounds is retained. Reduction of CrCl 3 ·3thf, MoCl 5 and WCl 6 with magnesium or of [WBr 4 (NCMe) 2 ] with zinc dust in the presence of tmbp gave120 [M(tmbp) 3 ] (M\Cr, Mo, W). The tungsten complex has a nearly trigonal prismatic structure (h\15°). The short W–P bond (2.35, 2.36Å) and a shortened C–C bridge (1.442Å) suggest significant metal-to-ligand electron transfer.The complex [WPL] [L\N(CH 2 CH 2 NSiMe 2 ) 3 ] reacted121 with [(GaCl 3 ) 2 ] to give yellow-brown [W(PGaCl 3 )L] with a linear N!9–W–P–Ga system. Decomposition of this product in CH 2 Cl 2 gave red [(WL@) 2 (l-P 2 )(GaCl 2 ) 2 ] [L@\N(CH 2 CH 2 NH 2 )(CH 2 CH 2 N) 2 ]. The GaCl 2 moieties bridge the two ligands L@ though nitrogen.The diphosphorus moiety bridges the two tungsten atoms in side-on mode, giving a tetrahedral disposition of the W 2 P 2 group. The reaction of [MRe(CO) 2 Cp*N2 (l-P 2 )] with [W(CO) 5 (thf)] gave122 two major products. The first of these, [MRe(CO) 2 Cp*N2MW(CO) 4N(P 2 )], contains a tetrahedral WReP 2 unit with the second rhenium atom g1-co-ordinated to one of the phosphorus atoms.The second, centrosymmetric [MRe(CO) 2 Cp*N2MP 2 [W(CO) 4 ]N], has a symmetrical rhombicWPWPunit with the rhenium atoms attached at phosphorus. TheW–W distance (3.0523Å) indicates a single bond. The molecule has a planar Re–(WPWP)–Re system. The splitting of the P–P bond in the starting material is worthy of remark. NMR spectra show signals characteristic of planar co-ordinated phosphorus.The abstraction of the hydrido bridge from [MMo(CO) 2 CpN2 (l-H)(l- PH 2 )] with LiBu5 in thf, followed by the addition of ECl 3 (E\P, As, Sb) gave123 orange air-stable [MMo(CO) 2 CpN2 (l-E)(l-P)] with a tetrahedrane Mo 2 PE core. The diphosphorus and diarsenic analogues are known and are not isomorphic. X-Ray structural analysis of the PE (E\As, Sb) products showed unit cells similar to the diarsenic analogue.In both, there is disorder with respect to the PAs and PSb positions. The Mo–Mo bond lengths indicate single bonds, as observed for the diphosphorus and diarsenic analogues. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 14112 Antimony- and arsenic-donor ligands The reaction of [M(CO) 5 (thf)] (M\Cr, Mo, W) with dpsm gave124 [M(CO) 5 (dpsm)].Reaction with further [M(CO) 5 (thf)] gave [MM(CO) 5N2 (dpsm)] for the chromium and tungsten complexes only. Similar dmsm complexes were obtained by reaction of the hexacarbonyls with the distibine for all three elements. The dinuclear complexes cis-[MMo(CO) 4N2 (l-L) 2 ] (M\Cr, Mo, W; L\dpsm, dmsm) were obtained in poor yield by displacement of nbd from [M(CO) 4 (nbd)] (M\Cr, Mo) or of the diamine from [W(CO) 4 (Me 2 NCH 2 CH 2 CH 2 NMe 2 )].The reaction of molybdenum hexacarbonyl with dpsm in ethanol with NaBH 4 as catalyst gave fac-[Mo(CO) 3 (dpsm) 3 ]. The analogous chromium complex was obtained in poor yield from [Cr(CO) 4 (nbd)] and the tungsten complex from [W(CO) 3 (NCMe) 3 ].Both of these decompose slowly in solution. It would appear that co-ordination of one stibine group inhibits the coordination of the other and no evidence for chelation was found. The complex [WClL] [L\NMCH 2 CH 2 N(CH 2 CMe 3 ) 3N] reacted125 with [LiSb(SiMe 3 ) 2 (dme)n] giving centrosymmetric and paramagnetic [LWSbWL] where the antimony atom symmetrically bridges the staggered WL units with short distances (W–Sb 2.5738Å) indicative of double bonds.The ethylene complex [WCl(C 2 H 4 )L] is a side-product of this reaction. The reaction of [MoR 2 ] (R\methylnaphthalene) with K 3 As 7 in the presence of 2,2,2-cryptand in en gave126 dark emerald green [K(2,2,2-crypt] 2 [MoAs 8 ]·en. X-Ray di§raction analysis showed a regular puckered ring of arsenic atoms around the central molybdenum atom with Mo–As and As–As distances of 2.56 and 2.429Å average.The As–As–As angle is 90.6° average. Compared with the known anion [NbAs 8 ]~, the arsenical ring adjusts to the smaller molybdenum atom by shortening the As–As bonds and increasing the amount of puckering of the ring (i.e. smaller As–As–As angle). The base-catalysed reaction of AsHPh 2 with [Mo(CO) 5MPPh 2 (CCMe)N] using KOBu5 in dme gave127 [Mo(CO) 4 (j2As,P-Ph 2 As- CMeCHPPh 2 )] with the octahedral geometry around Mo distorted by the formation of the five-membered MoAsCCP chelate ring.The structure is disordered across a mirror plane through the ethylenic double bond, the metal atom and the axial carbonyl groups. The Mo–P distance is slightly shorter than the Mo–As distance. 13 Oxygen-donor ligands The heterometallic aqua ion [(H 2 O) 4 Cr(l-OH) 2 Ir(H 2 O) 4 ]4` was formed128 from the separate hexa-aqua ions with careful pH and temperature control.The magnetic properties are consistent with the two separate component metals present and UV/VIS spectra indicate oxidation state ]3 for both. The reaction of [CrCln(thf)n] (n\2, 3) with stoichiometric amounts of Li[NRR@] gave129 [MCr(NRR@)N2 (l-NRR@) 2 ]· 3thf and [Cr(NRR@) 3 ] (R\R@\C 6 H 11 ; R\3,5-Me 2 C 6 H 3 , R@\adamantyl; RR@\2,2,6,6,-Me 4 C 6 H 6 N). All of these complexes reacted with dioxygen to give the dioxo complexes [Cr(NRR@) 2 O 2 ].The possible intermediate [MCr(NRR@) 2N2 (l-O) 2 ]· PhMe was isolated. The complex [CrMN(3,5-Me 2 C 6 H 3 )(Ad)N2 O 2 ] reacted with P(C 6 H 11 ) 3 to form diamagnetic [MCr[N(3,5-Me 2 C 6 H 3 )(Ad)] 2 ON2 (l-O)].Two equivalents of PMe 3 reacted130 with [MoCl 3MN(mes)N(dme)] followed by Na–Hg reduction in the presence of further PMe 3 to give [MoCl 2MN(mes)N(PMe 3 ) 3 ]. This product Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 142reacted with KX (X\Br, NCS) giving [MoX 2MN(mes)N(PMe 3 ) 3 ] whereas Pr*OCS 2 gave [MoMN(mes)N(S 2 COPr*) 2 (PMe 3 )].Phosphites and other p-acceptors led to substitution of the unique PMe 3 ligand trans to a chloro ligand while depe substituted two of the equatorial PMe 3 ligands. Dynamic behaviour in solution was observed in the NMR spectra due to restricted rotation of the aryl group about the C–N bond. The reaction of photochemically generated [W(CO) 5 (thf)] and [NEt 4 ][OH] in methanol gave131 [NEt 4 ][W(CO) 5 (OMe)].This rapidly loses CO to form [MW(CO) 4 (OMe)N2 ] quantitatively. The tetraethylammonium salt has bridging OMe groups in the anti-configuration. This dinuclear complex reacts with excess methoxide in a thf slurry to give the face-sharing octahedral [NEt 4 ][W 2 (CO) 6 (OMe) 3 ] with three bridging methoxide groups.Refluxing the slurry without additional methoxide gave the cubane [NEt 4 ] 4 [MW(CO) 3 (OMe)N4 ]. The salts [NEt 4 ][W(CO) 5 (OR)] (R\Ph, 3,5-F 2 C 6 H 3 ) lose CO more rapidly than the methoxide complex, consistent with the better p-donating property of the methoxide ligand. Anodic dissolution of molybdenum in ROH (R\Me, Et) in the presence of LiCl gave132 [LiMo 2 O 2 (OMe) 7 (MeOH)] and [LiMo 2 O 4 (OEt) 5 (EtOH)].Treatment of the latter with an excess of isopropanol gave [LiMo 2 O 4 (OPr*) 5 (Pr*OH)]. 2-Methoxyethanol gave partial replacement to form [LiMo 2 O 4 (OPr*) 4 (OC 2 H 4 OMe) 2 ]. Excess of methoxyethanol reacted with the ethanol product to give an equimolar mixture of [MoO 2 (OC 2 H 4 OMe) 2 ] and [LiMoO 2 (OC 2 H 4 OMe) 3 ].In Pr*OH, [Mo 6 O 10 (OPr*) 12 ] was formed. Anodic oxidation of tungsten gave [W(OMe) 6 ] and [WO(OMe) 4 ] in methanol, and, in ethanol, [WO(OEt) 4 ] and an amorphous glass. Excess methoxyethanol converted the latter to [MLiWO 2 (OC 2 H 4 OMe) 3N2 ·2Li(HOC 2 H 4 OMe) 2 ][W 6 O 19 ]. The crystal structures of cis-[CrCl(en)(dmso)][ZnCl 4 ], cis-[CrCl(en)(dmso)][NO 3 ][ClO 4 ], cis- [CrCl(tn)(dmso)][ZnCl 4 ] and sym-fac-cis-[CrCl(dien)(dmso)][ZnCl 4 ] show133 the sulfoxide ligand co-ordinated through oxygen with a shortened Cr–O bond (1.981Å) compared to sulfoxide complexes of other transition metals.There is concomitant widening of the Cr–O–S angle and lengthening of the S–O bond. The dmso ligand in the first of these complexes has trans,cis torsional conformation while the other three complexes are trans,trans. Acid-catalysed hydrolysis of [Mo(NR) 2 (S 2 CNEt 2 ) 2 ] (R\2,6-Pr* 2 C 6 H 3 ) gave134 [MMo(NR)(S 2 CNEt 2 ) 2N2 (l-MoO 4 ) 2 ], having a centrosymmetric eight-membered ring in a chair form of alternating molybdenum and oxygen atoms. The molybdenum atoms have alternate tetrahedral and distorted pentagonal bipyramidal dispositions.Oxo abstraction from [MoO 2 (ssp)] with PEtPh 2 in thf followed by oxidative addition of a quinone gave135 the intensely coloured [MoO(cat)(ssp)] (cat\3,5-di-tert-butylcatecholate, naphthalene-1,2-diolate, phenanthrene-9,10-diolate). The oxo abstraction step gives a mixture of MoO(ssp) and Mo 2 O 3 (ssp) 2 species. Ion exchange with K 3 [Cr(ox) 3 ] on a Dowex 50WX2 resin gave136 [NBu 4 ] 4 [Cr 2 (ox) 5 ]·2CHCl 3 .The structure, with a planar bridging bis(bidentate) oxalate ligand, was found to be the racemic and not the meso form. The distance between the two chromium atoms is 5.32Å. The Cr–O distances for the chelating terminal ligands are shorter, and the Cr–O bridging distances longer than the Cr–O distance in the starting compound.At 298K the magnetic moment is 5.32 kB corresponding to the theoretical 5.48 kB for uncoupled chromium centres, the strong decrease of susceptibility with temperature indicating antiferromagnetic interaction between the centres. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 143The complexes [Cr(acac)(X 2 bpdo) 2 ]2` (X\Me, MeO, EtO), obtained from the reaction of [Cr(acac) 3 ] with X 2 bpdo, crystallise137 in the lel 2 [*(kk),"(dd)] form as the perchlorates; they isomerise to a lelob[*(kd),"(dk)] form in water, with rapid changes in the absorption spectra, and then racemize slowly.The rates of isomerization are reduced by an increase in the electron-donating ability of X. The complexes [MO(g- C 5 H 4 R) 2 ] (M\Mo, R\Me; M\W, R\H) reacted138 with B(C 6 F 5 ) 3 at the oxo group to give [MMOB(C 6 F 5 ) 3N(g-C 5 H 4 R) 2 ] with an M–O–B linkage.Density functional theory calculations modeling the changes of the bis(cyclopentadienyl)metal fragment indicate that the geometry is charge- rather than orbital-controlled. The molybdenum product reacted with PhNCO to give [MoMOC(O)NPhNMB(C 6 F 5 ) 3N(g- C 5 H 4 Me) 2 ]. Spectroscopic evidence indicates that the Lewis acid is bound to the oxygen atom of the MoONC ring rather than the carbonyl oxygen.The complexes [MoOL 2 Tp@] (L 2 \OCH 2 CH 2 O, S 2 CNMe 2 ) and [MoO 2 (g2-ONR 2 ) 2 ] (R\Et, Bn) reacted139 similarly with B(C 6 F 5 ) 3 to form [MoMOBMC 6 F 5 ) 3NL 2 Tp@] and cis- [MoOMOB(C 6 F 5 ) 3N(g2-ONR 2 ) 2 ]. The peroxo complex [MoO(O 2 )Mg2- PhN(O)C(O)PhN2 ] gave initially [MoO(O 2 )MB(C 6 F 5 ) 3NMg2-PhN(O)C(O)PhN2 ] which decomposed to [MoOMOB(C 6 F 5 ) 3NMg2-PhN(O)C(O)PhN2 ].Reactions of [WOCl 4 ] with NaOSiPh 3 and Na 2 O 2 SiPh 2 in ice-cold thf gave140 [WOCl(OSiPh 3 ) 3 ] and [MWO 2 [(OSiPh 2 ) 2 O]N2 ] respectively. Under similar conditions[WO 2 Cl 2 (OSC 4 H 8 ) 2 ] and NaOSiPh 3 gave [WO 2 (OSiPh 3 ) 2 (OSC 4 H 8 ) 2 ].The cyclic (Ph 2 SiO) 3 and [WOCl 3 ] gave [WOMO(Ph 2 SiO) 3N2 (thf)] with two eight-membered rings of alternating oxygen and silicon/tungsten atoms. In this complex the thf ligand is trans to the oxo ligand. In refluxing toluene, SiH 3 R (R\Ph, tol, o-tolyl) reacted141 with [MoH 4 (dppe) 2 ] to give [MoH 3M(Ph 2 PCH 2 CH 2 PPhC 6 H 4 -2) 2 SiRN]. This has a pentadentate ligand with the four phosphorus donor atoms in the equatorial plane of the molecule, two hydrido ligands below this plane and the silicon donor and the third hydride above the plane.Solutions of these complexes in thf reacted rapidly with air giving [MoHM(Ph 2 PCH 2 CH 2 PPhC 6 H 4 -2)SiRN(g2-O 2 )] where the two hydrido ligands below the phosphorus atoms plane are replaced by the side-on bound dioxygen ligand, the structure being confirmed by X-ray crystallographic analysis.An excess of SiH 3 Ph in the above reaction led to SiH 2 Ph replacing one of the hydrido ligands below the phosphorus atoms plane. X-Ray analysis of this product also confirmed the formation of the pentadentate ligand. The similar p-tolyl derivative, if formed, is highly unstable and the o-tolyl product showed no further reaction.These are considerable di§erences for relatively small changes in the structure of the silane. In octahedral trans- [MoO(OH)(dppe) 2 ][ClO 4 ], hydrogen bonding from the hydroxo ligand to the perchlorate anion prevents142 the disorder between oxo and hydroxo ligands often seen in complexes of this type. The Mo–O(oxo) bond length is normal for this type of bond.The complex [MoVIO(O 2 )(tmp)] was obtained143 from the reaction of [MoVIO(tmp)] with dioxygen. IR and NMR spectroscopy showed that it has dioxygen co-ordinated to the molybdenum atom in side-on mode on the same side of the tmp ring system as the oxo group. Heating the solid, or irradiating a toluene solution, released the oxygen and both solid and solution readily reabsorbed oxygen from the air.Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 14414 Sulfur-donor ligands and sulfides The reaction of [Mo 2 (l-S 2 ) 2 (S 2 CNR 2 ) 4 ][BF 4 ] 2 (R\Me, Et) with two equivalents of Li(tcnq) in MeOH gave144 [Mo 2 (l-S 2 ) 2 (S 2 CNR 2 ) 4 ][tcnq] 2 . Further reaction with tcnq gave [Mo 2 (l-S 2 ) 2 (S 2 CNR 2 ) 4 ][tcnq] 3 . The centrosymmetric dinuclear cation of the latter product has a Mo–Mo distance (2.817Å) indicative of a single bond.The complexes [W(S 2 CNR 2 ) 4 ]I (R\Me, Et) reacted145 with tcnq in dmf–water at ambient temperature giving [W(S 2 CNR 2 ) 4 ][tcnq]. These compounds reacted further with tcnq in MeCNto give [W(S 2 CNR 2 ) 4 ][tcnq] 2 in which the tcnq moieties are in a mixed valence state.The structures of the monocations of the mono-tcnq compound and its molybdenum analogue are similar but the arrangement of the tcnq anion di§ers; the tungsten compound has alternating stacks along the c-axis whereas the molybdenum analogue has the common slipped formation. The second order rate constants for oxygen atom transfer between cis-[MoO 2 (RR@dtc) 2 ] (R,R@\alkyl groups or an aromatic or non-aromatic ring system) and PPh 3 in 1,2-dichloroethane correlate146 logarithmically with the redox potentials for the complex and its mono-anion.Deviations are found for those complexes with an aromatic ring on the sulfur donor cis to two oxo ligands. The reactions of [WO(CN) 4 ]4~ with a series of dimethylamino- or thione-protected asymmetric dithiolenes gave147 [WOL 2 ]2~ (L\SCHCRS,R\Ph, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, quinoxalin-4-yl).The typical, R\Ph, compound [PPh 4 ] 2 [WOL 2 ]·EtOH has a square pyramidal structure with the oxo ligand in the apical position. The phenyl groups have cis geometry although NMR spectra indicate both cis and trans isomers in the solid. The reaction of stoichiometric amounts of Li[SOCNR 2 ] (R\Pr*) with [Mo 2 (O 2 CMe) 4 ] in ethanol gave148 the monothiocarbamate [Mo 2 (SOCNR 2 ) 4 ].The crystal structure showed retention of the Mo–Mo quadruple bond with four bridging ligands; the oxygen and sulfur donor atoms alternate around each molybdenum atom. Further reaction with oxygen gave [Mo 2 O 3 (SOCNR 2 ) 4 ] having a Mo–O–Mo angle of 164.7°. There are two chelating monothiocarbamate ligands and an oxo ligand to complete the distorted octahedral disposition around each molybdenum atom. These reactions and structures are analogous to those of the corresponding carbamate complexes.Sodium molybdate reacted149 with [p-XC 6 H 4 CMe(SH)CO 2 H] (X\H, Me, Cl) in MeOH giving the octahedral [MoVIO 2MO 2 CCMe(S)C 6 H 4 XN2 ]2~, separated as the tetrabutylammonium salt.Reaction of this ion with the free thioatrolactic acid gave [MoVOMO 2 CCMe(S)C 6 H 4 XN]~, the rates of reaction being in the order Me[H[Cl. The same order is shown for the peak potential of the two-electron reduction step in the cyclic voltammograms. The potential tripodal ligands [MeC(X)(CH 2 SR@)(CH 2 SR@@)] (X\CH 2 PPh 2 , CH 2 SR; R, R@, R@@\Et, Pr*, Bu5, Ph, Bn) reacted150 with [Mo(CO) 3 (NCMe) 3 ] to give complexes such as [Mo(CO) 3MMeC(CH 2 PPh 2 )N(CH 2 SPh)(CH 2 SBn)].One of the CH 2 SR donor groups is readily displaced by CO at 1 atm, the CH 2 SPh group being the most labile. The chirality induced at sulfur, and the sterically strained and twisted neopentyl fragment, are evident in the solid state while epimerisation occurs in solution.The clusters [CoMoRuS(CO) 8Mg-C 5 H 4 C(O)RN] (R\H, Me, Ph, C 6 H 4 COMe) were obtained151 from the reaction of Na[Mo(CO) 3 (g-C 5 H 4 COR)] with [Co 2 RuS(CO) 9 ] in refluxing thf. X-Ray structural analysis of the second (R\Me) and fourth of these products showed the distorted tetrahedral arrangement of the CoMoRuS core. The unit cell of Annu. Rep. Prog. Chem., Sect.A, 1999, 95, 129–152 145the R\Me product contains two isomeric forms which were resolved in solution on ATP-coated cellulose. The enthalpies of protonation of [M(CO) 3 L] (L\cyclic and non-cyclic tridentate donors with N, P or S donor atoms) have been measured152 by titration calorimetry in CH 2 Cl 2 at 25 °C. The basicities increase in the order of ligand donor groups SOPPh@NR (R\Me, Et).Although thioethers are much less basic than the phosphines, the less than expected e§ect on the basicity of the complexes suggests that repulsion by the lone pair electrons on sulfur may increase the energy of the metal d electrons, making the metal centres more basic. There is a good correlation between the heats of protonation and the CO stretching frequencies, and between the CO stretching frequencies for the molybdenum and tungsten groups of complexes.Noncyclic ligands make the complexes more basic than the cyclic analogues and tungsten complexes are more basic than the molybdenum analogues. The complexes [Mo(CR)(CO) 2 Tp] or [Mo(CR)(CO)(PPh 3 )Tp] (R\p-tolyl) reacted153 with CS 2 to give [MoOMg2-jC,S,r-jS@-SCCRC(O)SNTp]. The X-Ray structural data indicate the distorted octahedral disposition around the molybdenum atom and the planar metallacycle with the thiocarbonyl group having p-co-ordination to the molybdenum atom.The C–S distance in this p-co-ordinated group suggests a multiple bond between the carbon and sulfur atoms. The disposition of the metallacycle suggests electronic delocalisation within this ring but the tolyl is su¶ciently twisted with respect to the metallacycle to indicate this delocalisation does not interact with the aryl group.Chromium metal reacted154 with thiophosphate fluxes to form the centrosymmetric [Cr 2 (PS 4 ) 2 (l-PS 4 ) 2 ]. The bridging groups have one sulfur atom bonded to both chromium atoms as well as one sulfur bonded to each chromium atom. The other, chelating, PS 4 groups ensure distorted octahedral disposition around each chromium.The compound is antiferromagnetic with a Cr–Cr distance of 3.523Å. 15 Selenium- and tellurium-donor ligands Hexamolybdenum octatelluride, which is isostructural with the analogous selenide, was obtained155 in crystalline form suitable for X-ray structural analysis by chemical vapour-transport reactions using antimony or arsenic as the transport agent at 1273 °C.The structure has a distorted octahedron of molybdenum atoms, the distortion being an elongation in the c direction. The tellurium atoms cap each triangular face of the octahedron, six of them making bridges to adjacent molecules. The reaction of [Mo(CO) 6 ], K 2 Se 4 and EtOH followed by further reaction with [NEt 4 ]Cl in a sealed tube at 100 °C gave156 [NEt 4 ] 2 [(Mo 2 O 2 Se 6 ) 0.2 (Mo 2 O 2 Se 7 ) 0.18 (Mo 2 O 2 Se 8 ) 0.62 ].X-Ray structural analysis showed that the anions present have a common core of MMoON2 (l-Se) 2 with symmetrical selenium bridges and an Mo–Mo distance indicative of a metal–metal bond. One molybdenum atom carries an Se 2 side-on bound ligand with some disorder in its position.The other molybdenum atom carries one of an Se 2 (side-on), or symmetrical, chelating Se 3 or Se 4 . The three di§erent anions are disordered in their distribution through the crystal. There are a number of short inter-ligand distances present, both intermolecular and intramolecular. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 14616 Halogen-donor ligands The complex [TiMN[C(CD 3 ) 2 Me](3,5-Me 2 C 6 H 3 )N3 ] abstracts157 chlorine from [WCl 4 (dme)] in thf giving yellow mer-[WCl 3 (thf) 3 ].The magnetic moment, 3.28 kB , is close to the spin-only value for three unpaired electrons ([3.4 kB ). The longer W–O bond is trans to the shorter W–Cl bond. Oxidation of zwitterionic [W(CO) 5MNPhNPhC(OMe)PhN] with Br 2 or PCl 5 gave158 [MWX(CO) 2 (NPh)N2 (l- X) 2 ] (X\Br, Cl).These react with MeCN to give [WX 2 (CO) 2 (NPh)(NCMe)] which are also formed when the oxidation is carried out in the presence of MeCN. The acetonitrile ligand is readily substituted by amines or phosphines. Oxidation of [W(CO) 5MNPhNPhC(OMe)PhN] with BrI gave [MWBrI(CO) 2 (NPh)N2 ] with traces of the tetrabromo and tetraiodo dimers.This main product reacted with MeCN to form [WBrI(CO) 2 (NPh)(NCMe)] with no dibromo or diiodo complex; the bridging halides must be identical though whether they are iodo or bromo could not be determined. TheW–C and C–O bond lengths of [MWX(CO) 2 (NPh)N2 (l-X) 2 ] (X\Cl, Br, I) are not significantly di§erent so that there is no evidence for variations in back bonding as the halide is changed.Air oxidation of solutions of [Mo 3 X 12 ]3~ (X\Br, I) gave159 [N(PPh 3 ) 2 ][MoOBr 4 ] and [PPh 4 ][MoOI 4 (H 2 O)] respectively. The anion of the former has square pyramidal form with an apical oxo group. The Mo–O distance is 1.636Å. The latter anion is octahedral with the oxo and aqua groups trans to each other, there being disorder in the orientation of these two groups. The molybdenum atom is displaced towards the oxo group from the plane of the four iodine ligands.The reaction of fac-[W(CO) 3 (NCMe) 3 ] with ICl gave160 [WClI(CO) 3 (NCMe) 2 ]. This reacted with an equimolar amount of C 2 Ph 2 in CH 2 Cl 2 eventually to give [MWCl(CO)(NCMe)(g2-C 2 Ph 2 )N2 (l-I) 2 ]. However, reaction at room temperature in CH 2 Cl 2 with two equivalents of C 2 R 2 (R\Me, Ph) gave [WClI(CO)(NCMe)(g2- C 2 Me 2 ) 2 ].The latter reacted with bipy to give [WCl(CO)(bipy)(g2-C 2 Me 2 ) 2 ]I, demonstrating the preferential displacement of iodide over chloride in such tungsten mixed halogeno complexes. Solvolysis of XeF 2 ·CrF 4 in anhydrous HF gave161 XeF 2 ·2CrF 4 . Recrystallisation from supercritical SF 6 gave ruby red crystals. This compound has a 2-D net of CrF 6 octahedra with di§erent XeF 2 units sharing a fluorine atom to link the nets into a 3-D structure.The compound [XeF 5 ][CrF 5 ] was obtained from the reaction of XeF 6 and CrF 4 at room temperature, or from the reaction of XeF 6 and CrF 5 at 333 K, as red crystals from anhydrous HF. The compound has an infinite chain of CrF 6 octahedra joined by sharing cis-oriented corners. 17 Other compounds The rapid precipitation metathesis reaction of CrCl 2 and K 3 GaTe 3 in water gave162 Cr 3 [GaTe 3 ] 2 .This shows antiferromagnetic coupling between localised magnetic moments and highly temperature dependent semiconductivity. The reaction of [M(CO) 3 (GeCl 3 )Cp] (M\Mo, W) with Li[M(CO) 3 Cp] in refluxing thf gave163 [MMo(CO) 3 CpN2 (l-GeCl 2 )].The reaction of [Mo(CO) 3 (GeCl 3 )Cp*] with K[Mo(CO) 3 Cp*] gave the Cp* analogue. The precursor [Mo(CO) 3 (GeCl 3 )Cp*] was obtained from [MoH(CO) 3 Cp*] by the reaction with [GeCl 2 (diox)] to form Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 147[Mo(CO) 3 (GeHCl 2 )Cp*] which was chlorinated with CCl 4 . CO/PMe 3 ligand exchange occurs readily with these dinuclear complexes, the phosphine entering a position trans to the germyl bridge.Reaction with LiAlH 4 converts the bridge to a GeH 2 group. The nido-2,3-[Et 2 C 2 B 4 H 4 ]2~ anion reacted164 with [M(CO) 3 (NCR) 3 ] (M\Mo, W; R\Me, Et) giving [M(CO) 3 (Et 2 C 2 B 4 H 4 )]2~, isolated as [Li(12-crown-4)]` salts. Treatment of these with [PPh 4 ]X (X\Cl, Br, I) followed by CF 3 SO 3 H gave red or orange [MM(CO) 2 (Et 2 C 2 B 4 H 4 )N2 (l-X) 2 ].X-Ray crystallography of the molybdenum dibromo complex showed the two pentagonal pyramidal MoC 2 B 3 moieties connected by cis-bromo bridges and a metal–metal bond. Spectroscopic evidence indicates the other products have analogous structures. The one boron atom of the carborane not bonded to molybdenum can be removed by the action of HCl–EtOAc in thf, giving [MM(CO) 2 (Et 2 C 2 B 3 H 5 )N2 (l-Br) 2 ], probably having open planar C 2 B 3 rings bonded to the molybdenum atoms.The half-sandwich [NMe 4 ] 2 [Mo(CO) 3 (C 2 B 9 H 11 )]·thf has165 a closo framework with molybdenum bonded to the planar B 3 C 2 ring. Two of the carbonyl ligands are trans to the carbon atoms of the ring. The addition of sulfur donors such as aldrithiol [(C 5 H 4 NS) 2 ] or [(Et 2 NS) 2 S 2 ] led to partial oxidative decarbonylation and the product [Mo(CO) 3 (C 2 B 9 H 11 )(C 5 H 4 NS)], with an S,N chelating donor, or [Mo(CO) 3 (C 2 B 9 H 11 )(S 2 CNEt 2 )]~ with an S,S chelating donor.In neutral [Mo(C 3 H 5 )(CO) 2MC 2 H 10 B 9 (SMe 2 )N], the carborane has a 4-dimethylsulfido group.The crystal structural determination showed166 carbonyl ligands approximately trans to the carbon atoms of the C 2 B 3 ring facing onto the molybdenum atom. The symmetrically-bound allyl group takes an exo configuration as found in the cyclopentadienyl analogue. The dimethylsulfido group is twisted further due to steric crowding compared to the free carborane C 2 H 10 B 9 (SMe 2 ).The chromaborane [(CrCp*) 2 (B 4 H 8 )] reacted167 with BHCl 2 ·SMe 2 to give greenbrown, diamagnetic [(CrCp*) 2 (B 5 H 9 )]. X-Ray crystallographic analysis showed a trigonal bipyramidal Cr 2 B 3 unit with the adjacent Cr 2 B faces capped by BH 3 fragments. Reaction with [Fe 2 (CO) 9 ] or [Co 2 (CO) 8 ] gave products of similar structure, [(CrCp*) 2 (B 4 H 8 )MFe(CO) 3N] or [(CrCp*) 2 (B 4 H 7 )MCo(CO) 3N], with metal carbonyl groups in place of one of the BH 3 units.At about 80 °C, the iron complex becomes fluxional, the Fe(CO) 3 group ‘swinging’ from one BH 2 to the other. The molybdaborane [(MoCp*) 2 (B 5 H 9 )] reacted with [Fe 2 (CO) 9 ] to give orange [(MoCp*) 2 (B 5 H 9 )MFe(CO) 3N] which an X-ray determination showed to have an octahedral arrangement of FeMo 2 B 3 and BH 3 groups bridging the FeMo 2 and BMo 2 faces.The reaction of Na 2 [M(CO) 5 ] (M\Cr, W) with Br 2 BN(SiMe 3 ) 2 gave168 the terminal borylene complexes [M(CO) 5MBN(SiMe 3 ) 2N]. NMR and IR spectroscopy and X-ray structural analysis of the tungsten complex showed an octahedral disposition around the tungsten atom. The W–B–N system is linear (177.9°). Both W–B (2.151Å) and B–N (1.338Å) bond lengths are consistent with double bonds.The trans-CO ligand has geometry little di§erent from the equatorial carbonyl ligands indicating that there is no trans e§ect from the borylene ligand. References 1 C.L. Hill (Editor), Chem. Rev., 1998, 98, pp. 1–388. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 1482 P.K. Baker, Chem. Soc. Rev., 1998, 27, 125. 3 I.Dance, Chem. Commun., 1998, 523. 4 R. Neumann, Prog. Inorg. Chem., 1998, 47, 317. 5 W.D. Wul§, Organometallics, 1998, 17, 3116. 6 C. Pariya, K. N. Jayaprakash and A. Sarkar, Coord. Chem. Rev., 1998, 168, 1. 7 I. S. Zowarine and C. P. Kubiak, Coord. Chem. Rev., 1998, 171, 419. 8 T.E. Baroni, S. Bembenek, J. A. Heppert, R. R. Hodel, B. B. Laird, M.D. Morton, D.L. Barnes and F. Takusagawa, Coord. Chem. Rev., 1998, 174, 255. 9 R. Poli and L.-S. Wang, Coord. Chem. Rev., 1998, 178–180, 169. 10 H. Arzoumanian, Coord. Chem. Rev., 1998, 178–180, 191. 11 F. Y. Pe� tillon, P. Schollhammer, J. Talarmin and K. W. Muir, Coord. Chem. Rev., 1998, 178–180, 203. 12 F. Rose-Munch, V. Gagliardini, C. Renard and E. Rose, Coord. Chem. Rev., 1998, 178–180, 249. 13 M.-M. Rohmer, M. Be� nard, J.-P. Blaudeau, J.-M. Maestre and J.-M. Poblet, Coord. Chem. Rev., 1998, 178–180, 1019. 14 C. Tanielian, Coord. Chem. Rev., 1998, 178–180, 1165. 15 C. Bre� mard, Coord. Chem. Rev., 1998, 178–180, 1647. 16 A. J. Lees, Coord. Chem. Rev., 1998, 177, 3. 17 E. J. Barends and A. Rosa, Coord. Chem. Rev., 1998, 177, 97. 18 A. Vogler and H. Kunkely, Coord. Chem.Rev., 1998, 177, 83. 19 M.W. George and J. J. Turne, Coord. Chem. Rev., 1998, 177, 201. 20 A. Vlc¡ek, Jr., Coord. Chem. Rev., 1998, 177, 219. 21 M. Ziegler and A. von Zelewsky, Coord. Chem. Rev., 1998, 177, 257. 22 J. C. Green, Chem. Soc. Rev., 1998, 27, 263. 23 F. A. Cotton, Inorg. Chem., 1998, 37, 5710. 24 C. J. Jones, Chem. Soc. Rev., 1998, 27, 289. 25 C. Bianchini and A.Meli, Acc. Chem. Res., 1998, 31, 109. 26 K. Severin, R. Bergs and W. Beck, Angew. Chem., Int. Ed., 1998, 37, 1634. 27 H. Braunschweig, Angew. Chem., Int. Ed., 1998, 37, 1787. 28 G. J. Irvine, M. J. G. Lesley, T. B. Marder, N. C. Norman, C. R. Rice, E. G. Robins, W.R. Roper, G. R. Whittell and L. J. Wright, Chem. Rev., 1998, 98, 2685. 29 J. R. Schoonover and G. F. Strouse, Chem. Rev., 1998, 98, 1335. 30 D. Braga, F. Grepioni and G. R. Desiraju, Chem. Rev., 1998, 98, 1375. 31 P. Chen and T. J. Meyer, Chem. Rev., 1998, 98, 1439. 32 S. Sabo-Etienne and B. Chaudret, Chem. Rev., 1998, 98, 2077. 33 A. L. Balch and M. M. Olstead, Chem. Rev., 1998, 98, 2123. 34 A. Vogler and H. Kunkely, Coord. Chem. Rev., 1998, 171, 399. 35 A. D. Garnovskii, A. P. Sadimenko, M. I. Sadimenko and D.A. Garnovskii, Coord. Chem. Rev., 1998, 173, 31. 36 K. J. Takeuchi, Coord. Chem. Rev., 1998, 174, 5. 37 J. P. Danks, N. R. Champness and M. Schro� der, Coord. Chem. Rev., 1998, 174, 417. 38 T. Ren, Coord. Chem. Rev., 1998, 175, 43. 39 D. Reinen, M. Atanasov and S.-L. Lee, Coord. Chem. Rev., 1998, 175, 91. 40 M.I. Bruce, Chem. Rev., 1998, 98, 2797. 41 M.D. Navalikhina and O.V. Krylov, Russ. Chem. Rev., 1998, 67, 587. 42 F. Tuczek and N. Lehnert, Angew. Chem., Int. Ed., 1998, 37, 2636. 43 L. Ouahab, Coord. Chem. Rev., 1998, 178–180, 1501. 44 M.I. Khan, S. Cevik, R. J. Doedens, Q. Chen, S. Li and C. J. O’Connor, Inorg. Chim. Acta, 1998, 277, 69. 45 P. A. Lorenzo Luis, P. Martin-Zarza, A. Sanchez, C. Ruiz-Pe� rez, M. Herna� ndez-Molina, X. Solans and P.Gili, Inorg. Chim. Acta, 1998, 277, 139. 46 S. H. Wasfi, A. L. Rheingold and B. S. Haggerty, Inorg. Chim. Acta, 1998, 282, 136. 47 S. H. Wasfi, W. L. Johnson III and D. L. Martin, Inorg. Chim. Acta, 1998, 278, 91. 48 S. H. Wasfi and S. A. Tribbitt, Inorg. Chim. Acta, 1998, 268, 329. 49 Y. Cui, L. Xu and J. Huang, Inorg. Chim. Acta, 1998, 277, 130. 50 C. R. Mayer and R. Thouvenot, J.Chem. Soc., Dalton Trans., 1998, 7. 51 S. Uchida, K. Inumaru, J. M. Dereppe and M. Misono, Chem. Lett., 1998, 643. 52 S. Himeno, K. Sano, H. Niiya, Y. Yamazaki, T. Ueda and T. Hori, Inorg. Chim. Acta, 1998, 281, 214. 53 Y. Xu, J.-Q. Xu, G.-Y. Yang, T.-G. Wang, Y. Xing, Y.-H. Lin and H.-Q. Jia, Acta Crystallogr., Sect. C., 1998, 54, 563. 54 C.-C. Jiang, Y.-G. Wei, Q. Liu, S.-W.Zhang, M.-C. Shao and Y.-Q. Tang, Chem. Commun., 1998, 1937. 55 A. Mu� ller, E. Krickemeyer, H. Bo� gge, M. Schmidtmann, C. Beugholt, P. Ko� gerler and C. Lu, Angew. Chem., Int. Ed., 1998, 37, 1220. 56 I. J. McLean, R. Hernandez-Molina, M. N. Sokolov, M.-S. Seo, A. V. Virovets, M. R. J. Elsegood, W. Clegg and A. G. Sykes, J. Chem. Soc., Dalton Trans., 1998, 2557. 57 R. Hernandez-Molina, A.J. Edwards, W. Clegg and A. G. Sykes, Inorg. Chem., 1998, 37, 2989. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 14958 C. S. Bahn, A. Tan and S. Harris, Inorg. Chem., 37, 2770. 59 V. P. Fedin, M.N. Sokolov, A. V. Virovets, N.V. Podberezskaya and V. E. Fedorov, Inorg. Chim. Acta, 1998, 269, 292. 60 R. Hernandez-Molina, D. N. Dybtsev, V. P. Fedin, M.R. J. Elsegood, W. Clegg and A.G. Sykes, Inorg. Chem., 1998, 37, 2995. 61 H. Akshi and T. Shibahara, Inorg. Chim. Acta, 1998, 282, 50. 62 R. Hernandez-Molina, V. P. Fedin, M.N. Sokolov, D. M. Saysell and A. G. Sykes, Inorg. Chem., 1998, 37, 4328. 63 L. Xu, Y. Cui and J. Huang, Chem. Lett., 1998, 35. 64 G. Sakane, K. Hashimoto, M. Takahashi, M. Takeda and T. Shibahara, Inorg. Chem., 1998, 37, 4231. 65 V. P. Fedin, I. V. Kalinina, A. V. Virovets, N. V. Podberezskaya and A. G. Sykes, Chem. Commun., 1998, 237. 66 C.-T. Lee, W.-K. Yang, J.-D. Chen, L.-S. Liu and J.-C. Wang, Inorg. Chim. Acta, 1998, 274, 7. 67 B. Fischer, E. Dubler, M. Meienberger and K. Hegetschweiler, Inorg. Chim. Acta, 1998, 279, 136. 68 H.-L. Chen, C.-T. Lee, C.-T. Chen, J.-D. Chen, L.-S. Liou and J.-C. Wanglton Trans., 1998, 31. 69 F. A. Cotton, L. M. Daniels, G. T. Jordan IV, C. Lin and C. A. Murillo, J. Am. Chem. Soc., 1998, 120, 3398. 70 F. A. Cotton, C. Lin and C. A. Murillo, J. Chem. Soc., Dalton Trans., 1998, 3151. 71 T. Tanase, T. Igoshi, K. Kobayashi and Y. Yamamoto, J. Chem. Res., 1998, (S), 538. 72 F. A. Cotton, E. V. Dikarev and S. Herrero, Inorg. Chem., 1998, 37, 5862. 73 M. H. Chisholm, K. Folting and D.-D. Wu, Acta Crystallogr., Sect. C, 1998, 54, 225. 74 M. H. Chisholm, K. Folting, K. S. Kramer and W. E. Streib, Inorg. Chem., 1998, 37, 1549. 75 V. Kolesnichenko, D. C. Swenson and L. Messerle, Chem. Commun., 1998, 2137. 76 S. Kaizaki, N. Azuma and A. Fuyuhiro, Inorg. Chim. Acta, 1998, 274, 210. 77 T. Rujihara, A. Fuyuhiro and S.Kaizaki, Inorg. Chim. Acta, 1998, 278, 15. 78 P. M. Boorman, N. L. Langdon, V. J. Mozol, M. Parvez and G. P. A. Yap, Inorg. Chem., 1998, 37, 6023. 79 T. A. Budzichowski, M. H. Chisholm, J. C. Hu§man, K. S. Kramer and O. Eisenstein, J. Chem. Soc., Dalton Trans., 1998, 2563. 80 S. M. Malinak, L. K. Madden, H. A. Bullen, J. J. MacLeod and D. C. Gaswick, Inorg. Chim. Acta, 1998, 278, 241. 81 J. Mizutani, S. Amari, H. Imoto and T. Saito, J. Chem. Soc., Dalton Trans., 1998, 819. 82 D. Cauzzi, C. Grai§, C. Massera, G. Mori, G. Predieri and A. Tiripicchio, J. Chem. Soc., Dalton Trans., 1998, 321. 83 A. B. Blake, E. Sinn, A. Yavari, K. S. Murray and B. Moubaraki, J. Chem. Soc., Dalton Trans., 1998, 45. 84 V. J. Murphy, D. Rabinovich, T. Hascall, W.T. Klooster, T. F. Koetzle and G.Parkin, J. Am. Chem. Soc., 1998, 120, 4372. 85 T. J. Crevier and J. M. Mayer, Inorg. Chim. Acta, 1998, 270, 202. 86 M. Hata, Y. Kawano and M. Shimoi, Inorg. Chem., 1998, 37, 4482. 87 B. Pleune, R. Poli and J. C. Fettinger, J. Am. Chem. Soc., 1998, 120, 3257. 88 A. Vlc¡ek, Jr., F.-W. Grevels, T. L. Snoeck and D. J. Stufkens, Inorg. Chim. Acta, 1998, 278, 83. 89 A. Vlc¡ek, Jr., F.Baumann, W. Kaim, F.-W. Grevels and F. Hartl, J. Chem. Soc., Dalton Trans., 1998, 215. 90 J. M. Oh, S. J. Geib and N. J. Cooper, Acta Crystallogr., Sect. C, 1998, 54, 581. 91 C.M. Bastos, K. S. Lee, M.A. Kjelsberg, A. Mayr, D. Van Engen, S. A. Koch, J. D. Franolic, W. T. Klooster and T. F. Koetzle, Inorg. Chim. Acta, 1998, 279, 7. 92 S. A. Fairhurst, D. L. Hughes, K. Marjani and R.L. Richards, J. Chem. Soc., Dalton Trans., 1998, 1899. 93 M. P. Y. Yu, K.-K. Cheung and A. Mayr, J. Chem. Soc., Dalton Trans., 1998, 2373. 94 M. P. Y. Yu, A. Mayr and K.-K. Cheung, J. Chem. Soc., Dalton Trans., 1998, 475. 95 P. K. Baker, M. A. Beckett, M. G. B. Drew, S. S. M.C. Godinho, N. Robertson and A. E. Underhill, Inorg. Chim. Acta, 1998, 279, 65. 96 P. Pertici, F.Borgherini, G. Vitulli, P. Salvadori, C. Rosini, C. Moi� se and J. Besanc�on, Inorg. Chim. Acta, 1998, 268, 323. 97 P. Go� mez Sal, I. Jime� nez, A. Marti� n, T. Pedraz, P. Royo, A. Selle� s and A. Va� zquez de Miguel, Inorg. Chim. Acta, 1998, 273, 270. 98 J. D. McKinney, H. Chen, T. A. Hamor, K. Paxton and C. J. Jones, J. Chem. Soc., Dalton Trans., 1998, 2163. 99 J. H. Shin and G.Parkin, Chem. Commun., 1998, 1273. 100 P. J. Alonso, L. R. Falvello, J. Fornie� s, M.A. Garci� a-Monforte, A. Marti� n, B. Menjo� n and G. Rodri� guez, Chem. Commun., 1998, 1721. 101 H. Sakaba, K. Ishida and H. Horino, Chem. Lett., 1998, 149. 102 J. Bendix, K. Meyer, T. Weyhermu� ller, E. Bill, N. Metzler-Nolte and K. Wieghardt, Inorg. Chem., 1998, 37, 1767. 103 C. Manzur, D.Carrillo, F. Robert, P. Gouzerh, P. Hamon and J.-R. Hamon, Inorg. Chim. Acta, 1998, 268, 199. 104 H. Ishino, Y. Ishii and M. Hidai, Chem. Lett., 1998, 677. 105 K. Takagahara, H. Ishino, Y. Ishii and M. Hidai, Chem. Lett., 1998, 897. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 150106 R. T. Henriques, E. Herdtweck, F. E. Ku� hn, A. D. Lopes, J. Mink and C. C. Rama8 o, J.Chem. Soc., Dalton Trans., 1998, 1293. 107 C.-H. Li, J.-D. Chen, L.-S. Liou and J.-C. Wang, Inorg. Chim. Acta, 1998, 269, 302. 108 W. Banße, J. Fliegner, S. Sawusch, U. Schilde and E. Uhlemann, Inorg. Chim. Acta, 1998, 269, 350. 109 B. Modec, R. Papoular and J. V. Brenc¡ic¡, Acta Crystallogr., Sect. C, 1998, 54, 736. 110 D. J. Ayres, D. A. House and W. T. Robinson, Inorg. Chim. Acta, 1998, 277, 177. 111 H. Seino, Y. Tanabe, Y. Ishii and M. Hidai, Inorg. Chim. Acta, 1998, 280, 163. 112 N. L. Armanasco, M. V. Baker, M. R. North, B. W. Skelton and A. H. White, J. Chem. Soc., Dalton Trans., 1998, 1145. 113 B. Nowicka, A. Samotus, J. Szklarzewicz, F. W. Heinemann and H. Kisch, J. Chem. Soc., Dalton Trans., 1998, 4009. 114 S. Thomas, P. J. Lim, R. W. Gable and C. G. Young, Inorg.Chem., 1998, 37, 590. 115 U. Siemeling, T. Tu� rk, W. W. Schoeller, C. Redshaw and V. C. Gibson, Inorg. Chem., 1998, 37, 4738. 116 J. Geicke, I.-P. Lorenz and K. Polborn, Inorg. Chim. Acta, 1998, 272, 101. 117 C. Collazo, M. del Mar Colejo, A. Pastor and A. Galindo, Inorg. Chim. Acta, 1998, 272, 125. 118 S. C. N. Hsu and W.-Y. Yeh, J. Chem. Soc., Dalton Trans., 1998, 125. 119 N. Brodie and S. Juge� , Inorg. Chem., 1998, 37, 2438. 120 P. Rosa, L. Ricard, P. Le Floch, F. Mathey, G. Sini and O. Eisenstein, Inorg. Chem., 1998, 37, 3154. 121 M. Scheer, J. Mu� ller, G. Baum and M. Ha� ser, Chem. Commun., 1998, 1051. 122 O. J. Scherer, M. Ehses and G. Wolmerha� user, Angew. Chem., Int. Ed., 1998, 37, 507. 123 J. E. Davies, L. C. Kerr, M. J. Mays, P. R. Raithby, P. K.Tompkin and A. D. Woods, Angew. Chem., Int. Ed., 1998, 37, 1428. 124 A.M. Hill, N. J. Holmes, A. R. J. Genge, W. Levason, M. Webster and S. Rutschow, J. Chem. Soc., Dalton Trans., 1998, 825. 125 M. Scheer, J. Mu� ller, G. Baum and M. Ha� ser, Chem. Commun., 1998, 2505. 126 B. W. Eichhorn, S. P. Mattamana, D. R. Gardner and J. C. Fettinger, J. Am. Chem. Soc., 1998, 120, 9708. 127 K. Maitra, V. J. Catalano, J. Clark III and J. H. Nelson, Inorg. Chem., 1998, 37, 1105. 128 V. A. Sa� nchez-Ortiz, L. G. Martinez-Jardines, S. E. Castillo-Blum and A. G. Sykes, J. Chem. Soc., Dalton Trans., 1998, 663. 129 K. B. P. Ruppa, K. Feghali, I. Kovacs, K. Aparna, S. Gambarotta, G. P. A. Yap and C. Bensimon, J. Chem. Soc., Dalton Trans., 1998, 1595. 130 F. Montilla, A. Galindo, E.Carmona, E. Gutie� rrez-Puebla and A. Monge, J. Chem. Soc., Dalton Trans., 1998, 1299. 131 D. J. Darensbourg, K. K. Klausmeyer, J. D. Draper, J. A. Chojnacki and J. H. Reibenspies, Inorg. Chim. Acta, 1998, 270, 405. 132 V. G. Kessler, A. N. Panov, N. Ya, Turova, Z. A. Starikova, A. I. Yanofsky, F. M. Dolgushin, A. P. Pisarevsky and Y. T. Struchov, J. Chem. Soc., Dalton Trans., 1998, 21. 133 D.A House and P. J. Steel, Inorg. Chim. Acta, 1998, 269, 229. 134 T. A. Co§ey, G. D. Forster and G. Hogarth, Inorg. Chim. Acta, 1998, 274, 243. 135 L. Sinclair, J. U. Mondal, D. Uhrhammer and F. A. Schultz, Inorg. Chim. Acta, 1998, 278, 1. 136 V.M. Masters, C. A. Sharrad, P. V. Bernhardt, L. R. Gahan, B. Moubaraki and K. S. Murray, J. Chem. Soc., Dalton Trans., 1998, 413. 137 H. Kanno, M. Yagi, S. Utsuno and J. Fujita, Inorg. Chim. Acta, 1998, 281, 221. 138 J. R. Galsworthy, J. C. Green, M. L. H. Green and M. Mu� ller, J. Chem. Soc., Dalton Trans., 1998, 15. 139 L. H. Doerrer, J. R. Galsworthy, M.L. H. Green and M.A. Leech, J. Chem. Soc., Dalton Trans., 1998, 2483; L. H. Doerrer, J. R. Galsworthy, M. L. H. Green, M. A. Leech and M. Mu� ller, J. Chem. Soc., Dalton Trans., 1998, 3191. 140 B. J. Brisdon, M.F. Mahon and C. C. Rainford, J. Chem. Soc., Dalton Trans., 1998, 3295. 141 D.-Y. Zhou, L. B. Zhang, M. Minato, T. Ito and K. Osakada, Chem. Lett., 1998, 187. 142 J. Bendix and A. Bogevig, Acta Crystallogr., Sect. C, 1998, 54, 206. 143 J. Tachibana, T. Imamura and Y. Sasaki, Bull. Chem. Soc. Jpn., 1998, 71, 363. 144 F. Conan, J. Sala Pala, M.-T. Garland and R. Gabbio, Inorg. Chim. Acta, 1998, 278, 108. 145 S. Le Stang, F. Conan, J. Sala Pala, Y. Le Mest, M.-T. Garland, R. Gabbio, E. Faulques, A. Leblanc, P. Molinie� and L. Toupet, J. Chem. Soc., Dalton Trans., 1998, 489. 146 K. Unoura, A. Yamazaki, A. Nagasawa, Y. Kato, H. Itoh, H. Kudo and Y. Fukuda, Inorg. Chim. Acta, 1998, 269, 260. 147 E. S. Davies, G. M. Aston, R. L. Beddoes, D. CWilson and C. D. Garner, J. Chem. Soc., Dalton Trans., 1998, 3647. 148 A. D. Calcaterra, S. G. Kimble, T. L. Groy and T. M. Brown, Inorg. Chim. Acta, 1998, 267, 101. 149 H. Li, P. Palanca, V. Sanz, M.T. Picher, L. R. Domingo, A. Dome� nech and J.-V. Folgado, Inorg. Chim. Acta, 1998, 268, 145. 150 R. Soltek, G. Huttner, L. Zsolnai and A. Driess, Inorg. Chim. Acta, 1998, 269, 143. 151 E.-R. Ding, Q.-S. Li, Y.-Q. Yin and J. Sun, J. Chem. Res., 1998, (S), 624. 152 O. P. Siclovan and R. J. Angelici, Inorg. Chem., 1998, 37, 432. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–152 151153 A. F. Hill, J. M. Malget, A. J. P. White and D. J. Williams, Inorg. Chem., 1998, 37, 598. 154 V. Derstro§, V. Ksenofontov, P. Gu� tlich and W. Tremel, Chem. Commun., 1998, 187. 155 G. J. Miller and M. Smith, Acta Crystallogr., Sect. C, 1998, 54, 709. 156 G.-C. Guo and T. C. W. Mak, Inorg. Chem., 1998, 37, 6538. 157 E. Kim, A. L. Odom and C. C. Cummins, Inorg. Chim. Acta, 1998, 278, 103. 158 Y. He, P. C. McGowan, K. A. Abboud and L. McElwee-White, J. Chem. Soc., Dalton Trans., 1998, 3373. 159 J. C. Fettinger, S. P. Mattamana and R. Poli, Acta Crystallogr., Sect. C, 1998, 54, 184. 160 P. K. Baker, M. G. B. Drew, M.M. Meehan, H. K. Patel and A. White, J. Chem. Res., 1998, (S), 379. 161 K. Lutar, H. Borrmann and B. Z¡ emva, Inorg. Chem., 1998, 37, 3002. 162 J.-S. Jung, H. H. Kim, S. G. Kang, J.-H. Jun, Y. L. Buisson, L. Ren and C. J. O’Connor, Inorg. Chim. Acta, 1998, 268, 271. 163 A. C. Filippou, J. G. Winter, G. Kociok-Ko� hn and I. Hinz, J. Chem. Soc., Dalton Trans., 1998, 2029. 164 M. A. Curtis, E. J. Houser, M. Sabat and R. N. Grimes, Inorg. Chem., 1998, 37, 102. 165 J.-H. Kim, M. Lamrani, J.-W. Hwang and Y. Do, Inorg. Chim. Acta, 1998, 283, 145. 166 K. Johansen, G. M. Rosair, A. S. Weller and A. J. Welch, Acta Crystallogr., Sect. C, 1998, 54, 214. 167 S. Aldridge, H. Hashimotro, K. Kawamura, M. Shang and T. P. Fehlner, Inorg. Chem., 1998, 37, 928. 168 H. Braunschweig, C. Kollan and U. Englert, Angew. Chem., Int. Ed., 1998, 37, 3179. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 129–1

ISSN:0260-1818    

DOI:10.1039/a804893b

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

12 Manganese, technetium and rhenium A. M. W. Cargill Thompson DERA, Fort Halstead, Sevenoaks, Kent, UK TN14 7BP 1 Manganese The solution structure of theMn2` ion in acetonitrile and five other organic nitriles, as determined by EXAFS spectroscopy, is six-co-ordinate with Mn–N bond lengths of 2.21(1)Å. The activation parameters for solvent exchange have been calculated by analysis of NMR line broadening e§ects.1 The octahedral tris(imidodiphosphinato) complex [MnM(OPPh 2 ) 2 NN3 ] is distorted tetragonally in the solid state, and its structure has been compared with those of other mononuclear MMnIIIO 6N complexes.2 [MnCl(CO) 3MMeSe(CH 2 )nSeMeN] (n\2, 3) and [MnBr(CO) 3MC 6 H 4 (SeMe) 2 -oN] are the first manganese(I) selenoether carbonyl halides to be crystallographically characterized.The 55Mn NMR spectra of these and related complexes have been compared with those of analogous thioether compounds.3 Mechanisms for the formation of the square pyramidal five-co-ordinate 16–electron complex anion [MnI(CO) 3 L1]~, which is stabilized by S,N n-donation, are proposed.4 The cyano ligand trans to the Mn–– – N in octahedral [MnVN(CN) 5 ]3~ is labile and can be lost to form [MnVN(CN) 4 ]2~.5 Octahedral [MnIII(L2) 3 ] adopts a mer configuration in the solid state, with significant Jahn–Teller distortion, and appears to be a promising catalyst for the epoxidation of styrene with H 2 O 2 .6 NH2 SH H2L1 N O OH HL2 The crystal structure of the spin-labelled 2,2@: 6@,2A-terpyridine complex [MnII(L3) 2 ]- [BF 4 ] 2 exhibits unusual O· · ·O contacts between aminoxyl centres on adjacent molecules.7 Reaction of [Mn 2 (CO) 10 ] with 3,6-di-tert-butyl-1,2-benzoquinone (3,6- dbq) in the presence of 2,2@-bithiophene, a§ords a complex with the charge distribution [MnIV(3,6-dbsq) 2 (3,6-dbcat)] at room temperature.An intense transition at 2300nm is ascribed to intervalence transfer between semiquinone and catecholate ligands; the Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 153intensity of this band decreases with increasing temperature suggesting a tautomeric transition to the [MnIII(3,6-dbsq) 3 ] redox isomer.8 The complex cis-[MnCl 2 (L4) 2 ] contains two ligands chelating in a bidentate manner through adjacent pyridine and azine nitrogens.9 Recrystallization of cis-[MnIIICl 2 ([14]aneN 4 )]Cl results in a transition to the trans isomer.Unusually, the cis isomer can be regenerated by a process involving an electrochemical step followed by a chemical step.10 The electronic spectra of trans-[MnVN([14]aneN 4 )L]n` (L\Cl~, MeCN, ClO 4 ~, CF 3 CO 2 ~) and related nitridomanganese(V) complexes display four d–d transitions which have been assigned unambiguously.11 Synthetic, structural and luminescence studies of stoichiometric crown ether compounds such as [NMe 4 ] 2 [Mn(12-crown-4) 2 ][MnBr 4 ] 2 and [Mn(15- crown-5)(H 2 O) 2 ][TlBr 5 ], in which manganese is in a variety of well defined coordination environments, have been conducted with a view to understanding the origin of emitting crystal defects in cubic [K 4 (18-crown-6) 4 MnBr 4 ][TlBr 4 ] 2 .12 [Mn(NO)(L5)] is trigonal bipyramidal with the NO occupying an equatorial site; spectroscopic analysis shows that the electron distribution is formally MnIIINO~.13 The solid state structure of distorted trigonal bipyramidal [MnL(sal)][ClO 4 ] [L\tris(benzimidazol-2-ylmethyl)amine] bears similarities to the active site of manganese superoxide dismutase, and the complex is catalytically active.14 N O N N N O• L3 N N N N L4 N (CH2)5 NH N (CH2)5 HN L5 Decomposition of hydrogen peroxide by [MnIII(salen)Cl] in dmf is suppressed in the presence of divalentMn2`, Co2`,Ni2` and Zn2` ions due to the formation of inactive dinuclear MnIIIMII and trinuclear MnIII 2 MII complexes.15 The manganese centre in [MnIII(L6)(H 2 O)(EtOH)]Cl is octahedrally co-ordinated by the salen donor set, water and ethanol.Transport studies of aqueous tryptophan across a chloroform barrier containing this complex suggests that the manganese(III) and 18-crown-6 sites contribute in a synergistic manner.16 The chiral ligand complex [MnIII(L7)Cl] crystallises in a non-centrosymmetric space group and exhibits an e¶ciency eight times that of urea in second harmonic generation at 1.9 lm.17 [MMn(salpn)N 3Nn] exhibits an azide-bridged chain structure with a distorted octahedral geometry about each manganese.Magnetic measurements suggest an antiferromagnetic intrachain interaction.18 The complexes [MMn[2-OH(X-salpn)]N2 ]n~ (X\5-OMe; H; 5-Cl; 3,5-Cl 2 ; 5-NO 2 ) are excellent catalysts for the disproportionation of hydrogen peroxide in acetonitrile, with the rate depending on the substituent electron density.19 Binuclear l-oxo [MMnIV(l- O)(salen)N2 ] type complexes with salen and related ligands exhibit two classes of structure in which the Schi§ base ligands either each co-ordinate to a single manganese Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 154centre in a tetradentate manner or bridge both centres in a bis(bidentate) configuration. 20 A detailed study has been conducted on the influence of the axial ligand on the solid state structures of a dozen five-co-ordinate manganese(III) tetraphenylporphyrin complexes. 21,22 Manganese K-edge EXAFS spectra were recorded for [Mn(tpp)X] (X\Cl, Br, I) both in the solid state and adsorbed onto the perfluorinated ion exchange polymer Nafion.23 5,10,15,20-Tetrakis(N-methyl-4@-pyridyl)porphyrinatomanganese( III) acts as an e¶cient peroxynitrite (ONOO~) reductase when coupled with antioxidants such as ascorbate and glutathione.24 The manganese(III) complex obtained by electrochemical oxidation of tetrakis(2,6-dichlorophenyl)-b-heptanitroporphyrinatomanganese( II) exhibits the highest redox potential (940mV vs.SCE) reported for a manganese(III) porphyrin.The manganese(II) complex is also an e¶cient catalyst for alkene epoxidation and alkane hydroxylation.25 The peripheral dimethylamino groups make 2,3,7,8,12,13,17,18-octakis(dimethylamino)porphyrazinatomanganese( III) chloride extremely electron rich with the result that the MnIII–MnII couple occurs as low as [1.3V (vs. ferrocenium–ferrocene).26 Coulombic interactions result in the assembly of heterodimers and trimers between b-tetracationic and meso-tetraanionic manganese(III) porphyrins in water at pH 12.27 Mo� ssbauer spectroscopy indicates that the charge distribution in the mixed valence low spin d8 system [(tpp)Mn(l-N)Fe(pc)] is unbalanced and approaches MnIV––N–FeIII.28 N N OH HO H2L7 Et2N NEt2 N N OH HO H2L6 O O O O O O tBu tBu tBu tBu The solid state structure of linear polymeric [MnIII(tpp)][C 3 (CN) 5 ] displays a novel asymmetric bridging mode of the pentacyanopropenide anions, and the [Mn(tpp)]` cations are unusually puckered.29 meso-Tetrakis(4-chlorophenyl)porphyrinatomanganese( III) tetracyanoethenide has been prepared and structurally characterized as toluene and dichloromethane disolvates.Both exhibit uniform linear polymeric structures and their magnetic properties have been investigated.30 Density functional theory has been used to predict the structures, relative energies and IR spectra of many possible isomers of [Mn 2 (CO) 8 ], in order to provide theoretical support for the existence of an unprecedented asymmetric unbridged isomer of the form [(CO) 3 Mn–Mn(CO) 5 ].31 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 155[MTl(l-NC)Mn(CO) 2 [P(OEt) 3 ](dppm)N2 ][PF 6 ] 2 contains cyanide ligands in an unusual l3 -jC: jN: jN bridging mode linking two thallium centres and one manganese. 32 Manganese(II) to ruthenium(III) intramolecular electron transfer has been investigated in manganese substituted cytochrome c modified by co-ordination of trans-[Ru(NH 3 ) 4 L] (L\NH 3 , py, isonicotinamide) fragments at histidine-33, and compared with that for analogous ruthenium modified, cobalt-substituted and iron cytochromes c.33 Nitro–nitrito and end-on azido bridges, both of which are known to favour ferromagnetic coupling between centres, have been incorporatedn trinuclear [(N 3 ) 2 MnIIM(l-N 3 )(l-ONO)NiII(en) 2N2 ] which has an S\9 2 ground state.34 The solid state structures of homo- and hetero-trinuclear [MMnIII(L8)(MeOH)(OH)M(bipy)N2 ] (MII\Mn, Cu, Ni, Zn) have incomplete double cubane MMn 2 M 2 O 6N cores; in all cases the manganese(III) centres are high spin S\2.35 HN NH O O OH HO H4L8 Studies of a l-oxo-di-l-carboxylato dimanganese(III) model complex have allowed a detailed experimental description of the catalytically relevant MnIII 2 active site of manganese catalase.36 Asymmetric [(bipy)(H 2 O)Mn(l-O)(l-O 2 CC 2 H 5 ) 2 Mn(Cr 2 O 7 )- (bipy)] is the first crystallographically characterised example of a complex in which dichromate acts as a monodentate ligand.The Mn–O$*#)30.!5% bond length of 2.132(23)Å indicates strong anionic co-ordination.37 1H NMR spectra of a series of dimanganese(III) complexes with [Mn 2 (l-O)(l-OAc) 2 ]2` cores exhibit resolvable acetate resonances between d 58 and 80, with the chemical shifts correlating strongly with the magnetic coupling constants.38 A number of dinuclear MnIII 2 , MnIIIMnIV and MnIV 2 complexes incorporating l-oxo and l-acetato bridges have been prepared as potential models for the oxygen evolving complex of Photosystem II, and various core interconversions investigated.39 Reaction of [(Pri 2 Tp)Mn(l-OH) 2 Mn(Pr 2 Tp)] with 3,5-Pri 2 pzH a§ords asymmetric [(Pri 2 Tp)Mn(l-OH)(l-3,5-Pri 2 pz)Mn(Pri 2 Tp)] in which the manganese centres have distorted square pyramidal and trigonal bipyramidal geometries, respectively.40 Reaction of [Mn(Pri 2 Tp)(SR)] with oxygen resulted in O–O bond activation to give ligand oxygenated complex 1.41 Reaction of [Mn(O 2 CR) 2 ] (R\Ph, 2-ClC 6 H 4 , 3-ClC 6 H 4 , 4-ClC 6 H 4 ) with bipy gave some or all of dinuclear [Mn 2 (l-O 2 CR) 2 (bipy) 4 ]2`, trinuclear [Mn 3 (l-O 2 CR) 6 (bipy) 2 ] and linear polymeric [MMn(l-O 2 CR) 2 (bipy)Nn].The Mn· · ·Mn distances in the dinuclear and chain complexes ([4.5Å) were greater than those for the trinuclear species ([3.6Å).42 The crystal structure of the trimanganese(III) cluster [Mn 3 O(O 2 CCMe 3 ) 6 (py) 3 ][ClO 4 ] exhibits pronounced Jahn–Teller distortion of the manganese centres which define approximate 3-fold screw axes.43 Tripodal H 2 L9 and related ligands in which one or both 2-hydroxybenzyl moieties bear additional substituents have been used to investigate the e§ects of steric control Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 156on the formation of polynuclear manganese carboxylate complexes.44 [Mn 4 O 3 (OAc) 4 (dbm) 3 ], proposed as a model for the photosynthetic water oxidation complex, causes disproportionation of water under non-forcing conditions and results in its incorporation in the Mn 4 core.45 Magnetization studies have shown that [Mn 4 O 3 Cl(OAc) 3 (dbm) 3 ] has a S\9 2 ground state and is a single molecule magnet that exhibits resonant magnetization tunnelling.46,47 The adamantane-like cation of [Mn 4 O 6 (bpea) 4 ][ClO 4 ] 4 approaches S 4 point symmetry which renders the l-oxo ligands inequivalent in both the solid state and in solution.48 Pulsed 55Mn ENDOR experiments demonstrate that the Photosystem II split EPR signal arises from a magnetically coupled manganotyrosyl complex.49 Magnetization studies have provided good evidence that the spin value 52 is responsible for the g\4.1 EPR signal in the S 2 state of theMn 4 water oxidation complex in Photosystem II.50 X-Ray crystallographic analysis of [MnIIIMnII 4 (O 2 CCMe 3 ) 2 (cat) 4 (py) 8 ]` shows it to consist of a central eight-co-ordinate manganese(III) surrounded by a tetrahedral arrangement of octahedral manganese(II) centres.51 The solid state structure of [MnIII 6 O 4 Cl 4 (Me 2 dbm) 6 ] consists of a Mn 6 octahedron with four l3 -O2~ and four l3 -Cl~ bridging the eight faces; the cluster has a S\12 ground state.52 The ferromagnetic cyclic cluster [NaMnIII 6 (OMe) 12 (dbm) 6 ]` consists of an MMn 6 (OMe) 12N crown with idealized S 6 symmetry acting as a host for the alkali metal ion.53 [Mn 7 (OMe) 12 (dbm) 6 ] has a MnII 2 MnIII 4 crown structure with a central valence localized manganese(II) ion.54 In contrast, disc shaped [MnIII 6 (L10) 6 (MeOH) 6 ] has a vacant cavity at its centre; the molecules are aligned in the solid state such that these cavities form 1-D channels approximately along the crystallographic a axis.55 OH N N O O H3L10 N H2L9 OH Me2N HO The cluster [Mn 9 K 2 O 7 (O 2 CCMe 3 ) 15 (HO 2 CCMe 3 ) 2 ] has an icosahedral core with five distinct manganese co-ordination environments.56 The core in [Mn 18 O 14 (OMe) 14 (O 2 CCMe 3 ) 8 (MeOH) 6 ] has the rock salt structure of bulk MnO; it consists of a central face sharing heptacubane MMn 16 (l3 -O) 8 (l4 -O) 2 (l6 -O) 4 (OMe) 2N with the final two manganese centres co-ordinated to the l4 -oxo bridges.57 Manganese( II) substituted polyoxometalates such as [MMn(H 2 O) 3N2MMn(H 2 O) 2N2 - Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 157(TeW 9 O 33 ) 2 ]8~ are oxidatively and solvolytically stable and are e¶cient catalysts for the regioselective epoxidation of dienes.58 Linear polymeric [Mn(l-1,3-N 3 ) 2 (2-HOpy) 2 ]n is antiferromagnetically homogeneous (J\[7 cm~1) while [Mn(l-1,3-N 3 ) 2 (3-Etpy) 2 ]n has alternating centres with J\[13.8 and [11.7cm~1, respectively.59 [MnCl 2 (thf) 1.6 ]n consists of open bis(cubane) MMn 4 (l3 -Cl) 2 (l2 -Cl) 4 Cl 2 (thf) 6N units linked by MMnCl 2 (thf) 2N moieties.60 cis-[MnII(btr) 2 (l-btr)(NCS)(H 2 O)]NCS has a 1-D puckered chain structure and exhibits weak antiferromagnetic coupling between manganese centres.61 The crystal structures of [MnIIIF 4 (H 2 O) 2 ]~ with three di§erent organic nitrogen cations all consist of 2-D hydrogen-bonded networks, though each has a di§erent topology.62 Polymeric [MnII(bpe)(H 2 O) 4 ] 0.5n(tp) 0.5n(bpe)n consists of cations forming a linear array through bpe bridges, with tp2~ and bpe moieties H-bonding to coordinated waters, thereby extending the array to 3-D.63 The radical scavenging properties of trans-[Mn(l-L) 2 (H 2 O) 2 ]n (HL\L-dihydroorotic acid) have been investigated by EPR spectroscopy and cyclic voltammetry, and compared to those of vitamin E and 2,6-di-tert-butyl-4-methylphenol.64 X-Ray structural studies of [MMnII(l-L) 3Nn]2n` [L\N,N@-butylenebis(imidazole)] with a range of counter ions have revealed the formation of a family of interpenetrating network structures with anion dependent cavity sizes.65 Metamagnetic [K(18-crown-6)(2-PrOH) 2 ]- [(MnL) 2MFe(CN) 6N] [L\N,N@-ethylenebis(acetylacetonylideneiminate)] has a layered structure with 2-D cyano-bridged anionic sheets H-bonded to interleaving cations.66 Isostructural MgMnGe, MgMnSn, CaMnSi, CaMnSn and SrMnSn have been prepared by reaction of the elements and are metamagnetic at low temperatures.67 The layered phosphate Na 2 MnP 2 O 7 was prepared by a high temperature solid state reaction and has a structure composed of slabs of fused MMn 4 P 4 O 26N cages.68 The manganese tellurides LiMnTe 2 and NaMnTe 2 have a 2-D solid state structure with layers comprised of MnTe 4 tetrahedra sharing three corners.69 2 Technetium Crystallographic characterization of [TcCl 2 (NO)(pyPPh 2 -P,N)(pyPPh 2 -P)] shows that the complex has an unusual cis arrangement of bulky phosphine ligands, one of which co-ordinates in a bidentate manner.70 The synthesis of water- and air-stable [99.Tc(H 2 O) 3 (CO) 3 ]` directly from [99.TcO 4 ]~ is reported.Displacement of the N COOH COOH N H2L11 three labile waters by L11 gives a complex with a pendant carboxylate moiety, providing a means for attaching such carbonyl complexes to biosystems.71 Structural and 99Tc NMR investigations of a number of tricarbonyl technetium macrocyclic thioether complexes such as fac-[Tc([9]aneS 3 )(CO) 3 ]Br, have been conducted.72 The complex [99.TcOMEt 2 NCH 2 CH 2 N(CH 2 CH 2 S) 2N(4-CH 3 OC 6 H 4 S)] has been identifi- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 158ed as a potential imaging agent that exhibits high brain uptake and retention in the animals tested; a mechanism is proposed for its retention.73 The complex anion [M99.TcO(Cys) 2NMH99.TcO(Cys) 2N]~ has been prepared by using disulfide cystine as a precursor for cysteine, and its properties as a renal imaging agent were investigated. 74 Spectroelectrochemical and computational studies have been conducted on [NBu 4 ][TcVINX 4 ] and [NBu 4 ][TcVOX 4 ] (X\Cl, Br); the lack of features in the visible spectra of the TcV species contrasts markedly with the charge transfer bands observed for the TcVI chromophore.75 Simple cationic dioxotechnetium(V) phosphine complexes [Tc(O) 2 (PR 3 ) 3 ]` can be prepared by a simple one-pot process and have been proposed as potential heart imaging agents.76 Technetium(VII) dioxide trifluoride [TcO 2 F 3 ] behaves as a Lewis acid towards F~ and MeCN, a§ording the cis- [TcO 2 F 4 ]~ anion in the former case.77 3 Rhenium [Re 2 H 8 (PMe 3 ) 4 (l-g2: g2@-C 60 ] 2, exhibits rare g4 co-ordination of C 60 .78 fac- [ReX(CO) 3 (L12)] (X\Cl, Br, I) exhibit fluxional processes associated with the exchange of co-ordinated and pendant oxazoline rings.79 On changing from one multiply substituted 2,2@: 6@,2A-terpyridine ligand (L) in fluxional [ReBr(CO) 3 L] to another, the main e§ect is to alter the relative populations of the two isomers observed.80 Dinuclear [(CO) 3 BrRe(L13)PtIMe 3 ], in which each end of the ‘back-to-back’ terpyridine ligand co-ordinates in a bidentate manner, exhibits two separately resolvable Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 159fluxional processes at the rhenium(I) and platinum(IV) centres, respectively.81 The photoinduced trans–cis isomerizations of the styryl moiety of [Re(CO) 3 L(N–N)] [L\4-(4-nitrostyryl)pyridine;N–N\bipy, phen] have been studied and their quantum yields determined.82 Routes have been devised for the synthesis of cis- [ReI(CO) 2 (N–N)(P–P)]`, where N–N and P–P are chelating polypyridine and phosphine ligands, respectively. The luminescent rhenium excited states are long lived and have spectral responses that are red-shifted with respect to those of fac- [ReI(CO) 3 L(bipy)]n` (L\neutral or anionic monodentate ligands).83 N N O O N CHMe2 Me2HC L12 N N N N N N L13 The electrophilicity of [Re(CO) 4 (PR 3 )]` is demonstrated by the ability of cis- [ReMe(CO) 4 (PR 3 )] (R\Ph, C 6 H 11 ) to undergo ligand exchange reactions with solvents such as diethyl ether and dichloromethane displacing the methyl moiety.84 Oxidative addition of an oxime uponN–Obond cleavage is observed in the reaction of Me 2 C––NOH with trans-[ReCl(N 2 )(dppe) 2 ] to give trans-[Re(OH)(N––CMe 2 )- (dppe) 2 ]`.85 X-Ray crystallographic analysis of [ReBr 2 (NNPh) 2 (PPh 3 ) 2 ] shows it to contain one doubly bent and one singly bent diazenide ligand, each of which is trans to, and exhibits a significant trans influence on, a bromine.86 Both the fac–cis and mer–trans isomers of [Re(NEt)Cl 3 (PMe 3 ) 2 ] have been prepared and crystallographically characterised.87 Amino dialkylated adenines R 2 AdH (R\Me, Et) react with cis- [ReCl 4 (NCMe) 2 ] to give [ReCl 4MR 2 AdC(Me):NHN] containing a cyclic amidine ligand resulting from the insertion of the acetonitrileCNinto theN9–Hbond of theN3 co-ordinated adenine unit.88 [NBu 4 ][ReVINCl 4 ] is readily prepared by the reaction of [NBu 4 ][ReO 4 ] with NaN 3 and HCl(g) in ethanol, and is a useful precursor for the synthesis of other rhenium nitrido complexes.89 [ReOCl 3 (PPh 3 ) 2 ] and [ReOCl 3 (OPPh 3 )(SMe 2 )] catalyse the oxidation of thiols to disulfides with sulfoxides under mild conditions; the former requires an induction phase during which PPh 3 is oxidized to OPPh 3 .90 Detailed NMR studies in CDCl 3 and CD 3 OD revealed that the amine proton in [ReVO(HL14)] is labile and undergoes intermolecular exchange between the two nitrogen centres.91 [ReVO(L15)] reacts with tertiary phosphines to give [ReVO(L16)(PR 3 )] with loss of SCH 2 CH 2 from ligand L15; replacement of L15 with dimethyl substituted analogue L17 prevents this C–S bond cleavage.92 Reaction of [ReO(OTf)XTp] (X\Cl, Br, I) with one equivalent of pyridine N-oxide a§ords unusual d1 rhenium(VI) cis-dioxo [ReO 2 XTp], which are fairly stable, disproportionating slowly to [ReVIIO 3 Tp] and [ReVOX 2 Tp].93 Potentially tridentate 2,6-bis(diphenylphosphino)pyridine acts as a bidentate N,Pchelate in [Re 2 Cl 4M2,6-(Ph 2 P) 2 pyN2 ] which has a triply bonded dirhenium(II) core.94 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 160HN HS S SH O H3L15 R = H H3L17 R = Me R R HN HS HS O H3L16 HN HS NH SH H4L14 [(Me 2 PhP) 3 Cl 2 ReV–– – N–ReIVCl 4 (PMe 2 Ph)] contains an asymmetric nitrido bridge with Re–N distances of 1.706(6) and 2.055(6)Å.95 The outcome of the reaction of [Re 2 Cl 8 ]2~ anions with PEt 2 H depends strongly on the conditions used, and has allowed novel dirhenium products with oxidation states ranging from]II to]IV to be prepared; for example, [NBu 4 ][Re 2 (l-PEt 2 ) 3 Cl 6 ] is a face sharing dirhenium(IV) complex with three phosphido bridges.96 Isomers of [(CO)BrRe(l-Br) 2 (l- dppm) 2 Re(CNxyl) 2 ]` have been isolated in which the MRe 2 (l-dppm) 2N core exists in either chair or boat configurations.97 Reaction of bis(trimethylsilyl)acetylene with [PPh 4 ][ReS 4 ] a§ords [M(Me 3 Si) 2 C 2 S 2NReS(l-S) 2 ReSMS 2 C 2 (SiMe 3 ) 2N] in which each rhenium(V) centre is square pyramidal.98 1H and 13C NMR spectroscopic studies suggest that [Re 3 (l-SPri) 3 (SPri) 6 ] has virtual C4 symmetry in solution due to the high barrier to inversion of the three-co-ordinate bridging sulfur atoms.99 Cyclic [Re 4 N 4 (S 2 CNEt 2 ) 4 Cl 4 (PMe 2 Ph) 4 ] consists of a non-planar eight-membered MReNN4 ring containing Re–– – N–Re linkages with mean distances 1.69 and 2.03Å.100 Molecular rectangles [M(CO) 3 Re(l-L) 2 Re(CO) 3 (l-4,4@-bipy)N2 ] (L\OMe,101 SR102), obtained by self assembly processes and structurally characterised, contain octahedral fac-Re(CO) 3 corners.Reaction of [Re(CO) 5 ]~ with [Re 2 (l-H) 2 (CO) 8 ] gives oligomeric chain cluster anions [Re(CO) 5MReH(CO) 4N2n]~, whose size depends on the initial stoichiometry. Penta- and hepta-nuclear anions (n\2, 3) have been characterised. 103 Co-ordination of di§erent metals to the macrocyclic centre has di§erent e§ects on the electrochemistry and photophysics of the MReICl(CO) 3 (bipy)N centre in [ReCl(CO) 3 (L18)M]2` (MII\Ni, Cu, Zn).For example, co-ordinated Ni2` and Cu2` quench the rhenium fluorescence completely.104 Ligand L19 has two inequivalent bipy binding sites, A and B. Room temperature time-resolved IR di§erence spectra of [(bipy) 2 RuII–AB–ReI(CO) 3 Cl]2` are consistent with a low lying RuIII–AB·~MLCT state, while the isomeric BA complex exhibits an equilibrium between ReII–AB·~ and RuIII–AB·~ states.105 A photoinduced electron transfer cascade is observed along N N N N N N A B HN NH N NH L18 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 161[(4,4@-Me 2 bipy)ReI(CO) 3 (l-bipy)RuIII(en) 2 (l-NC)FeIII(CN) 5 ]Br on excitation of the rhenium centre.106 Laser desorption/ionization mass spectrometry studies of halide clusters including [NBu 4 ] 2 [Re 2 Cl 8 ] and [Cs 3 Re 3 Cl 12 ] demonstrate the usefulness of these techniques for the characterization of metal clusters.107 The MRe 6 S 8N2` core clusters [Re 6 S 8 (PEt 3 )nBr 6~n](n~4)` (n\2-6) have been synthesised and proposed as useful building blocks for the synthesis of multinuclear assemblies.108 The first example of a sulfido-bridged octahedral hexarhenium(III) aqua cluster ion [Re 6 S 8 (H 2 O) 6 ]2` has been prepared and characterised.109 Disclaimer: any views expressed are those of the author, and do not necessarily represent those of DERA or H.M.Government. References 1 Y.Inada, T. Sugata, K. Ozutsumi and S. Funahashi, Inorg. Chem., 1998, 37, 1886. 2 N. Zuniga-Villareal, M. R. Lezama, S. Hernandez-Ortega and C. Silvestru, Polyhedron, 1998, 17, 2679. 3 J. Connolly, M.K. Davies and G. Reid, J. Chem. Soc., Dalton Trans., 1998, 3833. 4 W.-F. Liaw, C.-M. Lee, G.-H. Lee and S.-M. Peng, Inorg. Chem., 1998, 37, 6396. 5 J. Bendix, K. Meyer, T. Weyhermueller, E.Bill, N. Metzler-Nolte and K. Wieghardt, Inorg. Chem., 1998, 37, 1767. 6 M. Hoogenraad, K. Ramkisoensing, H. Kooijman, A. L. Spek, E. Bouwman, J. G. Haasnoot and J. Reedijk, Inorg. Chim. Acta, 1998, 279, 217. 7 M. A. Halcrow, E. K. Brechin, E. J. L. McInnes, F. E. Mabbs and J. E. Davies, J. Chem. Soc., Dalton Trans., 1998, 2477. 8 A. S. Attia and C. G. Pierpont, Inorg.Chem., 1998, 37, 3051. 9 D.A. Edwards, G.M. Hoskins, M. F. Mahon, K. C. Molloy and G. R. G. Rudolf, Polyhedron, 1998, 17, 2321. 10 F. Letumier, G. Broeker, J.-M. Barbe, R. Guilard, D. Lucas, V. Dahaoui-Gindrey, C. Lecomte, L. Thouin and C. Amatore, J. Chem. Soc., Dalton Trans., 1998, 2233. 11 K. Meyer, J. Bendix, N. Metzler-Nolte, T. Weyhermueller and K. Wieghardt, J. Am. Chem. Soc., 1998, 120, 7260. 12 H. O. N. Reid, I. A. Kahwa, A. J. P. White and D. J. Williams, Inorg. Chem., 1998, 37, 3868. 13 K. J. Franz and S. J. Lippard, J. Am. Chem. Soc., 1998, 120, 9034. 14 D. F. Xiang, C. Y. Duan, X. S. Tan, Q. W. Hang and W. X. Tang, J. Chem. Soc., Dalton Trans., 1998, 1201. 15 M. Uehara, M. Urade, A. Ueda, N. Sakagami and Y. Abe, Bull. Chem. Soc. Jpn., 1998, 71, 1081. 16 D. T. Rosa, V. G. Young and D. Coucouvanis, Inorg. Chem., 1998, 37, 5042. 17 G. Lenoble, P. G. Lacroix, J. C. Daran, S. D. Bella and K. Nakatani, Inorg. Chem., 1998, 37, 2158. 18 H. Li, Z. J. Zhong, C.-Y. Duan, X.-Z. You, T. C. W. Mak and B. Wu, Inorg. Chim. Acta, 1998, 271, 99. 19 A. Gelasco, S. Bensiek and V. L. Pecoraro, Inorg. Chem., 1998, 37, 3301. 20 H. Torayama, T. Nishide, H.Asada, M. Fujiwara and T. Matsushita, Polyhedron, 1998, 17, 105. 21 P. Turner, M. J. Gunter, B. W. Skelton and A. H. White, Aust. J. Chem., 1998, 51, 835. 22 P. Turner, M. J. Gunter, B. W. Skelton and A. H. White, Aust. J. Chem., 1998, 51, 853. 23 A. L. Maclean, G. J. Foran and B. J. Kennedy, Inorg. Chim. Acta, 1998, 268, 231. 24 J. Lee, J. A. Hunt and J. T. Groves, J. Am. Chem.Soc., 1998, 120, 6053. 25 K. Ozette, P. Battioni, P. Leduc, J.-F. Bartoli and D. Mansuy, Inorg. Chim. Acta, 1998, 272, 4. 26 D. P. Goldberg, A. G. Montalban, A. J. P. White, D. J. Williams, A. G. M. Barrett and B.M. Ho§man, Inorg. Chem., 1998, 37, 2873. 27 L. Ruhlmann, A. Nakamura, J. G. Vos and J.-H. Fuhrhop, Inorg. Chem., 1998, 37, 6052. 28 M.P. Donzello, C. Ercolani, K. M. Kadish, Z.Ou and U. Russo, Inorg. Chem., 1998, 37, 3682. 29 M.L. Yates, A. M. Arif, J. L. Manson, B. A. Kalm, B. M. Burkhart and J. S. Miller, Inorg. Chem., 1998, 37, 840. 30 E. J. Brandon, D. K. Rittenberg, A. M. Arif and J. S. Miller, Inorg. Chem., 1998, 37, 3376. 31 T. A. Barckholtz and B. E. Bursten, J. Am. Chem. Soc., 1998, 120, 1926. 32 N. G. Connelly, O. W. Hicks, G. R. Lewis, M.T. Moreno and A. G. Orpen, J. Chem. Soc., Dalton Trans., 1998, 1913. 33 J. Sun and J. F. Wishart, Inorg. Chem., 1998, 37, 1124. 34 T.M. Rajendiran, C. Mathoniere, S. Golhen, L. Ouahab and O. Kahn, Inorg. Chem., 1998, 37, 2651. 35 Y. Sunatsuki, H. Shimada, T. Matsuo, M. Nakamura, F. Kai, N. Matsumoto and N. Re, Inorg. Chem., 1998, Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 16237, 5566. 36 T. C. Brunold, D. R. Gamelin, T. L. Stemmler, S. K. Mandal, W. H. Armstrong, J. E. Penner-Hahn and E. I. Solomon, J. Am. Chem. Soc., 1998, 120, 8724. 37 B. C. Dave and R. S. Czernuszewicz, Inorg. Chim. Acta, 1998, 281, 25. 38 D.W. Wright, H. J. Mok, C. E. Dube and W. H. Armstrong, Inorg. Chem., 1998, 37, 3714. 39 T. K. Lal and R. Mukherjee, Inorg. Chem., 1998, 37, 2373. 40 H. Komatsuzaki, S. Ichikawa, S. Hikichi, M. Akita and Y. Moro-oka, Inorg. Chem., 1998, 37, 3652. 41 H. Komatsuzaki, H. Nagasu, K. Suzuki, T. Shibasaki, M. Satoh, F. Ebina, S. Hikichi, M. Akita and Y. Moro-oka, J. Chem. Soc., Dalton Trans., 1998, 511. 42 B. Albela, M. Corbella, J. Ribas, I. Castro, J. Sletten and H. Stoeckli-Evans, Inorg. Chem., 1998, 37, 788. 43 R. Wu, M. Poyraz, F.E. Sowrey, C. E. Anson, S. Wocadlo, A. K. Powell, U. A. Jayasooriya, R. D. Cannon, T. Nakamoto, M. Katada and H. Sano, Inorg. Chem., 1998, 37, 1913. 44 M. Hirotsu, M. Kojima, W. Mori and Y. Yoshikawa, Bull. Chem. Soc. Jpn., 1998, 71, 2873. 45 G. Aromi, M.W. Wemple, S. J. Aubin, K. Folting, D. N. Hendrickson and G. Christou, J. Am. Chem. Soc., 1998, 120, 5850. 46 S. M. J.Aubin, N. R. Dilley, M. W. Wemple, M. B. Maple, G. Christou and D. N. Hendrickson, J. Am. Chem. Soc., 1998, 120, 839. 47 S. M. J. Aubin, N. R. Dilley, L. Pardi, J. Krzystek, M.W. Wemple, L.-C. Brunel, M.B. Maple, G. Christou and D. N. Hendrickson, J. Am. Chem. Soc., 1998, 120, 4991. 48 C. E. Dube, D. W. Wright, P. J. Bonitatebus, Jr., S. Pal and W.H. Armstrong, J. Am. Chem. Soc., 1998, 120, 3704. 49 J. M. Peloquin, K. A. Campbell and R. D. Britt, J. Am. Chem. Soc., 1998, 120, 6840. 50 O. Horner, E. Riviere, G. Blondin, S. Un, A. W. Rutherford, J.-J. Girerd and A. Boussac, J. Am. Chem. Soc., 1998, 120, 7924. 51 R. A. Reynolds, III and D. Coucouvanis, J. Am. Chem. Soc., 1998, 120, 209. 52 G. Aromi, J.-P. Claude, C. M.J. Knapp, J. C. Hu§man, D. N. Hendrickson and G.Christou, J. Am. Chem. Soc., 1998, 120, 2977. 53 G. L. Abbati, A. Cornia, A. C. Fabretti, A. Caneschi and D. Gatteschi, Inorg. Chem., 1998, 37, 1430. 54 G. L. Abbati, A. Cornia, A. C. Fabretti, A. Caneschi and D. Gatteschi, Inorg. Chem., 1998, 37, 3759. 55 B. Kwak, H. Rhee, S. Park and M. S. Lah, Inorg. Chem., 1998, 37, 3599. 56 M. Murrie, S. Parsons and R. E. P. Winpenny, J. Chem.Soc., Dalton Trans., 1998, 1423. 57 E. K. Brechin, W. Clegg, M. Murrie, S. Parsons, S. J. Teat and R. E. P. Winpenny, J. Am. Chem. Soc., 1998, 120, 7365. 58 M. Boesing, A. Noeh, I. Loose and B. Krebs, J. Am. Chem. Soc., 1998, 120, 7252. 59 A. Escuer, R. Vicente, M. A. S. Goher and F.A Mautner, Inorg. Chem., 1998, 37, 782. 60 P. Sobata, J. Utko and L. B. Jerzykiewicz, Inorg. Chem., 1998, 37, 3428. 61 C. L. Zilverentant, W.L. Driessen, J. G. Haasnoot, J. J. Kolnaar and J. Reedijk, Inorg. Chim. Acta, 1998, 282, 257. 62 U. Jacobs, L. Schroeder, W. Massa, C. Elias, J. Fuentes, P. Nunez and U. Bentrup, Z. Anorg. Allg. Chem., 1998, 624, 1471. 63 C. S. Hong and Y. Do, Inorg. Chem., 1998, 37, 4470. 64 P. Castan, C. Viala, P.-L. Fabre, F. Nepveu, J.-P. Souchard and G. Bernardinelli, Can.J. Chem., 1998, 76, 205. 65 L. Ballester, I. Baxter, P. C. M. Duncan, D. M.L. Goodgame, D. A. Grachvogel and D. J. Williams, Polyhedron, 1998, 17, 3613. 66 H. Miyasaka, H. Okawa, A. Miyazaki and T. Enoki, Inorg. Chem., 1998, 37, 4878. 67 A. Dascoulidou, F. Schucht, W. Jung and H. U. Schuster, Z. Anorg. Allg. Chem., 1998, 624, 119. 68 Q. Huang and S.-J. Hwu, Inorg.Chem., 1998, 37, 5869. 69 J. Kim, C. Wang and T. Hughbanks, Inorg. Chem., 1998, 37, 1428. 70 T. Nicholson, M. Hirsch-Kuchma, A. Shellenbarger-Jones, A. Davison and A. G. Jones, Inorg. Chim. Acta, 1998, 267, 319. 71 R. Alberto, R. Schibli, A. Egli, A. P. Schubiger, U. Abram and T. A. Kaden, J. Am. Chem. Soc., 1998, 120, 7987. 72 R. Schibli, R. Alberto, U. Abram, S. Abram, A. Egli, P.A. Schubiger and T. A. Kaden, Inorg. Chem., 1998, 37, 3509. 73 M. Pelecanou, I. C. Permettis, B. A. Nock, M. Papadopoulos, E. Chiotellis and C. I. Stassinopoulou, Inorg. Chim. Acta, 1998, 281, 148. 74 M. Chatterjee, B. Achari, S. Das, R. Banerjee, C. Chakrabarti, J. K. Dattagupta and S. Banerjee, Inorg. Chem., 1998, 37, 5424. 75 J. Baldas, G. A. Heath, S. A. Macgregor, K. H. Moock, S.C. Nissen and R. G. Raptis, J. Chem. Soc., Dalton Trans., 1998, 2303. 76 F. D. Rochon, R. Melanson and P.-C. Kong, Inorg. Chem., 1998, 37, 87. 77 W.J. Casteel, Jr., D. A. Dixon, N. LeBlond, H. P. A. Mercier and G. J. Schrobilgen, Inorg. Chem., 1998, 37, 340. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 16378 A. N. Chernega, M. L. H. Green, J. Haggitt and A. H.H. Stephens, J. Chem. Soc., Dalton Trans., 1998, 755. 79 P. J. Heard and D. A. Tocher, J. Chem. Soc., Dalton Trans., 1998, 2169. 80 A. Gelling, K. G. Orrell, A. G. Osborne and V. Sik, J. Chem. Soc., Dalton Trans., 1998, 937. 81 A. Gelling, M. D. Olsen, K. G. Orrell, A. G. Osborne and V. Sik, J. Chem. Soc., Dalton Trans., 1998, 3479. 82 V. W.-W. Yam, V. C.-Y. Lau and L.-X. Wu, J.Chem. Soc., Dalton Trans., 1998, 1461. 83 E. Schutte, J. Helms, S. Woessner, J. Bowen and B. P. Sullivan, Inorg. Chem., 1998, 37, 2618. 84 J. Huhmann-Vincent, B. L. Scott and G. J. Kubas, J. Am. Chem. Soc., 1998, 120, 6808. 85 C.M. P. Ferreira, M. F. C. Guedes da Silva, V. U. Kukushkin, J. J. R. Frausto da Silva and A. J. L. Pombeiro, J. Chem. Soc., Dalton Trans., 1998, 325. 86 M.T. A. R. S. da Costa, J. R. Dilworth, M.T. Duarte, J. J. R. Frausto da Silva, A. M. Galvao and A. J. L. Pombeiro, J. Chem. Soc., Dalton Trans., 1998, 2405. 87 A. L. Ondracek, P. E. Fanwick and R. E. Walton, Inorg. Chim. Acta, 1998, 278, 245. 88 C. Pearson and A. L. Beauchamp, Inorg. Chem., 1998, 37, 1242. 89 U. Abram, M. Braun, S. Abram, R. Kirmse and A. Voigt, J. Chem. Soc., Dalton Trans., 1998, 231. 90 M. M. Abu-Omar and S. I. Khan, Inorg. Chem., 1998, 37, 4979. 91 K. Chryssou, M. Pelecanou, M. S. Papadopoulos, C. P. Raptopoulou, I. C. Permettis, E. Chiotellis and C. I. Stassinopoulou, Inorg. Chim. Acta, 1998, 268, 169. 92 M. J. Al-Jeboori, J. R. Dilworth and Y. Zheng, J. Chem. Soc., Dalton Trans., 1998, 3215. 93 D. D. DuMez and J. M. Mayer, Inorg. Chem., 1998, 37, 445. 94 F. A. Cotton, E. V. Dikarev, G. T. Jordan, IV, C. A. Murillo and M.A. Petrukhina, Inorg. Chem., 1998, 37, 4611. 95 A. Haug and J. Straehle, Z. Anorg. Allg. Chem., 1998, 624, 931. 96 F. A. Cotton, E. V. Dikarev and M. A. Petrukhina, Inorg. Chem., 1998, 37, 6035. 97 W. Wu, P. E. Fanwick and R. A. Walton, Inorg. Chem., 1998, 37, 3122. 98 J. T. Goodman and T. B. Rauchfuss, Inorg. Chem., 1998, 37, 5040. 99 W.-W. Zhuang, D. M. Ho§man, D. Lappas and J. Cohen, Polyhedron, 1998, 17, 2583. 100 D. V. Gri¶ths, S. J. Parrott, M. Togrou, J. R. Dilworth, Y. Zheng, S. Ritter and U. Abram, Z. Anorg. Allg. Chem., 1998, 624, 1409. 101 S. M. Woessner, J. B. Helms, Y. Shen and B. P. Sullivan, Inorg. Chem., 1998, 37, 5406. 102 K. D. Benkstein, J. T. Hupp and C. L. Stern, Inorg. Chem., 1998, 37, 5404. 103 M. Bergamo, T. Beringhelli, G. D’Alfonso, P. Mercandelli, M. Moret and A. Sironi, J. Am. Chem. Soc., 1998, 120, 2971. 104 I. Costa, L. Fabbrizzi, P. Pallavicini, A. Poggi and A. Zani, Inorg. Chim. Acta, 1998, 275–276, 117. 105 J. R. Schoonover, A. P. Shreve, R. B. Dyer, R. L. Cleary, M. D. Ward and C. A. Bignozzi, Inorg. Chem., 1998, 37, 2598. 106 B. W. Pfennig, J. K. Goertz, D. W. Wol§ and J. L. Cohen, Inorg. Chem., 1998, 37, 2608. 107 N. C. Dopke, P. M. Treichel and M. M. Vestling, Inorg. Chem., 1998, 37, 1272. 108 M. W. Willer, J. R. Long, C. C. McLauchlan and R. H. Holm, Inorg. Chem., 1998, 37, 328. 109 V. P. Fedin, A. A. Virovets and A. G. Sykes, Inorg. Chim. Acta, 1998, 271, 228. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 153–164 164

ISSN:0260-1818    

DOI:10.1039/a805976d

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

13 Iron, cobalt and nickel S. A. Cotton Uppingham School, Uppingham, Rutland, UK LE15 9QE 1 Introduction This report follows the pattern of recent years in covering the available 1998 literature, together with some late 1997 papers. A review has appeared of polyiron oxides, oxyhydroxides and hydroxides as models for biomineralisation1 whilst the structure and function of nickel sites in metalloproteins have been reviewed.2 Reviews have appeared covering the co-ordination chemistry of iron,3 cobalt4 and nickel5 for 1995, for nickel over the years 1985,6a 19866b and 1987–19896c, and for cobalt for 1994.7 Following its predecessor last year, dedicated to mononuclear iron complexes, a second review of structures of iron co-ordination compounds, this time covering over 400 dimeric and oligomeric complexes, has appeared.8 Electron-transfer reactions of nickel-(III) and -(IV) complexes have been examined.9 Abiological Fe–S clusters have been reviewed10 as have [1: 3] site-di§erentiated and sulfide-bridged cubane clusters. 11 A review has appeared covering diiron(II, II) complexes, with a bridging carboxylate, that react with dioxygen forming l-peroxo species.12 Bond valence sum calculations have been reported on 227 compounds with CoOn polyhedra (n\3–8) and used to recognise the oxidation state of cobalt.13 In addition to wastewater treatment, iron compounds can be used instead of toxic heavy metals in the dye and textile industries.14 MCD studies have been reported for 24 non-haem iron(II) complexes. 15 It is stated that variable-temperature variable-field MCD (VTVH MCD) studies can generally indicate the co-ordination number and geometry of an unknown iron(II) centre.More use is being made of EXAFS and other techniques.16 [Fe(tpp)(NO)] and [MbII(NO)]Miron(II) nitrosylmyoglobinN have closely related structures with Fe–N–O ca. 155°; on the other hand, [MbIII(NO)] has Fe–N–O ca. 180° again consonant with X-ray data for models like [Fe(oep)(NO)]`.Sulfur K-edge XAS has been used to investigate covalency in rubredoxins and simple models like [NEt 4 ] [FeMC 6 H 4 (CH 2 S) 2 -oN2 ] and Na[AsPh 4 ][FeMC 6 H 4 (CH 2 S) 2 -oN2 ].17 Keggin-type ironsubstituted polyoxometallates [c-SiW 10MFe(H 2 O)N2 O 38 ]6~ are very e¶cient homogeneous catalysts for the oxidation of alkanes with H 2 O 2 .18 2 Simple binary and co-ordination compounds of hydrogen, oxygen, nitrogen and halogen donors Nanometer sized Fe 3 O 4 particles have been synthesised by hydrothermal reactions of Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 165[Fe(OCH 2 CH 2 OMe) 2 ].19 An EXAFS study of b-NiO(OH) indicates that the Ni(III) sites experience a Jahn–Teller distortion, with four Ni–O bonds at 1.87Å and two at 2.03Å; in the g-phase, containing Ni(III) and Ni(IV), this is absent.20 Oxygen donors Iron is seven-co-ordinate in Ca[Fe(Hdtpa)][ClO 4 ]·7H 2 O; the protonated carboxylate group does not co-ordinate.21 The structure of Na[Fe(cdta)][ClO 4 ] has been determined in the solid state and solution.22 FeCl 3 reacts with pyridine-2,6–dicarboxylic acid forming [Fe(dipic)(H 2 O) 3 ][Fe(dipic) 2 ] in which both cation and anion contain octahedral iron(III).23 Syntheses and structures are reported for maricite (NaFePO 4 ) and sodium iron hydroxyphosphate, [Na 3 Fe(PO 4 ) 2 ·(Na 2~2xH 2xO)], two compounds implicated in boiler corrosion.24 [H 2 pip] 2 [Fe 6 (HPO 4 ) 2 (PO 4 ) 6 (H 2 O) 2 ]·H 2 O contains TBPY FeO 5 and octahedral FeO 6 polyhedra in a 3–D framework structure that contains channels which accommodate the cations.25 Quaternary ammonium ions act as templates26 for the framework in [H 3 N(CH 2 ) 4 NH 3 ] 2 - [Fe 8 (HPO 4 ) 12 (PO 4 ) 2 (H 2 O) 6 ].Two series of the familiar trinuclear carboxylates, this time with long alkyl chains, [Fe 3 O(O 2 CCnH 2n`1 ) 6 L 3 ]NO 3 (L\H 2 O, py; n\11, 13, 15, 17) have been synthesised.27 The salt [Fe 3 O(O 2 CC 13 H 27 ) 6 (py) 3 ]NO 3 has a singlelayer structure in which the interlamellar orientation of alkyl chains is alternate to those in adjacent layers.The electrochemical reduction of a range of carboxylates [Fe 3 O(O 2 CMe) 6 L 3 ]X (L\pyridine or substituted pyridine; X\NO 3 or ClO 4 ) and [Fe 3 O(O 2 CR) 6 (py) 3 ]X (R\Bu5, Ph, CH 2 Cl, CCl 3 , CH 2 CN, 4-NO 2 C 6 H 4 ; X\NO 3 or ClO 4 ) has been studied and the structure of [Fe 3 O(O 2 CPh) 6 (py) 3 ]NO 3 reported.28 The 6–methyl-2-pyridone complex, all trans-[CoCl 2 (Hmhp) 2 (H 2 O) 2 ]· 2Hmhp, is a 1–Dhydrogen-bonded polymer in which [CoCl 2 (Hmhp) 2 (H 2 O) 2 ] molecules alternate with the unco-ordinated ligand.29 The complex (CoCl 2 ) 2 ·(12–crown-4)·H 2 O has the structure [(12–crown-4)Co(H 2 O)(l-Cl)CoCl 3 ], featuring both tetrahedral and octahedral cobalt(II).30 The structure of hydrated nickel(II) perchlorate, [Ni(H 2 O) 6 ] [ClO 4 ] 2 ·2H 2 Ohas been determined.31 The complex NiCl 2 (dmf) 3 was shown by X-ray di§raction32 to be [Ni(dmf) 6 ][NiCl 4 ] whilst the structure of [Ni(dmf) 6 ][BF 4 ] 2 also shows octahedral co-ordination of nickel.33 Halide complexes Orange CsNiCl 3 has face-sharing NiCl 6 octahedra whilst turquoise Cs 3 NiCl 5 contains isolated [NiCl 4 ]2~ tetrahedra.34 [NHMe 3 ][MCl 3 (H 2 O) 2 ] (M\Mn, Ni, Co) are isomorphous, containing infinite chains of chloride edge-sharing trans- [MCl 4 (H 2 O) 2 ] octahedra.35 O 2 ` salts dissolve in anhydrous HF a§ording O 2 F, which oxidises NiF 2 to [NiF 6 ]2~ salts.36 Nitrogen donors Trigonal monopyramidal is a much less common geometry for four-co-ordination than either tetrahedral or square planar.Using the tripodal ligand tris[(N-tert- Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 166butylcarbamoyl)methyl]aminato [L]3~, a series of anionic species [MII([L]3~)]~ have been synthesised (1; M\Fe, Co, Ni, Zn) and the structures of the cobalt, nickel and zinc complexes determined.They are nearly identical, suggesting that the ligand is e§ective in enforcing the geometry.37 The nickel and iron complexes can be oxidised to EPR-active M(III) species. A number of iron(II) tris(2-pyridylmethyl)amine complexes have been synthesised. [Fe(tpa)(NCMe) 2 ][SO 3 CF 3 ) 2 is low-spin whilst [Fe(tpa)(SO 3 CF 3 ) 2 ] is high-spin. Reaction in the presence of [BPh 4 ]~ a§ords [Fe(tpa)(MeOH) 2 ][BPh 4 ] 2 whilst in the presence of excess ligand six-co-ordinate [Fe(tpa) 2 ][SO 3 CF 3 ] 2 and eight-co-ordinate [Fe(tpa) 2 ][BPh 4 ] 2 could be isolated.38 The structure 2 of fac-[FeCl 3 (bpma)] has been reported.39 The structure of [Fe(phen)Cl 3 (H 2 O)], the first well characterised mono(phen) iron(III) complex, has been reported.40 The new compound [Fe(bpm)Cl 3 (H 2 O)]·H 2 O has a similar structure; [Fe 2 (bpm)Cl 6 (H 2 O) 2 ]·2H 2 O is binuclear, with bridging bipyrimidine. 41 Croconate and squarate also form dinuclear complexes [Fe 2 (bpm)(C 5 O 5 )(H 2 O) 4 ]·2H 2 O and [Fe 2 (bpm)(C 4 O 4 )(H 2 O) 6 ]·2H 2 O respectively.42 The structure of the iron(II) compound K 2 [Fe(phen)(CN) 4 ]·2.5H 2 O has been determined. 43 Iron(II) pyridinebis(imine) complexes (3; R\Me, Et, Pr*) act as very e§ective ethene polymerisation catalysts.44a Similar iron and cobalt complexes with even bulkier ligands act similarly.44b Starting with [NEt 4 ][FeTp@Cl 3 ], chloride ligands can be replaced by nitrite, resulting in the iron(III) complexes [NEt 4 ][FeTp@(ONO)xCl 3~x] (x\1–3), in which nitrite is monodentate, and the iron(II) complex [NEt 4 ]- [FeTp@(ONO)Cl] in which nitrite is chelating.45 An iron(II) methyl complex ‘supported’ by a poly(pyrazolyl)borate ligand is discussed in Section 5.The structure of the [Fe(trans-dimmac)]2` ion, one of the few low-spin iron(II) complexes of saturated amines, shows distorted octahedral geometry with rather short Fe–N distances.46 Octahedral [Fe(en) 3 ]2` ions are found in [Fe(en) 3 ][Hen][SbSe 4 ].47 A potential model for superoxide dismutase active sites, [FeL][PF 6 ] 2 [L\N(CH 2 CH 2 N––CHR) 3 ; R\1-triphenylmethyl-4-imidazolyl] has octahedrally co-ordinated iron(II); the tripodal bridging nitrogen does not co-ordinate.48 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 167[Co(pm) 2 X 2 ] (X\Cl, Br) show weak ferromagnetic interactions at low temperatures; they have chiral 3–D network structures in which the trans-CoN 4 X 2 co-ordination sphere has pyrimidine rather than halogen bridges.49 [CoL 2 (NCS) 2 ] (L\pyrazine or pyrimidine) have sheet-like structures in which the azine ligands bridge between cobalt atoms; compressed octahedral co-ordination of cobalt is made of four long Co–N (azine) and two short axial Co–N (NCS) bonds.The pyrazine complex is antiferromagnetic at low temperatures whilst the pyrimidine complex displays magnetic ordering below 8.2 K. In contrast, pyridazine forms a monomeric complex trans-[Co(pyz) 4 (NCS) 2 ].50 Three cobalt(II) complexes of 4,4@-bipyridine have been studied.51 [Co(4,4@-bipy)(SO 4 )(H 2 O) 2 ]·2H 2 O and [Co(4,4@-bipy)Cl 2 (dmso) 2 ] have chains containing linear Co–bipy–Co groupings whereas [Co(4,4@-bipy)(OAc) 2 ] has double chains with acetate bridges.The structure of fac-[Co(bipy)(py)(N 3 ) 3 ] has been determined.52 Hydroxoaquatetraminecobalt(III) complexes in microemulsions catalyse the hydrolysis of nerve agent simulants.53 The tetrahedral high-spin cobalt(II) complexes [CoXMN(SiMe 2 CH 2 PPh 2 ) 2N] (X\Cl, Br, I) undergo alkylation forming the low-spin square-planar cobalt(II) compounds [CoRMN(SiMe 2 CH 2 PPh 2 ) 2N] (R\Me, CH 2 Ph, CH 2 SiMe 3 , Cp).PhCH 2 X oxidizes [CoXMN(SiMe 2 CH 2 PPh 2 ) 2N] to the five-co-ordinate paramagnetic Co(III) compounds (a combination still rare enough to be remarked on) [CoX 2MN(SiMe 2 CH 2 PPh 2 ) 2N]. In toluene, MeI or MeBr react with [CoMeMN(SiMe 2 CH 2 PPh 2 ) 2N] to form [CoXMN(SiMe 2 CH 2 PPh 2 ) 2N], probably via the unstable [Co(Me)XMN(SiMe 2 CH 2 PPh 2 ) 2N].Structures are reported for [CoIMN(SiMe 2 CH 2 PPh 2 ) 2N], [Co(CH 2 Ph)MN(SiMe 2 CH 2 PPh 2 ) 2N] and [CoBr 2MN(SiMe 2 CH 2 PPh 2 ) 2N].54 A number of cobalt complexes of 2,2@- dipyridylamine have been studied.55 [Co(dpa) 2 (Me 2 CO) 2 ][ClO 4 ] 2 and [Co(dpa)Cl 2 ] have octahedrally and tetrahedrally co-ordinated Co(II) respectively.Under aerobic conditions, oxidation to Co(III) occurs with the formation of [Co 2 (dpa) 4 (l-O 2 )(l-OH)]- [ClO 4 ] 3 . Deprotonated dpa is a ligand in [Co(dpa[H) 2 ] whilst the protonated ligand is found in [Hdpa] 2 [CoCl 4 ]. The crystal structure of [Ni(5–Mepz) 6 ][ClO 4 ] 2 has been determined; the EPR spectra of [Ni(5–Mepz) 6 ]X 2 (X\ClO 4 , BF 4 ) show a temperature-dependent zero-field splitting.56 [Ni(NH 3 ) 6 ]C 60 ·6NH 3 , prepared in liquid ammonia, is a new recruit to the ranks of nickel hexammine complexes; it has a distorted rock salt structure.57 The structure of cis-[Ni(phen) 2 (NCS) 2 ] has been reported.58 [Ni(bipy) 2 (Cr 2 O 7 )(NCMe)] = has a helical chain structure, whilst in [Ni(en) 2 - (Cr 2 O 7 )] = the chains cross.59 In [Ni(bipy)(O 2 CMe) 2 (H 2 O) 2 ] and [Ni(dmbipy)(O 2 CMe) 2 (H 2 O) 2 ] the molecules are self-assembled into 1-D infinite zig-zag chains by double intermolecular hydrogen bonds; the chains are stacked through the aromatic rings.In [Ni(phen)(O 2 CMe) 2 (H 2 O) 2 ]·0.5H 2 O, hydrogen bonds link molecules to form a 1-D chain, associated with another chain through double Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 168hydrogen bonds.60 The bimetallic assemblies [NiIIL 2 ] 3 [FeII(CN) 6 ]X 2 (L\en, tn, X\PF 6 , ClO 4 ) have 3-D networks with Fe–CN–Ni linkages leading to a ferromagnetic interaction between neighbouring Ni and Fe.61 A number of thermochromic nickel ammines have been studied.62–66 The dependence of alkyl group size in substituted en ligands upon nitrate co-ordination in nickel ammine complexes was discussed.Syntheses are reported of cis-[Ni(dpren) 2 (NO 3 )] [NO 3 ] and cis-[Ni(dipren) 2 (H 2 O) 2 ][NO 3 ] 2 ·2H 2 O; the latter undergoes loss of four water molecules on melting, accompanied by a colour change from greenish blue to deep green.62 Syntheses are reported for [Ni(dpren) 2 (H 2 O) 2 ]X 2 (X\Cl, Br, I, CF 3 CO 2 , CF3 SO 3 ), [Ni(dpren) 2 (NCS) 2 ], [Ni(dipren)Cl 2 ] and [Ni(dipren)(CF 3 CO 2 ) 2 (H 2 O) 2 ].[Ni(dpren) 2 (H 2 O) 2 ]X 2 lose water on heating, with various colour changes; on further heating, [Ni(dpren) 2 X 2 ] (X\Cl, Br) yield monodpren complexes.63 The thermal dehydration of a number of trans- [Ni(diamine) 2 (H 2 O) 2 ]X 2 systems has been studied.64 Some compounds such as trans-[Ni(stien) 2 (H 2 O) 2 ]Cl 2 convert first to cis-[Ni(diamine) 2 X 2 ], and on further heating isomerise to the trans-isomer. Rehydration occurs on standing to give the original complex.The nickel trifluoroacetate complexes [NiL 2 (CF 3 CO 2 ) 2 ] (L\meen, eten, pren or ipren) have been synthesised; [Ni(pren) 2 (CF 3 CO 2 ) 2 ] and [Ni(ipren) 2 (CF 3 CO 2 ) 2 ] have trans NiN 4 O 2 co-ordination spheres.They exhibit irreversible blue to light violet thermochromism whilst [Ni(meen) 2 (CF 3 CO 2 ) 2 ] shows a blue-violet to blue thermochromism that is reversed in a humid atmosphere.65 The structure of the high-temperature isomer of [NiL 2 (NCS) 2 ] (L\N,N-dimethylpropane- 1,3-diamine) has been determined;66 the isomers di§er in their molecular packing.Mixed ligand chelates of N- or N,N@-methylated ethylenediamines and tropolonate or hinokitiolate ligands have either octahedral or square-planar coordination, sometimes exhibiting an equilibrium in solution.67 [Ni(bpma) 2 ][ClO 4 ] 2 exhibits cis facial co-ordination of the bpma ligands; bond lengths were compared within the series [M(bpma) 2 ]2` (M\Mn, Fe, Ni, Cu, Zn).68 Reaction of NiCl 2 and tpa[ClO 4 ] 3 in the presence of NEt 3 yields [(tpa)Ni(l-Cl) 2 Ni(tpa)][ClO 4 ] 2 which in alkaline solution forms [(tpa)Ni(l-OH) 2 Ni(tpa)][ClO 4 ] 2 .This fixes atmospheric CO 2 a§ording [(tpa)Ni(l-HCO 3 ) 2 Ni(tpa)][ClO 4 ] 2 .69 A pyrazolate-based ligand [HL\3,5-bis(R 2 NCH 2 )pyrazolyl; R 2 N\Me 2 - N(CH 2 ) 3 NMe] forms a dinuclear nickel complex [LNi 2 (l-OH)(NCMe) 2 ][ClO 4 ] 2 in which the two nickels are bridged by the pyrazolate and hydroxide; each five-coordinate nickel has one MeCN completing its co-ordination sphere.A similar compound MR 2 N\[Me 2 N(CH 2 ) 3 ] 2 NN has extra ligand side arms so that the complex [HLNi 2 (l-OH)(NCMe) 2 ][ClO 4 ] 3 has an intramolecular N· · ·H· · ·N bridge.The nickel ions are su¶ciently close to exhibit strong antiferromagnetic coupling (J\[46.7 cm~1).70 Several nickel(II) complexes of a pentadentate ligand (pyN 4 ) have been synthesised with the formulae [Ni(pyN 4 )(H 2 O)]X 2 (X\Cl, I), [Ni(pyN 4 )(OClO 3 )][ClO 4 ] and [Ni(pyN 4 )X][PF 6 ] 4 as well as binuclear [(pyN 4 )Ni(l-Cl)Ni(pyN 4 )][PF 6 ] 3 .71 The binuclear compound shows antiferromagnetic coupling, resulting in a S\0 ground state at low temperatures.[Ni(Medien)(NCS)(l-NCS)]n has a chain structure in which nickel atoms are linked by cis-thiocyanates, causing ferromagnetic coupling.72 cis-[(l- jN,NA-N 3 ) 2MNi(dl-cth)N2 ][ClO 4 ] 2 exhibits significantly stronger antiferromagnetic coupling than cis-[(l1,3 -N 3 ) 2MNi(dl-cth)N2 ][PF 6 ] 2 ·dmf.73 The azide- and oxalate- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 169bridged dimer[MNi(Medpt) 2 (l-ox)(l-N 3 )Nn][ClO 4 ]n has a bond-alternating S\1 spin chain.74 Compounds [Ni 5 (l5 -tpda) 4 X 2 ]2` (X\Cl, CN, NCS, N 3 ) and [Ni 5 (l5 - tpda) 4 (NCMe) 2 ]2` all contain a linear chain of five nickels, terminated by two axial ligands and wrapped helically by the four tpda ligands.The nickels are not magnetically equivalent, the three inner ones being in square-planar low-spin environments whilst the outer two are square-pyramidal high-spin; magnetic behaviour indicates antiferromagnetic interaction of the two high-spin nickels.75 3 Complexes of tertiary phosphines The structure of trans-[FeHCl(depe) 2 ] has been determined.76 A compound believed to be [MFeCl(depe) 2N2 (l-N 2 )][BPh 4 ] 2 has been shown to have the structure trans- [Fe(N 2 )Cl(depe) 2 ][BPh 4 ]; [Fe(N 2 )X(depe) 2 ][BPh 4 ] (X\Cl, Br) are much less stable than the corresponding hydrides and undergo dinitrogen exchange even in the solid state at room temperature.77 In the presence of TlBF 4 , trans-[FeHCl(dppe) 2 ] reacts with P–– – CBu5, forming trans-[Fe(g1-P–– – CBu5)H(dppe) 2 ][BF 4 ].The related trans- [Fe(g1-P–– – CBu5)H(dppe) 2 ][BPh 4 ] has an exceptionally short P–– –C bond. On reaction with HBF 4 this forms trans-[Fe(g1-PF––CHBu5)H(dppe) 2 ]` and trans-[Fe(g1- PF 2 CH 2 Bu5)H(dppe) 2 ]`. trans-[FeHCl(dppe) 2 ] reacts with P–– – CBu5, in the presence of TlBF 4 and NH 4 BF 4 forming trans-[Fe(PH 3 )H(dppe) 2 ][BF 4 ].78 The dihydrogen ligand in trans-[FeH(H 2 )(dppm) 2 ]` is replaced by other ligands such as MeCN, py,N 2 and ethene; evidence was obtained for trans-[Fe(H 2 ) 2 (dppm) 2 ]2`, which undergoes substitution forming trans-[Fe(NCMe) 2 (dppm) 2 ]2`.The structures of trans- [FeH(NCMe)(dppm) 2 ][BF 4 ] and trans-[Fe(NCMe) 2 (dppm) 2 ][BF 4 ] 2 were reported. 79 cis-[FeH 2 (dppe) 2 ] reacts with acids in thf forming trans-[FeH(H 2 )(dppe) 2 ]` in a reaction first order in both reactants.80 cis-[Fe(bpe5) 2 Cl 2 ] is the first cis- [Fe(PP) 2 Cl 2 ] (PP\bidentate phosphine) system.81 In solution, it exhibits temperature- dependent paramagnetism owing to dissociation of chloride. Cobalt powder reacts with [IBz 2 P(CH 2 ) 2 PBz 2 I] forming [CoMBz 2 P(CH 2 ) 2 PBz 2NI 2 ]; aerial oxidation converts it to a phosphine oxide complex.82 [Ni(dppe) 2 ] reacts with DCl via the initial formation of [NiD(dppe) 2 ]`; at low acid concentration, the nickel-containing product is [NiCl 2 (dppe)], whose structure has been determined.83 [Ni(dppe)(SC 6 H 4 X)] (X\O, CO 2 , NH) have been reported;84 square-planar co-ordination for nickel has been confirmed for X\O.[Ni(dppmeSe) 2 ]Cl 2 has a square-planar NiP 2 Se 2 chromophore.85 A square-planar geometry is also found86 in the cation of [NiMPh 2 P(CH 2 ) 4 PBuPh 2N(S 2 CNEt 2 )]- [ClO 4 ]. The ligand tapa forms the nickel complexes [NiCl 2 (tapa) 2 ] and Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 170[Ni(CN) 2 (tapa) 3 ], the latter having a TBPY structure with axial cyanides.87 4 Complexes with sulfur, selenium and tellurium donors [FeCl 2 (th) 2 ] contains infinite linear chains where iron atoms are doubly linked by halide bridges;88 a similar structure was deduced for [NiBr 2 (th) 2 ] from powder neutron-di§raction data.89 [CoMN(SiMe 3 ) 2N2 ] reacts with RSH [R\2,6–(Me 3 Si) 2 C 6 H 3 ] to form the tetrahedral thiolate [Co(SR) 2 (thf) 2 ].90 [MCo(Py 2 S) 2 Cl 2Nn] has a two-layer interwoven sheet structure whilst [MCo(Py 2 S) 2 (NCS) 2 (H 2 O) 2Nn] has a double-stranded linear infinite structure.91 A number of complexes of the ‘extended reach’ S-donor ligands ebpt and p-xbpt have been synthesised.92 [MCo(NCS) 2 (ebpt)Nn] has a chain structure with tetrahedrally co-ordinated cobalt, whereas [MCoCl 2 (ebpt)N2 ] is a dimer with 18–membered rings.Polymeric [MCo(p-xbpt)N2 ][ClO 4 ] 2 ·MeNO 2 has a sheet structure with 52–membered rings; cobalt is again tetrahedrally co-ordinated. [MNi(NO 3 ) 2 (p-xbpt)Nn] has bidentate nitrates; bridging p-xbpt ligands link the octahedrally co-ordinated nickel atoms into chains. Compounds of the ligand ebpyt include [Fe(ebpyt)Cl 2 ], [Co(ebpyt)Br 2 ] and [Ni(ebpyt) 3 ][ClO 4 ] 2 ·2MeOH·MeNO 2 .Of these, the cobalt complex has a chain structure in which ebpyt ligands link tetrahedrally co-ordinated cobalts, whilst the nickel compound has NiS 6 centres in which the metal atoms are again linked by ebpyt bridges into a 3-D polymeric array.93 Compounds with amide-substituted arylthiolate ligands, such as [NMe 4 ] 2 [Fe(SC 6 H 4 NHCOMe-o) 4 ], [NMe 4 ] 2 [FeMSC 6 - H 3 (MeCONH) 2 -2,6N4 ], [NEt 4 ] 2 [M(SC 6 H 4 NHCOBu5-o) 4 ]·2EtCN (M\Fe, Co) and [PPh 4 ] 2 [CoMSC 6 H 3 (CF 3 CONH) 2 -2,6N4 ]·2Et 2 O appear to have unexpectedly short M–S distances as well as significantly shifted Fe(III)–Fe(II) redox potentials, due to intramolecular NH· · · S hydrogen bonds.94 Iron complexes of the ligand ns 3 have attracted attention.95 The paramagnetic TBPY iron(III) anionic complex [Fe(ns 3 )Cl]~ is reduced by CO–Na forming the paramagnetic TBPY iron(II) complex anion 5.The latter reacts with FeCl 2 forming an unusual paramagnetic Fe 3 S 4 carbonyl cluster 6. Dithiocarbamates and related ligands Electrochemical oxidation of [Co(Q 2 CNR 2 ) 3 ] (Q\S, Se) in MeCN involves96 [Co(Q 2 CNR 2 ) 3 ]`, [Co 2 (Q 2 CNR 2 ) 5 ]` and [Co(Q 2 CNR 2 ) 2 (NCMe) 2 ]`.The structure of [Co(S 2 CNEt 2 ) 3 ] has been reported.97 Soft X-ray photoreduction of Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 171[Ni(S 2 CNEt 2 ) 3 ][BF 4 ] gives a Ni(II) square-planar species, whilst [PPh 4 ]- [Ni(S 2 COEt) 3 ] is photoisomerised to a square-planar Ni(II) species.98 Adducts of [Ni(S 2 COPr*) 2 ] with amine ligands, such as [Ni(S 2 COPr*) 2 (dpa)]·Me 2 SO and [Ni(S 2 COPr*) 2 (amp)], have a cis-NiN 2 S 4 co-ordination sphere.99 [NiMPh 2 P(CH 2 ) 4 PPh 2N(S 2 CNEt 2 )] contains square-planar nickel(II).100 [NBu 4 ] 2 - [Ni(S 2 C––NC 6 H 4 CN-p) 2 ] also has distorted square-planar co-ordination of nickel.101 The electronic structure of [Ni(mnt) 2 ]~ has been probed by ENDOR and ESEEM (electron stimulated echo envelope modulation).102 Metal complexes of dmit have potential as molecular metals.A number of new salts of [Ni(dmit) 2 ]~ are semiconductors, though their conductivity increases on doping with iodine. The structure of [eda]- [Ni(dmit) 2 ] shows short S · · · S contacts between cation and anion.103 The bonding between [Ni(dmit) 2 ] monomers in the solid state has been analysed via density functional calculations.104 New selenoether complexes of nickel include [NiX 2 ([16]aneSe 4 )] (X\Cl, Br, I) and [NiX 2 (MeSeCH 2 CH 2 SMe) 2 ].105 5 Complexes with r-bonded carbon donors The colourless paramagnetic r-bonded methyl (7; R\Bu5) is unusual in being a four-co-ordinate iron(II) alkyl.It is the precursor for a number of iron(II) poly(pyrazolyl) borate complexes.106 The compound formerly reported as an iron(0) species [Li(OEt 2 )] 4 [FePh 4 ] is now believed to be an iron(II) compound [Li(OEt 2 )] 4 trans- [FeH 2 Ph 4 ].107 The unstable six-co-ordinate cobalt(II) isocyanide complex [Co(CNCy) 4 (PPh 3 ) 2 ][ClO 4 ] 2 has been isolated by rapid precipitation and filtration, the usual product being the cobalt(I) species [Co(CNCy) 3 (PPh 3 ) 2 ][ClO 4 ].On attempted recrystallisation of the cobalt(II) complex, [Co(CNCy) 3 (PPh 3 ) 2 ][ClO 4 ] 2 is obtained.108 6 Complexes with porphyrins and other macrocycles A resonance Raman study of dioxygen adducts of double-sided encumbered iron(II) porphyrins shows high O–O stretching frequencies, possibly owing to a decreased Fe–O–O angle caused by the narrow cavity.Skeletal vibrations were also readily assigned.109 BF 3 ·OEt 2 reacts with [K(18-crown-6)][Fe(tpivpp)(NO 2 ) 2 ] forming the unstable molecule [Fe(tpivpp)(NO 2 )]. This disproportionates forming Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 172[Fe(tpivpp)(NO)] and [Fe(tpivpp)(NO 3 )]; the latter has six-co-ordinate iron with a symmetrical bidentate nitrate.110 [N(PPh 3 ) 2 ][Fepc(OMe) 2 ] contains octahedrally co-ordinated iron,111 with the methoxides trans. The dimeric species [N(PPh 3 ) 2 ] 2 [MN 3 Fe(pc)N2 N]I 3 ·2Et 2 O has an almost linear (177°) Fe–N–Fe skeleton.112 Iron porphyrin thiolates are studied as models for cytochrome P-450.Two compounds with single and doubleNH· · · S hydrogen bonds, [Fe(oep)MSC 6 H 3 (RCONH) 2 -2,6N] and [Fe(oep)(SC 6 H 4 RCONH-2)], have been studied crystallographically.The hydrogen bond elongates the Fe–S bond, stabilises the Fe(III) state, makes the compounds less air- and water-sensitive and also makes the redox potential more positive; together this is more significant than the e§ects of steric hindrance.113 A number of complexes have been made from tetra(cyclohexyl)porphyrin. 114 High-spin [FeCl(thcp)] reacts with cyanide forming [Fe(CN) 2 (thcp)]~ which is low-spin with the unusual (dxzdyz)4(dxy)1 ground state. Imidazole complexes such as [FeL 2 (thcp)]` (L\imidazole, 1-methylimidazole, 1,2-dimethylimidazole) are also low-spin. Iron(III) porphycenes [Fe(etiopc)R] (8, R\Ph, 3,5–F 2 H 3 ,C 6 , 3,4,5- F 3 H 2 C 6 , 2,3,5,6-F 4 HC 6 ) can be high- or low-spin depending upon the axial ligand and temperature.115 The first one-electron oxidation step involves the metal; subsequent electrons are removed from the porphycene ligand.The iron atom is nearly in the basal plane in [Fe(etiopc)(3,5-F 2 H 3 C 6 )]. The complexes [FeX(tmcp)] ( X\Cl, Br, OH) have been studied; the structure of high-spin [FeCl(tmcp)] is unusual as the porphyrin is strongly rußed and domed, and the Fe–N distances are distinctly short.116 Low-spin derivatives of iron(III) chiroporphyrin, with cyanide and imidazoles include examples with the unusual (dxzdyz)4(dxy)1 ground state.117 Complexation of FeCl 3 with 1,4,7-tris[3,4-bis(decyloxy)benzyl]-1,4,7- triazacyclononane yields a liquid crystalline product.118 Of the iron(II) and iron(III) complexes [Fe([9]aneN 2 S) 2 ][ClO 4 ] 2 , [Fe([9]aneN 2 S) 2 ][ClO 4 ] 3 and [Fe([9]- aneNS 2 ) 2 ][ClO 4 ] 2 , the last two are low-spin, but the first exhibits spin–equilibrium behaviour.119 Seven-co-ordinate iron(III) complexes of [15]aneN 5 and related ligands are catalysts for the dismutation of superoxide ion.120 [Co(NO)(oep)] has a bent Co–N–O linkage (Co–N–O 122.7°) with the Co–N(NO) vector between the pair of short Co–N (porphyrin) bonds,121 but with less tilt than in similar iron compounds.This is seen as a bonding e§ect rather than a consequence of crystal packing. Stopped-flow EXAFS has been applied to the study of the reaction between Co(II) and a water-soluble sulfonated porphyrin.122 Several cobalt(III) complexes of cyclic thioethers have been prepared, including [Co([9]aneS 3 )Cl 3 ] and Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 173[Co([20]aneS 6 )][BF 4 ] 3 , and the structure of the latter determined.123 A decaaza macrocycle ligand (L1) forms a dicobalt complex [Co 2 (NCMe) 2 L][ClO 4 ] 4 in which trigonal-prismatic co-ordination is imposed because of the interaction between the MeCN ligands. However [Co 2 (l-OH)L][ClO 4 ] 3 is octahedral.124 [Ni(O 2 tpp)X 2 ] (X\halogen) react with aryl Grignards at 203K to produce rare paramagnetic organonickel(II) porphyrins such as [Ni(O 2 tpp)(Ph)X] and [Ni(O 2 tpp)Ph 2 ].On warming they decompose to the EPR-active Ni(I) species [Ni(O 2 tpp)Ph].125 [NiL]Cl 2 (L\3,14-dimethyl-2,6,13,17-tetraazatricyclo- [14,4,01.18,07.12]docosane) adds X~ (X\NCS, N 3 ) to form the tetragonally distorted high-spin [NiLX 2 ].126 Binding of pyrrolidine or piperidine to [Ni(tpp)] has been studied spectroscopically and the structure of [Ni(tpp)(pipd) 2 ] determined; there is a relationship between the orientation of the axial ligands and macrocyclic distortions. 127 [Ni([15]aneN 4 )N 3 ][PF 6 ] has a quasi 1-D structure with a superlattice along one axis.128 A dinickel complex of a macrocyclic ligand with two cyclam ligands arranged face-to-face has been described.129 The mixed complex [Ni([9]aneN 3 )([9]- aneS 3 )][ClO 4 ] 2 undergoes electrochemical and chemical oxidation to the corresponding Ni(III) species.130 A number of nickel(III) complexes of [14]aneN 6 ligands additionally bearing pendant arms (which in this case do not co-ordinate) have been synthesised. 131 7 Schi§ base and related complexes [Fe(salen)]` and [Fe(CN) 6 ]3~ react to form [MFe(salen)N2MFe(CN) 6N]~ units which have extended 2–D structures with Fe(S\5/2)–NC–Fe(S\1/2)–CN bridging units. The assembly depends upon the counter ion and the solvent; [NEt 4 ][MFe(salen)] 2 - [Fe(CN) 6N] is metamagnetic, and in ferromagnetic [MFe(salen)(MeOH) 2NMFe- (salen)N2MFe(CN) 6N] the [Fe(salen)(MeOH) 2 ]` ions act as counter cations between the interlayers.132 The structure of an oxygen-carrying Schi§ base complex 9, whose dimerization is prevented by bulky substituents, is reported.133 A five-co-ordinate high-spin cobalt Schi§ base complex reversibly binds O 2 in a Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 174range of solvents.134 When an oxygen-binding polymeric cobalt Schi§ base complex is compounded with a conductive carbon powder, the material can release absorbed oxygen when a voltage is supplied.135 Air-oxidation of a cobalt(II) salen system leads136 to an intramolecularly bridged compound 10 that is a simple model for coenzyme B 12 .The structure of the dimeric complex [Co 2 (sal-m-phen) 2 ] shows two bis(salicylideneaminato)cobalt(II) residues linked by two m-phenylene groups; cobalt has distorted tetrahedral co-ordination.137 Cobalt and nickel complexes have been prepared with similar ligands; they all show weak antiferromagnetic interactions between the metal ions.Nickel(II) and iron(III) complexes of the unsymmetrical N 3 O Schi§ base H 2 ambprsal (formed by reaction between 2-aminobenzaldehyde, propane- Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 1751,3-diamine and salicylaldehyde), planar [Ni(ambprsal)] and high-spin [FeCl(ambprsal)], have been synthesised.138 Nickel salicylaldimine complexes 11 act as catalysts for the polymerisation of ethene under mild conditions in the presence of a phosphine scavenger such as [Ni(cod) 2 ].139 The substitution of nickel for copper in [Cu(amben)]140 is catalysed by anions in the order [ClO 4 ]~\Br~\SCN~@Cl~, possibly reflecting their ability to form [Ni(dmf) 2 X 2 ].The reversal of the Irving–Williams order reflects the stability of the d8 square-planar complex [eqn.(1)]. A planar nickel complex 12 of a potential anti-inflammatory agent has been reported. 141 Nickel(III) Schi§ base complexes have been produced by electrochemical oxidation of Ni(II) complexes derived from naphthaldehyde, and identified by EPR spectroscopy. 142 Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 1768 Nitrosyl complexes X-Ray absorption spectroscopy143 of the inactive form of the enzyme nitrile reductase from Rhodoccus sp.R312 confirms that NO is bound to low-spin Fe3`.The structure of [Co(NO)(oep)] and other nitrosylporphyrins have already been alluded to.16,121 9 Iron binding agents The co-ordination chemistry of siderophores, including the thermodynamics and kinetics of iron chelation and release, has been reviewed.144 Hexadentate tris(salicylate) ligands have been used as models for triprotonated iron(III)-containing enterobactin.145A new macrocyclic bis(amine, amide, hydroxamate) ligand has a high complexing power for iron(III).146 A hexadentate chelating agent containing three 3-hydroxy-2(1H)-pyridinone moieties has a very high a¶nity for iron(III).147 A watersoluble tripodal ligand with three 2,2@-dihydroxybiphenyl groups connected to a tren framework has been synthesised as a new iron(III) chelator.148 Four amonabactins are siderophores from the pathogenic organism Aeromonas hydrophila; because they are tetradentate ligands, one molecule cannot complete the co-ordination sphere of one Fe3` and so they form complexes with the stoichiometry Fe 2 L 3 at high pH and excess ligand.(At lower pH and ligand concentration, 1: 1 complexes are formed.)149 The presence or absence of oxalate a§ects the oxidation state and phase of iron oxide or hydroxide produced by hydrolysis.150 Lariat crown ethers have been used for molecular recognition of ferrioxamine B through complexation of a pendant amine function by the lariat ether.151 10 Polynuclear complexes with oxo, hydroxo and related bridges, particularly those of iron A highlight is the synthesis of the 18–iron cyclic system, [MFe(OH)(xdk)Fe 2 (OMe)(O 2 CCH 3 ) 2N6 ], the largest cyclic cluster yet characterised.152 A ferric citrate complex has the composition [Hneo] 7 [Fe 9 O(cit) 8 (H 2 O) 3 ].This has a ‘triple-decker’ structure with three parallel triangular triiron units forming a slightly distorted trigonal prism.The two outer units are connected by three bridging citrates to the central triangle; the two remaining citrates cap the two ends. The central triangle has an oxo-bridged Fe 3 O core whilst the two terminal units have a Fe 3 O 4 core.153 Resonance Raman spectra of a number of compounds with a [Fe 2 (l-O) 2 ] ‘diamond’ core, [Fe 2 (l-O) 2 L 2 ][ClO 4 ] 3 (L\tpa, 5-Me 3 tpa, 5-Me 2 tpa, 5-Metpa, 5-Et 3 tpa, 3- Me 3 tpa) have been examined.154 It was proposed that a band between 650 and 700cm~1 is a signature for an iron cluster with such a core.A synthetic model of the deoxy form of hemerythrin 13 contains five- and six-coordinate iron, thus having a vacant site for the co-ordination ofO 2 ; it forms a dioxygen adduct with an optical spectrum very similar to that of oxyhemerythrin.155 The dimer [L(H 2 O)Fe(l-O)FeL(OH)][ClO 4 ] 3 ·H 2 O ML\N,N@-dimethyl-N,N@- bis(2-pyridylmethyl)ethane-1,2-diamineN has a hydrogen-bonded [(H 2 O)Fe(l- O)Fe(OH)] 3 ` unit with an Fe–O–Fe angle of 137.5° and significant antiferromagnetic Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 177coupling between the irons.156 On dissolution in MeCN it undergoes protonation and m4:.Fe–O–Fe shifts from 438 to 600cm~1, corresponding to a change in Fe–O–Fe to 111°, possibly associated with the formation of a diamond-shaped [(H 2 O)Fe(l-O)(l- OH)Fe(OH)]3` core. [FeIIFeIII(bplm)(OAc) 2 ] has a l-phenoxobis(acetato)diiron core with antiferromagnetically coupled high-spin irons; it is suggested as a model for the reduced form of purple acid phosphatase.157 In the presence of air, a methanolic solution of Fe(ClO 4 ) 3 containing tpa forms158 a dinuclear (l-oxo)(l-formato) complex [Fe 2 (tpa) 2 (l-O)(l-O 2 CH)][ClO 4 ] 3 ; if the reaction is performed in EtOH, the product is [Fe 2 (tpa) 2 (l-O)(l-O 2 CCH 3 )][ClO 4 ] 3 .Other compounds with l-oxo bridges supported by carbonate, bicarbonate and acetate bridges include [MFe-(bispicMe 2 ([)chxn)N2 (l-O)(l-CO 3 )][ClO 4 ] 2 ·4H 2 O, [MFe(bispicMe 2 ([)chxn)N2 (l-O)(l- HCO 3 )][ClO 4 ] 3 ·H 2 O and [MFe(bispicMe 2 ([)chxn)N2 (l-O)(l-OAc)][ClO 4 ] 3 · H 2 O whose structures have been reported.159 Diiron(II) complexes [Fe 2 (l-L)(l- O 2 CR)(O 2 CR)(base) 2 ] [L\dinucleating bis(carboxylate) based on mxylylenediaminebis( Kemp’s triacid imide); base\pyridine- or imidazole-derived ligand] have been synthesised as models for carboxylate-bridged non-heme diiron enzymes.The bridging carboxylate ligand shifts between monodentate and bidentate mode. Solutions of these iron(II) compounds turn deep blue when oxygenated, due to the formation of diiron(III) peroxo species, with a stoichiometry of one O 2 per Fe 2 centre.160 A dicarboxylate ligand based on a porphyrin rather than xylylenediamine binds three iron atoms, one in the porphyrin ring and two linked by two dicarboxylate bridges as a [Fe 2 (l-O 2 CR) 2 ]2` unit.161 The compound [Fe 2 L 2 (l-OMe) 2 ]·0.5MeOH [L\1,2-bis(2@-hydroxybenzyl)ethane-1,2-diamine] contains two asymmetric methoxo bridges with Fe–O distances of 1.980 and 2.040Å.162 [Fe 2 O(bipy) 4 Cl 2 ][ClO 4 ] 2 ·0.25MeCN·0.25MeOH·0.25H 2 O has a slightly bent oxo bridge (167.0°) and shows strong antiferromagnetic coupling between the Fe(III) centres.163 On recrystallisation from MeCN, [NEt 4 ][M 2 (OAc) 5 py 2 (l-OH 2 )] (M\Fe, Co) convert to trinuclear [NEt 4 ] 2 [M 3 (OAc) 8 ].The iron compound undergoes aerial oxidation to the mixed-valence compound [NEt 4 ][Fe 3 (l3 - O)(OAc) 7 (H 2 O)].Oxygen and peroxide oxidation of pyridine solutions of [NEt 4 ]- [Fe 2 (OAc) 5 (py) 2 (l-H 2 O)] in the presence of chloride gives [Fe 4 (l3 -O) 2 (OAc) 6 (py) 4 - Cl 2 ], which has a [FeIII 4 (l3 -O) 2 ] core. All these compounds catalyse the oxidation of adamantane to adamantanols and adamantanone under Gif conditions.164 Iron(III) nitrate reacts with H 5 dhpta and excess RCH(NH 2 )CO 2 H (R\H, Me) to a§ord tetranuclear iron(III) complexes Na[Fe 4 (dhpta) 2 (l-O)(l-OH)(O 2 CCHRNH 3 ) 2 ].These contain two identical dimer units, each bridged by dhpta, the units being linked by the oxo-, hydroxo- and carboxylate bridges.165 The high O–O stretching frequency in the binuclear l-1,2 peroxide-bridged iron(III) complex [Fe 2 (O 2 )(O 2 CPh) 2 (TpP3* ) 2 ] is due to strong coupling between the Fe–Oand O–O stretching vibrations rather than to an especially strong O–O bond.166 Use of multidentate ligands is now a well-established approach to cluster synthesis.Reaction of FeCl 3 with sodium benzoate and 2,2@-bipyridyl in MeCN gives [Fe 4 O 2 (O 2 CPh) 7 (bipy) 2 ][FeCl 4 ].Linking two bipy units together in 1,2–bis(2,2@- bipyridin-6-yl)ethane (L) a§ords a tetradentate ligand; its reaction with FeCl 3 and sodium benzoate in MeCN results in a six-iron cluster [Fe 6 O 4 Cl 4 (O 2 CPh) 4 L 2 ]- [FeCl 4 ] 2 which has a [Fe 6 (l3 -O) 4 ]10` core. Carrying out the reaction in MeOH gives a di§erent cluster, [Fe 2 (l-OMe) 2 (O 2 CPh)L][FeCl 4 ], with an [Fe 2 (l-OMe) 2 ]4` Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 165–188 178core.167 [(bipy) 2 (NO 3 ) 2 Fe(l-O)Fe(NO 3 ) 2 (bipy) 2 ] contains seven-co-ordinate iron.168 The compound Fe 3 (OAsPh 3 ) 4 Cl 6 (MeCN) is in fact [(Ph 3 AsO) 4 Fe(l-O)FeCl 3 ]- [FeCl 4 ]·MeCN.169 l-Oxo-bridged binuclear iron(III) complexes of the tetradentate ligand 2,2@: 6@,2A: 6A,2@@@-quaterpyridine, [M(H 2 O)(qtpy)FeN2 (l-O)][ClO 4 ] 4 ·2H 2 O, have been synthesised.170 Use of a poly(pyrazolyl)borate ligand permits the isolation of dimeric cobalt- and nickel-(III) complexes [TpM%3M(l-O) 2 MTpM%3] (M\Co, Ni) in which the metals are in SPY five-co-ordination. These are the first dinuclear nickeland cobalt-(III) bis(l-oxo) complexes to be characterised (though the nickel compound decomposes rather rapidly at room temperature).The corresponding M(II) complexes [TpM%3M(l-OH) 2 MTpM%3] were also isolated.171 11 Other cluster complexes Structure–function correlations in high-potential proteins, which contain [Fe 4 S 4 ] clusters, have been reviewed.172 [NEt 4 ] 3 [Fe 4 S 4 (SH) 4 ][NEt 4 ]Cl has been synthesised and its crystal structure determined.173 The structure previously reported to be of [NPr 4 ] 2 [Fe 4 S 4 (SH) 4 ] has been shown to be that of [NPr 4 ] 2 [Fe 4 S 4 Cl 4 ], formed by reaction with the solvent during crystal growth.The Fe–S bond lengths for [Fe 4 S 4 (SR) 4 ]z (z\[1, [2, [3) clusters in a range of oxidation states were compared. 173 The syntheses and structures of two cycloalkylthiolate clusters [NMe 3 Bz] 2 - [Fe 4 S 4 (SC 5 H 9 ) 4 ] and [NEt 4 ] 2 [Fe 4 S 4 (SC 6 H 11 ) 4 ] have been reported,174 as has that of the dithiocarbamate175 [NEt 4 ] 2 [Fe 4 S 4 (S 2 CNEt 2 ) 4 ].Successive protonation of [Fe 4 S 4 (SPh) 4 ]2~ labilizes the thiols towards substitution, whilst in the case of [Fe 4 S 4 Cl 4 ]2~ the first protonation labilizes the complex but the second protonation inhibits substitution of the chlorides.176 The ligand N,N@-diethyl-3,7–diazanonane- 1,9–dithiol forms hexanuclear complexes containing both stair-like [Fe 6 (l3 -S) 4 (l- SR) 4 ] and nest-like [Fe 6 (l3 -S) 2 (l-S) 2 (l4 -S)(l-SR) 4 ] cores.177 Cuboidal iron–sulfur clusters with bulky phosphines [Fe 4 S 3 (NO) 4 (PR 3 ) 3 ]n` (R\Et, Pr*, Cy; n\0, 1) have been characterized.178 [Fe 4 S 4 (SEt) 2 (CNBu5) 6 ] reacts with PhCH 2 SSSCH 2 Ph to form [Fe 8 S 12 (CNBu5) 12 ].This is a cluster based on two Fe 4 (l3 -S) 3 (l3:g2,g1-S 2 ) units bridged by two l-S ions. [Fe 4 S 4 (SEt) 2 (CNBu5) 6 ] has two octahedrally co-ordinated and two tetrahedrally co-ordinated irons.179 Iron and cobalt formamidinate clusters such as [M 4 O(dphf) 4 ] have the basic beryllium acetate structure.180 A ‘witches-brew’ reaction between CoCl 2 , Habt, NaOMe and PBu/ 3 , followed by addition of excess Li 2 S, a§ords a triangular sulfur-capped tricobalt cluster [Co 3 (l3 - S)(abt) 3 (PBu/ 3 ) 3 ].181 The optically active partial cubane cluster [Co 4 (l3 -OH) 3 (l3 - O)(edma) 3 ]Cl has been synthesised and resolved.182 The mixed-valence compound [Co 6 L 2 (CH 3 CO 2 ) 2 (OMe) 6 L@]·2MeOH [L\2,6-bis(salicylideneaminomethyl)-4- methylphenol; L@\salicylazine] has a structure made of two linked defective cubane cores.183 Syntheses and structures are reported184 for the symmetrical cubane [Co 4 (l3 -O) 4 (l3 -CH 3 CO 2 ) 4 (py) 4 ]·5CHCl 3 and the partial cubane [Co 4 (l3 -O) 4 (l3 - OH) 3 (l3 -CH 3 CO 2 )(CH 3 CO 2 )(py) 6 ][PF 6 ] 2 ·2H 2 O.The mixed cluster [Co 3 Fe(mp) 4 - (HMp)(PBu 3 ) 3 ], which contains a Co 3 FeS 4 O 3 core, results from another ‘witches brew’ synthesis involving CoCl 2 , FeCl 3 , H 2 mp, NaOMe and PBu 3 .185 [NH 4 ]- [Co 8 (OAc) 8 (OMe) 16 ][PF 6 ] is the result of a self-assembly reaction in methanolic solutions of cobalt(III) acetate in the presence of NH 4 PF 6 .186 Annu.Rep. Prog. Chem., Sect.A, 1999, 95, 165–188 179Reaction of NiCl 2 ·6H 2 O with Bu5CO 2 H and KOH forms a nonanickel cluster [Ni 9 (Bu5CO 2 H) 4 (l4 -O) 3 (l3 -OH) 3 (Bu5CO 2 ) 12 ], which contains both Ni-(II) and -(III). It is cleaved by donors such as pyridine, a§ording [Ni 2 (py) 4 (O 2 CBu5) 2 (l-O 2 CBu5) 2 (l- OH)] which gives the Ni(II) compound [Ni 2 (py) 2 (HO 2 CBu5) 2 (O 2 CBu5) 2 (l-OH 2 )] on pyrolysis.187 12 Complexes with unusual magnetic properties, including spin-crossover compounds The Kikuchi cluster variation method has been applied to modelling two step highspinflow- spin transitions.188 Iron(II) complexes Iron(II) complexes of 1,2,4-triazole, tetraazole and their derivatives that exhibit thermo- and photo-induced spin state transitions have been reviewed.189 Tris(2- pyridylmethyl)amine complexes of iron(II) illustrate how magnetic properties depend upon the anion.38 The Preisach model has been applied to a study of the hysteresis loops in [Fe(btr) 2 (NCS) 2 ]·H 2 O and [Fe(bt) 2 (NCS) 2 ].190 Three polymorphs of [Fe(dppa)(NCS) 2 ] all have octahedral co-ordination with cis-thiocyanates but with slightly di§erent crystal packing in the solid state.191 One polymorph has an S\2 ground state from 4.5 to 295 K, the second shows a gradual high-spinflow-spin transition without hysteresis and the third an abrupt high-spinflow-spin transition with hysteresis.[Fe(pybzim) 2 ][ClO 4 ] 2 ·H 2 O is diamagnetic \85K and high-spin (k%&& \4.5–5.3 kB )[160 K; it exhibits a spin–equilibrium.192 In [Fe(bzimpy) 2 ]- [ClO 4 ] 2 ·0.25H 2 O, iron is octahedrally co-ordinated by six nitrogens; it exhibits a spin-crossover with broad hysteresis.193 All of the complexes [Fe(bzimpy) 2 ][BPh 4 ] 2 · xH 2 O, (x\4, 2 and 0) have been synthesised; the tetrahydrate exhibits a spin transition centred at room temperature.194 The dihydrate and anhydrous complex are high-spin. The [Fe(bzimpy) 2 ]2` ion exhibits spin-crossover behaviour in 50% propanediol- 1,2–carbonate–MeOH.195 The structure of the spin equilibrium compound [Fe(pm-bia) 2 (NCS) 2 ] has been determined in both spin states and shows an unusually large di§erence in Fe–N bond lengths; it has a very abrupt spin state transition between the S\0 and S\2 states with a 5K hysteresis loop and exhibits LIESST at low temperatures.196 The syntheses and magnetic properties of [Fe(dpq) 2 (NCS) 2 ]· Me 2 CO and [Fe(abpt) 2 (NCX) 2 ] (X\S, Se) are reported.197 The first has an FeN 6 co-ordination sphere and is high-spin; the other two show S\5/2 and S\1/2 spin equilibria.A wide-angle X-ray scattering study of [Fe(Htrz) 2 (trz)][BF 4 ] and [Fe(Htrz) 3 ][NO 3 ] 2 revealed polymeric structures; they are low-spin at room temperature and high-spin above room temperature.198 In the low-spin state, the chain is linear; the magnetic transition causes an elongation and deformation of the chain.[Fe(hyetrz) 3 ][3-O 2 NC 6 H 4 SO 3 ] 2 ·3H 2 O is low-spin at room temperature; on heating, the three water molecules are lost and the anhydrous compound transforms via a metastable low-spin state to a high-spin form.199 A more extensive study showed that [Fe(hyetrz) 3 ]X 2 ·3H 2 O (X\Cl, Br, I, NO 3 , BF 4 , ClO 4 , PF 6 ) contain linear chains of Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 180Fe(II) ions involving the neighbouring N(1) and N(2) atoms in the triazole ring. Most of these compounds, like the 3-nitrophenylsulfonate, exhibit non-classical spin-crossover behaviour when the lattice water molecules that stabilise the low-spin state are removed.However, dehydration of the iodide and perchlorate shifts the spin-state transition temperature, which increases with decreasing ionic radius. A rarity, [Fe(hyetrz) 3 ]I 2 exhibits a crossover at room temperature (291 K) with a 12K hysteresis loop.200 At room temperature, [FeM(Et 2 N) 3 terpyN2 ][PF 6 ] 2 has k%&& \1.6 kB indicating thermal population of the S\2 state; studies on Co(II) complexes support the view that electron-donating p-substituents in the terpyridine rings weaken the ligand field.201 Complexes of a ligand derived from terpy, by replacing a terminal pyridine ring with a thiazole ring, have been studied.[Fe(thzby) 2 ][PF 6 ] 2 is low-spin, as is [Fe(mthzby) 2 ]- [BF 4 ] 2 , though in the latter there is evidence of a high-spin species at high temperatures.Replacing the central pyridine ring with a thiazole, forming pythiaz, reduces the ligand field, so that [Fe(pythiaz) 2 ][BF 4 ] 2 is high-spin. The structures of all three compounds show the characteristic Fe–N bond lengths for the spin state in question. 202a A further study in which the terminal pyridine ring of terpy is replaced by a triazole system, forming the ligands 6–(1,2,4–triazol-3-yl)-2,2@-bipyridine, 6-(1-methyl- 1,2,4-triazol-3-yl)-2,2@-bipyridine and 6-(1,5-dimethyl-1,2,4-triazol-3-yl)-2,2@-bipyridine, produced complexes that are low-spin at room temperature but where there is some population of the high-spin state on increasing the temperature.202b The complexes [Fe(bpyam) 2 ]X 2 (X\BF 4 , ClO 4 , CF 3 SO 3 ) are high spin; on cooling, the perchlorate and triflate undergo a partial transition to a singlet state.203 The structure of [Fe(bpyam) 2 ][BF 4 ] 2 was determined.The spin-crossover compound bis[hydrotris( 1,2,4-triazolyl)borato]iron has been studied as pure and diluted solids and also in solution.204 Iron(III) complexes The first low-spin iron(III) semiquinonate complex has been reported.205 [Fe(LN 4 Me 2 )(dnbsq)][ClO 4 ] 2 ·2.5H 2 O is low-spin with the unpaired electron of the Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 181semiquinonate strongly antiferromagnetically coupled with the unpaired electron of the metal. Iron(III) cryptates and podands have been studied 14.The cryptates, with FeN 6 co-ordination spheres, are S\3/2 systems compared with analogous azaphenolates with FeN 4 O 2 co-ordination spheres.206 Another example of an S\3/2 iron(III) system is provided by a complex 15 with a square-pyramidal FeClN 2 S 2 co-ordination sphere.207 Six-co-ordinate iron(III) Schi§ base species of the general type [Fe(salen@)(Him) 2 ]Y [e.g.salen@\N,N@-4-chloro-o-phenylenebis(3-methoxysalicylidineimine); Y\ClO 4 , PF 6 , BPh 4 ] can be high-spin, low-spin or exhibit a S\5/2fS\1/2 spin–equilibrium, 208 as in the case of [Fe(salen@)(Him) 2 ][ClO 4 ]. Magnetic properties are reported for iron(III) complexes of tridentate (O,N,O; O,N,S; and O,N,N) and of tetradentate (O,N,N,O) azomethine ligands.209 Spin–equilibria are observed for compounds of the (O,N,S) ligand such as 16 and for [FeXL(NCS)] [X\py or Me 2 CO; L\S-substituted N1-salicylidene-N4-M5–(R)-salicylideneisothiosemicarbazoneN].210 Spin– equilibrium behaviour is also reported for dinuclear diiron(III) complexes with thiolate bridges.211 Cobalt complexes [Co(bipy) 3 ]2` ions are high-spin in solid salts or solution; when encapsulated in zeolite-Y supercages, the normally trigonally distorted cation undergoes a twist that results in a near-octahedral geometry, causing it to exhibit spin-crossover behaviour. 212 Intramolecular electron transfer between cobalt(II) semiquinonate and cobalt( III) catecholate has been investigated in the compounds [Co(N–N)(3,6-dbbq) 2 ] Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 182(N–N\tmmda, tmen, tmpda).The transition temperature for redox equilibrium is lowest for [Co(tmpda)(3,6-dbbq) 2 ], attributed to the flexibility of the six-membered metal–chelate ring. The structures of [CoII(tmmda)(3,6-dbc)(3,6-dbsq)], [CoII(tmedn)(3,6-dbc)(3,6-dbsq)] and [CoIII(tmpda)(3,6-dbsq) 2 ] were reported.213 The compound [Co(L)(3,6-dbbq) 2 ] (L\phen or 4,7-substituted phen) shows solvent dependent redox equilibria214 and is mainly quinone-centred rather than metal-centred in CH 2 Cl 2 .A cobalt complex 17 of a Schi§ base diquinone [CoIII(cat-N-bq)(Cat-Nsq)] exhibits an equilibrium in solution forming [CoII(cat-N-bq) 2 ]. This is temperature- dependent, the solutions changing colour from green-blue to brick brown on cooling together with the appearance of an EPR signal.215 References 1 A.K.Powell, Struct. Bonding, 1997, 88, 2. 2 M. J. Maroney, G. Davidson, C. B. Allan and J. Figlar, Struct. Bonding, 1998, 92, 2. 3 E. Nordlander, A. Thapper, J. King, C. Lorber, H. Carlson, F. Prestopino and N. Focci, Coord. Chem. Rev., 1998, 172, 3. 4 M.B. Davies, Coord. Chem. Rev., 1998, 169, 237. 5 S. J. Higgins, Coord. Chem. Rev., 1997, 164, 503. 6 G. Foulds, Coord. Chem. Rev., (a) 1997, 162, 1; (b) 1997, 162, 75; (c) 1998, 169, 3. 7 M.B. Davies, Coord. Chem. Rev., 1998, 164, 27. 8 M. Melnik, V. Vancova, I. Ondrejkovicova and C. E. Holloway, Rev. Inorg. Chem., 1998, 18, 1. 9 S. Bhattacharaya, B. Saha, A. Dutta and P. Banerjee, Coord. Chem. Rev., 1998, 170, 47. 10 H. Ogino, S. Inomata and H. Tobita, Chem. Rev., 1998, 98, 2093. 11 R. H. Holm, Pure Appl. Chem., 1998, 70, 931. 12 M. Suzuki, Pure Appl. Chem., 1998, 70, 955. 13 R.M. Wood and G. J. Palenik, Inorg. Chem., 1998, 37, 4149. 14 A. Reife, E. Weber and H. S. Freeman, CHEMTECH, October 1997, 17. 15 E. G. Pavel, N. Kitajima and E. I. Solomon, J. Am. Chem. Soc., 1998, 120, 3949. 16 A.M. Rich, R. S. Armstrong, P. J. Ellis and P. A. Lay, J. Am. Chem.Soc., 1998, 120, 10 827. 17 K. Rose, S. E. Shadle, M. K. Eidsness, D.M. Kurtz, R. A. Scott, B. Hedman, K. O. Hodgson and E. I. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 183Solomon, J. Am. Chem. Soc, 1998, 120, 10 743. 18 N. Mizuno, C. Nozaki, I. Kiyoto and M. Misono, J. Am. Chem. Soc., 1998, 120, 9267. 19 D. Chen and R. Xu, Mater. Res. Bull., 1998, 33, 1015. 20 A.Demourgues, L. Gautier, A. V. Chadwick and C. Delmas, Nucl. Instrum. Methods Phys. Res., Sect. B, 1997, 133, 39; Chem. Abstr., 1998, 128, 135 677. 21 T. N. Polynova, A. L. Poznyak and A. B. Ilyukhin, Kristallografiya, 1997, 42, 929; Crystallogr. Rep. (Transl. Kristallogorafiya), 1997, 42, 858. 22 S. Seibig and R. van Eldik, Inorg. Chim. Acta, 1998, 279, 37. 23 K. A. Abboud, C. Xu and R.S. Drago, Acta Crystallogr., Sect. C., 1998, 54, 1270. 24 J. N. Bridson, S. Quinlan and P. R. Tremaine, Chem. Mater., 1998, 10, 763. 25 V. Zima and K.-H. Li, J. Solid State Chem., 1998, 139, 326. 26 M.B. Korzenski, G. L. Schimek and J. W. Collis, Eur. J. Solid State Inorg. Chem., 1998, 35, 143. 27 T. Nakamoto, M. Katada, K. Endo and H. Sano, Polyhedron, 1998, 17, 3507. 28 A.M.Bond, R. J. H. Clark, D. G. Humphrey, P. Panayiotopoulos, B. W. Skelton and A. H. White, J. Chem. Soc., Dalton Trans., 1998, 1845. 29 C. Buchanan, S. Parsons and R. E. P. Winpenny, Acta Crystallogr., Sect. C., 1998, 54, 762. 30 L. R. MacGillivray and J. L. Atwood, J. Chem. Crystallogr., 1997, 27, 453. 31 R. J. Staples, T. L. Hatfield and D. T. Pierce, Z. Kristallogr.-New Cryst.Struct., 1998, 213, 243. 32 R.W. Hay, S. Albedhyl and P. Lightfoot, Transition Met. Chem., 1998, 23, 257. 33 W.-S. Li, A. J. Blake, N. R. Champness, M. Schro� der and D.W. Bruce, Acta Crystallogr., Sect. C, 1998, 54, 349. 34 M. Sassmannshausen and H. D. Lutz, Acta Crystallogr., Sect. C, 1997, 54, 704. 35 G. Thiele and G. Wittenberg, Acta Crystallogr., Sect. C, 1998, 50, 764. 36 G.M.Lucier, C. Shen, S. H. Elder and N. Bartlett, Inorg. Chem., 1998, 37, 3829. 37 M. Ray, B. S. Hammes, G. P. A. Yap, A. L. Rheingold and A. S. Borovik, Inorg. Chem., 1998, 37, 1527. 38 A. Diebold and S. Hagen, Inorg. Chem., 1998, 37, 215. 39 K. R. J. Thomas, M. Velusamy and M. Palaniandavar, Acta Crystallogr., Sect. C., 1998, 50, 741. 40 P. Kulkarni, S. Padhye and E. Sinn, Polyhedron, 1998, 17, 2623. 41 G. De Munno, W. Ventura, G. Viau, F. Lloret, J. Faus and M. Julve, Inorg. Chem., 1998, 37, 1458. 42 J. Sletten, H. Daragmeh, F. Lloret and M. Julve, Inorg. Chim. Acta, 1998, 279, 127. 43 M. Nieuwenhuyzen, B. Bertram, J. F. Gallagher and J. G. Vos, Acta Crystallogr., Sect. C, 1998, 54, 603. 44 (a) B.L. Small and M. Brookhart, J. Am. Chem. Soc., 1998, 120, 7143; (b) B.L.Small, M. Brookhart and A.M. A. Bennett, J. Am. Chem. Soc., 1998, 120, 4049. 45 N. Arulsamy, D. S. Bohle, B. Hansert, A. K. Powell, A. J. Thomson and S. Wocaldo, Inorg. Chem., 1998, 37, 746. 46 H. Boerzel, P. Comba, H. Pritzkow and A. F. Sickmueller, Inorg. Chem., 1998, 37, 3853. 47 M.R. Girard, J. Li and D. M. Prosperio, Main Group Met. Chem., 1998, 21, 231. 48 I. Morgenstern-Badarau, F.Lambert, A. Deroche, M. Cesario, J. Guilhem, B. Keita and L. Nadjo, Inorg. Chim. Acta, 1998, 275–276, 234. 49 K. Nakayama, T. Ishida, R. Takayama, D. Hashizume, M. Yasui, F. Iwasaki and T. Nogami, Chem. Lett., 1998, 497. 50 F. Lloret, G. Di Munno, M. Julve, J. Cano, R. Ruiz and A. Caneschi, Angew. Chem., Int. Ed., 1998, 37, 135. 51 J. Lu, C. Yu, T. Niu, T. Paliwala, G.Crisci, F. Somosa and A. J. Jacobson, Inorg. Chem., 1998, 37, 4637. 52 Z. N. Chen, A. Siu, C. Y. Su, I. Williams and B. S. Kang, Acta Crystallogr., Sect. C, 1998, 54, 479. 53 F. Tafesse, Inorg. Chim. Acta, 1998, 269, 287. 54 M.D. Fryzuk, D. B. Lezno§, R. C. Thompson and S. J. Rettig, J. Am. Chem. Soc., 1998, 120, 10 126. 55 F. A. Cotton, L.M. Daniels, G. T. Jordan and C. A.Murillo, Polyhedron, 1998, 17, 589. 56 D. Collison, M. Helliwell, V. M. Jones, F. E. Mabbs, E. J. L. McInnes, P. C. Riedi, G. M. Smith, R. G. Pritchard and W. I. Cross, J. Chem. Soc., Faraday Trans., 1998, 94, 3019. 57 K. Himmel and M. Jansen, Chem. Commun., 1998, 1205. 58 Z. Travnicek, P. Kopel and J. Marek, Z. Kristallogr. -New Cryst. Struct., 1998, 213, 149. 59 Y. Hatashi, H.Mano and A. Uehira, Chem. Lett., 1998, 899. 60 B.-H. Ye, X.-M. Chen, G.-Q. Xue and L.-N. Ji, J. Chem. Soc., Dalton Trans., 1998, 2827. 61 N. Fukita, M. Ohba, H. Okawa, K. Matsuda and H. Iwamura, Inorg. Chem., 1998, 37, 842. 62 I. R. Laskar, D. Das, N. R. Chaudhuri, G. Mostafa and A. J. Welch, Polyhedron, 1998, 17, 1363. 63 I. R. Laskar, D. Das, G. Mostaf, A. J. Welch and N. R. Chaudhuri, Acta Chem.Scand., 1998, 52, 702. 64 Y. Ihara, T. Sakino, M. Ishikawa and T. Koyota, Bull. Chem. Soc. Jpn., 1997, 70, 3025. 65 D. Das, G. Mostafa, K.-I. Okamoto and N. R. Chaudhuri, Polyhedron, 1998, 17, 2567. 66 S. Ghosh, G. Mostafa, M. Mukherjee, A. K. Mukherjee, C. Pariya and N. R. Chaudhuri, Z. Kristallogr., 1998, 213, 493. 67 Y. Ihara, K. Teranishi, N. Hirose and K. Sone, Polyhedron, 1998, 17, 3247. 68 M. Velusamy, M. Palaniandavar and K. R. J. Thomas, Polyhedron, 1998, 17, 2179. 69 M. Ito, T. Ishihara and Y. S. Takita, Surf. Sci. Catal., 1998, 114, 499; Chem. Abstr., 1998, 129, 103 380. 70 F. Meyer, A. Jacobi, B. Nuber, P. Rutsch and L. Zsolani, Inorg. Chem., 1998, 37, 1213. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 18471 C. Dietz, F.W. Heinemann, J. Kuhnigk, C. Kru� ger, M. Gerdan, A. X. Trautwein and A. Grohmann, Eur. J. Inorg. Chem., 1998, 1041. 72 A. Escuer, S. B. Kumar, F. Mautner and R. Vicente, Inorg. Chim. Acta, 1998, 269, 313; N. P. Nayak, A. K. Mukherjee, A. Mondal and N. R. Chaudhuri, Acta Crystallogr., Sect. C, 1998, 54, 208. 73 A. Escuer, Rcente, M. Salah El Fallah, X. Solans and M. Font-Bardia, Inorg.Chim. Acta, 1998, 278, 43. 74 H. Nakano, M. Hagiwara, T. Chihara and M. Takahashi, J. Phys. Soc. Jpn., 1997, 66, 2997; Chem. Abstr., 1997, 128, 56 426. 75 C. C. Wang, W. C. Lo, C. C. Chou, G. H. Lee, J. M. Chen and S. M. Peng, Inorg. Chem., 1998, 37, 4059. 76 B. Wiesler, F. Tuczek, C. Na� ther and W. Bensch, Acta Crystallogr., Sect. C, 1998, 54, 44. 77 B. Wiesler, N. Lehnert, F. Tuczek, J.Neuhausen and W. Tremnel, Angew. Chem., Int. Ed., 1998, 37, 815. 78 M. F. Meidine, M. A. N. D. A. Lemos, A. J. L. Pombeiro, J. F. Nixon and P. B. Hitchcock, J. Chem. Soc., Dalton Trans., 1998, 3319. 79 Y. Gao, D. G. Holah, A. N. Hughes, G. J. Spivak, M. D. Havighurst and V. R. Magnuson, Polyhedron, 1998, 17, 3881. 80 M. G. Basalotte, J. Dura� n, J. Ferna� ndez-Trujillo and M. A.Ma� n8 ez, J. Chem. Soc., Dalton Trans., 1998, 2205. 81 L. D. Field, I. P. Thomas, T. W. Hambley and P. Turner, Inorg. Chem., 1998, 37, 612. 82 P. T. Ndifon, C. A. McAuli§e, A. G. Mackie and R. G. Pritchard, Inorg. Chim. Acta, 1998, 282, 25. 83 S. C. Davies, R. A. Henderson, D. L. Hughes and K. E. Oglieve, J. Chem. Soc., Dalton Trans., 1998, 425. 84 M. S. Thomas and J.Darkwa, Polyhedron, 1998, 17, 1811. 85 D. Cauzzi, C. Grai§, M. Lanfranchi, G. Predieri and A. Tiripicchio, Inorg. Chim. Acta, 1998, 273, 320. 86 K. Ramalingam, O. B. Shawkataly, H. K. Fun and R. Ibrahim, Acta Crystallogr., Sect. C, 1998, 54, 1223. 87 E. C. Alyea, G. Ferguson and S. Kannan, Polyhedron, 1998, 17, 2727. 88 M. James, H. Kawaguchi and K. Tatsumi, Polyhedron, 1998, 17, 1843. 89 M. James, J. Chem. Soc., Dalton Trans., 1998, 2757. 90 R. Hauptmann, J. Schneider and G. Henkel, Z. Kristallogr.-New Cryst. Struct., 1998, 213, 783. 91 O. S. Jung, S. H. Park, D. C. Kim and K. M. Kim, Inorg. Chem., 1998, 37, 610. 92 Z. Atherton, D.M. L. Goodgame, S. Menzer and D. J. Williams, Inorg. Chem., 1998, 37, 849. 93 Z. Atherton, D.M. L. Goodgame, D. A. Katahira, S.Menzer, A. J. P. White and D. J. Williams, Polyhedron, 1998, 17, 2257. 94 A. T. Okamura, S. Takamizawa, N. Ueyma and A. N. Akamura, Inorg. Chem., 1998, 37, 18. 95 S. C. Davies, D. L. Hughes, R. L. Richards and J. R. Sanders, Chem. Commun., 1998, 2699. 96 J. A. Alden, A. M. Bond, R. Colton, R. G. Compton, J. C. Eklund, Y. A. Mah, P. J. Mahon and V. Tedesco, J. Electroanal. Chem.Interfacial Electrochem., 1998, 447, 155. 97 D. Y. Kong, Q. Zhu, Y.-Y. Xie and X.-Y. Huang, Chinese J. Struct. Chem., 1998, 17, 337. 98 D. Collison, C. D. Garner, C. M. McGrath, J. F. Mosselmans, E. Pidcock, M. D. Roper, B. G. Searle, J. M.W. Seddon, E. Sinn and N. A. Young, J. Chem. Soc., Dalton Trans., 1998, 4179. 99 Z. Travnicek, R. Pastorek, Z. Sindelar and J. Marek, J. Coord.Chem., 1998, 44, 193. 100 K. Ramalingam, O. Bin Shawkataly, H. K. Fun and A. R. Ibrahim, Acta Crystallogr., Sect. C, 1998, 54, 1223. 101 S. B. Schougaard, T. Pittelkow, F. Krebs, H. O. Sørensen, D. R. Greve and T. Bjørnholm, Acta Crystallogr., Sect. C, 1998, 54, 470. 102 J. E. Huyett, S. B. Choudhury, D. M. Eichhorn, P. A. Bryngelson, M. J. Maroney and B. M. Ho§man, Inorg. Chem., 1998, 37, 1361. 103 S. Sun, P. Wu, D. Zhu, Z. Ma and N. Shi, Inorg. Chim. Acta, 1998, 268, 103. 104 A. Rosa, G. Ricciardi and E. J. Baerends, Inorg. Chem., 1998, 37, 1368. 105 M. K. Davies, W. Levason and G. Reid, J. Chem. Soc., Dalton Trans., 1998, 2185. 106 J. L. Kisko, T. Hascall and G. Parkin, J. Am. Chem. Soc., 1998, 120, 10 561. 107 J. M. Je§eris and G. S. Girolami, Organometallics, 1998, 17, 3630. 108 C. A. L. Becker, Synth. React. Inorg. Met.-Org. Chem., 1998, 28, 1145; Chem. Abstr., 1998, 129, 239 073. 109 J. Wu, T. Komatsu and E. Tsuchida, J. Chem. Soc., Dalton Trans., 1998, 2503. 110 O. Q. Munro and W.R. Scheidt, Inorg. Chem., 1998, 37, 2308. 111 R. Potz, H. Hueckstaedt and H. Homberg, Z. Anorg. Allg. Chem., 1998, 624, 173. 112 A. Kienast and H. Homberg, Z.Anorg. Allg. Chem., 1998, 624, 233. 113 N. Ueyama, N. Nishikawa, Y. Yamada, T. Okamura, S. Oka, H. Sakurai and A. Nakamura, Inorg. Chem., 1998, 37, 2415. 114 S. Wolowiec, L. Latos-Graztnski, D. Toronto and J.-C. Marchon, Inorg. Chem., 1998, 37, 724. 115 K.M. Kadish, A. Tabard, E. Van Caemelbecke, A. M. Aukauloo, P. Richard and R. Guilard, Inorg. Chem., 1998, 37, 6168. 116 M. Mazzanti, J.-C.Marchon, J. Wojaczynski, S. Wolowiec, L. Latos-Grazynski, M. Shang and W.R. Scheidt, Inorg. Chem., 1998, 37, 2476. 117 S. Wolowiec, L. Latos-Grazynski, M. Mazzanti and J.-C. Marchon, Inorg. Chem., 1997, 36, 5761. 118 G. H. Walf, R. Benda, F. J. Litterst, U. Stebani, S. Schmidt and G. Lattermann, Chem. Eur. J., 1998, 4, 93. 119 V. A. Grillo, L. R. Gahan, G. R. Hanson, R.Stranger, T. W. Hambley, K. S. Murray, B. Moubaraki and Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 185J. D. Cashion, J. Chem. Soc., Dalton Trans., 1998, 2341. 120 D. Zhang, D. H. Busch, P. L. Lennon, R. H. Weiss, W. L. Neumann and D. P. Riley, Inorg. Chem., 1998, 37, 956. 121 M. K. Ellison and W.R. Scheidt, Inorg. Chem., 1998, 37, 382. 122 K. Ozutsumi, S. Ohnishi, H.Ohtaki and M. Tabata, Z. Naturforsch., Teil B, 1998, 53, 469. 123 G. J. Grant, S. S. Shoup, C. E. Hadden and D. G. VanDerveer, Inorg. Chim. Acta, 1998, 274, 192. 124 C. Wendelstorf and R. Cramer, Angew Chem., Int. Ed. Engl., 1997, 36, 2791. 125 P. J. Chmielewski and L. Latos-Grazynski, Inorg. Chem., 1998, 37, 4179. 126 K. Y. Choi, H. Ryu and I. H. Suh, Polyhedron, 1998, 17, 1241. 127 S.-L.Jia, W. Jentzen, M. Shang, X.-Z. Song, J.-G. Ma, W.R. Scheidt and J. A. Shelnutt, Inorg. Chem., 1998, 37, 4402. 128 Y. Yu, Z. Honda and K. Katusmata, RIKEN Rev., 1997, 15, 93; Chem. Abstr., 1998, 128, 17 970. 129 M. Lachkar, R. Guilard, A. Atmani, A. De Cian, J. Fischer and R. Weiss, Inorg. Chem., 1998, 37, 1575. 130 A. McAuley, S. Subramanian, M. J. Zaworotko and R. Atencio, Inorg.Chem., 1998, 37, 4607. 131 M. P. Suh, E. Y. Lee and B. Y. Shim, Inorg. Chim. Acta, 1998, 269, 337. 132 N. Re, R. Crescenzi, C. Floriani, H. Miyasaka and N. Matsumoto, Inorg. Chem., 1998, 37, 2717. 133 D. K. Lyon, B. E. Miller, W. K. Miller, D. R. Tyler and T. J. R. Weakley, Acta Crystallogr., Sect. C, 1998, 54, 20. 134 R. Boca, H. Elias, W. Haase, M. Huber, R. Klement, L.Muller, H. Pauls, I. Svoboda and M. Valko, Inorg. Chim. Acta, 1998, 278, 127. 135 H. Nishide, Y. Tsukahara, Y. Suzuki and E. Tsuchida, Macromol. Symp, 1998, 131, 95; Chem. Abstr., 1998, 129, 141 083. 136 R. Blaauw, J. L. van der Baan, S. Balt, M.W. G. de Bolster, G.W. Klumpp, H. Kooijman and A. L. Spek, Chem. Commun., 1998, 1295. 137 R. Hernandez-Molina, A. Mederos, P. Gili, S.Dominguez, F. Lloret, J. Cano, M. Julve, C. Ruiz-Perez and X. Solans, J. Chem. Soc., Dalton Trans., 1997, 4327. 138 G. Brewer, P. Kamaras, L. May, S. Prytkov and M. Rapta, Inorg. Chim. Acta, 1998, 279, 111. 139 C. Wang, S. Friedrich, T. R. Younkin, R. T. Li, R. H. Grubbs, D. A. Bansleben and M.W. Day, Organometallics, 1998, 17, 3149. 140 S. Busse, H. Elias, J. Fischer, M. Poggemann, K.J. Wannowius and R. Boca, Inorg. Chem., 1998, 37, 3999. 141 D. U� klu� , M. N. Tahir, H. Nazir and H. Yilmaz, Acta Crystallogr., Sect. C, 1998, 50, 725. 142 C. Freire and B. de Castro, Polyhedron, 1998, 17, 4227. 143 R. C. Scarrow, B. S. Strickler, J. J. Ellison, S. C. Shoner, J. A. Kovacs, J. G. Cummings and M. J. Nelson, J. Am. Chem. Soc., 1998, 120, 9237. 144 A.-M. Albrecht-Gary and A.L. Crumbliss, Met. Ions. Biol. Syst., 1998, 35, 239; Chem. Abstr., 1998, 128, 148 700. 145 S. M. Cohen, M. Meyer and K. N. Raymond, J. Am. Chem. Soc., 1998, 120, 6277. 146 M. A. Santos, M. Gaspar, M.L. S. Simo8 es Gonc�alves and M.T. Amorin, Inorg. Chim. Acta, 1998, 278, 51. 147 Y. Sun, R. J. Motekaitis and A. E. Martell, Inorg. Chim. Acta, 1998, 281, 60. 148 P.Baret, C. Beguin, D. Gaude, J. L. Pierre and G. Serratrice, Chem. Eur. J., 1998, 4, 613. 149 J. R. Telford and K. N. Raymond, Inorg. Chem., 1998, 37, 4578. 150 M. Molinier, D. Price, P. T. Wood and A. K. Powell, J. Chem. Soc., Dalton Trans., 1997, 4061. 151 I. Batinic-Haberle, I. Spasojevic, Y. Jang, R. A. Bartsch and A. L. Crumbliss, Inorg. Chem., 1998, 37, 1438. 152 S. P. Walton, P.Fuhrmann, L. E. Pence, A. Caneschi, A. Abatti and S. J. Lippard, Angew. Chem., Int. Ed. Engl., 1997, 36, 2774. 153 A. Bino, I. Shweky, S. Cohen, E. R. Bauminger and S. J. Lippard, Inorg. Chem., 1998, 37, 5168. 154 E. C. Williamson, Y. Dong, Y. Zang, H. Fuiji, R. Fraczkiewicz, G. Fraczkiewicz, R. S. Czernuszewicz and L. Que, J. Am. Chem. Soc., 1998, 120, 954. 155 T.J. Mizoguchi and S. J. Lippard, J. Am. Chem. Soc., 1998, 120, 11 022. 156 S. Poussereau, G. Blondin, M. Cesario, J. Guilhem, G. Chottard, F. Gonnet and J.-G. Girrerd, Inorg. Chem., 1998, 37, 3127. 157 S. H. Yim, H. J. Lee, K. B. Lee, S. J. Kang, N. H. Hur and H. G. Jang, Bull. Korean Chem. Soc., 1998, 19, 654; Chem. Abstr., 1998, 129, 130 485. 158 R. E. Norman, R. Leisin, S. Yan and N.Que, Inorg. Chim. Acta, 1998, 273, 393. 159 J. Glerup, K. Michelsen, N. Arulsamy and D. J. Hodgson, Inorg. Chim. Acta, 1998, 274, 155. 160 D. D. LeCloux, A. M. Barrios, T. J. Mizoguchi and S. J. Lippard, J. Am. Chem. Soc., 1998, 120, 9001. 161 X. X. Zhang, P. Fuhrmann and S. J. Lippard, J. Am. Chem. Soc., 1998, 120, 10 260. 162 R. Visawanathan, M. Palaniandavar, P. Prabakaran and P.T. Muthiah, Inorg. Chem., 1998, 37, 3881. 163 D. F. Xiang, X. S. Tai, S. W. Zhang, Y. Han, K. B. Yu, and W.X. Tang, Polyhedron, 1998, 17, 2095. 164 R. A. Reynolds, W. R. Dunham and D. Coucouvanis, Inorg. Chem., 1998, 37, 1232. 165 T. Tanase, T. Inagaki, Y. Yamada, M. Kato, E. Ota, M. Yamazaki, M. Sato, W. Mori, K. Yamaguchi, M. Mikuriya, M. Takahashi, M. Takerda, I. Kinoshita and S.Yano, J. Chem. Soc., Dalton Trans., 1998, 713. 166 T. C. Brunold, N. Tamura, N. Kitajima, Y. Moro-oka and E. I. Solomon, J. Am. Chem. Soc., 1998, 120, 5674. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 186167 C.M. Grant, M. J. Knapp, J. C. Hu§mann, D. N. Hendrickson and G. Christou, Chem. Commun., 1998, 1753. 168 H. Matsushima, K. Iwasawa, J. Ide, M. Yeamin Reza, M.Koikawa and T. Tokii, Inorg. Chim. Acta, 1998, 274, 224. 169 I. Ondrejkovicova, T. Lis, J. Mrozinski, V. Vancova and M. Melnik, Inorg. Chim. Acta, 1998, 277, 127. 170 F. Calderazzo, L. Labella and F. Marchetti, J. Chem. Soc., Dalton Trans., 1998, 1485. 171 S. Hikichi, M. Yoshizawa, Y. Sasakura, M. Akita and Y. Moro-oka, J. Am. Chem. Soc., 1998, 120, 10 567. 172 J. A. Cowan and S.M. Lui, Adv. Inorg. Chem., 1998, 45, 313. 173 B. M. Segal, H. R. Hoveyda and R. H. Holm, Inorg. Chem., 1998, 37, 3440. 174 Q. Liu, C. Zhang, C. Chen, H. Zhu, Y. Deng and J. Cai, Sci. China, Ser. B, 1997, 40, 616; Chem. Abstr., 1998, 128, 69 902. 175 H. Sun and M. Tian, Huaxue Yu Nianhe, 1998, 30; Chem. Abstr., 1998, 128, 200 094. 176 R. A. Henderson and K. E. Oglieve, J.Chem. Soc., Dalton Trans., 1998, 1731. 177 F. Osterloh, W. Saak, S. Pohl, M. Kroeckel, C. Meier and A. X. Trautwein, Inorg. Chem., 1998, 37, 3581. 178 C. Goh and R. H. Holm, Inorg. Chim. Acta, 1998, 270, 46. 179 C. Goh, A. Nivorozhkin, S. J. Yoo, E. L. Bominaar, E. Mu� nck and R. H. Holm, Inorg. Chem., 1998, 37, 2926. 180 F. A. Cotton, L. M. Daniels, L. R. Favello, J. H. Matonic, C.A. Murillo, X. Wang and H. Zhou, Inorg. Chim. Acta, 1997, 266, 91. 181 Z. N. Chen, B. S. Kang, Z. Y. Zhou, W.J. Li, Y. X. Tong, Z. L. Lu and C. Y. Su, Bull. Chem. Soc. Jpn., 1998, 71, 1805. 182 T. Ama, M. Shiro, A. Takeuchi, T. Yonemura, H. Kawaguchi and T. YAsui, Bull. Chem. Soc. Jpn., 1997, 70, 2685. 183 M. Makuriya and M. Fukuya, Chem. Lett., 1998, 421. 184 J. K. Beattie, T.W. Hambley, J. A. Klepetko, A. F. Masters and P. Turner, Polyhedron, 1998, 17, 1343. 185 Z.-N. Chen, W. J. Li, B. S. Kang, H. X. Zhang, Z. Y. Zhou, T. C. W. Mak, Y. B. Cai, M. C. Hong and H. Q. Liu, J. Chin. Chem. Soc. (Taipei), 1998, 45, 367; Chem. Abstr., 1998, 129, 130 497. 186 J. K. Beattie, T. W. Hambley, J. A. Klepetko, A. F. Masters and P. Turner, Chem. Commun., 1998, 45. 187 I. L. Eremenko, M. A. Golubnichaya, S. E. Nefedov, A. A. Sidorov, I. F. Golovaneva, V. I. Burkov, O. G. Elert, V.M. Novotortsev, T. Eremenko, A. Sousa and M. R. Bermejo, Russ. Chem. Bull., 1998, 47, 704; Chem. Abstr., 1998, 129, 156 109. 188 H. Romstedt, H. Spiering and P. Gutlich, J. Phys. Chem. Solids, 1998, 59, 1353. 189 L. G. Lavrenova and S. V. Larionov, Koord. Khim., 1998, 24, 403; Russ. J. Coord. Chem., 1998, 24, 379. 190 H. Constant-Machado, A. Stancu, J. Linares and F. Varret, IEEE Trans. Magn., 1998, 34, 2213; Chem. Abstr., 1998, 129, 297 317. 191 G. S. Matouzenko, A. Bousseksou, S. Lecocq, P. J. van Koningsbruggen, M. Perrin, O. Kahn and A. Collet, Inorg. Chem., 1997, 36, 5869. 192 L. Dlha� n,W. Linert, F. Renz and R. Boca, Chem. Pap, 1997, 51, 332. 193 R. Boca, P. Baran and M. Mazur, Chem. Pap, 1997, 51, 339. 194 R. Boca, P. Baran, M. Boca, L. Dlhan, H. Fuess, W. Haase, W. Linert, B. Papankova and R. Werner, Inorg. Chim. Acta, 1997, 278, 190. 195 M. Enamullah, J. Bangladesh, Acad. Sci., 1998, 22, 63; Chem. Abstr., 1998, 129, 321 856. 196 J.-F. Letard, P. Guionneau, L. Rabardel, J. A. K. Howard, A. E. Goeta, D. Chasseau and O. Kahn, Inorg. Chem.,1998, 37, 4432. 197 N. Moliner, M. C. Munoz, P. J. Van Koningsbruggen and J. A. Real, Inorg. Chim. Acta, 1998, 274, 1. 198 M. Verelst, L. Sommier, P. Lecante, A. Mosset and O. Kahn, Chem. Mater., 1998, 10, 980. 199 Y. Garcia, P. J. Van Koningsbruggen, R. Lapouyade, L. Fournes, L. Rabardel, O. Kahn, V. Ksenofontov, G. Levchenko and P. Gutlich, Chem. Mater., 1998, 10, 2426. 200 Y. Garcia, P. J. Van Koningsbruggen, R. Lapouyade, L. Rabardel, O. Kahn, M. Wieczorek, R. Bronisz, Z. Ciunik and M.F. Rudolf, C. R. Acad. Sci., Ser IIc: Chim., 1998, 1, 523. 201 D. J. Hathcock, K. Stone, J. Madden and S. J. Slattery, Inorg. Chim. Acta, 1998, 282, 131. 202 (a) B. J. Childs, D. C. Craig, M.L. Scudder and H. A. Goodwin, Inorg. Chim. Acta, 1998, 274, 32; (b) B.J. Childs, D. C. Craig, M. L. Scudder and H. A. Goodwin, Aust. J. Chem., 1998, 51, 895. 203 B. J. Childs, J. M. Cadogan, D. C. Craig, M. L. Scudder and H. A. Goodwin, Aust. J. Chem., 1998, 51, 273. 204 C. Janiak, T. G. Scharmann, T. Bra� uniger, J. Holubova� and M. Na� dvorný� k, Z. Anorg. Allg. Chem., 1998, 624, 769. 205 W. O. Koch, V. Schu� nemann, M. Gerdan, A. X. Trautwein and H.-J. Kru� ger, Chem. Eur. J., 1998, 4, 1255. 206 F. A. Deeney, C. J. Harding, G. G. Morgan, V. McKee, J. Nelson, S. J. Teat and W. Clegg, J. Chem. Soc., Dalton Trans., 1998, 1837. 207 M.-A. Kopf, D. Varech, J.-P. Tuchagues, D. Mansuy and I. Artaud, J. Chem. Soc., Dalton Trans., 1998, 991. 208 R. Hernandez-Molina, A. Mederos, S. Dominguez, P. Gili, C. Ruiz-Perez, A. Castineirasa, X. Solans, F. Lloret and J. A. Real, Inorg. Chem., 1998, 37, 5102. 209 V. V. Zelentsov, Koord. Chem., 1998, 24, 313; Russ. J. Coord. Chem., 1998, 24, 295. 210 V. V. Zelentsov, G. I. Lapushkin, P. N. Kostikin, M.S. Byrke, M. A. Yampol’skaya and N. V. Gerbelev, Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 165–188 187Koord. Chem., 1998, 24, 682; Russ. J. Coord. Chem., 1998, 24, 638. 211 B. Kersting, M.J. Kolm and C. Janiak, Z. Anorg. Allg. Chem., 1998, 624, 775. 212 S. K. Tiwary and S. Vasudevan, Inorg. Chem., 1998, 37, 5239. 213 O. S. Jung, D. H. Jo, Y. A. Lee, Y. S. Sohn and C. G. Pierpont, Inorg. Chem., 1998, 37, 5875. 214 H. Lee, O. S. Jung and S. Jeon, Bull. Korean Chem. Soc., 1997, 18, 1109. 215 A. Caneschi, A. Cornia and A. Dei, Inorg. Chem., 1998, 37, 3419. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 1

ISSN:0260-1818    

DOI:10.1039/a804894k

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

14 Copper D. W. Smith Department of Chemistry, University of Waikato, Hamilton, New Zealand 1 Copper(I) chemistry Mononuclear species We begin with experimental and theoretical studies of the binding of copper(I) to ligands in the gas phase. Sequential bond dissociation enthalpies at 298K for [Cu(NH 3 )n]` (n\1–4) are found1a (by MS) to be respectively 237(15), 248(10), 46(6) and 45(6) kJ mol~1.Both free energy and entropy changes were measured for ligand exchange equilibria among [CuL 2 ]` species for 23 ligands L; histidine is found to be the most strongly-bound amino acid.1b A combination of experimental (MS) and theoretical (DFT) studies have been applied to the reaction of Cu` with formamide (a simple peptide model) in the gas phase;1c theoretical studies were extended to the isomers of formamide, formamidic acid and (aminohydroxy)carbene,1d and to the isomers of oxaziridine.1e High-level DFT calculations suggest that relativistic e§ects destabilize CuF(g) by only 2–5 kJ mol~1, compared with 50–70 kJ mol~1 for AuF.1f Mononuclear copper(I) compounds may be classified according to whether the co-ordination number of the metal is two, three or four. The structures of ‘higherorder’ cyanocuprates(I) CuCN·2LiR have aroused much debate: 15N NMR spectra in thf indicate cyclic structures with linear CuC 2 co-ordination,2a while the crystal structure of [MLi(Me 5 dien)(thf)N2 (l-CN)][CuBu5 2 ] reveals a Gilman cuprate anion.2b Methyl radicals react with Cu(CO)`(aq) to give the intermediate [CuMe(CO)]`, which undergoes CO insertion into the Cu–Me bond to give acetaldehyde.2c The reaction of CuX (X\Cl, Br) with pyrrolidine in MeCN gives [CuL 2 ]X [L\1-aza-2- (1-pyrrolidyl)] without the intermediate isolation of L; the copper atoms have linear CuN 2 co-ordination.2d Similar co-ordination is found in [Li(dme) 3 ]- [CuMNRCBu5––C(H)RN2 ] (R\SiMe 3 ).2e The dppf derivatives L\Fe[g5- C 5 H 4 P(E)Ph 2 ] 2 (E\S, Se) form two-co-ordinate [CuL][BF 4 ] (CuE 2 ) and four-coordinate [CuL 2 ][BF 4 ] (CuE 2 P 2 ), as well as polymeric three-co-ordinate species [Cu 2 L 3 ]n[BF 4 ] 2n.2f,g In a tetraarylstibonium salt, the [CuI 2 ]~ anions are considerably distorted from linearity with short (2.73Å) Cu–Cu distances.2h Two independent anions are found in [Pd(S 2 CNEt 2 )(dppe)][CuCl 2 ]; one is crystallographically centrosymmetric while the other has a Cl–Cu–Cl angle of 173°.2i The complex [NEt 4 ]- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 189[CuL 2 ] (HL\adamantane thiol) is the first two-co-ordinate copper(I) complex with an aliphatic thiolate.2j Of three nominally three-co-ordinate monomeric copper(I) complexes characterised this year, none has the ideal planar triangular geometry.A sterically-hindered tridentate ligand 1-(2-hydroxy-3,5-di-tert-butylbenzyl)-5-isopropyl-1,5-diazacyclooctane (HL) gives a complex [CuL] where the co-ordination is T-shaped, with a very short Cu–O bond (1.88Å) to a phenolate oxygen atom, and two bonds (1.98 and 2.28Å) to tertiary amino nitrogen atoms, so that the co-ordination is best described as (2]1); the reactivity of the complex towards dioxygen resembles that of galactose oxidase.3a Similar dissymmetric bonding (in this case to two nitrogen atoms which are equivalent in the free ligand) is found in [CuL(tmphen)] (HL\2,6-diphenylthiophenol).3b In [CuL(PPh 3 ) 2 ] (HL\orotic acid), the carboxylate group is monodentate.However, the copper atom lies 0.56Å out of the OP 2 plane, forming a weak (2.28Å) bond with an exocyclic oxygen atom in a neighbouring unit cell, so that the highly insoluble compound is better viewed as a polymer with distorted tetrahedral (3]1) co-ordination. 3c Looking now at unequivocally four-co-ordinate copper(I) complexes, a good correlation is found between 63Cu NMR chemical shifts and CO stretching frequencies in [CuL(CO)] complexes (L\Tp and derivatives).4a The nuclease activity of [Cu(phen) 2 ]`, the mechanism of which has been studied by kinetic isotope e§ects,4b continues to stimulate work on bis(diimine)copper(I) complexes. Examples include the complexes [CuL 2 ][BF 4 ] [L\N-alkyl-(2-pyridyl)methanimine] which catalyse atom-transfer polymerisation of methyl methacrylate.4c The complex [CuL 2 ][BF 4 ] [L\3-chloro-6-(3,5-dimethylpyrazol-1-yl)pyridazine] exhibits the most distorted CuN 4 tetrahedron of any [Cu(diimine) 2 ]` known so far; a useful parameterisation scheme for assessment of the degree of flattening of the tetrahedron is proposed.4d Apart from the acuteness (79.9°) of the N–Cu–N angle, the structure of [CuI(phen)(PPh 3 )] is as expected.4e The electronic excited states and redox properties of diiminecopper(I) complexes have possibilities in the field of solar energy harvesting; spectroelectrochemical studies are reported for a series of complexes [CuL(PPh 3 ) 2 ]- [BF 4 ] (L\substituted dipyrido[3,2-a: 2@,3@-c]phenazine),4f and for analogous complexes with binaphthyridine4g and 2,3-bis(2-quinolyl)quinoxaline4h derivatives.X-Ray structural data for the complexes [Cu(NCMe) 2 (PPh 3 ) 2 ]X (X\BF 4 , PF 6 , ClO 4 ) have been complemented by solid-state 31P NMR studies of the two independent phosphine ligands.4i In the presence of chloride, the reaction of copper(I) with dppe in non-polar solvents gives the tumouricide [MCuCl(dppe)N2 (l-dppe)]; in polar solvents [Cu(dppe) 2 ]Cl is obtained.4j Likewise CuClP 3 or CuP 4 co-ordination geometries can be obtained with 2,3-bis(diphenylphosphino)maleic anhydride.4k N-[2-(1-Naphthyl) ethyl]-1-aza-4,8-dithiacyclodecane (L) forms the first copper(I)-g2-naphthyl complex [CuL][PF 6 ].4l The relatively rare CuOS 2 P co-ordination is found in [CuL(PPh 3 )][ClO 4 ] (L\1-oxa-4,7-dithiacyclononane),4m while the more common S 2 P 2 donor set occurs in [NEt 4 ][CuMS 2 C 2 (CN) 2N(PPh 3 ) 2 ].4n Bi-, oligo-, poly- and hetero-nuclear and supramolecular species Dicopper(I) species.This year has seen much discussion of ‘cuprophilicity’, relatively short Cu–Cu contacts in bi-, oligo- and poly-nuclear copper(I) complexes which Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 190may or may not indicate some kind of bonding. The copper–copper distance is often around 2.5–2.6Å, compared with 2.56Å in the metal, and even longer distances of 2.8–2.9Å have been attributed to cuprophilicity.DFT calculations on [CuL][CuCl 2 ] [L\1,1@-bis(2-pyridyl)octamethylferrocene], which has an unsupported Cu–Cu distance of 2.81Å, show that the interaction is purely electrostatic.5a However, ab initio calculations on [MCuCl(NH 3 )N2 ] led to an optimal eclipsed structure, with intermolecularNH · · ·Cl hydrogen bonds and significant bonding electron density between the copper atoms even at a distance of 3.17Å.5b Similar calculations on transannular Cu–Cu interactions in [MCu(l-PPh 2 CH 2 SPh)N2 ]2` show that the inclusion of correlation e§ects results in a contraction of the Cu–Cu distance from 3.6 to 3.1Å.5c Similar calculations on four- and eight-membered rings likewise lead to a cuprophilic e§ect as a consequence of electron correlation.5d DFT studies of compounds containing the shortest Cu–Cu contacts (2.35–2.45Å) reveal no significant covalency, and the closeness of the metal atoms in bis(pyrimidine)dicopper(I) compounds, for example, is attributed to a combination of strong Cu–Nbonding and the very short bite distances of the ligands.5e This paragraph deals with new dicopper(I) compounds having short Cu–Cu contacts in which cuprophilicity might be invoked.An unsupported Cu–Cu distance of 2.70Å is found in [MCuLN2 ][ClO 4 ] 2 (L\4-isopropylideneaminobenzo-2-thia-1,3- diazole), where the copper atoms have linear two-co-ordination and a head-to-head arrangement.6a In [MCu(l-L) 2N(OCMe 2 )][PF 6 ] 2 (L\1,8-naphthyridine) one copper atom is two- and the other three-co-ordinate, with d(Cu–Cu)\2.53Å.6b The copper –copper distance in [MCu(tu) 2 (l-tu)N2 ]2` depends on the anion, and can be signifi- cantly shortened by intermolecular hydrogen bonding.6c The Cu–Cu distance shortens from 3.61Å in [MCu(NCMe)(l-L)N2 ][ClO 4 ] 2 [L\2-(diphenylphosphino)-6-(pyrazol- 1-yl)pyridine] to 2.52Å in [MCu(l-L)N2 (l-g1-C 2 Ph)][ClO 4 ], but this is doubtless dictated by the acetylide bridge.6d Among other dicopper(I) complexes, straightforward halogen bridging with Cu 2 X 2 rings occurs in [MCu(l-Cl)LN2 ] [L\Ph 2 PCH 2 CH(Et)OPPh 2 ,7a 4-benzoylpyridine7b] and [MCu(l-Br)L(PPh 3 )N2 ] (L\quinoline).7c An azoaromatic radical anion X~ (X\ 5,5@-dichloro-2,2@-azopyrimidine) has been stabilised in [MCu(PPh 3 )N2 (l-X)][PF 6 ].7d In [MCu(l-L)(PPh 3 ) 2N2 ] [HL\HON––C(CN) 2 ] double CuNCCNCu bridges are formed. 7e The discrete dimer [MCu(dmphen)(NCMe)N2 (l-4,4@-bipy)][BF 4 ] 2 points the way towards more complex 4,4@-bipy-bridged systems.7f Oligomeric species. A linear tricopper(I) array appears in [Cu 3 (l-L) 3 (NCMe)]- [ClO 4 ] 3 (L\7-diphenylphosphino-2,4-dimethyl-1,8-naphthyridine), with the MeCN ligand attached to a terminal copper atom.8a Most tricopper clusters have cyclic structures; a simple Cu 3 Cl 3 ring occurs in [Cu 3 (l3 -Cl)(l-Cl) 2 (l-L)] [L\2,5- bis(diphenylphosphino)thiophene].8b A Cu3 Br 2 C ring is found in [MCu 3 (l-Br) 2 (l- mes*)(SMe 2 ) 3N].8c Bridging pyrazoles enable (CuNN) 3 ring formation in [MCuLN3 ] [HL\2-M3(5)-pyrazolylN-6-methylpyridine].8d Turning now to tetracopper(I) complexes, a planar Cu 4 array is found in [MCu(l-L)N4 ] [L\ferrocenyltrisM(methylthio) methylNborate], where each S 3 ligand furnishes two terminal Cu–S bonds and the four bridging sulfur atoms are alternately above and below the Cu 4 plane.8e Another planar Cu 4 complex is [MCu(C 6 Me 5 )N4 ]; the Cu–Cu distance is 2.41Å and three-centre two-electron Cu–C–Cu bonds are postulated.8f An electrochemical synthesis with a Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 191copper anode, a platinum cathode and 1,3-thiazolidine-2-thione (L) in [NBu 4 ][BF 4 ]– toluene yields [MCuLN4 ][BF 4 ] 4 in which the Cu 4 core is an ‘open-butterfly’, with S 2 N co-ordination of the spinal copper atoms and S 3 N at the wingtips.8g Tetrahedral Cu 4 cores are found in [MCu(l3 -L)N4 ] [HL\SiMe 2 (PHCy) 2 ], the first tetranuclear copper( I) silylphosphido complex, prepared by an unexpected transphosphination/silylation reaction,8h and in [Cu 4 (l-tu) 6 (tu)][SO 4 ] 2 ·H 2 O, with one four-co-ordinate and three three-co-ordinate copper atoms.8i All the copper atoms have tetrahedral coordination in [Cu 5 (l2 -I) 3 (l3 -I) 2 L 2 ] (L\tetraethylthiuram monosulfide); each L is S 2 bidentate, with one sulfur atom on each L bridging two copper atoms.8j In [Cu 8 (l8 - Se)Ml4 -Se 2 P(OPr*) 2N6 ] an interstitial selenium atom sits at the centre of the Cu 8 cube, with a diselenophosphate bridging each face.8k Among high-nuclearity copper(I) clusters, the linear bidentate ligands bis(diphenylphosphino)acetylene and 1,4- bis(diphenylphosphino)benzene stabilise respectively Cu 16 and Cu 25 compounds by forming intramolecular bridges8l while [Cu 32 Se 16 (PPh 3 ) 12 ], [Cu 52 Se 26 (PPh 3 ) 16 ] and [Cu 72 Se 36 (PPh 3 ) 20 ] have been obtained by the reaction of Se(SiMe 3 ) 2 with copper(I) acetate in the presence of PPh 3 .8m Polymeric species.Beginning with chain structures, the vibrational spectrum of CuCN suggests a linear chain structure, similar to those found for AgCN and AuCN by powder neutron di§raction measurements.9a The chain polymer [MCu(CN)N4 L]n (L\2,2@-biquinoline) has alternate two- and three-co-ordinate copper(I) atoms.9b The polymeric anion in [ML]n[Cu 2 I 3 ]n (M\K, Rb, Cs: L\15-crown-5) is best described as catena-[M[Cu(l-I)Cu](l3 -I) 2Nn]n~, with an ‘up, up, down, down’ pattern for the doubly-bridging iodine atoms;9c with the cations [NEt 4 ]` and [K(18-crown-6)]` the pattern is ‘up, down, up, down’.9d In [Cu 2 Cl 2 L] (L\dipyrido[1,2-a: 2@,3@-d]- imidazole) the chain has alternate three- and four-co-ordinate copper atoms with both l and l3 bridging chlorine atoms.9e An electrochemical method in en provides a ‘bench-top’ synthesis for the chain polymer KCu 7~xS 4 (0\x\0.34) which has useful electrical properties for x[0.9f The compound BaDyCuTe 3 contains infinite chains of CuTe 3 5~ tetrahedra.9g Turning now to 2-D systems, [MCu(l-I)N2 L]n (L\1,2,5,6- tetrathiacyclooctane) consists of familiar Cu 2 I 2 chains linked into sheets by bridging L molecules.9h In [Cu(CM-TTF)]n[ClO 4 ]n each copper atom is tetrahedrally bonded to two methylsulfanyl sulfur atoms and two cyano nitrogen atoms from three tridentate CM-TTF molecules, leading to a 2-D net structure.9i Two distinct layers are present in KCuCeTe 4 , which might be rendered as [Kn]n`[MCuTeNn]n~[MCeTe 3Nn] with CuTe 4 tetrahedra in an anti-PbO layer;9j a similar [MCuTeNn]n~ layer can be discerned in Rb 2 Cu 3 CeTe 5 .9k Similar co-ordination of copper atoms occurs in CuTh 2 Te 6 , where Cu` ions link [MTh 2 Te 6N]n]n~ double chains into layers.9l The air-stable polymer [Cu 2 (g2-O 2 CCH–– CHCO 2 )]n, prepared by hydrothermal synthesis, is a rare example of trigonal planar copper(I) in an extended solid structure.9m Another hydrothermallyprepared 2-D polymer is [MCu(bipy)N2 (l-CN)] 2n[Cu 5 (CN) 7 ]n, which features anionic nets of alternating fused rows of MCu(CN)N6 and MCu(CN)N8 rings.9n 2-D oxide networks can be constructed by bridging oxomolybdate clusters such as [Mo 8 O 26 ]4~ with [Cu(4,4@-bipy)]` units.9o The co-ordination of the copper atoms in Cu 3 ClTeS 3 (sphalerite-type) is CuS 3 Cl.9p The remaining compounds in this section all have 3-D channelled structures.In [MCu(l-NCS)N2 (pyz)]n each copper atom is trigonally bonded to one nitrogen and two sulfur atoms of bridging thiocyanates, Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 192giving rise to honeycomb sheets with fused ten-membered rings linked by pyrazine bridges.9q In contrast, RbCuSb 2 Se 4 ·H 2 O contains CuSe 4 tetrahedra.9r Large van der Waals channels occur in CuAlCl 4 (corner-sharedMCl 4 tetrahedra), which adsorbs CO and ethylene reversibly.9s The hydrogen bonding capabilities of the cations in [NH 2 Et 2 ] 2 [CuCl 4 ][AlCl 4 ] give rise to the first reported ‘anti-zeotype’ structure.9t Supramolecular species.Here we cover copper(I) complexes whose assembly or topology is deemed to endow supramolecular status, although some species covered elsewhere might have been included.Tetrahedral CuN 4 cores are of special interest. A new double helicate cation has been established in [MCuLN2 ][PF 6 ] 2 , where L is a tetradentate ligand comprising two 3-(2-pyridyl)pyrazole units linked by an o- CH 2 C 6 H 4 CH 2 spacer.10a The self-assembled chiral metallophane [MCuLN2 ][BF 4 ] 2 [L\2-(2,2@-bipyridyl)-3-(2-pyridyl)pyrazine] is shown by 1H and 13C NMR spectra to be stable in CD 3 CN solution.10b Imine-bridged oligobipyridine ligands are shown by UV and NMR spectroscopy to form double helicates with copper(I).10c Double helical ‘twisted ring figure-of-eight loops’ characterise the topology of a series of dicopper(I) complexes with macrocyclic ligands having two N 2 S 2 donor sites, spaced by p-xylylene groups; in MeCN there is a dynamic equilibrium between the enantiomers, involving rupture of copper–ligand bonds and intermediate co-ordination of solvent.10d Another double helicate is [MCu(O 2 PX 2 )N2 ] [X\3-(2-pyridyl)pyrazol-1- yl], but in the analogous complex with OSPX 2 ~ co-ordination of the sulfur atoms prevents helication.10e The reaction of [Cu(NCMe) 4 ]` with 1,2,4,5-tetracyanobenzene (L) led to topologically-distinct polymers [Cu 2 L 3 ][PF 6 ] 2 depending on the solvent.10f In self-assembled [CuL 2 ][ClO 4 ] [L\2-Mbis(methylsulfanyl)methylene Npropane-1,3-dinitrile] each copper centre is bonded to nitrogen atoms from four di§erent L molecules, each L bridging two copper atoms to give a square grid arrangement.10g The reaction of [Cu(CN) 4 ]3~ with Me 3 SnCl and 4,4@-bipy gives [MCu[l-CNSn(Me 3 )NC]N2 (4,4@-bipy)] where the co-ordination is tetrahedral CuC 3 N; in each dimeric unit the copper atoms are bridged by cyano carbon atoms, and further polymerisation is achieved via both CNSnNC and 4,4@-bipy bridges to give a remarkable supramolecular structure.10h The chiral ligand L obtained by condensation of trans-cyclohexane-1,2-diamine with two molecules of 6-R-2-pyridinecarbaldehyde (R\H, Br) forms [MCuLN2 ]2`, whose self-assembly exhibits ligand self-recognition by virtue of chirality; the reaction of the metal ion with a racemic mixture of the ligands forms only homochiral complex ions.10i Heterometallic species.All the heteronuclear species containing copper(I) reported this year involve 4d or 5d elements as the hetero-metal.In [AgCu(SCN) 2 (py) 4 ], Cu(py) 3 units are linked via CuNCSAg bridges into infinite chains of thiocyanatebridged Ag(py) units. However, [AgCu(NCS) 2 (py) 3 ] contains ten-membered rings linked into infinite chains by 1,3-l and 1,1,3-l3 NCS groups (tetrahedral CuN 4 co-ordination) while [Ag 2 Cu(NCS) 3 (py) 3 ] has a 2-D structure; in all these compounds, the copper atoms have tetrahedral CuN 4 co-ordination, the softer Ag` ions having first claim on the sulfur donor atoms.11a Copper(I) thiomolybdate/tungstate complexes continue to attract attention.The solid state reaction of [NH 4 ] 2 [MS 4 ] (M\Mo, W) with [Cu(NCMe) 4 ][PF 6 ] and dppm produced [MCu(l-dppm)N4 (l-S 4 M)][PF 6 ] 2 , in Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 193which each sulfur atom bridges two copper atoms and the M atom, while in CH 2 Cl 2 the product was [MCu(dppm)N3 (l-S 4 M)][PF 6 ], where one sulfur atom bridges three copper atoms and M and the other sulfur atoms bridge only one copper and M.11b M(V) (M\Mo, W) is found in the clusters [NEt 4 ] 2 [MCuM(S)(O)- (SC 2 H 4 S)N6 (l6 -S 2 )], in which each sulfur atom of the central S 2 2~ ion is bonded to three copper atoms.11c Each of a series of four clusters [NBu 4 ] 4 [Cu 10 (l-S 3 EM) 3 (l- S 4 M)(l3 -S) 2 (l4 -S)] (M\Mo, W; E\S, O) contains one incomplete cubane Cu 3 MS 3 E, one trigonal prism-type Cu 3 MS 4 and two butterfly-type Cu 3 MS 3 E fragments, bridged by three sulfur atoms.11d The cuboidal clusters [Mo 2 WCuS 4 ]n`(aq) (n\4,5) have been studied by UV spectroscopy and cyclic voltammetry, completing the series [MxM 3~xCuS 4 ]n`(aq).11e Perhaps the most unexpected copper–tungsten cluster is [MCp*W(l-S) 3 Cu 2N3 (l3 -S) 2 ]; the copper–tungsten distances (2.67–2.68Å) are significantly shorter than the usual 2.80–2.82Å.11f The reaction between [Cu(CN)(AsPh 3 )(bipy)] and [RuCl 2 (bipy) 2 ] gives a product which has been characterised spectroscopically as [Cu(AsPh 3 ) 2 (l-CN)RuCl(bipy) 2 ][PF 6 ].11g The Cu–Re acetylide complex [MCu(dppm) 3NMl3 -g1-C 2 C 6 H 4 C 2 -p-Re(CO) 3 (bipy)N2 ][PF 6 ] and derivatives show rich photochemical and electrochemical properties.11h Both cis- and trans-[PtCl 2 (PPh 3 ) 2 ] react with Se(SiMe 3 ) 2 and CuCl in thf to give [MCuClN2MPt(PPh 3 ) 2N2 (l3 -Se) 2 ], in which the four metal atoms form a parallelogram with each selenium atom bridging one copper and both platinum atoms; the coordination about the copper atom is almost linear, and there is no reason to postulate Cu–Pt bonding at distances of 2.92 and 3.05Å.11i Photochemical and photophysical properties of copper(I) complexes Progress continues in the photochemistry of [Cu(phen) 2 ]` and related species; a concise review has appeared.12a The bulky Pr* groups in [Cu(2,9-Pr* 2 phen) 2 ]` inhibit structural relaxation in the photoexcited state, allowing reductive quenching by ferrocene derivatives; the phenyl groups in 2,3,6,7-tetraphenyl-1,4,5,8-tetraazaphenanthrene are even more e§ective.12b The photochemical and electrochemical e§ects of bulky electron-withdrawing substituents have been examined in the case of [CuL 2 ]` [L\2,9-bis(trifluoromethyl)-1,10-phenanthroline].12c For L\(2,3-b)-pineno-1,10- phenanthroline, both D and K stereoisomers of the chiral complex [CuL 2 ]` have been prepared.However, no enantioselective quenching was observed with D- and K- [Ru(bipy) 3 ]2` as donors.12d Photophysical studies of [CuL(PPh 3 ) 2 ]`, where L is a diimine ligand containing a thia-, selena- or tellura-crown ring, have established their potential as luminescence probes for soft cations.12e Complexes of the type CuXL (X\halogen, L\nitrogen donor) often exhibit oligomer/polymer isomerism, as well as rich photochemistry.Exposure of [CuIL]n (L\4-methylpyridine) to toluene liquid or vapour leads to the disappearance of the room temperature blue emission of the polymer and the appearance of the yellow emission characteristic of the oligomer [MCu(l3 -I)LN4 ]; exposure of the latter to n-pentane liquid or vapour reverses the process!12f The volatile cluster [MCu(l-L)N4 ][L\N(SiMe 3 ) 2 ], containing a square planar Cu 4 N 4 core, is phosphorescent both in solution and in the solid state at room temperature.12g The cluster [MCu(py) 2N2MCu(SCN)(py)N2 (l-S 4 W)] is among the best optical limiting materials yet discovered.12h Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 1942 Copper(I)–copper(II) chemistry Here we cover mixed-valence copper(I)–copper(II) compounds (other than oxides which are dealt with in the next section), as well as redox systems in which the two states are readily interconverted.Mixed-valence copper(I)–copper(II) compounds Welook first at compounds in which the two oxidation states are clearly distinguished. As well as discrete [CuBr 4 ]2~ ions, [LH] 4n[CuIIBr 4 ]n[CuI(l-Br) 2 ] 2n (L\4- aminopyridine) contains the first example of infinite chains of CuIBr 4 tetrahedra sharing edges.13a In contrast, [CuIICl(bipy) 2 ] 2n[CuICl 2 ] 2n·nC 6 O 2 (OH) 4 contains linear [CuCl 2 ]~ ions; hydrogen bonding via the tetrahydroxoquinone molecules holds together an infinite chain structure.13b Ab initio calculations have been performed on the electron-transfer matrix element in a model for the chain polymer [NEt 4 ]n[CuI(l- Cl) 2 CuII(l-Cl) 2 ]n.13c An electrochemical synthesis from copper metal, thiosalicylic acid (H 2 L) and triphenylphosphine in MeCN leads to the formation of [MCuI(PPh 3 ) 2N2 CuII(l-L) 2 ], where one copper(I) has S 2 P 2 and the other O 2 P 2 coordination. 13d The tellurite Ba 2 Cu 4 Te 4 O 11 Cl 4 contains oxide layers with square planar CuIIO 4 co-ordination and chloride layers with CuICl 4 tetrahedra.13e The pillared, layered compound Na 2 CuI 6 CuII 9 L 6 (OH) 2 ·H 2 O (L\1-hydroxyethylidenediphosphonate) is the first mixed-valence copper phosphonate; the copper(II) atoms are square planar while the copper(I) atoms have linear two-coordination. 13f UV irradiation of [MCu(OAc) 2 (H 2 O)N2 ] in HOAc–MeOH generates a CuI–CuII mixed valence species; electrochemical studies are consistent with two distinct sites.13g We turn now to delocalised systems where distinct copper(I) and copper(II) sites cannot be discerned (Class III in the Robin–Day scheme). The anion in [PPh 3 Me] 2 - [Cu 2 Br 5 ] has D 3) symmetry, a rare case of confacial tetrahedra for copper, containing a (Cu1.5`) 2 pair; the Cu–Cu distance is only 2.36Å, butDFT calculations indicate that the interaction is very weak.14a In [Cu 2 (l-pym)Mo 3 O 10 ]n, where equivalent CuO 3 N tetrahedra link chains of edge-sharing MoO 6 polyhedra with pym molecules bridging copper centres to give a 3-D structure, bond valence sums point to Cu1.5` [cf.ref. 9(o)].14b Models for the Cu A centre in cytochrome c oxidase and NO reductase continue to generate activity, both from synthetic14c and spectroscopic/theoretical approaches.14d The remainder of this section is devoted to copper(I)–copper(II) redox systems, beginning with bis(diimine) complexes.The kinetics of electron exchange for [CuL 2 ]`@2` (L\2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) have been studied in MeCN;15a the 4 and 7 substituents are apparently responsible for the e§ectiveness of [CuL 2 ]` in bridging pairs of DNA duplexes.15b A flexible bis(diimine) ligand L forms copper(II) complexes [CuL]X (X\[CuCl 4 ], [PF 6 ] 2 ) with square planar CuN 4 co-ordination; these undergo reversible reduction to copper(I) species with tetrahedral co-ordination. 15c The crystal structures of [Cu(dpphen) 2 ][PF 6 ] and [Cu(dpphen) 2 ][ClO 4 ] 2 have been compared, in the context of the room-temperature luminescence of [Cu(dpphen) 2 ]`; the structural change on oxidation is significant but less than for Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 195unhindered analogues where copper(II) tends to adopt five-co-ordination.15d Copper( I)–copper(II) complexes with 1,1@-bis(bipy) ester-bridged derivatives of ferrocene exhibit interesting electrochemistry; the dimer [MCuLN2 ][BF 4 ] 2 has a helical structure. 15e A terpy derivative having two imino nitrogen atoms as well as the three pyridine groups forms a helicate [MCuLN2 ]2` whose 15N NMR spectrum shows a dynamic fluctuation in which the non-co-ordinated and co-ordinated imino nitrogen atoms are interchanging; all five nitrogen atoms are co-ordinated on oxidation to copper(II), and the reversible redox properties o§er possibilities for the design of catalytically-active copper helicates.15f The couple [Cu(NCS)L]–[Cu(NCS)L]` [L\(S)-N,N@-bisM(2-quinolyl)methylN-1-(2-quinolyl)ethylamine] acts as a redox switch via the distinct CD spectra of the chiral ligand.15g The complex [MCu(NCMe)N2 (l-L)]n [L\3,4-bis(dicyanomethylene)cyclobutane-1,2-dione dianion] has a complex electrochemistry, involving the dianion, the radical anion and the neutral dione as well as CuI–CuII.15h The photochemical reduction of copper(II) dicarboxylate complexes has been the subject of a thorough investigation;15i one of the ligands studied, fumarate, has interesting e§ects on the kinetics of the oxidation of Cu`(aq) by dioxygen, elucidated by pulse radiolysis studies.15j This paragraph is devoted to copper(I)–(II) redox systems of biological importance.Beginning with the blue (type I) copper proteins, X-ray MCD measurements on plastocyanin o§er promise that this technique will be valuable as an electronic structure probe in metalloproteins.16a Further work on the resonance Raman spectra of plastocyanin from various sources emphasises the sensitivity of this technique to the copper environment;16b ‘chromophore-in-protein’ modelling successfully reproduces some of the complex features of these spectra.16c Type I copper sites (CysHis 2 Met) have been constructed in the hydrophobic core of thioredoxin; it was necessary, however, to introduce an exogenous azide ligand to exclude water from the coordination sphere.16d Among studies of other mononuclear systems, XAS/EXAFS studies on amine oxidases show that the oxidised form probably contains five-coordinate copper(II) (three histidine nitrogen atoms and two water molecules) while the reduced form has three-co-ordinate copper(I); the latter presumably reacts with dioxygen in the enzyme.16e The toxicity of cyanide is believed to involve the bridging of the iron and copper atoms at the haem a 3 /Cu B site in cytochrome c oxidase; model studies on [(oep)Fe(NC)Cu(tmpa) 3 ]n` with FeIII–CuII, FeIII–CuI and FeII–CuI have been reported.16f Dopamine b-hydroxylase contains two copper sites Cu A (three histidines and one water) and Cu B (two histidines, one water, one other ligand and a weakly-bound methionine sulfur atom), more than 4Å apart; a ligand L having one tertiary amino and two pyridine nitrogen donor atoms, plus a thiol sulfur atom, has been used in modelling studies of the Cu B site.16g The same laboratory has investigated the mechanism of dioxygen activation of dopamine b-hydroxylase by appeal to a binuclear model system, using a ligand derived from 2-aminoindane with two pendant pyridyl groups attached to the amino nitrogen atom; the CuI 2 form reacts with dioxygen to give the bridged peroxo complex CuIIOOCuII, which then transfers an oxygen atom to the ligand, resulting in a dicopper(II) complex with bridging phenolate and hydroxide.16h Kinetic studies of a similar reaction, but with a Schi§ base ligand in which each copper has an imino nitrogen donor in place of the amino nitrogen in ref. 16(h), provide evidence for an intermediate peroxo complex which cannot be detected spectroscopically.16i With the bis[2-(2-pyridyl)ethyl]amine ligands more commonly Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 196used in such studies, the l-g2:g2 side-on peroxo-bridged intermediate can be observed by resonance Raman spectroscopy, and this can be used to monitor the kinetics.16j There is both spectroscopic and chemical evidence for the bis(l-alkylperoxo) intermediate.16k With a di§erent but related ligand, the mechanism of hydroxylation is believed to involve intramolecular C–H bond activation with a bis(l- oxo)dicopper(III) intermediate.16l The l-1,1-hydroxoperoxo-bridged dimer has also been studied both spectroscopically and theoretically.16m 3 Copper–oxygen chemistry Here we cover oxides, mixed oxides and precursors thereto, and copper exchanged silicates, etc., without regard for the (often indeterminate) oxidation state of copper.Oxides and oxocuprates Copper(I) oxide catalyses the photolysis of water by visible light.17a The adsorption of CO on Cu 2 O has been studied by He II UPS, supported by SCF-Xa calculations.17b Turning to superconducting oxocuprates, the high-pressure synthesis of high T C systems has been reviewed.17c X-Ray absorption spectroscopy has been used to investigate the hole distribution in Y(Ba 2~ySry)Cu 3 O 6`d and (Cd 0.5 Pb 0.5 )Sr 2 (CaxY 1~x)Cu 2 O 7 .17d,e FT-IR spectroscopy, supported by MM calculations, has elucidated the ordering of amine monolayers adsorbed on YBa 2 Cu 3 O 7 .17f Electron energy-loss and XPS spectra show that the adsorption of NO on LaBaSrCu 2 O 6~d produces holes in oxygen 2p states; the resulting NO~ ions abstract oxygen from the lattice to form nitrite.17g In chlorooxocuprates, p-type superconductivity occurs when the apical sites are completely occupied by chlorine atoms.17h The intercalation of a superionic conducting Ag–I layer into the superconducting Bi 2 Sr 2 Can~1 CunOy lattice leads to hybrid systems having both high electronic and ionic conductivities.17iWe now look at non-superconducting lanthanoid oxocuprates, whose structures and preparations are not without relevance to the superconductor industry.High pressure stabilises the perovskite structure; the ambient-pressure phase of La 4 Cu 3 MoO 12 is transformed into a perovskite under a pressure of 6 GPa, with a change in the co-ordination geometry about copper from trigonal bipyramidal CuO 5 to elongated-octahedral CuO 6 .17j The e§ect of pressure (up to 36 GPa) on the structure of Nd 2 CuO 4 has been studied using synchrotron radiation.17k Among lanthanide oxocuprates, La 4 BaCu 5 O 13`d is unique in exhibiting metallic behaviour down almost to absolute zero without superconductivity; metallic conductivity is preserved on partial substitution of copper by nickel, but with iron or cobalt transitions to insulating phases are observed.17l Di§raction data alone can give only an approximate structure, with averaged cation distributions, of the perovskite Gd 2 Ba 2 CaCu 2 Ti 3 O 14 , which contains two CuO 2 layers.However, the use of EXAFS data for all five metals in the refinement (combining the determination of long-range order and of local environments) gives a more accurate structure.17m The catalytic activity of (CeO 2 ) 1~y(La 2 CuO 4 )y for the reduction of NO by CO is attributed mainly to Cu2` at the surface, but the bulk plays a part via oxygen exchange with the surface.17n Four new Ba–Cu–Ir oxides have been predicted and duly characterised.17o Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 197Precursors This paragraph covers studies of volatile complexes which decompose on heating to give thin films of copper metal, copper oxides or mixed oxides. The liquid copper(I) complex [CuLMP(OMe) 3N] (HL\tert-butyl-3-oxobutanoic acid) is probably the best of several [CuLL@] complexes studied as precursors for theCVDof copper metal.18a In [Ba 4 CuI 6 (l4 -O)(l-OCEt 3 ) 12 ] the central oxygen atom is surrounded by four barium atoms, with each MCu(OCEt 3 ) 2N unit (linear CuO 2 ) bridging an edge of the Ba 4 tetrahedron; in [BaCu 6 (l-OCEt 3 ) 8 ] two MCu 3 (OR) 4N moieties are co-ordinated to a central barium atom having an unusually low co-ordination number of four.Interesting though these structures may be, neither compound has much potential as a CVD precursor.18b Much more promising are polynuclear Ln–Sr/Ba–CuII complexes with bifunctional ligands such as 2-hydroxypyridine and 1,3-bis(dimethylamino)propan-2- ol.18c The 2-D solids [MCu(l-O 2 CCH 2 CO 2 ) 2 (H 2 O) 4 ] (M\Sr, Ba), where the copper atoms have elongated-octahedral co-ordination, are not volatile but mixed oxides MCuO 2 can be obtained by ceramic methods.18d Copper-exchanged silicates and related species A new Cu` site in calcined Cu-ZSM-5, described as defective (AlOd~)Cu`, has been identified by FT-IR spectra of adsorbed CO.19a DFT analyses have been extensively employed to investigate the binding of small molecules to copper in zeolites; examples include studies of the energetics of water adsorption to H-ZSM-5 and Cu-ZSM-5,19b comparison of the binding ofNO 2 to Cu` in the gas phase with that in zeolites,19c and the decomposition of NO in copper-exchanged zeolites.19d A general expression has been derived for the rate constant for NO decomposition in these systems.19e Experimental work has not been altogether forsaken; the first observation (by NMR spectroscopy) of complexation of a neutral organic free radical (cyclohexadienyl) with a diamagnetic metal ion in a zeolite has been reported for Cu-ZSM-5.19f Copperexchanged silicates other than ZSM-5 are also of interest; an example is MFIferrisilicate, where activity towards the reduction of NO with ammonia is independent of the exchange level.19g The adsorption of water, ammonia, methanol and ethylene on CuH-SAPO-35, a small-pore silicoaluminophosphate similar to the zeolite levyne, has been studied by EPR spectroscopy.19h Alkali metal cations increase the yield of benzaldehyde in the gas-phase oxidation of benzyl alcohol catalysed by copperexchanged Y-type zeolite.19i Most of the aforementioned systems are prepared by treating the zeolite with Cu2`(aq), followed by calcining which results in at least partial reduction to copper(I).Highly-exchanged CuI–mordenite has been prepared by treating the zeolite with CuCl vapour; this material adsorbs CO at room temperature, with formation (according to EXAFS and FT-IR spectra) of CuI(CO)n adducts: at 77 K, tricarbonyl species can be detected.19j Hyperfine sublevel correlation spectroscopy has been applied to [Cu(py) 4 ]2` in the molecular sieves Cu-Na-Y-zeolite and MCM-41; in the former the planes of the py rings are perpendicular to the CuN 4 , while in the latter the py planes are parallel to the equatorial plane.19k The complex [Cu(salen)] encapsulated in Na-Y zeolite changes from green to red on treatment with MeCN; the red form catalyses organic oxidations while the green form is inactive.19l Finally, the first example of a copper-exchanged silicon-free aluminophosphate molecular sieve has been reported.19m Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 1984 Copper(II) chemistry Mononuclear species Complexes with N-donor ligands.This section covers copper(II) complexes where the primary ligands are deemed to be nitrogen donors, although the focus of interest may lie in other ligands. Wefollow the sequence: amines, imines; nitrogen heterocycles; phen and bipy complexes; porphyrins and phthalocyanins. Both the isomers [CuL 2 ][NO 3 ] 2 ·2H 2 O(red) and [CuL 2 (H 2 O)][NO 3 ] 2 ·H 2 O(blue) exhibit thermochromism (L\N1-isopropyl-2-methylpropane-1,2-diamine).20a The conformations of six-membered rings in 174 copper(II) diamine complexes in the Cambridge Structure Database have been analysed; 167 have chair and 5 boat conformations, with one representative each of the d- and k-twist boat conformations. 20b The cation in [CuL(Me 5 dien)][ClO 4 ] (HL\valine) has trigonal bipyramidal co-ordination geometry, which is unusual for a copper(II) complex with a chelating amino acid.20c An EPR study of [CuL(en)][ClO 4 ] 2 [L\NH 2 (CH 2 ) 3 NH(CH 2 ) 3 NH 2 ] is perhaps the most detailed yet published for a trigonal bipyramidal CuN 5 complex.20d The e§ects of methyl substituents on the structural, spectroscopic, thermodyamic and kinetic properties of [CuL(H 2 O)]2` (L\Mentren; n\3,6) have been studied.20e The bulky ligand in [CuCl 2 L] [L\([)-sparteine] enforces a distorted tetrahedral co-ordination geometry about the copper atom.20f The kinetics of substitution of nickel for copper in [CuL] [H 2 L\N,N@-ethylenebis(2-aminobenzaldimine)], studied in dmf, show that the rate is strongly dependent on the anion X in the order ClO 4 ~\Br~\NCS~@Cl~; the mechanism apparently involves the reaction of [CuL] with [NiX 2 (dmf) 2 ] to form a binuclear intermediate.20g This paragraph covers copper(II) complexes with heterocyclic N-donors, apart from bipy and phen derivatives.Solutions of copper(II) chloride in pyridine, methylpyridines or dimethylpyridines act as homogeneous catalysts for the water–gas shift reaction.21a Ferromagnetic coupling between the unpaired spins on CuII and 4-NOpy [\4-(Noxyl- tert-butylamino)pyridine] in [Cu(facac) 2 (4-NOpy) 2 ] leads to an S\3 2 ground state.However, [Cu(facac) 2 (3-NOpy) 2 ] behaves as if the spins on the radical ligands are strongly antiferromagnetically coupled, and the complex is simply an S\1 2 paramagnet. 21b From solutions of copper(II) nitrite and the tridentate ligand 2,6-bis[(3,5- dimethyl)pyrazol-1-yl]pyridine (L) in MeCN–H 2 O a compound can be crystallised containing neutral square pyramidal [Cu(ONO) 2 L] molecules; the unit cell also contains discrete [Cu(ONO) 4 ]2~ ions and nitrite-bridged dimeric units.21c Co-ordinated hydroperoxide has been established structurally and spectroscopically in [Cu(OOH)L][ClO 4 ], where L is a tripodal pyridylamine.21d The first example of hexafluorosilicate acting as a bidentate chelating ligand is found in [CuL(MeOH)]- [Cu(F 2 SiF 4 )L][BF 4 ] 2 , where L is a tetradentateN 4 ligand containing two pyridyl and two pyrazolyl rings; the Cu–F distances (2.20 and 2.36Å) are intermediate between the ‘short’ and ‘long’ bonds found in elongated-octahedral fluoro-complexes of copper( II).10a Several new copper(II) complexes with 3-chloro-6-(pyrazol-1-yl)pyridazine (L) have been characterised; intramolecular NH· · ·N hydrogen bonding between L and L@ (\2-cyanoguanidine) and the presence of both co-ordinated and non-coordinated tetrafluoroborate are features of [Cu(FBF 3 )L(L@)(H 2 O)][BF 4 ].21e By Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 199adding bulky (mesityl) substituents in the 3,3A positions of 2,6-di(pyrazol-1-yl)pyridine, a compressed octahedral structure with a (dz2)1 ground state can be sterically imposed in [CuL 2 ]X 2 (X\BF 4 , ClO 4 ).21f Pulsed EPR studies of polyimidazole copper(II) complexes show how the mode of co-ordination of histidine to copper (via Nd or Ne) in proteins can be determined.21g This paragraph deals with copper(II) complexes having bipy, phen and their derivatives as primary ligands.Trigonal bipyramidal co-ordination geometry is found in [Cu(NCO)(bipy) 2 ][C(CN) 3 ]; attempts to prepare the phen analogue result in [Cu(NCO) 2 (phen)].22a A chiral bipy derivative (L), having asymmetric substituents in the 3 and 3@ positions, forms the complexes [CuX 2 L 2 ] (X\Cl, triflate); the triflate catalyses the asymmetric cyclopropanation of alkenes.22b The complexes [Cu(phen) 2 Br]X (X\Br, ClO 4 , NO 3 , PF 6 ) have co-ordination geometries described as ‘square based pyramidal distorted trigonal bipyramidal’, while with X\BPh 4 the co-ordination is ‘extreme trigonal bipyramidal square based pyramidal’; as with the chloro-analogues, a common structural pathway between the regular five-co-ordinate geometries can be traced.22c The EPR spectrum of [Cu(HL)(phen) 2 ]·0.5phen·7H 2 O [H 3 L\1,3,5-triazine-2,4,6-(1H,3H,5H)trione] can be interpreted in terms of a mixed dz»–dx»~y» ground state, consistent with the co-ordination geometry which is intermediate between trigonal bipyramidal and square pyramidal; although binuclear units (via hydrogen bonding) can be discerned in the structure, there is no evidence of magnetic coupling down to 4.2 K.22d Elongated octahedral co-ordination, with long bonds to water and one phen nitrogen atom, is found in [CuMONC(CN) 2N(phen) 2 (H 2 O)].22e In [Cu(dmphen) 2 (H 2 O)][CF 3 SO 3 ] 2 the equatorial Cu–O distance in the distorted trigonal bipyramidal co-ordination polyhedron is considerably shorter (2.08Å) than in [Cu(phen) 2 (H 2 O)][BF 4 ] 2 ; the kinetics of NO reduction by the dmphen complex point to formation of an inner-sphere NO complex. 22f A conformational transition from B (right-handed) to Z (left-handed) DNA is induced22g by [Cu(5,6-Me 2 phen)]2`. The unsymmetrical chelation of dafone in complexes such as [CuBr 2 (dafone) 2 ] can be rationalised in terms of the unusually large bite (ca. 3.0Å, compared with ca. 2.6Å for bipy and phen).22h Measurements of the temperature dependence of the Soret bandwidth combined with resonance Raman spectroscopy have been applied in the study of the coupling of solvent motion to vibrations involving the metal atom in [M(oep)]; such coupling was found to be almost negligible for M\Cu, weak for Co and strong for Ni and Pd.23a The ‘sitting-atop’ complex [Cu(H 2 tpp)]2` has been established in acetonitrile; 1H NMR spectra show that the copper atom is co-ordinated to two trans pyrrolenine nitrogen atoms with two pyrrole nitrogens remaining protonated.23b The complex [CuL] with the new ligand L\tetrakis(1,2,5-thiadiazole)porphyrazine should be of interest to workers in the field of conducting materials.23c Eight tetraazomacrocycles with co-ordinated metal ions can be attached to the benzenoid rings in [Cu(pc)]; their e§ect on the CuII EPR parameters is small, and can be correlated with the electronegativities of the metal centres.23d Complexes with O- or N,O-donor ligands.Beginning with aqua-complexes, MS studies show that when [Cu(OH)(H 2 O) 4 ]` reacts with D 2 O in the gas phase, ligand exchange but not hydrogen/deuterium exchange takes place.24a Irradiation of[NH 4 ] 2 - [Cu(H 2 O) 6 ][SO 4 ] 2 , containing about5% deuterium, at theN–Dstretching frequency Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 200induces switching between the di§erent structures of the deuteriated and nondeuteriated Tutton salt, via coupling of the O–D modes to the Jahn–Teller distortion. 24b ESEEM spectra of the same salt are particularly sensitive to the vibronic dynamics which produce the Jahn–Teller distortion.24c Aqueous solutions containing 0.5 mol kg~1 CuCl 2 and 5 mol kg~1 NaCl induce the condensation of amino acids to peptides; neutron di§raction studies and Monte Carlo simulations show that [CuCl(H 2 O) 5 ]` is the dominant species.24d This paragraph deals with mononuclear copper(II) carboxylate complexes. Discrete cations with square planar CuO 4 co-ordination are found in [CuL 4 ][ClO 4 ] 2 and in Na[CuL 4 ][ClO 4 ] 3 (L\trimethylammonioacetate),25a while square pyramidal coordination is found in [CuClL 2 (H 2 O) 2 ][ClO 4 ] (L\4-pyridinioacetate).25b In [CuL 2 (tn) 2 ] (HL\2-, 3- or 4-aminobenzoic acid) the monodentate L groups form long Cu–O bonds in the elongated octahedral co-ordination; in the 4-aminobenzoate complex, there are two molecules of water in the lattice which form hydrogen bonds with the amino groups.25c Elongated octahedral co-ordination also occurs in [CuL 2 (L@) 2 ] (HL\nonanoic acid, L@\2-aminoethanol); the monodentate carboxylates and amino nitrogen atoms furnish the equatorial ligands, while the alcohol oxygen atoms form long (2.48Å) axial bonds.25d The only other studies of copper(II) complexes with purely O-donor ligands involve dionates.The square planar complexes [CuL 2 ] (HL\5-alkoxytropolone) exhibit both enantiotropic and mesophase behaviour.25e The square pyramidal complex [CuL 2 (H 2 O)] (HL\4-tert-butylacetyl- 3-methyl-1-phenylpyrazol-5-one) is of interest on account of its intricate hydrogen bonding network, the ability of other ligands to displace the apical water and the possibilities a§orded by the bulky neopentyl group.25f Looking now at complexes with amino acids and peptides, the structures of copper( II) complexes with glycine in aqueous solution have been studied by XAS.In the mono- and bis-species, the glycinate is bidentate with water molecules completing elongated octahedral co-ordination; the tris-species is square pyramidal, the apical position being occupied by an amino nitrogen atom.26a In [CuLL@] (H 2 L\glycylglycine, L@\isocytosine) L is tridentate N 2 O bonding with the pyrimidine contributing a nitrogen donor atom.26b The complexes [CuL]` and [CuClL@]`, where HLand L@ are bis(2-pyridylmethyl) derivatives of glycylglycine and glycylglycylglycine respectively, perform site-specific single-strand DNA scission.26c Among numerous papers on copper(II) complexes with Schi§ bases and related ligands, we mention four of special interest.In complexes [CuL], where H 2 L is obtained by condensation of 2-(2-pyridylmethyl)propane-1,3-diamine with substituted salicylaldehydes, the pendant arm is enganged in neither inter- nor intra-molecular bonding.27a The EPR spectrum of [CuClL] [L\(o-O)C 6 H 4 CH––NC(Me)(CH 2 OH) 2 ] indicates an S\1 ground state, the molecules interacting via extended hydrogenbonded networks.27b Copper(II) complexes with chiral Schi§ bases catalyse the peroxidation of PhMeS to PhMeSO, with a modest enantiomeric excess.27c The smectogenic properties of complexes [CuL 2 ] [L\4-alkoxy-N-(4-ethoxyphenyl)salicylaldiminate] have been examined.27d Among complexes with miscellaneous O- and N,O-donor ligands,DFT calculations have been performed on 18 possible structures for [Cu(NO 2 ) 2 ]; the most stable is found to be the planar, D 2) structure [Cu(g2-O 2 N) 2 ].28a The fungal enzyme galactose oxidase (GOase), whose active site contains a square-pyramidally co-ordinated cop- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 201per(II) atom with an O-bonded tyrosyl radical in the equatorial plane, is EPR-silent; this suggests antiferromagnetic coupling between Cu2` and the tyrosyl radical which is surprising since in model systems examined to date similar coupling is always ferromagnetic.Studies of the model complexes [CuXL] MX\Cl, R 2 acac (R\Ph, Bu); HL\N 3 Oligand based on [9]aneN 3N show that antiferromagnetic vs. ferromagnetic coupling depends on the dihedral angle between the equatorial plane and the plane of the phenyl ring of the radical ligand.28b In another EPR-silent GOase model, the nitrogen atoms in the N 3 O 2 donor set are furnished by TpP) and the oxygen atoms by a salicylaldehyde derivative; its electronic spectrum is remarkably similar to that of the active enzyme.28c Another GOase model contains square-pyramidally bonded copper( II) with a long (2.57Å) apical bond to a phenolic oxygen atom.28d The first structurally-characterised copper(II) nitrone complex [Cu(facac) 2 L] (L\N-tertbutyl- 2-pyridylmethyleneamine N-oxide) contains two independent molecules in the unit cell, both having slightly elongated octahedral co-ordination geometry; in one molecule the axial atoms are one nitrone oxygen and one facac oxygen, while in the other the axial oxygen atoms are furnished by two facac ligands.28e Finally, a cryptand N 4 ligand L forms a complex [CuL(H 2 O)][pic] 2 in which the hydrogen atoms of the water molecule, the apical ligand in a square pyramidal arrangement, appear to be hydrogen bonded to benzene rings.28f Complexes with S- and Se-donor ligands.This year’s highlight is the characterisation of the first stable CuIIS 4 compound, [CuMPt 2 (dppe) 2 (l3 -S) 2N2 ]; the co-ordination geometry is distorted tetrahedral.29a Exact ferrodistortive ordering is found in the distorted square planar complex [CuLL@] (H 2 L\N-salicylideneglycine, L@\N,N@- dibutylthiourea).29b EPR spectra are useful in the characterisation of copper(II) complexes with thiourea derivatives (HL) of the types R 2 NC(S)NHC(O)R (which are S,O bidentate ligands) and R 2 NC(S)N–– C(NHR)(R@) (S,N bidentate); in chloroform–methanol [CuL 2 ], where L is an (S,O) ligand, consists of both cis and trans isomers but for (S,N) ligands only one isomer is present.29c In [CuL 2 ]·2H 2 O [HL\4-(benzimidazol- 2-yl)-3-thiabutanoic acid] the equatorial ligands in the elongated octahedron are cis-N 2 O 2 with distant (2.74–2.75Å) axial sulfur atoms; in the nickel analogue the sulfur atoms occupy cis positions.29d Two new acyclic ligands, each furnishing N 2 (pyridyl) N 2 (amido)S 2 (thioether) donor sets give complexes [CuL] and [CuL@], where the sulfur atoms are spaced by two or three methylene groups in L and L@ respectively; [CuL] has an axially-compressed octahedral structure (which, however, becomes axially-elongated in solution) while [CuL@] exhibits flattened tetrahedral CuN 4 coordination. 29e The tridentate N 2 S thiosemicarbazone HL formed from 2-formylpyridine forms dimeric copper(II) complexes but with a methyl group in the 6-position the monomeric species [CuXL(H 2 O)n] (n\0, 1; X\NCS, OAc, N 3 ) and [Cu(OSO 3 )L(H 2 O)] can be prepared.29f Bis(thiosemicarbazone)copper(II) complexes are of considerable medical interest for imaging hypoxic tissues; structure–activity relationships, including correlations involving the CuI–CuII redox potential, have been explored.29g In [Cu([9]aneNS 2 ) 2 ][PF 6 ] 2 the co-ordination geometry is a slightly compressed octahedron, with four relatively long Cu–S distances.29h The first copper( II) 1,2-diselenooxalate (L) complex [CuL 2 ]2~ has been identified in solution by EPR spectroscopy; it decomposes rapidly.29i Annu.Rep.Prog. Chem., Sect. A, 1999, 95, 189–211 202Bi-, oligo-, poly- and hetero-nuclear species Binuclear complexes. We begin with complexes where the metal centres have simple bridges (halide, alkoxide, etc.), through diatomic and polyatomic bridges to binucleating ligands where the co-ordination sites are remote from each other. The complex [Cu(Se 2 CNEt 2 ) 2 ] reacts with CuX 2 (X\Cl, Br,NO 3 ) in dmf, for example, to give both [CuX(Se 2 CNEt 2 )]n and the EPR-silent dimers [MCu(Se 2 CNEt 2 )(l-X)N2 ].30a The bidentate nitrate in [Cu(O 2 NO)(ONO 2 )(bipy)] is easily displaced by OH~ and N 3 ~ (X) to give [MCu(ONO) 2 (l-X)(bipy)N2 ].30b DFT calculations reproduce satisfactorily the ferromagnetic coupling constants found experimentally in end-on azidobridged copper(II) complexes.30c The spin distribution in the triplet ground state of [MCu(l-1,1-N 3 )L 2N2 ][ClO 4 ] 2 (L\p-tert-butylpyridine) has been investigated by polarised neutron di§raction; while DFT calculations reproduce qualitatively the spin density map, they overestimate the spin delocalisation towards the ligands.30d Zero field electron magnetic resonance spectrocopy has produced accurate spin- Hamiltonian parameters for the triplet ground state of [MCu(l-1,1-N 3 )(Me 5 dien)N2 ]- [BPh 4 ] 2 .30e The new chelating ligand L (2-methoxymethylamino-3-methylpyridine) was formed in situ from Cu(NO 3 ) 2 , 2-amino-3-methylpyridine, MeOH and O 2 , giving the complex [MCu(l-OMe)(ONO 2 )LN2 ].30f Another unexpected product is the dimethoxy-bridged complex [MCuBr(l-OMe)LN2 (MeOH)] [L\N-tert-butyl-N-M(2- pyridyl)methylideneNamine], prepared by the reaction of CuBr with two equivalents of L and two of phenol; in the absence of phenol (presumably the oxidising agent) [CuBrL] is the product.30g Four new bridging modes for carbonate have been established in dicopper(II) complexes with alkyl-substituted dien.30h Bis-bidentate sulfate is the bridging ligand in [MCu(HL)(H 2 O)N2 (l-O 2 SO 2 )] (H 2 L\pyruvic acid thiosemicarbazone).30i Many more complexes contain alkoxo- or phenoxo-bridged copper(II) atoms which form part of a much larger binucleating ligand. Several magnetically- diverse phenoxo-bridged dicopper(II) species (including both ferro- and antiferro- magnetic species) exhibit sharp hyperfine-shifted 1HNMRsignals; these provide probes of the active sites of, for example, hyperactive copper(II)-substituted aminopeptidase. 30j A dicopper(II) complex with a Schi§ base ligand exhibits, as expected, an oxime bridge, CuNOCu, but also (unexpectedly) a Cu–O–Cu bridge via a ketonic oxygen atom.30k A double oxime bridge in [MCu(l-L)(l-O 2 ClO 2 )N2 ] (HL\2,6-diformyl- 4-methylphenol dioxime) is supplemented by asymmetrically-bridging perchlorate ions, with long Cu–O bonds (2.51 and 2.76Å).30l Other binucleating ligands with fairly short inter-copper bridges include diazines,30m hydrazones,30n tetra-amino substituted diamines,30o and oxamidates.30p This paragraph is devoted to dicopper(II) complexes with carboxylate bridges.The familiar ‘paddlewheel’ structure, as in [MCu(l-OAc) 2 (H 2 O)N2 ], has been established in the superoxide dismutase mimetic [MCu(l-L) 2 (NCMe)N2 ] [HL\a-methyl-4-(2- thienylcarbonyl)phenylacetic acid],31a [MCuCl(l-L) 2N2 ]Cl 2 ·H 2 O (L\b-alanine),31b and [MCu(l-L) 2 (H 2 O)N2 ][NO 3 ] 2 [ClO 4 ] 2 (L\pyridinioacetate).31c Attempts to displace the co-ordinated MeOH by py in [MCu(l-L) 2 (MeOH)N2 ] (HL\4-chlorophenoxyisobutyric acid) led to a mononuclear complex [CuL 2 - (py) 2 ].31d The first example of two non-equivalent apical ligands in the paddlewheel dimer is found in [MCu(l-L)N2 L@(H 2 O)] (HL\flufenamic acid; L@\ca§eine).31e The dimers [MCuL 2 L@N2 ] (HL\diphenylacetic acid, L@\MeCN, Me 2 CO) have been Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 203detected as intermediates in the CuII-catalysed oxidation of carboxylic acids.31f Just two bridging carboxylate groups are present in [MCu(l-L)(bipy)N2 ][ClO 4 ] 2 (HL\ferrocenecarboxylic acid)31g and in [MCu(l-OAc)N2 (l-L)][ClO 4 ] where HL is an N 4 O binucleating ligand furnishing a phenolate bridge.31h Among dicopper(II) complexes with one bridging carboxylate [MCuLN2 (l-OAc)(l-OH)(l-OH 2 )][ClO 4 ] 2 (L\1,4- dimethyl[9]aneN 3 ) contains a rare example of a bridging water molecule.31i The reaction of one equivalent each of Cu(BF 4 ) 2 and [MCu(OAc) 2 (H 2 O)N2 ] with two equivalents of cis,cis-1,3,5-triaminocyclohexane and one equivalent of isophthalaldehyde led to the self-assembly of the EPR-silent complex [Cu 2 (l-OAc)(l-OH)(l-L)]- [BF 4 ] 2 [L\bis-1,3-(cis,cis-1,3,5-triaminocyclohexane)xylylidiene].31j However, ferromagnetic coupling, presumably due to accidental orthogonality of the magnetic orbitals, is present in [MCu(H 2 O)N2 Cl(l-OAc)(l-L)][ZnCl 4 ] where L is an N 5 binucleating ligand.31k Among dicopper(II) complexes where the copper sites are remote from each other, an unusual case of hydrate isomerism is found in [MCu(OAc)(H 2 O)N2 (l-L)][ClO 4 ] 2 and [MCu(OAc)N2 (l-L)][ClO 4 ] 2 ·2H 2 O where L is a binucleating (N 3 ) 2 ligand.32a Other types of binucleating ligands for copper(II) include amide-based cyclophanes,32b a pyrazole-bridged bis(N 2 S-macrocycle),32c a triaminopentabenzimidazole (which provides a tyrosinase model),32d a calix[4]arene,32e bis([9]aneN 3 ) macrocycles with 2- pyridylmethyl arms,32f a tetraoxime whose two compartments are linked by a C––C bond,32g and a metallacyclic oxime complex with two copper atoms occupying opposite positions in the ring.32h Oligonuclear complexes.The template reaction of Cu(CF 3 SO 3 ) 2 with 2- aminopyridine or 2-aminopyrimidine and triethylorthoformate in EtOH results in the complexes [Cu 3 L 4 ][CF 3 SO 3 ] 2 , where HL is a formamidine; the cations have a propeller-like structure about the linear Cu–Cu–Cu axis.33a Other linear Cu 3 arrays are found in [Cu 3 (l-OMe) 4 L 2 ][BF 4 ] 2 , where L is a stereochemically-rigidN 3 -trisubstituted derivative of 1,3,5-triaminocyclohexane,33b and [Cu 3 L 4 ][BF 4 ] 2 [HL\(2- hydroxyphenyl)bis(pyrazolyl)methane].33c An equilateral triangle of copper atoms occurs in a dodecaaza macrotetracyclic complex, prepared by the simple template condensation of tren with formaldehyde in the presence of Cu2`; an unusual l3 - oxygen atom sits above the centre of the Cu 3 plane.33d A polyamine alcohol H 3 L having three OH groups and six amine nitrogen atoms forms the complex [Cu 3 Cl 2 (HL)][ClO 4 ] 2 where two copper atoms are bridged by the two chlorine atoms and the others are bridged by alkoxo-oxygen atoms.33e In [MCuL(py)N3 ] (H 2 L\2,2@- dihydroxyazobenzene) the monomeric units are joined by long (2.52–2.77Å) Cu–O bonds.33f Quadruply-bridging phosphate is an unusual feature of [MCuL(NCMe)N4 (l4 -O 4 P)][PF 6 ] 5 , where L is a tridentate bipy derivative.33g In the ‘dimer of dimers’ [MCu 2 L[OPO(OH) 2 ][O 2 P(OH) 2 ]N2 ][NO 3 ] 2 [HL\bis(pyridine-2- aldehyde) thiocarbohydrazone] one phosphate ligand in each dimeric unit is monodentate and the other bidentate.33h Other Cu 4 species include a linear oximate-bridged array,33i a cyclic tetramer formed by deprotonation of the monomer,33j a number of l4 -oxo- and -peroxo-bridged systems33k and a double-helical complex with a bis(bidentate) Schi§ base ligand.33l Benzotriazole (LH) is a useful corrosion inhibitor for copper metal and its alloys; its l3 -bridging mode in complexes such as [Cu 5 L 6 L@4 ] (HL@\substituted butane-1,3-dione) may be involved in the formation of protective Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 204monolayer coatings on oxidised copper surfaces.33m Finally, an octanuclear complex with the immunosuppressant azathioprine is perceived as two Cu 4 units bridged by two azothioprine ligands.33n Polycopper(II) compounds.Reports of new polymeric copper(II) compounds (mostly chain structures with the usual bridging ligands) are legion; here we focus on polymers which qualify as products of crystal engineering. The chain polymer [Cu(l- O 4 C 4 )(H 2 O) 2 (dmf) 2 ]n lacks the zigzag motif characteristic of the Mn, Co, Ni and Zn analogues.34a Unlike the ferromagnetic cobalt and nickel analogues, the rutile-related [CuMl3 -N(CN) 2N2 ]n is a ‘near-paramagnet’.34b Copper(II) nitrate reacts with 1,2-bis(4- pyridyl)ethyne (L) in EtOH to give the 1-D ladder polymer [Cu(l-L)(l- ONO 2 )(O 2 NO)]n and a more complex product having a triply-penetrating chiral frame based on square planar centres.34c 2-D square grids, with large (11]11Å) square cavities characterise the structure of [4,4@-H 2 bipy]n[Cu(4,4@-bipy) 2 (H 2 O) 2 ]n- [ClO 4 ] 4n,34d while [Cu(4,4@-bipy)(pyz)(H 2 O) 2 ]n[PF 6 ] 2n has rectangular grids with smaller (11]7Å) cavities.34e However, instead of the expected square grid, [Cu(ONO 2 ) 2 L 2 ]n [L\1,2-bis(4-pyridyl)ethane] is the first example of a co-ordination polymer having the NbO 3-D network structure.34f Rugged hexagonal grids are the feature of [Cu 6 (l3 -OH) 2 (l-L) 3 (H 2 O) 2 ]nBr 4n [H 2 L\trans-N,N@-bis(2- aminoethyl)oxamide].34g Tetrakis-(4-cyanophenyl) and -(4-nitrophenyl) derivatives of copper(II) porphyrins form the basis for 2-D polymers having large cavities.34h The hydrothermal reaction of CuSO 4 ·5H 2 O with MoO 3 and ligands such as 1,2,4-triazole and 1,2-trans-(4-pyridyl)ethene produces 3-D organic–inorganic hybrid materials.34i,j Heteronuclear complexes.These are covered in increasing order of the atomic numbers of the heteroatoms present. The unsymmetrical tridentate Schi§ base HL obtained by condensation of 2-imidazolecarbaldehyde and histamine forms the Vshaped, imidazolate-bridged trinuclear complexes [Cu(facac)(l-L)M(facac) 2 (l- L)Cu(facac)] (M\Mn, Ni, Zn).35a A cytochrome c oxidase model in which an FeII atom is bonded to tpp and a CuI atom to tmpa, the tpp and tmpa being linked by a peptide bridge, reversibly binds dioxygen in l-1,2-peroxo fashion.35b The oxidised (FeIII–CuII) form of a similar model, with the copper attached to a tris(imidazolyl)methane moiety, has been prepared.35c An EPR study of cytochrome bo 3 indicates that the FeIII–CuII coupling is much weaker than previously proposed.35d Ageneral approach has been developed for the rational synthesis of linear FeIIICuIINiII, FeIIINiIICuII and CoIIICuIINiII complexes where two metal atoms are bound to a binucleating Schi§ base oxime and the third to Me 3 [9]aneN 3 .35e The tetradentate Schi§ base H 2 L, derived from imidazole-2-carbaldehyde and tn, forms [Cu(OClO 3 )(H 2 L)][ClO 4 ] which reacts with [Ni(facac) 2 ] under basic conditions to give an imidazolate-bridged NiIICuIINiII complex with a quartet ground state.35f The central copper(II) atom in [Cu(l-ONO) 2MNiL(dmf)N2 ] is bonded to two nitrite oxygen atoms and four more oxygen atoms from the Schi§ base L.35g In a tetranuclear [NiII(l-L)CuII] 2 system, where L is bis(3-aminopropyl)oxamide, the binuclear units are linked by thiocyanate bridges.35h Although spectroscopic and electrochemical measurements show no ground state coupling between the metal centres in [RuII(bipy) 2 (l-L)CuII(phen)(H 2 O)][PF 6 ] 3 (HL\a,x-diamino acid-substituted bipy), Annu.Rep. Prog. Chem., Sect.A, 1999, 95, 189–211 205their luminescence is significantly quenched compared with the parent RuII complexes. 35i The 2-D complex [NBu 4 ][RuIIICuII(l-ox) 3 ] is ferrimagnetic.35j While carboxylate- bridged CuII 2 MIII 2 (M\Ce, Gd) complexes obey the Curie–Weiss law,35k there is evidence of antiferromagnetic Cu–Pr exchange in [Pr 2 Cu 4 (l6 -O)(l-L) 3 (l- HL) 2 (facac) 4 ] (H2 L\2,2@-thiodiethanol).35l The reaction of copper powder with Pb(SCN) 2 and 2-dimethylaminoethanol (HL) in MeCN gave [MCu 2 Pb(l-SCN) 3 (l- L) 3N2 ]; the trinuclear units, within which the metal atoms are alkoxo-bridged, are dimerised via bridging thiocyanate groups.35m 5 Copper(III) chemistry The stability of [PPh 4 ][CuL]·MeCN [H 4 L\bis(methylamide) of N,N@-ophenylenebis( oxamic acid)] is attributed to its large crystal field stabilisation energy; electrochemical studies of this and related compounds show a correlation between the CuII–CuIII redox potentials and the absorption maxima in the d–d spectra of the copper(II) species.36a The template reaction of Cu(OH) 2 with oxalodihydrazide and formaldehyde produced a square planar copper(III) macrocyclic anion.36b The reaction between [NHEt 3 ] 2 [MnIVL 3 ] (H2 L\quinoxaline-2,3-dithiol) and [MCu(OAc) 2 (H 2 O)N2 ] in dmf led to [MnII(dmf) 4 (H 2 O) 2 ][CuIIIL 2 ] 2 .36c The product of the reaction between [CuL(NCMe)]` [L\bisM2-(2-pyridyl)ethylNmethylamine] and O 2 is a mixture of l-g2:g2-peroxodicopper(II) and bis-l-oxodicopper(III) species.36d The reaction of [CuL(NCMe)]` (L\N,N,N@,N@-tetramethylcyclohexane-1,2-diamine) with O 2 gives [MCuLN3 (l3 -O) 2 ][CF 3 SO 3 ] 3 which is best described as a localised CuIICuIICuIII mixed-valence species.36e References 1 (a) D.Walter and P. B. Armentrout, J. Am. Chem. Soc., 1998, 120, 3176; (b) H. Deng and P. Kebarle, J. Am. Chem. Soc., 1998, 120, 2925; (c) A. Luna, B. Amekraz, J. Tortajada, J. P. Morizur, M.Alcami, O. Mo and M. Yanez, J. Am. Chem. Soc., 1998, 120, 5411; (d) A. Luna, J. P. Morizur, J. Tortajada, M. Alcami, O.Mo and M. Yanez, J. Phys. Chem. A, 1998, 102, 4652; (e) M. Alcami, O. Mo, M. Yanez, A. Luna, J. P. Morizur and J. Tortajada, J. Phys. Chem. A, 1998, 102, 10 120; ( f )M. Ilias, P. Furdik and M. Urban, J. Phys. Chem. A, 1998, 102, 5263. 2 (a) S.H. Bertz, K. Nilsson, O.Davidsson and J. P. Snyder, Angew. Chem., Int. Ed., 1998, 37, 314; (b)G. Boche, F. Bosold, M. Marsch and K. Harms, Angew. Chem., Int. Ed., 1998, 37, 1684; (c) A. Szulc, D. Meyerstein and H. Cohen, Inorg. Chim. Acta, 1998, 270, 440; (d) F. Khajehnouri, N. Amstutz, E. A. C. Lucken and G. Bernardinelli, Inorg. Chim. Acta, 1998, 271, 231; (e) P.B. Hitchcock, M.F. Lappert and M.Layh, J. Chem. Soc., Dalton Trans., 1998, 1619; ( f ) G. Pilloni, B. Longato, G. Bandoli and B. Corain, J. Chem. Soc., Dalton Trans., 1998, 819; (g) G. Pilloni, B. Longato and G. Bandoli, Inorg. Chim. Acta, 1998, 277, 163; (h) D.W. Allen, J. P. L. Mißin and S. Coles, Chem. Commun., 1998, 2115; (i) G. Exarchos, S. C. Nyburg and S. D. Robinson, Polyhedron, 1998, 17, 1257; (j) K. Fujisawa, S.Imai, N. Kitajima and Y. Moro-oka, Inorg. Chem., 1998, 37, 168. 3 (a) B.A. Jazdzewski, V. G. Young and W.B. Tolman, Chem. Commun., 1998, 2521; (b) A. F. Stange, T. Sixt and W. Kaim, Chem. Commun., 1998, 469; c) D. J. Darensbourg, D. L. Larkins and J. H. Reibenspies, Inorg. Chem., 1998, 37, 6125. 4 (a) S. Imai, K. Fujisawa, T. Kobayashi, N. Shirasawa, H. Fujii, T. Yoshimura, N.Kitajima and Y. Moro-oka, Inorg. Chem., 1998, 37, 3066; (b) O. Zelenko, J. Gallagher, Y. Xu and D. S. Sigman, Inorg. Chem., 1998, 37, 2198; (c) D.M. Haddleton, D. J. Duncalf, D. Kukulj, M.C. Crossman, S. G. Jackson, S. A. F. Bon, A. J. Clark and A. J. Shooter, Eur. J. Inorg. Chem., 1998, 1799; (d) A. J. Blake, D. E. Hibbs, P. Hubberstey and C. E. Russell, Polyhedron, 1998, 17, 3583; (e) Q.-H.Jin, X.-L. Xin, C.-J. Dong and H.-J. Zhu, Acta Crystallogr., Sect. C, 1998, 54, 1087; ( f ) M.R. Waterland, K. C. Gordon, J. J. McGarvey and P. M. Jayaweera, J. Chem. Soc., Dalton Trans., 1998, 609; (g) S.M. Scott, K. C. Gordon and A. K. Burrell, J. Chem. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 206Soc., Dalton Trans., 1998, 2873; (h) S.E. Page, K.C. Gordon and A. K. Burrell, Inorg. Chem., 1998, 37, 4452; (i) J.V. Hanna, R. D. Hart, P. C. Healy, B. W. Skelton and A. H. White, J. Chem. Soc., Dalton Trans., 1998, 2321; (j) J. S. Lewis, J. Zweit and P. J. Blower, Polyhedron, 1998, 17, 513; (k) J. S. Lewis, S. L. Heath, A. K. Powell, J. Zweit and P. J. Blower, J. Chem. Soc., Dalton Trans., 1998, 855; (l) W. S. Striejewske and R.R. Conry, Chem. Commun., 1998, 555; (m)W. Liang, S. Liu, C. R. Lucas and D. O. Miller, Polyhedron, 1998, 17, 1323; (n)W. Su, M. Hong, R. Cao and H. Liu, Acta Crystallogr., Sect. C, 1998, 54, 337. 5 (a) J.-M. Poblet and M. Benard, Chem. Commun., 1998, 1179; (b) X.-Y. Liu, F. Mota, P. Alemany, J. J. Novoa and S. Alvarez, Chem. Commun., 1998, 1149; (c) E. J. Fernandez, J. M.Lopez-de-Luzuriaga, M. Monge, M.A. Rodriguez, O. Crespo, M. C. Gimeno, A. Laguna and P. G. Jones, Inorg. Chem., 1998, 37, 6002; (d) P. Pyykko and F. Mendizabal, Inorg. Chem., 1998, 37, 3018; (e) F.A. Cotton, X. Feng and D. J. Timmons, Inorg. Chem., 1998, 37, 4066. 6 (a) M. Munakata, H. He, T. Kuroda-Sowa, M. Maekawa and Y. Suenaga, J. Chem. Soc., Dalton Trans., 1998, 1499; (b)M. Maekawa, M.Munakata, S. Kitagawa, T. Kuroda-Sowa, Y. Suenaga and M. Yamamoto, Inorg. Chim. Acta, 1998, 271, 129; (c)K. Johnson and J. W. Steed, J. Chem. Soc., Dalton Trans., 1998, 2601; (d) S.-M. Kuang, Z.-Z. Zhang, Q.-G. Wang and T. C. W. Mak, J. Chem. Soc., Dalton Trans., 1998, 1115. 7 (a) A. Bayler, A. Schier and H. Schmidbaur, Inorg. Chem., 1998, 37, 4353; (b) M.A. S. Goher and T.C.W. Mak, Polyhedron, 1998, 17, 3485; (c) Q.-H Jin, D.-L. Long, Y.-X. Wang and X.-Q. Xin, Acta Crystallogr., Sect. C, 1998, 54, 948; (d)N. Doslik, T. Sixt and W. Kaim, Angew. Chem., Int. Ed., 1998, 37, 2403; (e) L. Jager, C. Tretner, H. Hartung and M. Biedermann, Eur. J. Inorg. Chem., 1998, 1051; (f) A. J. Blake, S. J. Hill, P. Hubberstey and W. S. Li, J. Chem. Soc., Dalton Trans., 1998, 909. 8 (a) W.-H. Chan, S.-M. Peng and C.-M. Che, J. Chem. Soc., Dalton Trans., 1998, 2867; (b) B.-L. Chen, K.-F. Mok and S.-C. Ng, J. Chem. Soc., Dalton Trans., 1998, 2861; (c) C.-S. Hwang, M.M. Olmstead, X. He and P. P. Power, J. Chem. Soc., Dalton Trans., 1998, 2599; (d) K. Singh, J. R. Long and P. Stavropoulos, Inorg. Chem., 1998, 37, 1073; (e) P. J. Schebler, C. G. Riordan, L.Liable-Sands and A. L. Rheingold, Inorg. Chim. Acta, 1998, 270, 543; ( f )H. Eriksson, M. Hakansson and S. Jagner, Inorg. Chim. Acta, 1998, 277, 233; (g) E.S. Raper, J. R. Creighton, W. Clegg, L. Cucurull-Sanchez, M.N. S. Hill and P. D. Akrivos, Inorg. Chim. Acta, 1998, 271, 57; (h) M. Faulhaber, M. Driess and K. Merz, Chem. Commun., 1998, 1887; (i) R.C. Bott, G. A. Bowmaker, C.A. Davis, G. A. Hope and B. E. Jones, Inorg. Chem., 1998, 37, 651; (j) L. I. Victoriana, M. T. Garland, A. Vega and C. Lopez, J. Chem. Soc., Dalton Trans., 1998, 1127; Inorg. Chem., 1998, 37, 2060; (k) C.W. Liu, H.-C. Chen, J.-C. Wang and T.-C. Keng, Chem. Commun., 1998, 1831; (l) M. Semmelmann, D. Fenske and J. F. Corrigan, J. Chem. Soc., Dalton Trans., 1998, 2541; (m) A. Eichhofer and D.Fenske, J. Chem. Soc., Dalton Trans., 1998, 2969. 9 (a) G.A. Bowmaker, B. J. Kennedy and J. C. Reid, Inorg. Chem., 1998, 37, 3968; (b) D. J. Chesnut and J. Zubieta, Chem. Commun., 1998, 1707; (c) A.K. Nurtaeva and E. M. Holt, Acta Crystallogr., Sect. C, 1998, 54, 594; (d) A.K. Nurtaeva, G. Hu and E.M. Holt, Acta Crystallogr., Sect. C, 1998, 54, 597; (e) J.Y. Lu, B. R.Cabrera, R.-J. Wang and J. Li, Inorg. Chem., 1998, 37, 4480; ( f ) S.-J. Hwu, H. Li, R. Mackay, Y.-K. Kuo, M.J. Skove, M. Mahapatro, C. K. Bucher, J. P. Halladay and M. W. Hayes, Chem. Mater., 1998, 10, 6; (g) F. Q. Huang, W. Choe, S. Lee and J. S. Chu, Chem. Mater., 1998, 10, 1320; (h) R.D. Adams, M. Huang and S. Johnson, Polyhedron, 1998, 17, 2775; (i) L.P. Wu, J. Die, M. Munakata, T.Kuroda-Sowa, M. Maekawa, Y. Suenaga and Y. Ohno, J. Chem. Soc., Dalton Trans., 1998, 3255; (j) R. Patschke, J. Heising and M. Kanatzidis, Chem. Mater., 1998, 10, 695; (k) R. Patschke, P. Brazis, C. R. Kannewurf and M. Kanatzidis, J. Mater. Chem., 1998, 8, 2587; (l) A. A. Narducci and J. A. Ibers, Inorg. Chem., 1998, 37, 3798; (m)D.M. Young, U. Geiser, A. J. Schultz and H.H. Wang, J. Am. Chem. Soc., 1998, 120, 1331; (n) D. J. Chesnut, A. Kusnetsow and J. Zubieta, J. Chem. Soc., Dalton Trans., 1998, 4081; (o) D. Hagrman, C. Sangregorio, C. J. O’Connor and J. Zubieta, J. Chem. Soc., Dalton Trans., 1998, 3707; (p) A. Pfitzner, Inorg. Chem., 1998, 37, 5164; (q) A.J. Blake, N. R. Champness, M. Crew, L. R. Hanton, S. Parsons and M. Schroder, J. Chem. Soc., Dalton Trans., 1998, 1533; (r) J.A.Hanko and M.G. Kanatzidis, Angew. Chem., Int. Ed., 1998, 37, 342; (s) J.D. Martin, B. R. Leafblad, R. M. Sullivan and P. D. Boyle, Inorg. Chem., 1998, 37, 1341; (t) J.D. Martin and B. R. Leafblad, Angew. Chem., Int. Ed., 1998, 37, 3318. 10 (a) J. S. Fleming, K. L. V. Mann, S. M. Couchman, J. C. Je§ery, J. A. McCleverty and M. D. Ward, J. Chem.Soc., Dalton Trans., 1998, 2047; (b) T. Bark, T. Weyhermuller and F. Heirtzler, Chem. Commun., 1998, 1475; (c) R. Stiller and J.-M. Lehn, Eur. J. Inorg. Chem., 1998, 977; (d) P. Comba, A. Fath, T. W. Hambley, A. Kuhner, D. T. Richens and A. Vielfort, Inorg. Chem., 1998, 37, 4389; (e) J. S. Fleming, E. Psillakis, J. C. Je§ery, K. L. V. Mann, J. A. McCleverty and M. D. Ward, Polyhedron, 1998, 17, 1705.( f) M. Munakata, G. L. Ning, T. Kuroda-Sowa, M. Maekawa, Y. Suenaga and T. Horino, Inorg. Chem., 1998, 37, 5651; (g) Y. Suenaga, S. G. Yan, L. P. Wu, I. Ino, T. Kuroda-Sowa, M. Maekawa and M. Munakata, J. Chem. Soc., Dalton Trans., 1998, 1121; (h) A.M.A. Ibrahim, E. Siebel and R. D. Fischer, Inorg. Chem., 1998, 37, 3521; (i) M.A. Masood, E. J. Enemark and T.D. P. Stack, Angew. Chem., Int. Ed., 1998, 37, 928. 11 (a) H. Krautscheid, N. Emig, N. Klaasen and P. Seringer, J. Chem. Soc., Dalton Trans., 1998, 3071; (b) J.-P. Lang and K. Tatsumi, Inorg. Chem., 1998, 37, 6308; (c) P. Lin, X. Wu, Q. Huang, Q. Wang, T. Sheng, W. Zhang, J. Guo and J. Lu, Inorg. Chem., 1998, 37, 5672; (d) J. Guo, T. Sheng, W. Zhang, X. Wu, P. Lin, Q. Wang and J.Lu, Inorg. Chem., 1998, 37, 3689; (e) J.E. Varey, J. Chem. Res., 1998, (S), 200; ( f ) J.-P. Lang and K. Tatsumi, Inorg. Chem., 1998, 37, 160; (g) S. Ranjan and S. K. Dikshit, Polyhedron, 1998, 17, 3071; (h) V. W.-W. Yam, K.-M. Fung, K. M.-C. Wong, V. C.-Y. Lau and K.-K. Cheung, Chem. Commun., 1998, 777; (i) Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 207P. D. Harvey, A.Eichhofer and D. Fenske, J. Chem. Soc., Dalton Trans., 1998, 3901. 12 (a) D.R. McMillin and K. M. McNett, Chem. Rev., 1998, 98, 1201; (b) K.L. Cunningham and D. R. McMillin, Inorg. Chem., 1998, 37, 4114; (c)M. T. Miller, P. K. Gantzel and T. B. Karpishin, Angew. Chem., Int. Ed., 1998, 37, 1556; (d) E.C. Riesgo, A. Credi, L. De Cola and R. P. Thummel, Inorg. Chem., 1998, 37, 2145; (e) V.W.-W. Yam, Y.-L. Pui, W.-P. Li, K. K.-W. Lo and K.-K. Cheung, J. Chem. Soc., Dalton Trans., 1998, 3615; ( f ) E. Cariati, J. Bourassa and P. C. Ford, Chem. Commun., 1998, 1623; (g) A.M. James, R. K. Laxman, F. R. Fronczek and A. W. Maverick, Inorg. Chem., 1998, 37, 3785; (h) M. K. W. Low, H. Hou, H. Zheng, W. Wong, G. Jin, X. Xin and W. Ji, Chem. Commun., 1998, 505. 13 (a) J.Sertucha, A. Luque, F. Lloret and P. Roman, Polyhedron, 1998, 17, 3875; (b)M. Munakata, L. P. Wu, T. Kuroda-Sowa, M. Yamamoto, M. Maekawa and K. Moriwaki, Inorg. Chim. Acta, 1998, 268, 317; (c) C.J. Calzado and J. F. Sanz, J. Am. Chem. Soc., 1998, 120, 1051; (d) R.C. Bott, P. C. Healy and D. S. Sagatys, Chem. Commun., 1998, 2403; (e) C.R. Feger and J. W. Kolis, Inorg. Chem., 1998, 37, 4046; ( f ) L.-M.Zheng, C.-Y. Duan, X.-R. Ye, L.-Y. Zhang, C. Wang and X.-Q.-Xin, J. Chem. Soc., Dalton Trans., 1998, 905; (g) I. Toledo, M. Arancibia, C. Andrade and I. Crivelli, Polyhedron, 1998, 17, 173. 14 (a) C. Horn, I. Dance, D. Craig, M. Scudder and G. Bowmaker, J. Am. Chem. Soc., 1998, 120, 10 549; (b) D. Hagrman, C. J. Warren, R. C. Haushalter, C. Seip, C.J. O’Connor, R. S. Rarig, K. M. Johnson, R. L. LaDuca and J. Zubieta, Chem. Mater., 1998, 10, 3294; (c)D.D. LeCloux, R. Davydov and S. J. Lippard, J. Am. Chem. Soc., 1998, 120, 6810; (d) D. R. Gamelin, D. W. Randall, M. T. Hay, R. P. Houser, T. C. Mulder, G.W. Canters, S. de Vries, W. B. Tolman, Y. Lu and E. I. Solomon, J. Am. Chem. Soc., 1998, 120, 5246. 15 (a) Y. Kuchiyama, N. Kobayashi and H.D. Takagi, Inorg. Chim. Acta, 1998, 277, 31; (b) S. Mahadevan and M. Palaniandavar, Inorg. Chem., 1998, 37, 693; (c) R. Bhalla, M. Helliwell, R. L. Beddoes, D. Collison and C. D. Garner, Inorg. Chim. Acta, 1998, 273, 225; (d) M. T. Miller, P. K. Gantzel and T. B. Karpishin, Inorg. Chem., 1998, 37, 2285; (e)M. Buda, J.-C. Moutet, E. Saint-Aman, A. De Cian, J. Fischer and R.Ziessel, Inorg. Chem., 1998, 37, 4146; ( f ) A. El-ghayouy, A. Harriman, A. De Cian, J. Fischer and R. Ziessel, J. Am. Chem. Soc., 1998, 120, 9973; (g) S. Zahn and J. W. Canary, Angew. Chem., Int. Ed., 1998, 37, 305; (h) C. Pena, A.M. Galibert, B. Soula, P.-L. Fabre, G. Bernardinelli and P. Castan, J. Chem. Soc., Dalton Trans., 1998, 239; (i) L. Sun, C.-H. Wu and B. C. Faust, J.Phys. Chem. A, 1998, 102, 8664; (j) N. Navon, H. Cohen, R. van Eldik and D. Meyerstein, J. Chem. Soc., Dalton Trans., 1998, 3663. 16 (a)H. Wang, C. Bryant, D. W. Randall, L. B. La Croix, E. I. Solomon, M. LeGros and S. P. Cramer, J. Phys. Chem. B, 1998, 102, 8347; (b) E. Fraga and G. R. Loppnow, J. Phys. Chem. B, 1998, 102, 7659; (c) D. Qiu, S. Dasgupta, P. M. Kozlowski, W.A. Goddard and T. G. Spiro, J. Am. Chem. Soc., 1998, 120, 12 791; (d) H.W. Hellinga, J. Am. Chem. Soc., 1998, 120, 10 055; (e)D.M. Dooley, R. A. Scott, P. F. Knowles, C. M. Colangelo, M.A. McGuirl and D. E. Brown, J. Am. Chem. Soc., 1998, 120, 2599; ( f ) B. S. Lim and R. H. Holm, Inorg. Chem., 1998, 37, 4898; (g) F. Champloy, N. Benali-Cherif, P. Bruno, I. Blain, M. Pierrot, M.Reglier and A. Michalowicz, Inorg. Chem., 1998, 37, 3910; (h) I. Blain, P. Bruno, M. Giorgi, E. Lojou, D. Lexa and M. Reglier, Eur. J. Inorg. Chem., 1998, 1297; (i) S. Ryan, H. Adams, D. E. Fenton, M. Becker and S. Schindler, Inorg. Chem., 1998, 37, 2134; (j) E. Pidcock, H. V. Obias, C. X. Zhang, K. D. Karlin and E. I. Solomon, J. Am. Chem. Soc., 1998, 120, 7841; (k) J.A. Halfen, V.G. Young and W. B. Tolman, Inorg. Chem., 1998, 37, 2102; (l) S. Itoh, H. Nakao, L. M. Berreau, T. Kondo, M. Komatsu and S. Fukuzumi, J. Am. Chem. Soc., 1998, 102, 2890; (m) D.E. Root, M. Mahroof-Tahir, K. D. Karlin and E. I. Solomon, Inorg. Chem., 1998, 37, 4838. 17 (a)M. Hara, T. Kondo, M. Komoda, S. Ikeda, K. Shinohara, A. Tanaka, J. N. Kondo and K. Domen, Chem. Commun., 1998, 357; (b) P.M.Jones, J. A. May and E. I. Solomon, Inorg. Chim. Acta, 1998, 275–276, 327; (c) E. Takayama-Muromachi, Chem. Mater., 1998, 10, 2686; (d) R. S. Liu, C. Y. Chang and J. M. Chen, Inorg. Chem., 1998, 37, 5527; (e) R.-S. Liu, T. Yu, J.-M. Chen and H.-J. Lo, J. Chem. Soc., Dalton Trans., 1998, 2569; ( f ) J.E. Ritchie, C. A. Wells, J.-P. Zhou, J. Zhao, J. T. McDevitt, C. R.Ankrum, L. Jean and D. R. Kanis, J. Am. Chem. Soc., 1998, 120, 2733; (g) F. Munakata, M. Tanimura and Y. Akimune, J. Chem. Soc., Faraday Trans., 1998, 94, 933; (h) S. Adachi, T. Tatsuki, T. Tamura and K. Tanabe, Chem. Mater., 1998, 10, 2860; (i) J.-H. Choy, Y.-I. Kim and S.-J. Hwang, J. Phys. Chem. B, 1998, 102, 9191; (j)D.A. Vander Griend, S. Boudin, K. R. Poeppelmeier, M. Azuma, H.Toganoh and M. Takano, J. Am. Chem. Soc., 1998, 120, 11 518; (k) H. Wilhelm, C. Cros, E. Reny, D. Demazeau and M. Hanfland, J. Mater. Chem., 1998, 8, 2729; (l) C. Shivakumara, M. S. Hegde, K. Sooryanarayana, T. N. Guru Row and G. N. Subbanna, J. Mater. Chem., 1998, 8, 2695; (m) M. T. Weller, M. J. Pack and N. Binsted, Angew. Chem., Int. Ed., 1998, 37, 1094; (n) C. Oliva, L.Forni, A.M. Ezerets, I. E. Mukovozov and A. V. Vishniakov, J. Chem. Soc., Faraday Trans., 1998, 94, 587; (o) G.R. Blake, J. Sloan, J. F. Vente and P. D. Battle, Chem. Mater., 1998, 10, 3536. 18 (a)H. Choi and S. Hwang, Chem. Mater., 1998, 10, 2326; (b) A.P. Purdy and C. F. George, Polyhedron, 1998, 17, 4041; (c) S. Wang, Polyhedron, 1998, 17, 831; (d) I.G. de Muro, F. A. Mautner, M.Insausti, L. Lezama, M.I. Arriortua and T. Rojo, Inorg. Chem., 1998, 37, 3243. 19 (a) L. Chen, H. Y. Chen, J. Lin and K. L. Tan, Inorg. Chem., 1998, 37, 5294; (b)M. J. Rice, A. K. Chakraborty and A. T. Bell, J. Phys. Chem. A, 1998, 102, 7498; (c) L. Rodriguez-Santiago, M. Sierka, V. Branchadell, M. Sodupe and J. Sauer, J. Am. Chem. Soc., 1998, 120, 1545; (d)W. F. Schneider, K.C. Hass, R. Ramprasad and J. B. Adams, J. Phys. Chem., B, 1998, 102, 3692; (e) R. Tsekov and P. G. Smirniotis, J. Phys. Chem. B, 1998, 102, 9525; ( f )M. Stolmar and E. Roduner, J. Am. Chem. Soc., 1998, 120, 583; (g) T. Komatsu, T. Ueda and T. Yashima, J. Chem. Soc., Faraday Trans., 1998, 94, 949; (h) A.M. Prakash, M. Hartmann and L. Kevan, Chem. Mater., 1998, 10, 932; (i) J. Xu, M.Ekblad, S. Nishiyama, S. Tsuruya and M. Masai, J. Chem. Soc., Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 208Faraday Trans., 1998, 94, 473; (j) C. Lamberti, S. Bordiga, A. Zecchina, M. Salvalaggio, F. Geobaldo and C. O. Arean, J. Chem. Soc., Faraday Trans., 1998, 94, 1519; (k) A. Poppl, M. Gutjahr, M. Hartmann, W. Bohlmann and R. Bottcher, J. Phys. Chem. B, 1998, 102, 7752; (l) S.Koner, Chem. Commun., 1998, 593; (m) T. Munoz, A. M. Prakash, L. Kevan and K. J. Balkus, J. Phys. Chem. B, 1998, 102, 1379. 20 (a) C. Pariya, A. Ghosh, M. M. Bhadbhade, B. Narayanan and N. R. Chaudhuri, Polyhedron, 1998, 17, 3263; (b) M.F. DaCruz and M. Zimmer, Inorg. Chem., 1998, 37, 366; (c) T. Murakami and S. Kita, Inorg. Chim. Acta, 1998, 274, 247; (d)M. Velayutham, B.Varghese and S. Subramanian, Inorg. Chem., 1998, 37, 5983; (e) F. Thaler, C. D. Hubbard, F. W. Heinemann, R. van Eldik, S. Schindler, I. Fabian, A. M. Dittler-Klingemann, F. E. Hahn and C. Orvig, Inorg. Chem., 1998, 37, 4022; ( f ) S. Lopez, I. Muravyov, S. R. Pulley and S. W. Keller, Acta Crystallogr., Sect. C, 1998, 54, 355; (g) S. Busse, H. Elias, J. Fischer, M. Poggemann, K.J. Wannowius and R. Boca, Inorg. Chem., 1998, 37, 3999. 21 (a)M. Mediavilla, D. Pineda, F. Lopez, D. Moronta, C. Longo, S. A. Moya, P. J. Baricelli and A. J. Pardey, Polyhedron, 1998, 17, 1621; (b) Y. Ishimaru, M. Kitano, H. Kumada, N. Koga and H. Iwamura, Inorg. Chem, 1998, 37, 2273; (c) A. J. Blake, S. J. Hill and P. Hubberstey, Chem. Commun., 1998, 1587; (d) A. Wada, M.Harata, K. Hasegawa, K. Jitsukawa, H. Masuda, M. Mukai, T. Kitagawa and H. Einaga, Angew. Chem., Int. Ed., 1998, 37, 798; (e) A. J. Blake, P. Hubberstey, W.-S. Li, C. E. Russell, B. J. Smith and L. D. Wraith, J. Chem. Soc., Dalton Trans., 1998, 647; ( f ) N.K. Solanki, E. J. L. McInnes, F. E. Mabbs, S. Radojevic, M. McPartlin, N. Feeder, J. E. Davies and M. A. Halcrow, Angew. Chem., Int.Ed., 1998, 37, 2221; (g) C. Place, J.-L. Zimmermann, E. Mulliez, G. Guillot, C. Bois and J.-C. Chottard, Inorg. Chem., 1998, 37, 4030. 22 (a) I. Potocnak, M. Dunaj-Jurco, D. Miklos and L. Jager, Acta Crystallogr., Sect. C, 1998, 54, 313; (b) H.-L. Kwong, W.-S. Lee, H.-F. Ng, W.-H. Chiu and W.-T. Wong, J. Chem. Soc., Dalton Trans., 1998, 1043; (c) G. Murphy, C. O’Sullivan, B.Murphy and B. Hathaway, Inorg. Chem., 1998, 37, 240; (d) J. Server-Carrio, E. Escriva and J.-V. Folgado, Polyhedron, 1998, 17, 1495; (e) D. Miklos, I. Potocnak, M. Dunaj-Jurco and L. Jager, Acta Crystallogr., Sect. C, 1998, 54, 33; ( f ) D. Tran, B. W. Skelton, A. H. White, L. E. Laverman and P. C. Ford, Inorg. Chem., 1998, 37, 2505; (g) S. Mahadevan and M. Palaniandavar, Inorg.Chem., 37, 3927; (h) S. Menon and M.V. Rajasekharan, Polyhedron, 1998, 17, 2463. 23 (a)M. Cupane, M. Leone, E. Unger, C. Lemke, M. Beck, W. Dreybrodt and R. Schweitzer-Stenner, J. Phys. Chem. B, 1998, 102, 6612; (b) Y. Inada, Y. Sugimoto, Y. Nakano, Y. Itoh and S. Funahashi, Inorg. Chem., 1998, 37, 5519; (c) P.A. Stuzhin, E. M. Bauer and E. Ercolani, Inorg. Chem., 1998, 37, 1533; (d) F.Koksal, F. Ucun, E. Agar and I. Kartal, J. Chem. Res., 1998, (S), 96. 24 (a) S.B. Nielsen and G. Bojesen, Chem. Commun., 1998, 613; (b) Z. Chen, S. Fei and H. L. Strauss, J. Am. Chem. Soc., 1998, 120, 8789; (c) J. Goslar, W. Hilczer and S. K. Ho§mann, Inorg. Chem., 1998, 37, 5936; (d) N. R. Texler, S. Holdway, G.W. Neilson and B. M. Rode, J. Chem. Soc., Faraday Trans., 1998, 94, 59. 25 (a) S.K. Ng, X.-M. Chen and G. Yang, Acta Crystallogr., Sect. C, 1998, 54, 1389; (b) Y.-L. Wu, Y.-X. Tong, X.-M. Chen and T. C. W. Mak, Acta Crystallogr., Sect. C, 1998, 54, 606; (c)M.R. Sundberg, J. K. Koskimies, J. Matikainen and H. Tylli, Inorg. Chim. Acta, 1998, 268, 21; (d)M. Petric, F. Pohleven, I. Turel, P. Segedin, A. J. P. White and D. J. Williams, Polyhedron, 1998, 17, 255; (e) J.R. Chipperfield, S.Clark, J. Elliott and E. Sinn, Chem. Commun., 1998, 195; ( f ) F. Marchetti, C. Pettinari, A. Cingolani, D. Leonesi, A. Drozdov and S. I. Troyanov, J. Chem. Soc., Dalton Trans., 1998, 3325. 26 (a) P. D’Angelo, E. Bottari, M.R. Festa, H.-F. Nolting and N. V. Pavel, J. Phys. Chem. B, 1998, 102, 3114; (b) A. Garcia-Raso, J. J. Fiol, B. Adrover, V.Moreno, E. Molins and I. Mata, J. Chem. Soc., Dalton Trans., 1998, 1031; (c) T. Kobayashi, O. Okuno, T. Suzuki, M. Kunita, S. Ohba and Y. Nishida, Polyhedron, 1998, 17, 1553. 27 (a) H. Adams, R. M. Bucknall, D. E. Fenton, C. O. Rodriguez de Barbarin, M. Garcia and J. Oakes, Polyhedron, 1998, 17, 3803; (b) C.P. Raptoptoulou, A. N. Papadopoulos, D. L. Malamatari, E. Ioannidis, G.Moisidis, A. Terzis and D. P. Kessissoglou, Inorg. Chim. Acta, 1998, 272, 283; (c) S. Bunce, R. J. Cross, L. J. Farrugia, S. Kunchandy, L. L. Meason, K.W. Muir, M. O’Donnell, R. D. Peacock, D. Stirling and S. J. Teat, Polyhedron, 1998, 17, 4179; (d)N. Hoshino, K. Takahashi, T. Sekiuchi, H. Tanaka and Y. Matsunaga, Inorg. Chem., 1998, 37, 882. 28 (a) L. Rodriguez-Santiago, X. Solans-Monfort, M.Sodupe and V. Branchadell, Inorg. Chem., 1998, 37, 4512; (b) J. Muller, T. Weyhermuller, E. Bill, P. Hildebrandt, L. Ould-Moussa, T. Glaser and K. Wieghardt, Angew. Chem., Int. Ed., 1998, 37, 616; (c) M.A. Halcrow, L. M.L. Chia, X. Lu, E. J. L. McInnes, L. J. Yellowlees, F. E. Mabbs and J. E. Davies, Chem. Commun., 1998, 2465; (d) S. Ito, S. Nishino, H. Itoh, S. Ohba and Y.Nishida, Polyhedron, 1998, 17, 1637; (e) F.A. Villamena, M. H. Dickman and D. R. Crist, Inorg. Chem., 1998, 37, 1446; ( f ) D.K. Chand and P. K. Bharadwaj, Inorg. Chem., 1998, 37, 5050. 29 (a) M. Capdevila, Y. Carrasco, W. Clegg, R. A. Coxall, P. Gonzalez-Duarte, A. Lledos, J. Sola and G. Ujaque, Chem. Commun., 1998, 597; (b) S. A. Warda, Acta Crystallogr., Sect. C, 1998, 54, 460; (c) E.Guillon, I. Dechamps-Olivier and J.-P. Barbier, Polyhedron, 1998, 17, 3255; (d) C. J. Matthews, S. L. Heath, M. R. J. Elsegood, W. Clegg, T. A. Leese and J. C. Lockhart, J. Chem. Soc., Dalton Trans., 1998, 1973; (e) Y. Sunatsuki, T. Matsumoto, Y. Fukushima, M. Mimura, M. Hirohata, N. Matsumoto and F. Kai, Polyhedron, 1998, 17, 1943; ( f )M.A. Ali, N. E. H. Ibrahim, R.J. Butcher, J. P. Jasinski, J. M. Jasinski and J. C. Bryan, Polyhedron, 1998, 17, 1803; (g) J.L. J. Dearing, J. S. Lewis, D. W. McCarthy, M.J. Welch and P. J. Blower, Chem. Commun., 1998, 2531; (h) A. J. Blake, J. P. Danks, I. A. Fallis, A. Harrison, W.-S. Li, S. Parsons, S. A. Ross, G. Whittaker and M. Schroder, J. Chem. Soc., Dalton Trans., 1998, 3969; (i) P. Strauch, S. Abram and Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 209U. Drutkowski, Inorg. Chim. Acta, 1998, 278, 118. 30 (a) N.D. Yordanov, M. Y. Mihaylov and P. O’Brien, Polyhedron, 1998, 17, 3501; (b) A. Tadsanaprasittipol, H.-B. Kraatz and G. D. Enright, Inorg. Chim. Acta, 1998, 278, 143; (c) E. Ruiz, J. Cano, S. Alvarez and P. Alemany, J. Am. Chem. Soc., 1998, 120, 11 122; (d) M.A.Aebersold, B. Gillon, O. Plantevin, L. Pardi, O. Khan, P. Bergerat, I. von Seggern, F. Tuczek, L. Ohrstrom, A. Grand and E. Lelievre-Berna, J. Am. Chem. Soc., 1998, 120, 5238; (e) C.D. Delfs and R. Bramley, J. Chem. Soc., Dalton Trans., 1998, 1191; ( f) S.A. Komaei, G. A. van Albada, I. Mutikainen, U. Turpeinen and J. Reedijk, Eur. J. Inorg. Chem., 1998, 1577; (g) D.M. Haddleton, A. J.Clark, D. J. Duncalf, A. M. Heming, D. Kukulj and A. J. Shooter, J. Chem. Soc., Dalton Trans., 1998, 381; (h) A. Escuer, F. A. Mautner, E. Penalba and R. Vicente, Inorg. Chem., 1998, 37, 4190; (i)M. B. Ferrari, G. G. Fara, C. Pelizzi, G. Pelozi and P. Tarasconi, Inorg. Chim. Acta, 1998, 269, 297; (j) R.C. Holz, B. Bennett, G. Chen and L.-J. Ming, J. Am. Chem. Soc., 1998, 120, 6329; (k) J.-P.Costes, F. Dahan, A. Dupuis and J. P. Laurent, J. Chem. Soc., Dalton Trans., 1998, 1307; (l) D. Black, A. J. Blake, K. P. Dancey, A. Harrison, M. McPartlin, S. Parsons, P. A. Tasker, G. Whittaker and M. Schroder, J. Chem. Soc., Dalton Trans., 1998, 3953; (m) L.K. Thompson, Z. Xu, A. E. Goeta, J. A. K. Howard, H. J. Clase and D. O. Miller, Inorg. Chem., 1998, 37, 3217; (n) J.D. Ranford, J.J. Vittal and Y. M. Wang, Inorg. Chem., 1998, 37, 1226; (o) P.V. Bernhardt and E. J. Hayes, J. Chem. Soc., Dalton Trans., 1998, 1037; (p) J.M. Dominguez- Vera, N. Galvez, J. M. Moreno and E. Colacio, Polyhedron, 1998, 17, 2713. 31 (a) P. Kogerler, P. A. M. Williams, B. S. Parajon-Costa, E. J. Baran, L. Lezama, T. Rojo and A. Muller, Inorg. Chim. Acta, 1998, 268, 239; (b) J.Jezierska, T. Glowiak, A. Ozarowski, Y. V. Yablokov and Z. Rzaczynska, Inorg. Chim. Acta, 1998, 275–276, 28; (c) X.-M. Chen, X.-L. Feng, Z.-T. Xu, X.-H. Zhang, F. Xue and T. C. W. Mak, Polyhedron, 1998, 17, 2639; (d) Y. Kani, S. Ohba, H. Matsushima and T. Tokii, Acta Crystallogr., Sect. C, 1998, 54, 193; (e)M. Melnik, M. Koman and T. Glowiak, Polyhedron, 1998, 17, 1767; ( f ) F.P. W. Agterberg, H. A. J. Provokluit, W. L. Driessen, J. Reedijk, H. Oevering, W. Buijs, N. Veldman, M. T. Lakin and A. L. Spek, Inorg. Chim. Acta, 1998, 267, 183; (g) R. Costa, C. Lopez, E. Molins and E. Espinosa, Inorg. Chem., 1998, 37, 5686; (h) T.M. Rajendiran, R. Venkatesan, P. S. Rao and M. Kanaswamy, Polyhedron, 1998, 17, 3427; (i)D.C. Elliott, L. L.Martin and M. R. Taylor, Acta Crystallogr., Sect. C, 1998, 54, 1259; (j) C. J. Boxwell, R. Bhalla, L. Cronin, S. S. Turner and P. H. Walton, J. Chem. Soc., Dalton Trans., 1998, 2449; (k) S. Tirado-Guerra, N. A. Cuevas-Garibay, M. E. Sosa-Torres and R. Zamorano-Ulloa, J. Chem. Soc., Dalton Trans., 1998, 2431. 32 (a) H.-L. Zhu, L.-M. Zheng, C.-Y. Duan, X.-Y. Huang, W.-M. Bu, M.-F. Wu and W.-X.Tang, Polyhedron, 1998, 17, 3909; (b) M.B. Inoue, E. F. Velazquez, F. Medrano, K. L. Ochoa, J. C. Galvez, M. Inoue and Q. Fernando, Inorg. Chem., 1998, 37, 4070; (c) H. Weller, T. A. Kaden and G. Hopfgartner, Polyhedron, 1998, 17, 4543; (d) E. Monzani, L. Quinti, A. Perotti, L. Casella, M. Gulloti, L. Randaccio, S. Geremia, N. Nardin, P. Faleschini and G. Tabbi, Inorg.Chem., 1998, 37, 553; (e) P. Molenveld, J. F. J. Engbersen, H. Kooijman, A. L. Spek and D. N. Reinhoudt, J. Am. Chem. Soc., 1998, 120, 6726; ( f ) S. J. Brudenell, L. Spiccia, A.M. Bond, P. Comba and D. C. R. Hockless, Inorg. Chem., 1998, 37, 3705; (g) S. Karabocek and N. Karabocek, Polyhedron, 1998, 17, 319; (h) I.O. Fritsky, H. Kozlowski, E. V. Prisyazhnaya, A. Karaczyn, V. A.Kalibabchuk and T. Glowiak, J. Chem. Soc., Dalton Trans., 1998, 1535. 33 (a) G.A. van Albada, I. Mutikainen, U. Turpeinen and J. Reedijk, Eur. J. Inorg. Chem., 1998, 547; (b) L. Cronin and P. H. Walton, Inorg. Chim. Acta, 1998, 269, 241; (c) T.C. Higgs, K. Spartalian, C. J. O’Connor, B. F. Matzanke and C. J. Carrano, Inorg. Chem., 1998, 37, 2263; (d) M.P. Suh, M.Y. Han, J. H. Lee, K. S. Min and C. Hyeon, J. Am. Chem. Soc., 1998, 120, 3819; (e) P.V. Bernhardt and P. C. Sharpe, J. Chem. Soc., Dalton Trans., 1998, 1087; ( f ) H. Adams, R. M. Bucknall, D. E. Fenton, M. Garcia and J. Oakes, Polyhedron, 1998, 17, 4169; (g) A.M.W. Cargill Thompson, D. A. Bardwell, J. C. Je§ery and M.D. Ward, Inorg. Chim. Acta, 1998, 267, 239; (h) B. Moubaraki, K. S. Murray, J. D. Ranford, X. Wang and X. Yu, Chem. Commun., 1998, 353; (i) R. Ruiz, F. Lloret, M. Julve, J. Faus, M. C. Munoz and X. Solans, Inorg. Chim. Acta, 1998, 268, 263; (j)M. Mimura, T. Matsuo, T. Nakashima and N. Matsumoto, Inorg. Chem., 1998, 37, 3553; (k) J. Reim, R. Werner, W. Haase and B. Krebs, Chem. Eur. J., 1998, 4, 289; (l) N. Yoshida, H. Oshio and T. Ito, Chem. Commun., 1998, 63; (m) M. Murrie, D. Collison, C. D. Garner, M. Helliwell, P. A. Tasker and S. S. Turner, Polyhedron, 1998, 17, 3031; (n) F. Zhu, H. W. Schmalle, B. Fischer and E. Dubler, Inorg. Chem., 1998, 37, 1161. 34 (a) B.D. Alleyne, L. A. Hall, H.-A. Hosein, H. Jaggernauth, A. J. P. White and D. J. Williams, J. Chem. Soc., Dalton Trans., 1998, 3845; (b) S.R. Batten, P. Jensen, B. Moubaraki, K. S. Murray and R. Robson, Chem. Commun., 1998, 439; (c) L. Carlucci, G. Ciani, P. Macchi and D. M. Proserpio, Chem. Commun., 1998, 1837; (d) M.-L. Tong, B.-H. Ye, J.-W. Cai, X.-M. Chen and S. W. Ng, Inorg. Chem., 1998, 37, 2645; (e) M.-L. Tong, X.-M. Chen, X.-L. Yu and T. C. W. Mak, J. Chem. Soc., Dalton Trans., 1998, 5; ( f ) K.N. Power, T. L. Hennigar and M.J. Zaworotko, Chem. Commun., 1998, 595; (g) Z.-N. Chen, H.-X. Zhang, C.-Y. Su, Z.-Y. Zhou, K.-C. Zheng and B.-S. Kang, Inorg. Chem., 1998, 37, 3877; (h) R.K. Kumar, S. Balasubramanian and I. Goldberg, Inorg. Chem., 1998, 37, 541; (i) D. Hagrman, R. C. Haushalter and J. Zubieta, Chem. Mater., 1998, 10, 361; (j) D. Hagrman and J. Zubieta, Chem. Commun., 1998, 2005. 35 (a) E. Colacio, J. M. Dominguez-Vera, M. Ghazi, R. Kivekas, M. Klinga and J. M. Moreno, Inorg. Chem., 1998, 37, 3040; (b) T. Sasaki, N. Nakamura and Y. Naruta, Chem. Lett., 1998, 351; (c) F. Tani, Y. Matsumoto, Y. Tachi, T. Sasaki and Y. Naruta, Chem. Commun., 1998, 1731; (d) V. S. Oganesyan, C. S. Butler, N. J. Watmough, C. Greenwood, A. J. Thomson and M. R. Cheesman, J. Am. Chem. Soc., 1998, 120, 4232; (e) Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 210C. N. Verani, T. Weyhermuller, E. Rentschler, E. Bill and P. Chaudhuri, Chem. Commun., 1998, 2475; ( f ) J. M. Dominguez-Vera, F. Camara, J. M. Moreno, E. Colacio and H. Stoeckli-Evans, Inorg. Chem., 1998, 37, 3046; (g) M.N. Tahir, D. Ulku, O. Atakol and O. Cakirer, Acta Crystallogr., Sect. C, 1998, 54, 468; (h) J. Ribas, C. Diaz, R. Costa, J. Tercero, X. Solans, M. Font-Bardia and H. Stoeckli-Evans, Inorg. Chem., 1998, 37, 233; (i) B. Geisser and R. Alsfasser, Eur. J. Inorg. Chem., 1998, 957; (j) J. Larionova, B. Mombelli, J. Sanchiz and O. Khan, Inorg. Chem., 1998, 37, 679; (k) X.-M. Chen, Y.-L. Wu, Y.-Y. Yang, S. M. J. Aubin and D. N. Hendrickson, Inorg. Chem., 1998, 37, 6186; (l) S.R. Breeze, S. Wang, J. E. Greedan and N. P. Raju, J. Chem. Soc., Dalton Trans., 1998, 2327; (m) L.A. Kovbasyuk, O. Y. Vassilyeva, V. N. Kokozay, W. Linert, J. Reedijk, B. W. Skelton and A. G. Oliver, J. Chem. Soc., Dalton Trans., 1998, 2735. 36 (a) R. Ruiz, C. Surville-Barland, A. Aukauloo, E. Anxolabehere-Mallart, Y. Journaux, J. Cano and M.C. Munoz, J. Chem. Soc., Dalton Trans., 1998, 745; (b) I.O. Fritzky, H. Kozlowski, P. J. Sadler, O. P. Yefetova, J. Swatek-Kozlowska, V. A. Kalibabchuk and T. Glowiak, J. Chem. Soc., Dalton Trans., 1998, 3269; (c) J.A. Ayllon, I. C. Santos, R. T. Henriques, M. Almeida, L. Alcacer and M. T. Duarte, Polyhedron, 1998, 17, 4023; (d)H.V. Obias, Y. Lin, N. N. Murthy, E. Pidcock, E. I. Solomon, M. Ralle, N. J. Blackburn, Y.-M. Neuhold, A. D. Zuberbuhler and K. D. Karlin, J. Am. Chem. Soc., 1998, 120, 12 960; (e) D.E. Root, M. J. Henson, T. Machonkin, P. Mukherjee, T. D. P. Stack and E. I. Solomon, J. Am. Chem. Soc., 1998, 120, 4982. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 189–211 211

ISSN:0260-1818    

DOI:10.1039/a804895i

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

15 The noble metals Peter Thornton Department of Chemistry, Queen Mary andWestfield College, Mile End Road, London, UK E1 4NS 1 Introduction As with previous contributors to this series, this year’s survey concentrates on preparative and structural chemistry, with fewer reports on solution work, kinetic studies, and catalytic and biological activity or papers without experimental work. There is a concentration on work which may not appear in other sections and on results that will be of interest to readers beyond the specialist circle directly addressed by the original authors.Much excellent work has been excluded for space reasons in order to describe the best work adequately. Reviews and general interest articles The latest volume of Inorganic Syntheses1 contains many valuable contributions, including ligands for water soluble organometallics, convenient quick syntheses for cisplatin and other familiar Pt, Ru, Ag and Au complexes and syntheses for [M 3 (CO) 11 ]2~ (M\Ru, Os) and other carbonyl clusters. A collection of papers on nanoparticles includes many accounts of noble metals.2 One of these papers specially deals with bimetallic nanoparticles containing Pd, Pt and Au and their use in homogeneous catalysis.3 Many good reviews of general interest have appeared.One covers activities from 1985 to 1995 in Ag and Au chemistry with Group 15, 16 and 17 donors.4 The formation and structure of polymers and dendrimers containing Au and Pt are reviewed.5 Other series of co-ordination compounds reviewed include boryl complexes6 and chiral phosphine complexes, with emphasis on catalysis and 2-D NMR studies.7 Among many reviews on organometallic chemistry, general readers will find interesting matter in those on photochemistry in a special issue of Journal of Organometallic Chemistry,8 on allenylidene [:C–– C––CR 2 ] and cumulenylidene [other CnR 2 ] complexes,9 the use of electrospray mass spectrometry in organometallic chemistry, 10 the use of organometallics in the synthesis of biologically significant molecules (the field is dubbed ‘bioorganometallic chemistry’),11 and organometallic reactions in the solid state.12 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 2132 Ruthenium Simple compounds Ruthenium metal can be formed in single walled carbon nanotubes by the H 2 reduction of deposited RuCl 3 .13 The a-form of RuCl 3 has become another of the few lattices to support intercalative redox polymerization, in this case of aniline.14 High pressure converts the rutile form of RuO 2 to a new cubic phase, whose short O–O distance explains the very low compressibility which is comparable to that of diamond.15 Co-ordination compounds EXAFS shows aqueous Ru4` is indeed tetranuclear, with an adamantyl Ru 4 O 6 4` cage structure rather than rectangular with OH bridges.16 The first aqua dihydrogen complex, [Ru(H 2 O) 5 (H 2 )]2`, has been identified by 1H and 17O NMR spectroscopy, from the reaction between [Ru(H 2 O) 6 ]2` and H 2 under pressure.17 Tetrachlorocatechol (H 2 L) reacts with [Ru 2 (O 2 CCH 3 ) 4 Cl] to give [Ru 2 L 4 ]3~, the first structurally characterised unbridged Ru–Ru bonded complex; this can be oxidised by Ag` to the Ru 2 6` analogue.18 Synthetic and magnetochemical studies of [NBu 4 ]- [MRu(ox) 3 ] show these are isostructural with the known Cr complexes; for M \Fe, Cu the complexes are ferrimagnetic, but whenM\Mn the material is ferromagnetic.It is asserted that simple orbital rules for magnetic interactions are not as valid for Ru as for 3d metals.19 Ru is found to follow the example of Rh in forming IR-detectableN 2 complexes such as [Ru(N 2 ) 2 ]2` or [Ru(N 2 ) 2 (CO)n]2` (n\1 or 2) on zeolite DAY.20 The oxidation of Ru(II) ammines by Br 2 proceeds by outer sphere one-electron transfer to Br 2 to make reactive [Br 2 ]~, inhibition by Br~ being attributed to the formation of inert [Br 3 ]~.21 The observation that the antitumor active [RuCl 4 (Him) 2 ]2~ loses its imidazoles as well as its chlorides in the presence of histidine or glutathione suggests extra subtleties in the interpretation of its biological activity.22a In a classic study, a combination of X-ray crystallographic and NMR methods shows the all cis-[RuCl 2 (dmso)(L)(1,2- Me 2 Him)] (L\3,5-dimethylpyridine) has the same mixture of conformers in the solid state as in the solution equilibrium.22b [Ru(Me 3 [9]aneN 3 )Cl 3 ] has been used to prepare various g5:g6 half sandwich compounds.23 Polyaminopolycarboxylate complexes of Ru have been reviewed with emphasis on substitution mechanisms and applications to electrocatalysis.24a 1H NMR spectroscopic evidence suggests pyrimidine co-ordinates through a C–– N bond in solution in [Ru(hedta)(pym)(H 2 O)] ~.24b The reaction of P(CH 2 OH) 3 with hydrated RuCl 3 to make a water-soluble catalyst gave elimination of HCHO to form [RuMP(CH 2 OH) 3N2MP(CH 2 OH) 2 HN2 Cl 2 ].25 A new convenient synthesis of [RuHX(dppm) 2 ] (X\H, Cl) from [RuCl 2 (dppm) 2 ] is reported.26 [Ru(H) 2 (dmpe) 2 ] is converted by N 2 O into [RuH(OH)(dmpe) 2 ], whose reactions include the formation of carboxylate complexes by reaction with 4- CH 3 C 6 H 4 CHO or (CF 3 ) 2 CO.27 [RuHX(dmpe) 2 ] (X\Cl, OH) may be used to make low oxidation state amide complexes by reaction with NH 3 and NaNH 2 to give [RuH(NH 2 )(dmpe) 2 ].28 The co-ordination chemistry of 2,6-(Ph 2 PCH 2 ) 2 C 5 H 3 N(pnp) Annu. Rep.Prog.Chem., Sect. A, 1999, 95, 213–238 214has been extended by the synthesis of the meridional complexes [RuHX(PPh 3 )(pnp)] (X\H, Cl, O 2 CCH 3 ).29 The hydrazine derivative Ph 2 PNMeNMePPh 2 (L) reacts with [RuCl 2 (cod)]x and NaOMeto give [RuH 2 L 2 ], whose wide reactivity was studied, e.g. the reaction with S 8 to give [RuL 2 (S 2 )] with a slightly short S–S bond of 205 pm.30 The vitality of research into Ru stibine complexes has been confirmed by mass spectral evidence that the compound assigned the formula [RuCl 2 (SbPh 3 ) 3 ] is most probably [RuCl 2 (SbPh 3 ) 4 ] and by the benchmark crystal structure determination for [Ru(NO)Cl 3 (SbPh 3 ) 2 ].31 Polypyridyl complexes This field continues to be very active, with much good work having to be excluded. An analysis of [Ru(bipy) 3 ]n` (n\0,2,3) structures shows these normally involve six face to face interactions, given the soubriquet Sextuple Aryl Embrace, with other cations, each of the pair of participants needing to have opposite chirality.32 A review of the time-resolved vibrational spectra of Ru(II) [and Os(II)] polypyridyl complexes shows how e§ective these are as a way of studying excited state structure and bonding.33 The time-resolved IR spectra of [Ru(phen) 3 ]2`* favour a description having Ru(III) and one anionic ligand rather than a delocalised negative charge.34a The time-resolved resonance Raman spectrum also leads to this conclusion.34b The synthesis of heteroleptic tris(chelate) complexes of Ru(II) has been improved by using pairwise replacement of ligands in [RuCl 2 (dmso) 4 ].35 A discussion of synthetic methodologies for polynuclear cyclometallated complexes makes special reference to Ru(III) complexes of bipy units linked by diphenyl moieties in which cyclometallation occurs.36 The use of [Ru(CN) 3 (terpy)]~ for photochemical studies, including solvatochromism, shows that the lifetime of the MLCT state is two orders of magnitude longer lasting than for [Ru(terpy) 2 ]2`.37 The contentious issue of the binding of diimine complexes to DNA now leans toward intercalation in the minor groove of the protein after 1H NMR studies of [Ru(phen) 2 (dpq)]2` (crystal structure) and other complexes with oligonucleotides.38 The use of [(phen) 2 RuM4-Mebipy(CH 2 )nbipyMe-4NRu(phen) 2 ]4` to co-ordinate to double stranded DNA gives more stable complexes than [Ru(phen) 3 ]2`, with best results for n\7.39 Among studies of mixed ligand complexes, it is found that, in addition to prolonging the lifetime of the excited state, immobilising such complexes as [Ru(bipy) 2 (py) 2 ]Cl 2 in, for example, polymethylmethacrylate also inhibits photochemical ligand loss.40 When an excess of 4,4@-bipy reacts with [RuCl 2 (dmso)([9]aneS 3 )] the product is cubic [MRu([9]aneS 3 )N8 (4,4@-bipy) 12 ]16`, with Ru at the cube corners and 4,4@-bipy along the edges.41 Complexes containing a bis(pyridyl) and a tris(pyridyl) type ligand with CO can be formed by a new and improved photochemical method; the CO can be substituted by many monodentate ligands, with consequent changes in CT spectra and redox potentials.42 Complexes containing [Ru(4,4@-Bu5 2 bipy) 2 ]` units linked by semiquinone bridges may be diradicals or diamagnetic depending on the points of attachment of conjugated chains at the aromatic rings in the bridge.43 The use of cationic exchange resin chromatography with SP Sephadex C-25 allows separation of the stereoisomers of [Ru 2 (4,4@-Me 2 bipy) 4 (l-bipym)]4`.44 A redox and EPR study Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 215of [MRu(NH 3 ) 4N2 (l-bipym)]4` showed the 3] cation involved Ru(II) and [bipym]~, but the EPR-inactive 5]ion might be Ru(II,III).45 Carboxylates and other bridged complexes All aspects of [Ru 2 (O 2 CR) 4 ]n` chemistry have been comprehensively reviewed.46 Various [Ru 2 (O 2 CR) 4 ] have been prepared by the Zn–Hg reduction of [Ru 2 Cl(O 2 CR) 4 ], but the phenylglyoxylate complex was made from [Ru 2 Cl(O 2 CCH 3 ) 4 ] and PhOCCO 2 H; all are spin doublets.47 Temperature control of the reaction of [Ru 2 Cl(O 2 CCH 3 ) 4 ] with 2-amino-4,6-dimethylpyridine gave controlled stepwise replacement of one bridging ligand by the other; the d* orbital is raised in energy during this to give a change from a quartet spin state to a doublet when complete substitution is achieved.48 Magnetic studies of various [Ru 2 Cl(O 2 CR) 4 ], including some which are mesomorphic, show they are antiferromagnetic in addition to having a very high zero field splitting; the magnitude of the antiferromagnetism depends on the RuClRu angle.49 The technique of liquid secondary ion mass spectrometry may be useful for distinguishing between binuclear and polymeric structures, as in [Ru 2 Cl(O 2 CR) 4 L] (L\monodentate ligand).50a The use of O 3 –O 2 mixtures for convenient preparations of many high oxidation state compounds is exemplified by the synthesis of the new [Ru 2 (l-O)(l-O 2 CC 2 H 5 ) 2 Cl 6 ]2~.50b The determination of the crystal structure of [Ru 2 (chp) 4 (thf)][BF 4 ] prompted comparison with that of the neutral Ru(II) complex; the Ru 2 5` core has a longer Ru–Ru bond than does Ru 2 4`, in line with the relationship of the pentacation to Ru 2 6`.51 Porphyrins and other related macrocylic complexes The synthesis of Ru(II) complexes of tetraazaporphyrins (porphyrins with N instead of CH bridges between the pyrrole rings) is described, including polymers with such bridging ligands as 1,4-(NC) 2 C 6 Me 4 .52 The use of Ru to isolate analogues of unstable Fe porphyrin derivatives from nitrosations is shown by the demonstration that RSNO add across [Ru(oep)] to give nitrosyl thiolate complexes (R\penicillamine residue). 53 The crystal structure, magnetism and EPR studies of [Ru 2 (tpp) 2 ][PF 6 ] con- firm this is a spin doublet, not the quartet found normally in bridged Ru(II,III) dimers; the Ru–Ru distance of 229pm agrees with the EXAFS result for the oep analogue.54 Placing a 4-pyridyl group in one meso position of a tetraarylporphyrin allows the formation of a cyclic tetramer based on an Ru 4 square.55 Such complexes have distinctive redox properties and electronic spectra.56 Mononuclear organometallics P(C 7 H 7 ) 3 (L) forms [Ru(CO) 4 L] on reaction with [Ru 3 (CO) 12 ], but irradiation of this gives loss of one or two CO ligands, with one or two C 7 H 7 rings co-ordinating as alkene or diene with further loss of CO.57 A thorough study of hydrosilation catalysed by [RuHCl(CO)(PPh 3 ) 3 ] shows involvement of both the Chalk–Harrod and the so-called modified Chalk–Harrod mechanisms, their connecting processes and the identification of some key intermediates.58 The discovery of the stability of Ru(II) Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 216stibine complexes prompted the synthesis of [RuHCl(CO)(SbPr* 3 ) 3 ], for example, from which useful intermediate many interesting complexes may be made, including the allenylidene [RuCl 2 (––C–– C––CPh 2 )(CO)(SbPr* 3 ) 2 ].59 Tp shows i2N,N@ co-ordination in [RuH(CX)(PPh 3 ) 2 Tp] (X\O,S); this finding is supplemented by reactivity studies involving conversion to the j3N,N@,NA mode with displacement of PPh 3 .60 Treating cis-[Ru(phen) 2 (CO) 2 ]2` with [NEt 4 ][BH 4 ] gave the new formyl complex [Ru(phen) 2 (CO)(CHO)]`, whose reactions include the formation of the bridged CO 2 complex [MRu(phen) 2 (CO)N2 (l-C,O-CO 2 )]2` with H 2 O and O 2 .61 The first cyclometallated hydridoruthenium(II) complex is claimed to be formed when [RuH 2 (CO)(PPh 3 ) 3 ] reacts with 2-phenylpyridine or N-benzylideneaniline and triethoxyvinylsilane.62 The new phosphaalkenyl complex [RuMP(O)CBu5C(O)N- (CNBu5) 2 (PPh 3 ) 2 ] is formed from the reaction of [Ru(P––CHBu5)Cl(CO)(PPh 3 ) 2 ] or its CNBu5 adduct with CNBu5 in air.63 Nucleophilic attack at Cc in [Ru(PPh 3 ) 2 (–– C––C––C––CH 2 )Cp]` gives, for example, [Ru(PPh 3 ) 2M––C–– C––C(CH 3 )NPh 2NCp]` and [Ru(PPh 3 ) 2 (CCCH––CHCl)Cp].64 The porphyrin carbene complex [Ru(tpp)MC(CO 2 Et) 2N] has been prepared, and its formation of six-co-ordinate complexes in solution studied.65 The macrocyclic complex of Ru with dibenzotetramethyltetraazaannulene (L1) forms five-co-ordinate carbene complexes with various –– CRR@.With CO these give bridges across to the macrocycle, notably for CPh(MeO 2 C), which forms an ester bond to Ru and an alkenyl bond to the ring.66 NMe MeN NMe MeN L1 The first stable Ru(III) alkene complexes have been made by using chelating alkenes to give, for example, [Ru(acac) 2 (2-CH 2 ––MeCC 6 H 4 NMe 2 )]`.67 The versatility of the ligand CH 2 ––CHPPh 2 , known to show g3 or g1 co-ordination, is matched by CH 2 ––CHCH 2 PPh 2 (L), which gives both modes in [RuL 2 Cp*]`.68 The useful synthetic intermediate [Ru(SbPr* 3 ) 2 (g3-C 3 H 5 ) 2 ] reacts with acetic acid to give the binuclear Ru(II) complex [Ru 2 (O 2 CCH 3 ) 5 (H 2 O)(SbPr* 3 ) 2 ], with bridging by acetates and the water molecule.69 The ‘open ruthenocene’ complex [Ru(C 7 H 11 ) 2 ], containing two 2,4-dimethylpentadienyl ligands, reacts with [Ru 3 (CO) 12 ] to give the first homoleptic metallabenzene complex [RuMC 7 H 11 Ru(CO) 3N2 ].70 Various new complexes derived from dialkynes include [MRu(dppm) 2 ClN2 (l-CCC 6 H 4 CC)], its quinonoid cation and the monodentate [Ru(dppm) 2 Cl(––C––C––CHC 6 H 5 )]`, with an allenylidene ligand.71 A thermochemical study has shown that the stability of diphosphine (L) complexes [RuClLX] (X\Cp, Cp*) depends on good ligand p-acceptor properties, the best being (PhO) 2 PNMeNMeP(OPh) 2 .72 One of many flash vacuum thermolysis studies in this area shows that a complete set of [Ru(C 5 HnF 5~n)Cp*] is obtained from application of this technique to the products of the reaction between [Ru(NCMe) 3 Cp*]` with the Tl salts of fluorinated phenols.73 The new benzothiaborolide ligand (L2) forms an Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 217B S NPri 2 L2 g5 complex [Ru(L2)Cp*].74 The Me 2 N donor function from [Ru(dppm)MC 5 H 4 (CH 2 )nNMe 2N]` (n\2,3) is displaced from Ru by H 2 to give a dihydrogen complex believed to be in equilibrium with an isomer containing hydride and C 5 H 4 (CH 2 )nNMe 2 ` ligands.75 The range of organometallic clusters containing polyoxometalate ligands is extended by the synthesis of [MRu(cym)N4 (Mo 4 O 16 )], for example, but the Ru fragments do not interact.76 [RuCl 2Mg6-C 6 H 5 (CH 2 ) 3 PPh 2N] is the first chelating arene Ru complex.77 Binuclear organometallics The bridging carbonyl in [Ru 2 (CO) 5 (dppm) 2 ] reacts with S or Se (E) to give [Ru 2 (CO) 4 (l-E)(dppm) 2 ], and with SO 2 to give bridging SO 2 , all these having single Ru–Ru bonds.78 [Ru(CO) 3 (dppe)], with intermediate five-co-ordinate geometry, is oxidised by the ferrocenium ion to the Ru–Ru bonded fluxional dimer [Ru 2 (CO) 6 (dppe) 2 ]2`.79 The reaction of [Ru 3 (CO) 9 (Ph 2 PC 5 H 4 N-4) 3 ] with Hg or Cd halides resulted in Ru–Ru bond cleavage to give, for example, [Ru 2 (CO) 4 I 2 (l- Ph 2 PC 5 H 4 N-4) 2 ] rather than co-ordination of the free pyridine N atom to the new metal.80 1,8-Diphenyloctatetraene forms complexes with two [RuClCp*] or [Ru(acac) 2 ] moieties, the former having s-cis, the latter s-trans structures.81 The products from the reaction of N 2 H 4 with [Ru 2 (l-H) 3 (C 6 Me 6 ) 2 ]` include the amide complex [Ru 2 (C 6 Me 6 ) 2 (l-H)(l-g1:g1-N 2 H 4 )(l-NH 2 )]2` and [Ru 2 (C 6 Me 6 ) 2 (l-H)(l-g1:g1- N 2 H 4 )(l-g1:g1-N 2 H 3 )]2`.82 The first g4-naphthalene complexes have been isolated, most spectacularly [Ru(cod)(l-g6,g4-C 10 H 8 )Ru(cod)(PEt 3 )].83 [HgMRu(CO) 4N2 ]2~, prepared from 2 K 2 Ru(CO) 4 and HgCl 2 in thf, has linear Hg and trigonal bipyramidal Ru, but a 1: 1 ratio of reactants gives polymeric HgRu(CO) 4 ; the Os analogues were also made.84 Reacting [MRu(CO) 2 CpN2 (l-CC)] with [Mo 2 (CO) 4 Cp 2 ] gave the carbide complex [MoRu 2 (l-CO) 3 Cp 2Ml3 -CC[Ru(CO) 2 - Cp]N, the first l3 -carbide outside Cu and Li.85 The use of [Ru(NCMe) 3 Cp]` as a capping agent gives many heterometallic complexes, including [Ru 2 Os 3 (CO) 11 - Cp 2 ].86 Polynuclear organometallics Anumber of reviews have appeared in this area.Topics include linked arene clusters,87 nitrene complexes,88 structures and statistical analysis of penta- and hexa-nuclear Ru and Os complexes containing g6-arene or g5-Cp ligands,89a and those containing [2.2]paracyclophane.89b A new convenient synthesis of [Ru 3 (l-H)(l-X)(CO) 10 ] (X\Br, Cl, I) is achieved by the photochemical reaction of [Ru 3 (CO) 12 ] with HX in diethyl ether.90 The neglected co-ordination chemistry of melamine, C 6 H 3 (NH 2 ) 3 -1,3,5, is augmented by a study of Annu.Rep. Prog. Chem., Sect.A, 1999, 95, 213–238 218its reaction with [Ru 3 (CO) 12 ] to give, inter alia, two isomers of [MRu 3 (l- H)(CO) 9N2Ml3 ,l3 -(NH) 2 C 3 H 3 (NH 2 )N].91 The stabilisation of unusual structures by bulky phosphines is exemplified by the formation of the 44-electron [Ru 3 H 2 (CO) 6 (PCy 3 ) 3 ] from [Ru 3 H(CO) 11 ]~ and PCy 3 .92 The electrochemical oxidation of many [Ru 3 H 3 (CX)(CO) 6 (PPh 3 ) 3 ] (X\OMe, SEt, Ph, etc.) gave 47-electron monocations of remarkable stability.93 The useful synthon [Ru 3 (CO) 9 (NCMe) 3 ] gives a good e¶cient route to ruthenaboranes.For example, B 3 H 8 ~ followed by acid gives [Ru 3 H(CO) 9 (B 2 H 5 )].94 Another ruthenaborane is obtained when [MRuCl 2 Cp*Nn] and LiBH 4 give the capped nido-[Ru 3 (B 3 H 8 )Cp* 3 ], showing the e§ect of bridging hydrogens opening a cluster in comparison with isoelectronic [Co 3 (B 3 H 5 )Cp* 3 ].95 The reaction of [Ru 3Ml3 -HC 2 (CO 2 Me)N(l-dppm)(CO) 8 ] with C 2 Ph 2 gave alkyne coupling, and isomers of [Ru 3Ml3 -C 2 Ph 2 CHC(CO 2 Me)N(l-dppm)(CO) 6 ].96 The structure of [Ru 4 H 2 (CO) 12 ]2~, obtained as the [NaL]` salt (L\cryptand 221), has two l-H and three l-CO ligands.97 [Ru 3 (CO) 12 ] reacts with but-3-yn-2-ol to give five cluster complexes with four to seven Ru atoms and including metallocyclic ketone rings.98 New phosphinidene complexes include [Ru 4 (CO) 11 (PPh)(PNPr* 2 )] (62 electrons) and [Ru 4 (CO) 12 (PNPr* 2 )] (64 electrons).99 All isomers of diphenyl(pyrrolyl)phosphine react with [Ru 3 (CO) 12 ] to give two isomers of [Ru 4 (CO) 11 (l4 -PPh)(l4 -C 4 H 3 N)], containing C–CorC–Npyrrolyne.100 Me 3 PBMe 3 unexpectedly extracts Cl from [MRuClCp*N4 ] and [MRuCl 2 Cp*N2 ] to give [Ru(PMe 3 )(g2-HnBCl 4~n)Cp*] (n\2,3).101 The first l4 -PF and -PO complexes are formed by modification of [Ru 5 (CO) 15 (l4 - PNCy 2 )], by reaction with HBF 4 ·OEt 2 and HBF 4 ·H 2 O respectively.102 A minor product from [Ru 3 (CO) 12 ] and 1-naphthyldiphenylphosphine is [Ru 6 (CO) 14 (C 10 H 6 )(PPh)], which has l6 -naphthalenediyl, with both r- and p-interactions. 103 Under anaerobic conditions electrochemical reduction of [Ru 6 C(CO) 17 ] gives [Ru 6 C(CO) 16 ]2~, but ifO 2 is present about one mole of CO 2 is also formed, with some cluster degradation.104 The reactivity of C 6 H 6 in [Ru 6 C(CO) 14 (g6-C 6 H 6 )] includes reaction with LiMe followed by [CPh 3 ]`, giving conversion to an g6-xylene complex.105 Two benzocrown ethers (L) react with [Ru 6 C(CO) 17 ] to give [Ru 6 C(CO) 14 L], one of which can complex to sodium or ammonium ions with modification of the electrochemistry.106 The attractive square antiprismatic cluster [Ru 8 (l8 -P)(CO) 22 ]` is formed as the [N(PPh 3 ) 2 ]` salt after reaction of [Ru 3 (l-H)(l-NC 5 H 4 )(CO) 10 ] with PClPh 2 .107 In one of many similar studies, allene formed l-g2:g2 complexes with [Ru 10 C 2 - (CO) 24 ]2~, progressively replacing pairs of CO by one or two C 3 H 4 ligands.108 The new potentially useful synthon nido-[Ru 3 (l3 -Se) 2 (CO) 7 (PPh 3 ) 2 ] gives closo bicapped square planar clusters [Ru 2 M 2 (l4 -Se) 2 (CO) 10 (PPh 3 ) 2 ] (M\Mo, W) with [M(CO) 3 (NCMe) 3 ].109 Studies of the reactivity of Cp* in cluster complexes include the thermolysis of [Ru 3 Rh(l-H) 2 (CO) 10 Cp*] to give products including [Ru 3 Rh 2 (l3 - H)(l-CO)(l3 -CO) 2 (CO) 6 (l-g1:g5-CH 2 C 5 Me 4 )Cp*] in which the modified Cp* coordinates g5 to Rh and through r-bonding by CH 2 to Ru.110 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 2193 Osmium Simple and co-ordination compounds The crystal structures, IR and Raman spectra are reported for trans-[OsO 2 (ox) 2 ]2~ and its malonate analogue.111New reactions of the nitride complex [Os(terpy)Cl 2 N]` include that with azide in MeCN to form an MeCN complex which further reacts to give [Os(terpy)Cl 2 (L)] (L\methyltetrazolate), but reacting with azide and CS 2 gives [Os(terpy)(NS)][NCS].112 Varying the conditions gave a wider range of products, including trans-[Os(terpy)Cl 2 (py)] and [Os(terpy)Cl 2 (NS)].113 The action of Se on [OsCl 2 NTp] gives the first metal selenonitrosyl complex [OsCl 2 (NSe)Tp].114 The X-ray crystal structure determination identified the cis form of [OsF 4 Br 2 ]2~ as its dipyridiniomethane salt, having a shorter Os–Br bond than [OsBr 6 ]2~.115 A better synthesis of [Os 2 X 10 ]2~ (X\Cl, Br) uses the reaction of [OsX 6 ]2~ withCF 3 CO 2 Hat 40 °C; magnetochemistry shows these have k[1.5 kB per Os and electrochemistry shows that anions having one to five charges can be made.116 Both chlorides in [OsH 2 Cl 2 (PPr* 3 ) 2 ] can be substituted by acetate; the product, which has both monoand bi-dentate acetate, is a useful synthon, for [Os(CO) 2 (O 2 CCH 3 )(PPr* 3 ) 2 ]` for example.117 [Os(acac) 3 ] can be made from aqueous pentane-2,4-dione and [OsCl 6 ]2~; reactions using [OsX 3 Y 3 ]2~ (X, Y\Cl, Br, I) give all six isomers of [OsXY(acac) 2 ].118 When [OsBr 4 (acac)]~ reacts with EPh 3 (L; E\P, As), the product [OsBr 2 (acac)L 2 ] has cis-Br and trans-L.119 The crystal structure shows that the dmso ligands in both isomers of [OsCl 2 (dmso) 4 ] are fully S-bonded, despite solutions of the cis-form being believed to have one O-bonded.120 Studies of various hydrazine complexes [OsH(RNHNH 2 )- L 4 ]` (L\tertiary phosphine or phosphite) led to variants such as complexes of amidrazone, NH––CRNR@NH 2 .121 The first clearly described synthesis of [OsH 2 (dmpe) 2 ] uses the reaction of the dichloro analogue with sodium and hydrogen; laser flash photolysis generates square planar [Os(dmpe) 2 ].122 Nitrosylation of [OsH 3 Cl(PPr* 3 ) 2 ] gives a new route to [OsH 2 Cl(NO)(PPr* 3 ) 2 ]; this complex loses chloride to give [OsH 2 (NO)(PPr* 3 ) 2 ]`, which reversibly binds H 2 , forming [Os(H) 2 H 2 (NO)(PPr* 3 ) 2 ].123 The pyrazine-bridged [MOs(CN) 5N2 (pyz)]6~ has been synthesised and oxidised to the mixed-valence pentaanion in which the charge is thought to be more localised than in the ammonia analogue.124 Polypyridyl complexes The isotope e§ect found in solvent dependence studies of [Os(bipy) 3 ]2` and [Os(phen) 3 ]2` radiationless transitions from the excited MLCT triplet state is attributed to hydrogen bonding between water molecules and ligands.125 IR spectra of [MOs(bipy) 2 ClN2 (l-pyz)]3` give the curious conclusion that the bipy vibrations suggest valence delocalisation, but the pyz vibrations indicate localisation.126 The synthesis, structure and properties of [OsM4,4@-(MeO) 2 bipyN3 ]2`, apparently a good sensor for glucose oxidase, are described.127 The use of 1,2,4,5-(Ph 2 P) 4 C 6 H 2 (L) to make linear trinuclear complexes [Os(bipy) 2 LNiLPdM1,2-(Ph 2 P) 2 C 6 H 4N]6` gives a Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 213–238 220switchable photochemical electron transfer ion, with the Os catching the light, the Ni acting as the switchable tracer and the Pd as the electron acceptor.128 Porphyrins The use of Os to make stable compounds not isolable for Fe is shown by the characterization of [Os(oep)(NO)X] (X\OBu, O 2 PF 2 ) and [Os(oep)(SPh) 2 ].129 Other new Os oep complexes include [Os 2 (l-O)(oep) 2 (NO) 2 ], curiously obtained as an HCl solvate, from NOCl and [Os(oep)(CO)].130 Various bis(tosylimido) (NTs) Os porphyrin (por) complexes are made from [Os(por)(CO)(MeOH)] and PhI––NTs, but the Ru analogues decompose in solution.131 Mononuclear organometallics The limited range of Os carbonyl fluoride complexes is extended by the conversion of [Os(CO)Br 5 ]2~ to [Os(CO)Br 3 F 2 ]2~ by reaction with TlF; the [Os(CO)F 5 ]2~ which is also formed can be oxidised by chlorine to the monoanion [Os(CO)F 5 ]~.132 New hydride complexes such as [OsH 3 (CO)(PPr* 3 ) 2 ]~ can be prepared from [OsHCl(CO)(PPr* 3 ) 2 ], hydrogen,KHand 1-aza-crown-6, and are stabilised by hydrogen bonds between co-ordinated hydride and H on the crown N.133 The crystal structure of the rare boryl complex [Os(CO)(B-1,2-O 2 C 6 H 4 )Cl(PPh 3 ) 2 ] is reported, together with its substitution of chloride, by NCMe for example, to give cationic boryl complexes.134 The scanty OsCp chemistry is expanded by the synthesis of inter alia the remarkably nucleophilic [OsCl(PPr* 3 )(––C––C––CPh 2 )Cp] allenylidene complex.135 The reaction between [Os(–– CCl 2 )Cl 2 (CO)(PPh 3 ) 2 ] and naphthyllithium (LiR) gives [Os(CR)Cl(CO)(PPh 3 ) 2 ]; its reactions with CO, HX and PhICl 2 are discussed.136 The reaction of [OsH 2 Cl 2 (PPr* 3 ) 2 ] and terminal alkenes like styrene gives [OsHCl 2 (CCH 2 Ph)(PPr* 3 ) 2 ], with the first formation of a carbyne from an alkene.137 The reaction of this complex with CO is accompanied by migration to give carbene complexes [Os(CO)Cl 2 (––CHCH 2 R)(PPr* 3 ) 2 ]; with R\Ph, excess of CO gives HCl elimination and [Os(CO) 2 ClM(E)-CH––CHPhN(PPr* 3 ) 2 ].138 [OsBr(CO) 2 (g5-C 5 Ph 5 )], formed from [Os 3 (CO) 12 ] and C 5 Ph 5 Br, is the first Os pentaphenylcyclopentadienyl complex.139 Polynuclear organometallics Activation of biphenylene with metal carbonyls gives, with [Os 3 (CO) 12 ] for example, [Os 2 (CO) 6Ml-g2,g4-(C 6 H 4 ) 2N], suggested to be a metallacyclopentadienylg5 bonding an [Os(CO) 3 ] unit.140 Reviews of polynuclear Os complexes include one on heterometallic clusters and trinuclear alkylidyne complexes,141 and another on penta- and hexa-nuclear carbonyls with arene and Cp type ligands.89a Fluoride complexes in very low oxidation states are exemplified by [Os 3 (l-H)(CO) 10 (AsPh 3 )F], made by substitution of F for ON(CF 3 ) 2 using HF.142 The photochemical reaction of [Os 3 (CO) 12 ] is better than thermal methods for making [Os 3 H(CO) 10 (l-L)] (LH\pz, 3,5-Me 2 pz) for example, with appropriate choice of solvent.143 Further studies of the products of Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 221the reactions of quinolines with [Os 3 (CO) 10 (NCMe) 2 ] gave mechanistic results and crystal structures of some hydride-bridged trinuclear cyclometallated compounds.144 The synthesis and photochemistry of various new [Os 3 (CO) 10 (a-diimine)] complexes are reported.145 Photochemistry is also a good method for synthesising heterometallic clusters, as shown by the preparation of [Os 3 (CO) 10 (l-Cl)Ml-Au(PPh 3 )N] from [Os 3 (CO) 12 ] and [AuCl(PPh 3 )].146 Reaction of [Os 3 (CO) 9 (l-C 4 Ph 4 )] with phosphines having cone angles less than 143° gives carbonyl substitution, but bulkier phosphines break down the cluster.147 4 Rhodium This section includes discussions of iridium chemistry when the reported research includes both Rh and Ir.Simple and co-ordination compounds New antiferromagnetic mixed valence Sr 6 Rh 5 O 15 is synthesised by heating rhodium with SrCO 3 ; it has RhO 6 octahedra linked as linear tetramers, which are then linked together by RhO 6 trigonal prisms to give RhO 3 chains.148 The known Cr(III)Rh(III) aqua complexes have now been joined by [CrRhM(l-OH) 4 (H 2 O) 9 ]5` (M\Cr, Rh)149 and [(H 2 O) 4 M(l-OH) 2 Ir(H 2 O) 4 ]4` (M\Cr, Rh).150 [RhCl(PW 11 O 39 )]5~, synthesised from RhCl 3 and [PW 11 O 39 ]7~, forms [Rh 2 (PW 11 O 39 ) 2 ]10~ on controlled potential reduction; this has an Rh–Rh bond and characteristic spectroscopy and reactivity.151 New Rh(III) complexes of the unfamiliar class of distibine ligands have been prepared and studied by X-ray di§raction and 103Rh NMR spectroscopy, including [RhMPh 2 Sb(CH 2 ) 3 SbPh 2NCl 2 ]`.152 The RhH 3 complex of the triphosphine CH(CH 2 PPh 2 ) 3 (L) reacts with P 4 to give PH 3 and [RhL(g3-P 3 )] through the intermediate [RhL(g1: g2-HP 4 )]; for the analogous Ir system the intermediate [IrL(P 4 )H] was also found.153 [Rh(PPh 3 ) 2 Tp], formed from KTp and [RhCl(PPh 3 ) 3 ], is a useful synthetic intermediate, giving [RhMg2-C 2 (CO 2 Me) 2N(PPh 3 )Tp], [RhCl 2M––C(SMe) 2NTp] and [Rh(g2-SCNMe 2 )(PPh 3 )Tp]`.154 The synthesis of the first monomeric Rh(0) complex, by using a very hindered phosphine, has been claimed.155 All four heterodinuclear porphyrins of Rh(I) with Tl(III) using tpp and oep have been prepared and characterized (UV, 1H, 13C and 205Tl NMR spectroscopy); pyridine adds to the Rh, but the dimer is split by I 2 or MeI.156 The porphyrin H 2 L with four meso-(4-Bu5C 6 H 4 ) groups forms [RhClL(NCC 6 H 5 )], which can be converted to [RhL(CH 2 CH 2 C 6 H 5 )], which rearranges to [RhLMCH(CH 3 )C 6 H 5N] after the manner of vitamin B 12 , possibly through formation of cis bis adducts on the same side of the porphyrin ring.157 Reduction of [MCl 2 (pc)]~ (M\Rh, Ir) with [NBu 4 ][BH 4 ] gives the M(I) species [M(pc)]~.158 Mononuclear organometallics The unusually stable monomeric Rh(II) complex [RhH(CO)(PPh 3 ) 3 ]` is prepared by Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 222the electrochemical oxidation of [RhH(CO)(PPh 3 ) 3 ] and is shown by EPR spectroscopy to have square pyramidal geometry; it can be further oxidised to the dication, which loses a proton to give [Rh(CO)(PPh 3 ) 3 ]`.159 The use of para-enriched hydrogen revealed the exceptionally rich reaction of H 2 with [RhI(CO)(PMe 3 ) 2 ], five reaction products being found.160 New amine (L) complexes [RhCl(CO)(PPh 3 )L] are made by the reaction of L with [MRh(CO)(PPh 3 )N2 (l-Cl) 2 ]; some undergo oxidative addition with CX 4 .161 Mesomorphic [Rh(CO) 2 (diket)] containing up to 29-atom chains at the c-position of the diketonate are unusual in not having the metal atom at the centre of the molecule.162 [Rh(SiHPh 2 )(PMe 3 ) 4 ] is formed from Ph 2 SiH 2 and the analogous Rh methyl complex, but use of the mesityl reagent gave metallation of one Me ortho to Si, forming [RhHMSiH(mes)C 6 H 2 (CH 3 ) 2 CH 2N(PMe 3 ) 4 ].163 A variety of products is given from the reaction of MgCl(C 6 Cl 5 ) with [RhCl 3 (tht) 3 ], namely [Rh(C 6 Cl 5 ) 3 ], [Rh(C 6 Cl 5 ) 2 (tht) 2 ] and [Rh(C 6 Cl 5 )(C 12 Cl 8 )(tht) 2 ]; these include chelating C 6 Cl 5 ~ and a biphenylene ligand.164 Carbene chemistry of Rh has been very active.Azide migrates from [RhN 3 (––C–– C––CRR@)(PPr* 3 ) 2 ] in the presence of CO, losing N 2 to give [Rh(CO)MC(CN)––CRR@N(PPr* 3 ) 2 ].165 The synthesis of [Rh(OH)(––C––CRR@)(PPr* 3 ) 2 ] allowed further reaction of co-ordinated hydroxide to give notably [Rh 2 (–– C––CRR@) 2 (PPr* 3 ) 4 (l-C 4 )] with (Ph 3 Sn) 2 C 4 (R\H, R@\Ph; R, R@\Me).166 Migratory insertion occurs when [RhM––C(C 6 H 5 ) 2N(PPr* 3 ) 2 Cp] is treated with PF 3 , HCl or CF 3 CO 2 H to give [Rh(PPr* 3 )(PF 3 )MC 5 H 4 CH(C 6 H 5 ) 2N] or [Rh(PPr* 3 )(H)XMC 5 H 4 CH(C 6 H 5 ) 2N]; more acid gives [Rh(PPr* 3 )X 2MC 5 H 4 CH- (C 6 H 5 ) 2N].167 The useful new synthons [Rh(C 2 H 4 ) 2 X] (X\Tp, Tp@) have been prepared and their reactivity by substitution of ethene studied.168 Arylallenes form r-complexes such as [RhClMg2-C 6 H 4 C(H)––C–– CH 2 -pN(PMe 3 ) 3 ], which allows study of isomerisation at the unco-ordinated alkene.169 The reaction of [RhCl(PPh 3 ) 3 ] with various NaOAr gives [Rh(OAr)(PPh 3 ) 3 ] with r-bonded phenoxide, but in solution this is in equilibrium with [Rh(g4-OAr)(PPh 3 ) 2 ] and free phosphine.170 The photochemical displacement of ethene from [Rh(PPh 3 )(C 2 H 4 )Cp] can be a useful method for preparing [RhH(SiPr* 3 )(PPh 3 )Cp] for example.171 Polymeric complexes such as [MRh(C 2 O 4 )Cp*Nn] are given by the reaction of [(RhCp*) 2 Cl 4 ] and a silver salt; these are depolymerized by monodentate ligands, to give for example [Rh(C 2 O 4 )(PPh 3 )Cp*], which photochemically loses CO 2 in CHX 3 (X\Cl, Br) to give [RhX 2 (PPh 3 )Cp*].172 The polymeric arene borole complex cation [Rh(l-g5:g6- C 4 H 4 BPh)]` is made from [MRhI(C 4 H 4 BPh)N4 ] via [Rh(C 4 H 4 BPh)(NCMe)]`.173 Polynuclear organometallics [Rh 2 Cl 2 (CO) 4 ] reacts with a range of hydrazines to give [MRhCl(CO) 2N2 (l-g1:g1- H 2 NNHMe)] and [RhCl(CO) 2 ClMN(Ph)–– NPh)N] for example.174 Studies of Rh carbonyl halide complexes showed the occurrence of six-co-ordinate Rh(I) in compounds such as [Rh 2 Cl 2 (l-CO) 3 (py) 4 ] and [Rh 2 (l-Cl) 2 (CO) 2 (py) 2 (C 2 H 4 ) 2 ].175 Heating [Rh 2 H 3 Cl(SiPh 3 ) 2 (PPr* 3 ) 2 ] gives [Rh 2 H 2 Cl(––SiPh 2 )(SiPh 3 )(PPr* 3 ) 2 ]; both of the silyl ligands are bridging, this being the first symmetrical bridge by an SiR 3 group.176 The time-resolved resonance Raman spectrum shows the triplet excited state of [Rh 2 (tmb) 4 ]2` has a stronger Rh–Rh bond than the ground state.177 The use of Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 223[Rh 2 (l-OH) 3 Cp* 2 ]` to deprotonate [Rh 2 (l-CH 2 ) 2 (l-SH)Cp* 2 ]` gave the first coupling of two methylenes to form the alkyne complex [Rh 3 (l3 -g2-C 2 H 2 )(l3 -S)- Cp* 3 ]2`.178 The reaction of [Rh(NCMe) 3 Cp*]2` with [Rh(CN) 3 Cp*]~ gives [Rh 7 Cp* 7 (CN) 12 ]2`, whose structure is an Rh 8 cube with one vacant vertex and cyanide bridges.Using [Ir(CN) 3 Cp*]~ gives [Ir 4 Rh 3 Cp* 7 (CN) 12 ]2`.179 5 Iridium Some iridium chemistry has been mentioned in the previous section when papers referred to both Rh and Ir.Ion-exchange chromatography allowed the separation of [Ir(SCN) 6 ]3~ from its isomers, leading to X-ray crystallographic, IR and Raman studies.180 A reinterpretation of the electronic spectrum of [IrCl 5 (NCMe)]2~ suggests all the transitions are spin-allowed.181 A convenient new synthesis of [IrCl 2 (tn) 2 ]` and [Ir(tn) 3 ]3` starts with [IrCl 3 (tht) 3 ]; the cation of [Ir(tn) 3 ][Co(CN) 6 ]·5H 2 O has the chair configuration. 182 Me 3 SiX reagents are used for substitution of F in [Ir(H) 2 F(PBu5 2 Ph) 2 ] to give, for example, [Ir(H) 2 (NHCOCH 3 )(PBu5 2 Ph) 2 ].183 The new water-soluble complex [IrMe(CO)(tppms) 2 ] and its K analogue were prepared and their reactivity with H 2 , CO and O 2 studied, involving hydrolysis of the Ir–Me bond.184 H 2 oxidatively adds to the Ir(II) complex of the dianion of 1,8- diaminonaphthalene (X), [Ir 2 (l-X)(CO) 2 (PPr* 3 ) 2 ], to give ultimately [Ir 2 (l-X)(l- H)(H) 2 (CO) 2 (PPr* 3 ) 2 ]` andH`, implying heterolytic activation of H 2 .185 New metallacyclobutenes include [IrCl(CO)MCH 2 C(PPh 3 )CHN(PPh 3 )]`.186 O L3 The first o-quinone methide complexes are reported using L3, e.g.[Ir(L3)Cp*]`, with co-ordination by the ring in g4-diene mode.187 The elusive late transition metal alkoxides may be obtained by using RCH 2 ONa (R\Me, Bu5, Np) with RCH 2 OH in the reaction with [IrPh(OH)(PMe 3 )Cp*] to give substitution of OH with OCH 2 R.188 The g6-mode of co-ordination by hydroquinone is stabilised by complexation with the electron-rich IrCp*2` moiety, allowing isolation and reactivity studies.189 Thus, deprotonation gives g5-semiquinone and g4-quinone complexes.190 The S and Se atoms (E) in [Ir(CO)(EPh) 2 Cp*], made by photochemical reaction of [Ir(CO) 2 Cp*] with Ph 2 E 2 , can co-ordinate further to give such heterometallic complexes as [MIr(CO)Cp*N(l-SePh) 2 Mo(CO) 4 ].191 [Ir 2 (l-pyz) 2 (CNBu5) 4 Cl(CH 2 C 6 H 5 )] shows a new form of tautomerism, one isomer having chloride and benzyl on the same Ir atom, and the other on di§erent metals.192 The unfamiliar tellurophenoxide ligand forms cluster complexes in [Ir 6 (CO) 14 (l-TePh)]~ and [Ir 6 (CO) 13 (l-TePh) 2 ].193 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 2246 Palladium Co-ordination compounds In this section monomeric compounds are dealt with before polymeric compounds and within this division entries are given in order of decreasing hardness of the dominant ligand. The limited range of ROO~ complexes has been extended by the synthesis of [Pd(OOR)(py)(TpP32)] (R\H, Bu5).194 [Pd 2 (O 2 CCH 3 ) 4 (dmso) 2 ] has two bridging acetates and S-bonded dmso.195 In crystals [PdPh(PPh 3 ) 2 (O 2 CC 6 H 4 SEt)] shows monodentate O-bonded carboxylate, but in solution the S atom can displace one phosphine ligand.196 Pd(II) complexes have been prepared with new 2-acylphenolates, analogues of diketonates.197 The reaction of Na 2 PdCl 4 and 1-methyluracil (HL) at pH 9–10 produces [Na 2 PdL 4 (H 2 O)]n, with a columnar structure having one water molecule acting as a guest molecule and the host lattice being sustained by p–p interactions and hydrogen bonds.198 The first platinum metal penicillamine (HL) complexes include [Pd 2 L 2 Cl 2 ] and [Pd 3 L 3 ]·0.875KCl·2.375H 2 O, which has a triangular structure with bridging anions.199 The undeveloped field of metallocarbohydrate chemistry may expand following identification of structures, including ligand conformation changes, of complexes formed by the interaction of [Pd(OH) 2 (en) 2 ] with anhydroerythritol, anhydroglucose and glucose.200 [Pd(dppe)(S 2 CNEt 2 )]` was prepared as halogenometalate salts by reacting [PdX 2 (dppe)] with metal dithiocarbamates, but no heterometallic complexes were formed.201 Cysteine hydrochloride and [PdCl 4 ]2~ react to give the first polynuclear Pd(II) amino acid complex [Pd 4 Cl 4 (l-Cys) 4 ] with all the S atoms bridging two Pd.202 The role of the cation in determining which complex a metal–polyanion system may adopt is highlighted in a study of the formation of Pd polyselenide salts such as [MeN(CH 2 CH 2 ) 3 N] 2 [Pd(Se 6 ) 2 ].203 [Pd(SePh) 2 (PBu/ 3 ) 2 ] is the first structurally characterized Pd(II) selenolate complex.204 Kinetic studies showed that substitution of en for Cl~ in [PdCl 2 - MRR@N(CH 2 ) 2 NRAR@@@N2 ] (R,R@,RA,R@@@\H, alkyl, aryl) was promoted by the electron withdrawing properties of phenyl substituents and retarded by steric e§ects of alkyl groups, but that substitution of en for bipy in [Pd(bipy)MRR@N(CH 2 ) 2 NRAR@@@N2 ]2` was faster with more alkyl groups, possibly due to hydrogen bonding e§ects between solvent water and co-ordinated diamine hydrogens.205 The reaction of [Pd(NO 3 ) 2 (en) 2 ] with either 4-pyridylmethyl acetate or 2,4,6-tris(3-pyridyl)triazine gave cluster molecules containing six Pd(en) 2 moieties and four of either ligand.206 The co-ordination chemistry of Ph 3 P––NCN shows the terminal N atom is the better donor, as in [PdCl 2 (NCNPPh 3 ) 2 ].207 New co-ordination compounds of pyridine-2-selenolate (L) include [Pd 2 Cl 3 L(PR 3 ) 2 ], in which one Pd is co-ordinated by L through N and Se and the other by Se.208 The first binuclear Pd(III) compound has been claimed; palladium(II) acetate reacts with the anion of HL4 giving [Pd 2 L4 4 ], which undergoes two-electron oxidation with PhICl 2 to give [Pd 2 L4 4 Cl 2 ], which has the shortest Pd–Pd bond yet (239.1 pm).209 Stoichiometric mixtures of the appropriate pyridylporphyrins gave a square array containing nine ligands and twelve PdCl 2 moieties.210 A review on the design of cyclic nanostructures uses Pd compounds as the most frequent metallic Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 213–238 225NH N N HL4 building unit.211 The unexpected synthesis of the double A-framed complex [MPd 2 Br 2 (l-PPh 2 )(l-dppm)N2 (l-CN) 2 ] arose from the NaBH 3 CN reduction of [Pd 2 (Np) 2 Br(dppm) 2 ]`.212 The variability of the Pd–Pd single bond length in Pd(I) dimers is exemplified by its length (318.5 pm) in [Pd 2 (C 4 H 6 ) 2 (PPh 3 ) 2 ]2` and its shortness (248.8 pm) in [Pd 2 (PPh 3 ) 2 (NCMe) 4 ]2` (equatorial PPh 3 ), made from the former on dissociation in MeCN.213 The terminal phosphines were found to be more readily substituted by other phosphines than their bridging sibling in [Pd 2 (l-PBu5 2 )(l- PBu5 2 H)(PBu5 2 H) 2 ]`.214 [Pd 2 (l-OH) 2 (PPh 3 ) 2 ]2` forms [Pd 3 (PPh 3 ) 4 ]2` in alcoholic CH 2 Cl; the product has a linear structure with two phenyl rings showing l-g2:g2 co-ordination.215 Another of the relatively rare type of rectangular Pd 4 complexes, [Pd 4 (l-Cl) 2 (l-dppm) 4 ][ClO 4 ] 2 ·dpe, has been prepared from [Pd 2 Cl 2 (l-dppm) 2 ], AgClO 4 and dpe, the last not being co-ordinated.216 Organometallic compounds The first stable Me 2 PdIV units have been formed from the reaction of [PdMe 2 (bipy)] and Ph 2 Se 2 , giving [PdMe 2 (SePh) 2 (bipy)], and from other similar reactions.217 The trans to cis isomerization of [Pd(C 6 Cl 2 F 3 ) 2 (tht) 2 ] is catalysed by [Au(C 6 Cl 2 F 3 )(tht)] with intermediates involving aryl exchange between Pd and Au.218a The oxidative addition of C 6 Cl 2 F 3 I to [Pd(PPh 3 ) 4 ] gave the unusually stable cis- [Pd(C 6 Cl 2 F 3 )I(PPh 3 ) 2 ], whose slow isomerization to the trans form was studied kinetically.218b The new ligand 2,6-bis(pyrimidin-2-yl)pyridine (L) forms [PdMeL]`, which gives an acetyl derivative; the fluxionality of the diimine ligand was studied.219 The reaction of palladium(II) acetate, phen, nitromethane and CO gave the Pd(phen) complex of MeN(CO)CO 2 2~, shown by powder X-ray methods to be co-ordinated through two C atoms.220 Pd 6 hexagons occur in [Pd 6 (4,7-phen) 3MC 6 H 2 (CH 2 SR) 4 - 1,2,4,5N3 ]6` (R\Bu, Ph).221 The reaction of CO with methyl Pd(II) complexes of a diphosphine and various PhC––NR gave acyl formation followed by formation of chelating CH 3 CONRCHPh.222 Reviews on mononuclear Pd organometallics include one on the use of [Pd(L)(solv)]2` (L\triphosphine) as catalysts for reducing CO 2 to CO,223 and a wide ranging survey of carbonyl–ylide complexes which emphasises the role of the ylide C co-ordination.224 Tris(1-naphthyl)phosphine (HL) gives various cyclometallated Pd complexes, including [Pd 2 L 2 (O 2 CCH 3 ) 2 ], a good catalyst for the Heck reaction (aromatic alkenation).225 A new mechanism for the Heck reaction involves nucleophilic attack on the Pd-co-ordinated alkene.226 The crystal structures and fluxionality in solution (29Si and 31P NMR) have been studied for various [ML 2 X 2 ] (M\Pd, L\PMe 2 Ph, X\SnMe 3 ; M\Pt, L\PEt 3 , PMe 2 Ph, X\SiMePh 2 , SiF 2 Me).227 Many new examples of [PdL(g2-1,6-diene)] complexes have been reported, including [Pd(PMe 3 )M(g2-CH 2 ––CHCH 2 ) 2 ON] (X-ray di§raction).228 The photochemistry of Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 226[PdCl 2 (cod)] gives the cod radical cation and [PdCl 2 ]~, which in MeCN gives isomerization to 1,3-cod and in ethanol decomposition to Pd and acetaldehyde.229 Various Pd(II) allyl diketonates act as good Pd CVD precursors, some of them being liquid, e.g.[Pd(C 3 H 5 )MBu5C(O)CHC(O)C 3 F 7N].230 Palladium(II) acetate and [Ni 6 (CO) 12 ]2~ give a Ni–Pd heterometallic cluster which reacts with PMe 3 to give, inter alia, [Pd 59 (CO) 32 (PMe 3 ) 21 ], which has 11 interior Pd atoms and is described as the largest crystallographically determined metal atom core with direct metal–metal bonding.231 7 Platinum Co-ordination compounds In this section complexes of oxidation state IV are considered before those of oxidation state II.Within each section the order is of decreasing hardness of the dominant ligand.The crystal structures and IR, Raman and 195Pt NMR spectra have been reported for [PtCl 5 (SCN)]2~, cis-[PtCl 4 (SCN) 2 ]2~,232 both isomers of [PtCl 3 (SCN) 3 ]2~, cis- [PtCl 2 (SCN) 4 ]2~, [PtCl(SCN) 5 ]2~,233 and [Pt(SCN) 6 ]2~.234 The reaction of halogens with [Pt(ox) 2 ]2~ gives [PtX 2 (ox) 2 ]2~, also described by crystallographic and spectral studies.235 Reacting [9]aneN 3 with [PtCl 2 (dmso) 2 ] in air results in oxidation to Pt(IV) and the formation of a peroxide complex [MPt 2 Cl 2 ([9]aneN 3 )N2 (l-O 2 ) 2 ]2`.236 [Pt(OH) 2 (ox) 2 ]2~, though long known, has now been obtained for X-ray study as the [(py) 2 CH 2 ]2` salt of the double complex with [Pt(OH)(ox) 2 (H 2 O)]~.237 New Pt(IV) amino acid complexes characterized by crystallography include cis-[PtCl 4 (Ala)- H 2 O]·18-crown-6, with the zwitterion co-ordinated through O, and the glycinium salt of [PtCl 4 (Gly)]2~·2(18-crown-6)·1.25H 2 O, with N,O-chelating glycinate.238 [Pt(L)Me 3 ]` (L\glucopyranoside) complexes show a new co-ordination mode for carbohydrate by using the 2- and 4-hydroxyls and the pyranose acetal oxygen.239 POCl 3 oxidises Pt(II) to Pt(IV) giving, for example, [Pt(en)(NO 2 )Cl 3 ] from [Pt(en)(NO 2 ) 2 ].240 Reacting [Pt 2 (l-SO 4 ) 4 (H 2 O) 2 ] with acetic acid gave [Pt 4 (l-O 2 CCH 3 ) 4 (H 2 O) 8 ]4`, which reacts with py to give the square structured [Pt 4 (l-O 2 CCH 3 ) 6 (py) 4 ]2`.241 New polymeric Pt(II) complexes based on repeating Pt 4 units include K 4 [Pt 4 (NO 2 ) 6 (OH) 4 (ox)]·2(MeO) 3 PO.242 Various new binuclear Pt (and Pd) diphenylphosphinate complexes described include [Pt 2 Cl 2 (l-O 2 PPh 2 ) 2 (PMe 2 Ph) 2 ] (crystal structure).243 In studies involving biochemical ligands, the trans-[Pt(NH 3 ) 2 ]2` complex with trimethyladenine and 9-ethylguanidine forms three intermolecular H bonds with the ion of the complex with deprotonated guanine, the two guanine entities interacting to give a Z-shaped structure.244a AWAXS (anomalous wide angle X-ray scattering) studies on Pt 5-fluorouridine green sulfate suggest this has binuclear and mononuclear Pt components.244b [PtCl(dien)]` forms an S-bonded methionine complex at pH 7, which becomes N-bonded at pH 8; at pH 3 the triamine is monoprotonated, and methionine becomes bidentate, four diastereoisomers being identified.245 The bridging ligand bptz is particularly e§ective at stabilising mixed valence com- Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 213–238 227N N N N N N bptz plexes formed by reduction and oxidation of [MPt(mes) 2N2 (l-bptz)].246 Time-resolved IR spectra have been used for the first time to study various photochemical processes involving [Pt(N 3 ) 2 L 2 ] (L\PPh 3 , 1/2 dppp).247 Carbazole oxidatively adds across its N–H bond to [Pt(PR 3 ) 2 ] (R\Me, Et), in contrast to dibenzothiophene, which gives insertion into the C–S bond.248 The alkyne bond in PhSCCSiMe 3 is broken by [PtH(MeOH)(PEt 3 ) 2 ]` to give the benzenethiolate complex [MPt(PEt 3 ) 2N2 (l- SPh) 2 ]2`.249 Among reactions of 2,3-dppn is that with [PtCl 2 (NCC 6 H 5 ) 2 ] and Ag`, giving [Pt(1,2-dppn) 2 ]2`, one of many such ligand isomerizations.250 The determination of the crystal structures of cis-[PtCl 2 (SbPh 3 ) 2 ] and trans- [PtI 2 (SbPh 3 ) 2 ] indicated that SbPh 3 has a similar static trans-e§ect to PPh 3 .251 The protonation of [PtHX(PCy 3 ) 2 ] depends on the trans ligand X, the reaction occuring at H (X\H, Me, Ph), Pt (X\Cl, Br, I) or X (X\CN).252 Organometallic compounds [PtMe 2 (cod)] undergoes photochemical oxidative addition of MeI to give [MPtMe 3 IN4 ],253a while the elusive [MPtMe 3 FN4 ] has finally been made by the reaction of the iodide with XeF 2 .253b The rare aryl halide oxidative addition process to Pt(II) has been achieved by using Schi§ bases of the type RN––CHC 6 H 4 X-2 (X\Br, Cl) and [Pt 2 Me 4 (l-SMe 2 ) 2 ].254 The limited range of Pt cyclopentadienyl compounds has been extended by the synthesis of [PtMe 2 (CO)Cp*]` and [PtMe 2 (SC 6 H 4 CH 3 -4)- Cp*].255 The first crystal structure of a Pt acetonyl complex, [Pt(bipy)MCH 2 C(O)CH 3N2 ], has been reported.256 In a new reaction of the fairly unfamiliar chloride bridged platina-b- diketone, [Pt 2M(COCH 3 ) 2 HN(l-Cl) 2 ] reacts with bipy and its derivatives to give Pt(IV) acyls [Pt(bipy)HCl(COCH 3 ) 2 ] which may eliminate acetaldehyde at the low temperature of 180 °C to give [Pt(bipy)Cl(COCH 3 )].257 a-(Diisopropylphosphino)isodurene (HL) forms cis-[PtMeL(HL)] which gives selective C–Si coupling with various HSiR 3 to give MeSiR 3 and [PtHL(HL)].258 [Pt(PPr* 3 ) 2 Me(OTf)] undergoes metallation of the phosphine when catalytic amounts of HCl are added, giving a phosphacyclobutane complex with Cl replacing Me.259 The thermolysis of many Pt(0) PPh 3 complexes gave [Pt 2 (PPh 3 ) 2 (l-PPh 2 )Ml-C 6 H 4 (PPh 2 ) 2 -1,2N], which is probably what was previously formulated as [Pt 2 (PPh 3 ) 4 ] or [Pt 2 (l-PPh 2 ) 2MC 6 H 4 (PPh 2 ) 2 -1,2N2 ].260 [Pt(CNMe) 4 ]- [Pt(mnt) 2 ] 2 occurs in three di§erent lattice structures depending on the crystallization solvent, each having di§erent magnetochemistry.261 Li 2 [Pt(CCBu5) 4 ] and HPPh 2 in acetone–ethanol gives [LiMOC(CH 3 ) 2N] 2 - [Li 2 (H 2 O) 2 ][Pt(CCBu5) 2 (PPh 2 O)] 2 , the phosphinyl O bridging two types of Li.262 The diplatinum complex [Pt 2 (dppf) 2 (l-CHCH 2 C 6 H 4 OMe)(l-H)]` has the rare combination of bridging hydride and alkylidene.263 [Pt(acac) 2 ] and PPh 3 give [Pt 2 (l- L)(PPh 3 ) 4 ]`, in which the deprotonated acac, L, co-ordinates one Pt through both oxygens and the other Pt in an allyl mode.264 The range of rare five-co-ordinate alkyne complexes is extended by the synthesis of [PtI 2 (2,9-Me 2 phen)(g2-C 6 H 5 CCC 6 H 5 )] and Annu.Rep.Prog. Chem., Sect. A, 1999, 95, 213–238 228some analogues.265 The elusive benzyne complex [Pt(PPh 3 ) 2 (g2-C 6 H 4 )] is made from [Pt(PPh 3 ) 2 (C 2 H 4 )], chlorobenzene and base, but is only isolated as derivatives such as [Pt(PPh 3 ) 2 (g1:g1-C 6 H 4 C 6 H 4 )].266 Dry etching of Pt can be obtained using a chlorine–COgas mixture, with the benefit of the easy removal of sublimable [PtCl 2 (CO) 2 ].267 The first crystallographically characterised ‘buckybowl’ complex, [Pt(C 30 H 12 )(PPh 3 ) 2 ], is prepared (10% yield) by reacting the hydrocarbon with [Pt(PPh 3 ) 2 (C 2 H 4 )]; the ligand co-ordinates by oxidatively adding a C–C bond in an outside pentagon.268 Unlike its PEt 3 analogue, [Pt(PMe 2 Ph) 2 (g5-7-CB 10 H 11 )]~ gives a complex mixture of products on protonation with HCl, including [Pt 2 (PMe 2 Ph) 4 (l-CB 10 H 10 ) 2 ], which has g5-co-ordination supplemented by B–B and Pt–B links.269 Two new bipyridyl thiocarborane Pt complexes act as powerful oxidising agents in their photochemical excited states.270 A new synthesis of [PtMe 2 (PMe 2 Ph) 2 ] using MeLi and [PtCl 2 (PMe 2 Ph) 2 ] facilitates the use of this as a synthon for big metalloboranes such as [PtHMg4- B 18 H 19 (PMe 2 Ph)N(PMe 2 Ph)].271 The oxidative addition of B 2 F 4 to [Pt(PPh 3 ) 2 (C 2 H 4 )] gives the first Pt–BF 2 complex, cis-[Pt(BF 2 ) 2 (PPh 3 )].272 The first neutral Pt silylene complexes [PtMSi(mes) 2N(PR 3 ) 2 ], (R\Cy, Pr*), made by the photolysis of [Pt(PR 3 ) 2 ] with (Me 3 Si) 2 Si(mes) 2 , has a 69° dihedral angle between the C 2 Si and P 2 Pt planes.273 The germyl complex [PtMGe[N(SiMe 3 ) 2 ] 2N(PEt 3 ) 2 ] reacts with O 2 to form [Pt(l-g2-O 2 )MGe[N(SiMe 3 ) 2 ] 2N(PEt 3 ) 2 ], which is transformed by light into the germanate isomer [PtO 2MGe[N(SiMe 3 ) 2 ] 2N(PEt 3 ) 2 ] and by SO 2 into [Pt(l- g2-SO 4 )MGe[N(SiMe 3 ) 2 ] 2N(PEt 3 ) 2 ].274 In a typical result from many thermochemical studies on various terminal phosphide complexes [Pt(dppe)Me(PRR@)], prepared from [Pt(dppe)Me(OMe)] and HPRR@, the Pt–P bond strength depends on both steric and electronic e§ects.275 In other zerovalent Pt studies, reacting cyclopropene (L) complexes of the type [PtL(PPh 3 ) 2 ] with HCl gave either cyclopropane (L\C 3 H 4 ) or propene (L\3,3- Me 2 C 3 H 2 ).276 New Pt 2 M 2 square clusters include [MPt(PPh 3 ) 2N2MMXN2 Se 2 ] (M\Cu, Ag, X\Cl; M\Au, X\SeH).277 [Pt(C 6 H 5 CCCCC 6 H 5 )(PPh 3 ) 2 ], con- firmed (crystal structure) as having one triple bond co-ordinated, forms trinuclear complexes [Pt 2 M(l3 -g1:g1: g2-(C 6 H 5 CCCCC 6 H 5 )(PPh 3 ) 2 (CO) 5 ], still with only one triple bond involved.278 8 Silver In this section compounds are discussed in decreasing order of oxidation state.For each oxidation state the order is of decreasing hardness of the dominant ligand. MAgF 4 (M\K, Li) has been made by the photochemical reaction of AgF 2 with MF and fluorine in HF. Treating KAgF 4 with GeF 4 and fluorine in HF gives the purest AgF 3 yet and K 2 GeF 6 .279 The elusive potential proton conductor AgHSO 4 has been made from Ag 2 O or Ag 2 SO 4 and sulfuric acid; it absorbs CO reversibly in concentrated H 2 SO 4 .280 The rare category of Ag–Hg complexes has been augmented by the synthesis of [MAg 2 Hg(mes) 2 X 2N2 (X\OTf, ClO 4 ), from AgX and Hg(mes) 2 ; the triflate shows the first tridentate mode for this ligand.281 A low temperature synthesis of Ag 2 E (E\S, Se, Te) has been achieved by the reaction of E with silver oxalate in organic solvents at Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 229140–180 °C.282 The new complex [Ag 4 (SPh) 4 (PPh 3 ) 4 ] has a chair configuration which is suggested to include Ag–Ag connections from correlation e§ects after the manner of Au(I) compounds.283 The first l4 -sulfide ligand outside Cu chemistry is found in the polymeric zwitterionic complex [Ag 8 (SC 2 H 4 NH 3 ) 6 Cl 8 ].284 Thianthrene (L5) forms [Ag 2 (L5) 2 (ClO 4 ) 2 ], with each Ag co-ordinated by 2S from one ligand, one C––C of another and a perchlorate O atom.285 The first co-ordination by S in di-2-pyridylsulfide (L) has been found in [Ag 2 L 2 (NO 3 ) 2 ], with 2N on one Ag and the S on the other.286 The reaction of AgS 2 CNEt 2 with Na 2 Se or [MoSe 4 ]2~ gives [Ag 11 Se(S 2 CNEt 2 ) 9 ], containing l5 -Se.287 The protecting action of phosphine ligands in forming large clusters is emphasised in various Ag–Se examples, giving up to [Ag 172 Se 40 (SeBu) 92 (dppp) 4 ].288 S S L5 [Ag(pym)]` forms as cyclic tetranuclear cations which stack to give channels in which the oxyanions can be located.289 Earlier work on terpy derivative Cu(I) complexes has found some analogies in the probable formation in solution of a double helical complex, but only planar [Ag(terpy)(NCMe)]` was isolated; this has Ag–Ag contacts of 317 pm, comparable to many macrocyclic Ag 2 complexes.290 Two chiral derivatives (L) of terpy form [AgL(NCMe)]` complexes in acetonitrile, but in less co-ordinating solvents double helicates [Ag 4 L 4 ]4` were indeed found.291 A new cage structure with approximately an Ag 6 octahedron was found in [Ag 6 (triphos) 4 (OTf) 4 ]2`.292 3,6-Bis(diphenylphosphino)pyridazine (L) forms zigzag chains [Ag 2 L(NCMe) 2 ]2` with each L co-ordinated to four Ag and each Ag bonded to anNfrom one ligand and a P from another.293 Aqueous co-crystallisation of Ag 2 C 2 with AgClO 4 gives corner-shared Ag 6 clusters encapsulating acetylide units and generating cavities for ClO 4 ~ and H 2 O; there are many examples of similar channeled structures this year.294 Adding Ag 2 C 2 to AgF in water gave [Ag 10 F 8 C 2 ] with an exohedral Ag outside an Ag 9 cage again encapsulating an acetylide and with F bridges to other cages.295 The structure of Tl[Ag(CN) 2 ] shows an Ag–Ag separation of 311 pm, but no Tl–Ag bonding.296a The luminescence of this complex is interpreted as showing Ag–Ag interactions, said to imply the first solid state metal–metal bound exciplex.296b The reaction of AgCN or AgSCN with [SnMCH(SiMe 3 ) 2N2 ] gave dinuclear complexes with the pseudo-halide N-bonded to Sn, and showing the first coupling to 109Ag or 107Ag in an 119Sn NMR spectrum.297 The first Ag–Sn compound was claimed in Rb 4 Sn 4 Ag 4 (P 2 Se 6 ) 3 .298 9 Gold In this section, compounds are discussed in decreasing order of oxidation state.For each oxidation state the order is of decreasing hardness of the dominant ligand. [AuF 6 ]~ has been prepared by the oxidation of [AuF 4 ]~ byO 2 F formed fromO 2 ~ in anhydrous HF.299 Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 213–238 230[AuBr(C 6 F 5 ) 3 ]~ reacts with NaSH to give the first Au hydrosulfide complex [Au(SH)(C 6 F 5 ) 3 ]~, which in turn leads to other derivatives, such as [MAu(C 6 F 5 ) 3N2 SMM(PPh 3 )N]~ (M\Ag, Au).300 [Au(Se 3 ) 4 ]5~ is the first Au(III) chalcogenide mononuclear anion; its square planar configuration has bent Se 3 chains which give the overall anion structure the appearance of a swastika.301 Gold dissolves in alkali polysulfide solutions to form MAuS, (M\Li, Na), with [AuS] chains which, in the Na compound, interweave after the manner of chicken wire.302 [Au 3 S 2 ]~ has been found together with [Au 3 Sb 4 S 8 ]~, which is better formulated as [(Au 3 S)`·(Sb 4 S 7 )2~], in Rb 2 Au 6 Sb 4 S 10 .303 Colourless [AuMS 2 CN(C 5 H 11 ) 2N] becomes orange when solvated by various aprotic organic molecules, with a decrease in the intermolecular Au–Au separation from 814pm to about 300 pm; this is suggested to imply potential as a sensor.304 Heating calcium nitride with gold in nitrogen gave Ca 2 AuN, having a new structure with Au zigzag chains between Ca 6 N octahedra.305 Determining the structure of new [MM(PPh 2 )Au(C 6 F 5 ) 3N]~ (M\Ag, Au) showed the Au(I)–P bonds were shorter by 69pm than Ag–P bonds.306a A similar conclusion arose when determination of the structure of [Ag(PPh 3 ) 2 ][BF 4 ] induced a comparison of 14 isostructural pairs of Ag and Au compounds, with Au` deduced to have a smaller ionic radius by about 10 pm.306b The phenylborole complex [FeH(CO) 2 (g5-C 4 H 4 BPh)]~ reacts with [AuCl(PPh 3 )] to give first [Fe(CO) 2MAu(PPh 3 )N2 (C 4 H 4 BPh)] with an Au–Au separation of 273.7 pm, and then [Fe(CO) 2MAu(PPh 3 )N3 (C 4 H 4 BPh)] with tetrahedral FeAu 3 .307 [AuMPOPh) 3N]` and some similar cations are said to be unusual among gold compounds in showing catalytic activity, in this case for the addition of alcohols to alkynes.308 S L6 The Au–Au contacts of solid [(AuCl) 3 (PhPMC 6 H 4 (PPh 2 )-2N2 )] appear to be retained in solution.309 [AgMAu 2 (CH 2 SiMe 3 ) 2 (l-dppm)N2 ]` contains the first unsupported Ag–Au bonds.310 The chemistry of phenylacetylide complexes has been extended by reacting [Au(C 2 C 6 H 5 ) 2 ]~ with Au and Cu phenylacetylides giving [Au 3 Cu 2 (C 2 C 6 H 5 ) 6 ]~, containing linear Au co-ordination and with each triple bond co-ordinated to a copper atom.311 Tetramethylthiacycloheptyne (L6) forms the first g2-Au alkyne complex in [MAu(L7)ClNn].312 Au catalysts for CO oxidation can be prepared by decomposition of [Au(NO 3 )(CNEt)] (crystal structure) on Fe(OH) 3 .313 Various new complexes [AuX(CNxyl-o)], (X\Cl, Br, I, CN), have di§erent structures but are all luminescent.314 Powder neutron di§raction shows AuCN has polymeric chains with each Au at the centre of an Au 6 hexagon, but that there are no Ag–Ag interactions in AgCN, in which the chains are di§erently arranged.315 [(Ph 3 P)Au(l- C 4 H 9 CO)MRe 2 (l-PPh 2 ) 2 (CO) 7N], the first gold acyl, has the acyl C bonded to Au and the O to Re.316 The improbable procedure of the photolysis of a mixture of [AuCl(PPh 3 )], Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 231[Au(N 3 )(PPh 3 )] and Na 2 [V(CO) 3 Cp] gives [Au(AuCl)MAu(PPh 3 )N8 ]`, comprising an MAu(PPh 3 )N8 crown with a central Au carrying an AuCl unit.317 The benzimidazolate (L) complex [Au 3 (l-N 3 ,C2-L) 3 ] reacts with silver ions to form [AgMAu 3 (l-N3,C2- L) 3N2 ]`, having a trigonal prism structure with six Ag–Au bonds.318 Finally, a review on various aspects of cluster molecules and nanoscience gives particular emphasis to Au 55 species.319 References 1 M.Y.Darensbourg (Editor), Inorg. Synth., 1998, 32. 2 New J. Chem., 1998, 22, 667, 1177. 3 N. Toshima and T. Yonezawa, New J. Chem., 1998, 23, 1179. 4 P.D. Akrivos, H. J. Katsikis and A. Koumoutsi, Coord.Chem. Rev., 1997, 167, 95. 5 R. J. Puddephatt, Chem. Commun., 1998, 1055. 6 G. J. Irvine, M. J. G. Lesley, T. B. Marder, N. C. Norman, C. R. Rice, E. G. Robins, W.R. Roper, G. R. Whittell and L. J. Wright, Chem. Rev., 1998, 98, 2685. 7 P. S. Pregosin and G. Trabesinger, J. Chem. Soc., Dalton Trans., 1998, 727. 8 J. Organomet. Chem., 1998, 554. 9 M. I. Bruce, Chem. Rev., 1998, 98, 2797. 10 W. Henderson, B. K. Nicholson and L. J. McCa§rey, Polyhedron, 1998, 17, 4291. 11 K. Severin, R. Bergs and W. Beck, Angew. Chem., Int. Ed., 1998, 37, 1415. 12 N. J. Coville and L. Cheng, J. Organomet. Chem., 1998, 571, 149. 13 J. Sloan, J. Hammer, M. Zwiefka-Sibley and M.L. H. Green, Chem. Commun., 1998, 347. 14 L. Wang, P. Brazis, M. Rocci, C. R. Kannewurf and M.G. Kanatzidis, Chem.Mater.,1998, 10, 3298. 15 J. Haines, J. M. Leger, M.W. Schmidt, J. P. Petitet, A. S. Pereira, J. A. H. Da Jordana and S. Hull, J. Phys. Chem. Solids, 1998, 59, 239. 16 J. R. Osman, J. A. Crayston and D. T. Richens, Inorg. Chem., 1998, 37, 1665. 17 N. Aebischer, U. Frey and A. E. Merbach, Chem. Commun., 1998, 2303. 18 M. Kondo, M. Hamatani, S. Kitagawa, C. G. Pierpoint and K.Unoura, J. Am. Chem. Soc., 1998, 120, 455. 19 J. Larionova, B. Mombelli, J. Sanchiz and O. Kahn, Inorg. Chem., 1998, 37, 679. 20 H. Miessner and K. Richter, Angew. Chem., Int. Ed., 1998, 37, 117 21 S. Plotkin and A. Haim, Inorg. Chim. Acta., 1998, 270, 189. 22 (a) M. Hartmann, K.-G. Lipponer and B. K. Keppler, Inorg. Chim. Acta, 1998, 267, 137; (b) E. Alessio, E. Zangrando, R.Roppa and L. G. Marzilli, Inorg. Chem., 1998, 37, 2458. 23 S.-M. Yang, M. C.-W. Chan, S.-M. Peng and C.-M. Che, Organometallics, 1998, 17, 151. 24 (a) D. Chatterjee, Coord. Chem. Rev., 1998, 168, 273; (b) Y. Chen, F.-T. Lin and R. E. Shepherd, Inorg. Chim. Acta, 1998, 268, 287. 25 L. Higham, A. K. Powell, M. K. Whittlesey, S. Wocadlo and P. T. Wood, Chem. Commun., 1998, 1107. 26 G.S. Hill, D. G. Holah, A. N. Hughes and E.M. Propchuk, Inorg. Chim. Acta, 1998, 278, 226. 27 A.W. Kaplan and R. G. Bergman, Organometallics, 1998, 17, 5072. 28 A.W. Kaplan,, J. C. M. Ritter and R. G. Bergman, Organometallics, 1998, 17, 6828. 29 N. Rahmouni, J. A. Osborn, A. de Cian, J. Fischer and A. Ezzamarty, Organometallics, 1998, 17, 2470. 30 J. Shen, E. D. Stevens and S. P.Nolan, Organometallics, 1998, 17, 3875. 31 S. Chand, R. K. Coll and J. S. McIndoe, Polyhedron, 1998, 17, 507. 32 I. G. Dance and M. Scudder, J. Chem. Soc., Dalton Trans., 1998, 1341. 33 J. R. Schoonover, C. A. Bignozzi and T. J. Meyer, Coord. Chem. Rev., 1997, 165, 239. 34 (a) K.M. Omberg, J. R. Schoonover, S. Bernhard, J. A. Moss, J. A. Treadway, E. M. Kober, R. B. Dyer and T.J. Meyer, Inorg. Chem., 1998, 37, 3391; (b) J.R. Schoonover, K. M. Omberg, J. A. Moss, S. Bernhard, V. J. Malueg, W. H. Woodru§ and T. J. Meyer, Inorg. Chem., 1998, 37, 2585. 35 S.MZakeeruddin, M. K. Nazeeruddin, R. Humphry-Baker andMGra� tzel, Inorg. Chem., 1998, 37, 5251. 36 E. C. Constable and D. G. F. Rees, Polyhedron, 1998, 17, 3281. 37 M.T. Indelli, C. A. Bignozzi, F. Scandola and J.-P.Collin, Inorg. Chem., 1998, 37, 6084. 38 J. G. Collins, A. D. Sleeman, J. R. Aldrich-Wright, I. Gregoric and T. W. Hambley, Inorg. Chem., 1998, 37, 3133. 39 F.M. O’Reilly and J. M. Kelly, New J. Chem., 1998, 22, 215. 40 M. Adelt, M. Devenney, T. J. Meyer, D. W. Thompson and J. A. Treadway, Inorg. Chem., 1998, 37, 2616. 41 S. Roche, C. Haslam, H. Adams, S. L. Heat and J.A. Thos, Chem. Commun., 1998, 1681. 42 N. C. Fletcher and F. R. Keene, J. Chem. Soc., Dalton Trans., 1998, 2293. 43 A.M. Barthram, R. L. Cleary, J. C. Je§ery, S. M. Couchman and M.D. Ward, Inorg. Chim. Acta, 1998, 267, 1. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 23244 N. C. Fletcher, P. C. Junk, D. A. Reitsma and F. R. Keene, J. Chem. Soc., Dalton Trans., 1998, 133. 45 F. Baumann, W. Kaim, M. Garcý� a Posse and N. E. Katz, Inorg. Chem., 1998, 37, 658. 46 M.A. S. Aquino, Coord. Chem. Rev., 1998, 170, 141. 47 M.C. Barral, R. Jime� nez-Aparacio, J. L. Priego, E. C. Royer, F. A. Urbanos and U. Amador, Inorg. Chim. Acta, 1998, 279, 30. 48 F. A. Cotton and A. Yokochi, Inorg. Chem., 1998, 37, 2723. 49 F. D. Cukiernik, D. Luneau, J.-C. Marchon and P.Maldivi, Inorg. Chem., 1998, 37, 3698. 50 (a)M.C. Barral, R. Jime� nez-Aparacio, J. L. Priego, E. C. Royer and F. A. Urbanos, Inorg. Chim. Acta, 1998, 277, 76; (b) A. J. Bailey, W. P. Gri¶th, S. P. Marsden, A. J. P. White and D. J. Williams, J. Chem. Soc., Dalton Trans., 1998, 3673. 51 F. A. Cotton and A. Yokochi, Polyhedron, 1998, 17, 959. 52 P. A. Stuzhin, S. I. Vagin and M. Hanack, Inorg.Chem., 1998, 37, 2655. 53 G.-B. Yi, M.A. Khan, D. R. Powell and G. B. Richter-Addo, Inorg. Chem., 1998, 37, 208. 54 J. P. Collman and S. T. Harford, Inorg. Chem., 1998, 37, 4152. 55 K. Funatsu, T. Imamura, A. Ichimura and Y. Sasaki, Inorg. Chem., 1998, 37, 1798. 56 K. Funatsu, T. Imamura, A. Ichimura and Y. Sasaki, Inorg. Chem., 1998, 37, 4986. 57 M. Heberhold, K. Bauer and W.Milius, J. Organomet. Chem., 1998, 563, 227. 58 Y. Maruyama, K. Yamamura, I. Nakayama, K. Yoshiuchi and F. Ozawa, J. Am. Chem. Soc., 1998, 120, 1421. 59 H. Werner, C. Gru� nwald, P. Steinert, O. Gevert and J. Wolf, J. Organomet. Chem., 1998, 565, 231. 60 I. D. Burns, A. F. Hill, A. J. P. White, D. J. Williams and J. D. E. T. Wilton-Ely, Organometallics, 1998, 17, 1552. 61 D.H. Gibson, Y. Ding, J. G. Andino, M. S. Mashuta and J. F. Richardson, Organometallics, 1998, 17, 5178. 62 K. Hiraki, M. Koizumi, S. Kira and H. Kawano, Chem. Lett., 1998, 47. 63 A. F. Hill, C. Jones, A. J. P. White, D. J. Williams and J. D. E. T. Wilton-Ely, Chem. Commun., 1998, 367. 64 M.I. Bruce, P. Hinterding, P. J. Low, B. W. Skelton and A. H. White, J. Chem. Soc., Dalton Trans., 1998, 467. 65 E. Galardon, P. Le Maux, L. Toupet and G. Simonneaux, Organometallics, 1998, 17, 565. 66 A. Klose, E. Solari, C. Floriani, S. Geremia and L. Randaccio, Angew. Chem., Int. Ed., 1998, 37, 148. 67 M.A. Bennett, G. A. Heath, D. C. R. Hockless, I. Kovacik and A. C. Willis, J. Am. Chem. Soc., 1998, 120, 932. 68 L. P. Barthel-Rosa, K. Maitra and J. H. Nelson, Inorg. Chem., 1998, 37, 633. 69 C. Gru� nwald, M. Laubender, J. Wolf and H. Werner, J. Chem. Soc., Dalton Trans., 1998, 833. 70 U. Englert, F. Podewils, I. Schi§ers and A. Salzer, Angew. Chem., Int. Ed., 1998, 37, 2134. 71 M.C. B. Colbert, J. Lewis, N. J. Long, P. R. Raithby, M. Younus, A. J. P. White, D. J. Williams, N. N. Payne, L. Yellowlees, D. Beljonne, N. Chawdhury and R. H. Friend, Organometallics, 1998, 17, 3034. 72 J. Shen, E. D. Stevens and S. P. Nolan, Organometallics, 1998, 17, 3000. 73 R. P. Hughes, X. Zheng, C. A. Morse, O. J. Curnow, J. R. Lamprey, A. L. Rheingold and G. P. A. Yap, Organometallics, 1998, 17, 457. 74 A. J. Ashe, X. Fang and J. W. Kampf, Organometallics, 1998, 17, 2379. 75 H. S. Chu, C. P. Lau, K. Y. Wong and W. T. Wong, Organometallics, 1998, 17, 2768. 76 G.Su� ss-Fink, L. Plasseraud, V. Ferrand, S. Stanislas, A. Neels, H. Stoeckli-Evans, M. Henry, G. Laurenczy and R. Roulet, Polyhedron, 1998, 17, 2817. 77 P. D. Smith and A. H. Wright, J. Organomet. Chem., 1998, 559, 141. 78 J. Kuncheria, H. A. Mirza, H. A. Jenkins, J. J. Vittal and R. J. Puddephatt, J. Chem. Soc., Dalton Trans., 1998, 285. 79 S. J. Skoog, A. L. Jorgenson, J. P.Campbell, M. L. Douskey, E. Munson and W.L. Gladfelter, J. Organomet. Chem., 1998, 557, 13. 80 S.-M. Kuang, F. Xue, Z.-Y. Zhang, T. C. W. Mak and Z.-Z. Zhang, J. Organomet. Chem., 1998, 559, 31. 81 K. Mashima, H. Fukumoto, K. Tani, M. Haga and A. Nakamura, Organometallics, 1998, 17, 410. 82 M. Jahncke, A. Neels, H. Stoeckli-Evans and G. Su� ss-Fink, J. Organomet. Chem., 1998, 565, 97. 83 M.A. Bennett, Z. Lu, X. Wang, M. Bown and D. C. R. Hockless, J. Am. Chem. Soc., 1998, 120, 10 409. 84 S.-H. Chun, E. A. Meyers, F.-C. Liu, S. Lim and S. G. Shore, J. Organomet. Chem., 1998, 563, 23. 85 C. S. Gri¶th, G. A. Koutsantonis, B. W. Skelton and A. H. White, Chem. Commun., 1998, 1805. 86 R. Buntem, J. Lewis, C. A. Morewood, P. R. Raithby, M.C. Ramirez de Arellano and G.P. Shields, J. Chem. Soc., Dalton Trans., 1998, 1091. 87 B. F. G. Johnson, C.M. Martin and P. Schooler, Chem. Commun., 1998, 1239. 88 W.-T. Wong, J. Chem. Soc., Dalton Trans., 1998, 1253. 89 (a) P.R. Raithby and G. P. Shields, Polyhedron, 1998, 17, 2829; (b) P. J. Dyson, B. F. G. Johnson and C.M. Martin, Coord. Chem. Rev., 1998, 175, 59. 90 N. E. Leadbeater, J. Lewis, P. R. Raithby and M.-A.Rennie, Polyhedron, 1998, 17, 1755. 91 R. Dorta, H. Stoeckli-Evans, U. Bodensieck and G. Su� ss-Fink, J. Organomet. Chem., 1998, 553, 307. 92 G. Su� ss-Fink, I. Godefroy, V. Ferrand, A. Neels and H. Stoeckli-Evans, J. Chem. Soc., Dalton Trans., 1998, 515. 93 W.G. Feighery, H. Yao, A. F. Hollenkamp, R. D. Allendoerfer and J. B. Keister, Organometallics, 1998, 17, 872.Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 23394 N. E. Leadbeater, Organometallics, 1998, 17, 5913. 95 X. Lei, M. Shang and T. P. Fehlner, Inorg. Chem., 1998, 37, 3900. 96 M. I. Bruce, J. R. Hinchcli§e, P. A. Humphrey, R. J. Surynt, B. W. Skelton and A. H. White, J. Organomet. Chem., 1998, 552, 109. 97 R. Suter, A. A. Bhattacharyya, L.-Y. Hsu, J. A. Krause Bauer and S.G. Shore, Polyhedron, 1998, 17, 2889. 98 C. S.-W. Lau and W.-T. Wong, J. Chem. Soc., Dalton Trans., 1998, 3391. 99 W. Wang, J. F. Corrigan, G. D. Enright, N. J. Taylor and A. J. Carty, Organometallics, 1998, 17, 427. 100 A. J. Aru, A. J. Deeming, Y. de Sanctis, S. K. Johal, C. M. Martin, M. Shinhmar, D. M. Speel and A. Vassos, Chem. Commun., 1998, 233. 101 Y. Kawano and M. Shimoi, Chem.Lett., 1998, 935. 102 J. H. Yamamoto, K. A. Udachin, G. D. Enright and A. J. Carty, Chem. Commun., 1998, 2259. 103 A. J. Deeming and C. M. Martin, Angew. Chem., Int. Ed., 1998, 37, 1691. 104 R. J. H. Clark, P. J. Dyson, D. G. Humphrey and B. F. G. Johnson, Polyhedron, 1998, 17, 2985. 105 T. Borchert, J. Lewis, P. R. Raithby, G. P. Shields and H. Wadepohl, Inorg. Chim. Acta, 1998, 274, 201. 106 D. S. Shephard, B. F. G. Johnson, J. Matters and S. Parsons, J. Chem. Soc., Dalton Trans., 1998, 2289. 107 M. P. Cifuentes, S. M. Waterman, M. G. Humphrey, G. A. Heath, B. W. Skelton, A. H. White, M. P. Seneka Perera and M.L. Williams, J. Organomet. Chem., 1998, 565, 193. 108 K. Lee and J. R. Shapley, Organometallics, 1998, 17, 4030. 109 D. Cauzzi, C. Grai§, C. Massera, G.Mori, G. Predieri and A. Tiripicchio, J. Chem. Soc., Dalton Trans., 1998, 321. 110 W. Clegg, N. Feeder, S. Nahar, P. R. Raithby, G. P. Shields and S. J. Teat, New J. Chem., 1998, 22, 1111. 111 A. Streuss and W. Preetz, Z. Naturforsch., Teil B, 1998, 53, 823. 112 K. D. Demadis, E.-S. El-Samanody, T. J. Meyer and P. S. White, Inorg. Chem., 1998, 37, 838. 113 K. D. Demadis, T.J. Meyer and P. S. White, Inorg. Chem., 1998, 37, 3610. 114 T. J. Crevier, S. Lovell, J. M. Meyer, A. L. Rheingold and I. A. Guzei, J. Am. Chem. Soc., 1998, 120, 6607. 115 M. Ho� hling and W. Preetz, Acta Crystallogr., Sect. C, 1998, 54 , 481. 116 G. A. Heath, D. G. Humphrey and K. S. Murray, J. Chem. Soc., Dalton Trans., 1998, 2417. 117 P. Crochet, M.A. Esteruelas, A.M. Lo� pez, M.-P.Martý� nez, M. Oliva� n, E. On8 ate and N. Ruiz, Organometallics, 1998, 17, 4500. 118 K. Dallmann and W, Preetz, Z. Naturforsch., Teil B, 1998, 53, 227, 232. 119 K. Dallmann and W. Preetz, Z. Anorg. Allg. Chem., 1998, 624, 685. 120 A.M. McDonagh, M. G. Humphrey and D. C. R. Hockless, Aust. J. Chem., 1998, 51 , 807. 121 G. Albertin, S. Antoniutti, A. Bacchi, M. Bergamo, E.Bordignon and G. Pelizzi, Inorg. Chem., 1998, 37, 479. 122 z and A. Tekkaya, Organometallics, 1998, 17, 5557. 123 D. V. Yandulov, W. E. Streib and K. G. Caulton, Inorg. Chim. Acta, 1998, 280, 125. 124 F. M. Hornung, F. Baumann, W. Kaim, J. A. Olahe, L. D. Slep and J. Fiedler, Inorg. Chem., 1998, 37, 311. 125 A. Masuda and Y. Kaizu, Inorg. Chem., 1998, 37, 3371. 126 K. D. Demadis, G. A. Neyhart, E. M. Kober and T. J. Meyer. J. Am. Chem. Soc., 1998, 120, 7121. 127 V. Shklover, S. M. Zakeeruddin, R. Nesper, D. Fraser and M. Gra� tzel, Inorg. Chim. Acta, 1998, 274, 64. 128 E. Zahavy and M. A. Fox, Chem. Eur. J., 1998, 4, 1647. 129 L. Chen, M. A. Khan and G. B. Richter-Addo, Inorg. Chem., 1998, 37, 533. 130 L. Cheng, L. Chen, H.-S. Chung, M.A. Khan, G. B. Richter-Addo and V. G. Young, Organometallics, 1998, 17, 3853. 131 S.-M. Au, W.-H. Fung, J.-S. Huang, K.-K. Cheung and C.-M. Che, Inorg. Chem., 1998, 37, 6564. 132 E. Bernhardt and W. Preetz, Z. Anorg. Allg. Chem.,1998 , 624, 694. 133 D. G. Gusev, A. J. Lough and R. H. Morris, J. Am. Chem. Soc., 1998, 120, 13 138. 134 C. E. F. Rickard, W. R. Roper, A. Williamson and L. J.Wright, Organometallics, 1998, 17, 4869. 135 P. Crochet, M.A. Esteruelas, A. M. Lo� pez, N. Ruiz and J. I. Tolosa, Organometallics, 1998, 17, 3479. 136 L.-J. Baker, G. R. Clark, C. E. F. Rickard, W. R. Roper, S. D. Woodgate and L. J. Wright, J. Organomet. Chem., 1998, 551, 247. 137 G. J. Spivak, J. N. Coalter, M. Oliva� n, O. Eisenstein and K. G. Caulton, Organometallics, 1998, 17, 999. 138 G.J. Spivak and K. G. Caulton, Organometallics, 1998, 17, 5260. 139 L. D. Field, T. W. Hambley, P. A. Humphrey, A. F. Masters and P. Turner, Polyhedron, 1998, 17, 2587. 140 W.-Y. Yeh, S. C. N. Hsu, S.-M. Peng and G.-H. Lee, Organometallics, 1998, 17, 2477. 141 W.-T. Wong, J. Chem. Soc., Dalton Trans., 1998, 1253. 142 H. G. Ang, S. G. Ang, W. Y. Leong and J. Winfield, J.Fluorine Chem., 1998, 88, 5. 143 N. E. Leadbeater, J. Lewis, P. R. Raithby and G. P. Ward, Eur. J. Inorg. Chem., 1998, 1479. 144 E. Arcý` a, D. S. Kolwaite, E. Rosenberg, K. Hardcastle, J. Ciurash, R. Duque� , R. Gobetto, L. Milone, D. Osella, M. Botta, W. Dastru� , A. Viabe and I. Fiedler, Organometallics, 1998, 17, 415. 145 J. Nijho§, M.J. Bakker, F. Hartl, D. J. Stufkens, W.-F.Fu and R. van Eldik, Inorg. Chem., 1998, 37, 661. 146 C.M. Hay, N. E. Leadbeater, J. Lewis, P. R. Raithby and K. Burgess, New J. Chem., 1998, 22, 787. 147 A. J. Poe, D. H. Farrar, R. Ramachandran and C. Moreno, Inorg. Chim. Acta, 1998, 274, 82. 148 J. B. Claridge and H.-C. zur Loye, Chem. Mater., 1998, 10, 2320. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 234149 S.J. Crimp, A. Drljaca, D. Smythe and L. Spiccia, J. Chem. Soc., Dalton Trans., 1998, 375. 150 V. A. Sa� nchez-Ortiz, L. G. Martý� nez-Jardine` s, S. E. Castillo-Blum and A. G. Sykes, J. Chem. Soc., Dalton Trans., 1998, 663. 151 X. Wei, R. E. Bachman and M. T. Pope, J. Am. Chem. Soc., 1998, 120, 10 248. 152 A.M. Hill, W. Levason and M. Webster, Inorg. Chim. Acta, 1998, 271, 203. 153 M. Peruzzini, J. A. Ramirez and F. Vizza, Angew. Chem., Int. Ed., 1998, 37, 2255. 154 A. F. Hill, A. J. P. White, D. J. Williams and J. D. E. T. Wilton-Ely, Organometallics, 1998, 17, 3152. 155 H. Scho� nberg, S. Boulmaa� z, M.Wo� rle, L. Liesum, A. Schweiger and H. Gru� tzmacher, Angew. Chem., Int. Ed., 1998, 37, 1423. 156 D. Daphnomili, W. R. Scheidt, J. Zajicek and A. G. Coustolelos, Inorg.Chem., 1998, 37, 3675. 157 K.W. Mak and K. S. Chan, J. Am. Chem. Soc., 1998, 120, 9686. 158 H. Hu� cksta� dt and H. Homborg, Z. Anorg. Allg. Chem., 1998, 624, 715. 159 D. Menglet, A.M. Bond, K. Coutinho, R. S. Dickson, G. G. Lazarev, S. A. Olsen and J. R. Pilbrow, J. Am. Chem. Soc., 1998, 120, 2086. 160 P. D. Morran, S. A. Colebrooke, S. B. Duckett, J. A. B. Lohman and R.Eisenberg, J. Chem. Soc., Dalton Trans., 1998, 3363. 161 M. G. L. Petrucci, A.-M. Lebuis and A. K. Kakkar, Organometallics, 1998, 17, 4966. 162 W. Wan, W.-J. Guang, K.-Q. Zhao and L.-F. Zhang, J. Organomet. Chem., 1998, 557, 157. 163 G. P. Mitchell and T. D. Tilley, Organometallics, 1998, 17, 2912. 164 M. P. Garcia, M. V. Jime� nez, F. J. Lahoz, J. A. Lo� pez and L. A. Oro, J.Chem. Soc., Dalton Trans., 1998, 4211. 165 M. Laubender and H. Werner, Angew. Chem., Int. Ed., 1998, 37, 150. 166 J. Gil-Rubio, M. Laubender and H. Werner, Organometallics, 1998, 17, 1202. 167 U. Herber, E. Bluel, O. Gevert, M. Laubender and H. Werner, Organometallics, 1998, 17, 10. 168 M. J. Baena, M. L. Reyes, L. Rey, E. Carmona, M.C. Nicasio, P. J. Pe� rez, E. Gutie� rrez and A.Monze, Inorg. Chim. Acta, 1998, 273, 244. 169 J.-C. Choi, S. Sarai, T. Koizumi, K. Osakada and T. Yamamoto, Organometallics, 1998, 17, 2037. 170 V. F. Kuznetsov, G. P. A. Yap, C. Bensimon and H. Alper, Inorg. Chim. Acta, 1998, 280, 172. 171 S. N. Heaton, M.G. Partridge, R. N. Perutz, S. J. Parsons and F. Zimmermann, J. Chem. Soc., Dalton Trans., 1998, 2515. 172 P. Jutzi, M.So� te, B. Neumann and H.-G. Stammler, J. Organomet. Chem., 1998, 556, 97. 173 G. E. Herberich, H. J. Eckenrath and U. Englert, Organometallics, 1998, 17, 519. 174 J. V. Barkley, B. T. Heaton, C. Jacob, R. Mageswaran and J. T. Sampanthar, J. Chem. Soc., Dalton Trans., 1998, 697. 175 B. T. Heaton, C. Jacob and J. T. Sampanthar, J. Chem. Soc., Dalton Trans., 1998, 1403. 176 K. Osakada, T.Koizumi and T. Yamamoto, Angew. Chem., Int. Ed., 1998, 37, 349. 177 R. F. Dallinger, M.J. Carlson, V. M. Miskowski and H. B. Gray, Inorg. Chem., 1998, 37, 5011 178 T. Nishioka, K. Isobe, I. Kinoshita, Y. Ozawa, A. Va� squez de Miguel, T. Nakai and S. Miyajima, Organometallics, 1998, 17, 1637. 179 S. M. Contakes, K. K. Klausmeyer, R. M. Milberg, S. R. Wilson and T. B. Rauchfuss, Organometallics, 1998, 17, 3633. 180 J.-U. Rohde and W. Preetz, Z. Anorg. Allg. Chem., 1998, 624, 1319. 181 J. D’Olieslager, C. Go� rller-Walrand, K. Schoutens and B. Gilliams, Polyhedron, 1998, 17, 1773. 182 M. Brorson, F. Galsbol, K. Simonsen, L. K. Skov and I. Sotofte, Acta. Chem. Scand., 1998, 52, 1017. 183 A. C. Cooper, J. C. Hu§man and K. G. Caulton, Inorg. Chim. Acta, 1998, 270, 261. 184 D. P. Paterniti and J. D. Atwood, Polyhedron, 1998, 17, 1177. 185 M. V. Jime� nez, E. Sola, J. A. Lo� pez, F. J. Lahoz and L. A. Oro, Chem. Eur. J., 1998, 4, 1398. 186 Y.-C. Cheng, Y.-K. Chen, T.-M. Huang, C.-I. Yu, G.-H. Lee, Y. Wang and J.-T. Chen, Organometallics, 1998, 17, 2953. 187 H. Amouri, Y. Besace, J. Le Bras and J. Vaissermann, J. Am. Chem. Soc., 1998, 120, 6171. 188 J.C.M. Ritter and R. G. Bergman, J. Am. Chem. Soc., 1998, 120, 6826. 189 J. Le Bras, H. Amouri and J. Vaissermann, Organometallics, 1998, 17, 1116. 190 J. Le Bras, H. Amouri and J. Vaissermann, J. Organomet. Chem., 1998, 553, 483. 191 M. Heberhold, G.-X. Jin and A. L. Rheingold, J. Organomet. Chem., 1998, 570, 241. 192 C. Tejel, M. A. Ciriano, J. A. Lo� pez, F. J. Lahoz and L.A. Oro, Organometallics, 1998, 17, 1449. 193 R. della Pergola, A. Ceriotti, A. Cinquantini, F. Fabrizi di Biani, L. Garlaschelli, M. Manassero, R. Piacentini, M. Sansoni and P. Zanello, Organometallics, 1998, 17, 802. 194 M. Akita, T. Miyaji, S. Hikichi and Y. Moro-oka, Chem. Commun., 1998, 1005. 195 A. I. Stash, T. I. Perepelkova, S. V. Kravtsova, Yu. G. Noskov and I. P. Romm, Russ.J. Coord. Chem. (Transl. of Koord. Khim.), 1998, 24, 36. 196 W. H. Meyer, R. Bru� ll, H. G. Raubenheimer, C. Thompson and G. J. Kruger, J. Organomet. Chem., 1998, 553, 83. 197 M. Beller, T. H. Riermeier, W. Ma� gerlein, T. E. Mu� ller and W. Scherer, Polyhedron, 1998, 17, 1165. 198 M. Mizutani, K. Jitsukawa, H. Masuda, Y. Aoyama and H. Einaga, Chem. Lett., 1998, 663. Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 213–238 235199 G. Cervantes, V. Moreno, E. Molins and M. Quiro� s, Polyhedron, 1998, 17, 3343. 200 R. Ahlrichs, M. Ballau§, K. Eichkorn, O. Hanemann, G. Kettenbach and P. Klu� fers, Chem. Eur. J., 1998, 4, 835. 201 G. Exarchos, S. C. Nyburg and S. D. Robinson, Polyhedron, 1998, 17, 1257. 202 X. Chen, L. Zhu, C. Duan, Y. Liu and N. M. Kostic, Acta Crystallogr., Sect.C, 1998, 54 , 909. 203 K.-W. Kim and M. G. Kanatzidis, J. Am. Chem. Soc., 1998, 120, 8124. 204 E. C. Al31. 205 M. Cusumano, A. Giannetto and A. Imbalzano, Polyhedron, 1998, 17, 125 206 M. Fujita, S.-Y. Yu, T. Kusukawa, H. Funaki, K. Ogura and K. Yamaguchi, Angew. Chem., Int. Ed., 1998, 37, 2082. 207 L.R. Favello, S. Ferna� ndez, M. M. Garcia, R. Navarro and E. P. Urriolbeita, J. Chem. Soc., Dalton Trans., 1998, 3745. 208 S. Narayan, V. K. Jain and B. Varghese, J. Chem. Soc., Dalton Trans., 1998, 2359. 209 F. A. Cotton, J. Gu, C. A. Murillo and D. J. Timmons, J. Am. Chem. Soc., 1998, 120, 13 280. 210 C.M. Drain, F. Nifiatis, A. Vasenko and J. D. Batteas, Angew. Chem., Int. Ed., 1998, 37, 2344. 211 B. Olenyuk, A. Fechlenko� tter and P. J. Stang, J. Chem. Soc., Dalton Trans., 1998, 1707. 212 R. A. Stockland, G. K. Anderson and N. P. Rath, Inorg. Chim. Acta, 1998, 271, 236. 213 T. Murahashi, T. Otani, E. Mochizuki, Y. Kai, H. Kurosawa and S. Sakaki, J. Am. Chem. Soc., 1998, 120, 4536. 214 P. Leoni, G. Puri and M. Pasquali, J. Chem. Soc., Dalton Trans., 1998, 657. 215 S. Kannan, A. J. James and P. R. Sharp, J. Am. Chem. Soc., 1998, 120, 215. 216 M. Maekawa, M. Munakata, T. Kuroda-Sowa and Y. Suenaga, Anal. Sci., 1998, 14, 451. 217 A. J. Canty, H. Jin, B. W. Skelton and A. H. White, Inorg. Chem., 1998, 37, 3975. 218 (a) A. L. Casado and P. Espinet, Organometallics, 1998, 17, 3677; (b) A.L. Casado and P. Espinet, Organometallics, 1998, 17, 954. 219 J. H. Green, P. W. N. M. van Leeuwen and K. Vrieze, J. Chem. Soc., Dalton Trans., 1998, 113. 220 M. Maschiocchi, F. Ragaini, S. Cenini and A. Sironi, Organometallics, 1998, 17, 1052. 221 J. R. Hall, S. J. Loeb, G. K. H. Shimizu and G. P. A. Yap, Angew. Chem., Int. Ed., 1998, 37, 121. 222 S. Kacker, J. S. Kim and A. Sen, Angew. Chem., Int. Ed., 1998, 37, 1251. 223 D. L. Dubois, Comments Inorg.Chem., 1997, 19, 307. 224 U. Belluco, R. A. Michelin, M. Mozzon, R. Bertani, G. Facchin, L. Zanotto and L. Pandolfo, J. Organomet. Chem., 1998, 557, 37. 225 B. L. Shaw, S. D. Perera and E. A. Staley, Chem. Commun., 1998, 1361. 226 B. L. Shaw, New J. Chem., 1998, 22, 77. 227 Y. Tsuji, K. Nishiyama, S. Hori, M. Ebihara and T. Kawamura, Organometallics, 1998, 17, 507. 228 K.-R.Po� rschke, Chem. Commun., 1998, 1291. 229 H. Kunkely and A. Vogler, J. Organomet. Chem., 1998, 559, 223. 230 Y. Zhang, Z. Yuan and R. J. Puddephatt, Chem. Mater., 1998, 10, 2293. 231 N. T. Tram, M. Kawano, D. R. Powell and L. F. Dahl, J. Am. Chem. Soc., 1998, 120, 10 986. 232 J. Seemann and W. Preetz, Z. Anorg. Allg. Chem.,1998, 624, 179. 233 J. Seemann and W. Preetz, Z. Anorg.Allg. Chem., 1998, 624, 185. 234 J. Seemann and W. Preetz, Z. Naturforsch., Teil B, 1998, 53, 13. 235 W. Preetz and J.-G. Uttecht, Z. Naturforsch., Teil B, 1998, 53, 93. 236 M. S. Davies and T. W. Hambley, Inorg. Chem., 1998, 37, 5408. 237 J.-G. Uttecht and W. Preetz, Z. Naturforsch., Teil B, 1998, 53, 569. 238 D. Steinborn, O. Gravenhorst, H. Junicke and F. Heinemann, Z. Naturforsch., Teil B, 1998, 53, 581. 239 H. Junicke, C. Bruhn, D. Stro� hl, R. Kluge and D. Steinborn, Inorg. Chem., 1998, 37, 4603. 240 Yu. N. Kukushkin and Z. A. Khromenkova, Russ. J. Gen. Chem., 1997, 67, 1136. 241 A. N. Zhilyaev, S. B. Kaster, G. N. Kuznetsova and T. A. Fomina, Russ. J. Inorg. Chem. (Transl. of Zh. Neorg. Khim.), 1998, 37, 1137. 242 V. I. Korsunskii, I. G. Fomina and V.E. Abashkin, Russ. J. Coord. Chem. (Transl. of Koord. Khim.), 1998, 24, 114. 243 V. K. Jain and R. J. Butcher, Polyhedron, 1998, 17, 1317. 244 (a) C. Meiser, E. Freisinger and B. Lippert, J. Chem. Soc., Dalton Trans., 1998, 2059; (b) V. Etela� niemi, R. Serimaa, T. Laitalainen and T. Paakkari, J. Chem. Soc., Dalton Trans., 1998, 3001. 245 Y. Chen, Z. Guo, P. del S. Murdoch, E. Zang and P.J. Sadler, J. Chem. Soc., Dalton Trans., 1998, 1503. 246 A. Klein, S. Hasenzahl, W. Kaim and J. Fiedler, Organometallics, 1998, 17, 3532. 247 H. Hennig, K. Ritter, A. K. Chibisov, H. Go� rner, F.-W. Grevels, K. Kerpen and K. Scha§ner, Inorg. Chim. Acta, 1998, 271, 160. 248 J. J. Garcia, A. L. Casado, A. Iretskii, H. Adams and P. M. Maitlis, J. Organomet. Chem., 1998, 558, 189. 249 C. Bruhn, S. Becke and D. Steinborn, Acta Crystallogr., Sect. C, 1998, 54 , 1102. 250 J. Barkley, S. J. Higgins and M. K. McCart, J. Chem. Soc., Dalton Trans., 1998, 1787. 251 O. F. Wendt, A. Scodinu and L. I. Elding, Inorg. Chim. Acta, 1998, 277, 237. 252 S. S. Stahl, J. A. Labinger and J. E. Bercaw, Inorg. Chem., 1998, 37, 2422. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 213–238 236253 (a) H.Kunkely and A. Vogler, J. Organomet. Chem., 1998, 553, 517; (b) H. Donath, E. V. Avtomonov, I. Sarraje, K.-H. von Dahlen, M. El - Essawi, J. Lorberth and B.-S. Seo, J. Organomet. Chem., 1998, 559, 191. 254 C. R. Baar, G. S. Hill, J. J. Vittal and R. J. Puddephatt, Organometallics, 1998, 17, 32. 255 W. A. Howard and R. G. Bergman, Polyhedron, 1998, 17, 803. 256 J. Vicente, J.A. Abad, M.-T. Chicote, M.-D. Abrisqueta, J.-A. Lorca and M. C. Ram©¥¢¥ rez de Arellano, Organometallics, 1998, 17, 1564. 257 M. Gerisch, C. Bruhn, A. Vyater, J. A. Davies and D. Steinborn, Organometallics, 1998, 17, 310. 258 M. E. van der Boom, J. Ott and D. Milstein, Organometallics, 1998, 17, 4263. 259 D. L. Thorn, Organometallics, 1998, 17, 348. 260 M. A. Bennett, D.E. Berry, T. Dirnberger, D. C. R. Hockless and E. Wenger, J. Chem. Soc., Dalton Trans., 1998, 2367. 261 H. Bois, N. G. Connelly, J. G. Crossley, J.-C. Guillorit, G. R. Lewis, A. G. Orpen and P. Thornton, J. Chem. Soc., Dalton Trans., 1998, 2833. 262 L. R. Favello, J. Fornie¢¥ s, E. Lalinde, A. Martin, T. Moreno and J. Sacrista¢¥ n, Chem. Commun., 1998, 141. 263 M. A. Zhuravel, D.S. Glueck, M. Liable-Sands and A. L. Rheingold, Organometallics, 1998, 17, 574. 264 S. Okeya, Y. Kasuyama, K. Isobe, Y. Nakamura and S. Kawaguchi, J. Organomet. Chem., 1998, 551, 117. 265 F. P. Fanizzi, G. Natile, M. Lanfranchi, A. Tiripicchio and G. Pacchioni, Inorg. Chim. Acta, 1998, 275.276, 500. 266 M. A. Bennett, T. Dirnberger, D. C. R. Hockless, E. Wenger and A. C. Willis, J.Chem. Soc., Dalton Trans., 1998, 271. 267 J. H. Kim and S. I. Woo, Chem. Mater., 1998, 10, 3576. 268 R.M. Shaltout, R. Sygula, A. Sygula, F. R. Fronczek, G. G. Stanley and P. W. Rabideau, J. Am. Chem. Soc., 1998, 120, 835. 269 I. Blandford, J. C. Je¡×ery, H. Redfearn, L. H. Rees, M.D. Rudd and F. G. A. Stone, J. Chem. Soc., Dalton Trans., 1998, 1669. 270 K. Base and M. W.Grinsta¡×, Inorg. Chem., 1998, 37, 1432. 271 P. Kaur, A. Brownless, S. D. Perera, P. A. Cooke, T. Jellnek, J. D. Kennedy, B. S¢§t©¥¢¥ br and M. Thornton-Pett, J. Organomet. Chem., 1998, 558, 71. 272 A. Kerr, T. B. Marder, N. C. Norman, A. G. Orpen, M. J. Quayle, C. R. Rice, P. L. Timms and G. R. Whittell, Chem. Commun., 1998, 319. 273 J. D. Feldman, G. P. Mitchell, J.-O. Nolte and T.D. Tilley, J. Am. Chem. Soc., 1998, 120, 11 184. 274 K. E. Litz, M.M. Banaszak Hall, J. W. Kampf and G. B. Carpenter, Inorg. Chem., 1998, 37, 6461. 275 D. K. Wicht, S. N. Paisner, B. M. Lew, D. S. Glueck, G. P. A. Yapp, L. M. Liable-Sands, A. L. Rheingold, C.M. Haar and S. P. Nolan, Organometallics, 1998, 17, 652. 276 G. J. Leigh, C. E. McKenna and C. N. McMahon, Inorg. Chim. Acta, 1998, 280, 193. 277 P. D. Harvey, A. Eichho¡§ fer and D. Fenske, J. Chem. Soc., Dalton Trans., 1998, 3901. 278 S. Yamazaki, A. J. Deeming and D.M. Speel, Organometallics, 1998, 17, 775. 279 G.M. Lucier, J. M. Whalen and N. Bartlett, J. Fluorine Chem., 1998, 89, 101. 280 D. B. Dell¡�Amico, F. Calderazzo, F. Marchetti and S. Merlino, Chem. Mater., 1998, 10, 524. 281 M. Laguna, M. D. Villacampa, M. Contel and J. Garrido, Inorg. Chem., 1998, 37, 133. 282 S.-H. Yu, Z.-H. Han, J. Yang, R.-Y. Yang, Y. Xie and Y.-T. Qian, Chem. Lett., 1998, 1111. 283 L. S. Ahmed, J. R. Dilworth, J. R. Miller and N. Wheatley, Inorg. Chim. Acta, 1998, 278, 229. 284 W. Su, R. Cao, M. Hong, J. Chen and J. Lu, Chem. Commun., 1998, 1389. 285 M. Munakata, S. G. Yan, I. Ino, T. Kuroda-Sowa, M. Mackawa and Y. Suenaga, Inorg. Chim. Acta, 1998, 271, 145. 286 R. J. Anderson and P. J. Steel, Acta Crystallogr., Sect. C, 1998, 54 , 223. 287 Q. Zhang, R. Cao, M. Hong, W. Inorg. Chim. Acta, 1998, 277, 171. 288 D. Fenske, N. Zhu and T. Langetepe, Angew. Chem., Int. Ed., 1998, 37, 2640. 289 C. V. Krishnamohan Sharma, S. T. Gri¢Òn and R. D. Rogers, Chem. Commun., 1998, 215. 290 E. C. Constable, A. J. Edwards, G. R. Haire, M. J. Hannon and P. R. Raithby, Polyhedron, 1998, 17, 243. 291 G. Baum, E. C. Constable, D. Fenske, C. E. Housecroft and T. Kulke, Chem. Commun., 1998, 2659. 292 S. L. James, D.M. P. Mingos, A. J. P. White and D. J. Williams, Chem. Commun., 1998, 2323. 293 S.-M. Kuang, Z.-Z. Zhang, Q.-G. Wang and T. C. W. Mak, Chem. Commun., 1998, 581. 294 G.-C. Guo, Q.-G. Wang, G.-D. Zhou and T. C. W. Mak, Chem. Commun., 1998, 339. 295 G.-C. Guo, G.-D. Zhou, Q.-G. Wang and T. C. W. Mak, Angew. Chem., Int. Ed., 1998, 37, 630. 296 (a)M.A. Omany and H. H. Patterson, Inorg. Chem., 1998, 37, 1380; (b)M.A. Omany and H. H. Patterson, Inorg. Chem., 1998, 37, 1060. 297 P. B. Hitchcock, M. F. Lappert and J. L.-M. Pierssons, Organometallics, 1998, 17, 2686. 298 K. Chondroudis and K. G. Kanatzidis, Inorg. Chem., 1998, 37, 2848. 299 G.M. Lucier, C. Shen, S. H. Elder and N. Bartlett, Inorg. Chem., 1998, 37, 3829. 300 F. Canales, S. Canales, O. Crespo, M. C. Gimeno, P. G. Jones and A. Laguna, Organometallics, 1998, 17, 1617. 301 K. O. Klepp and C. Weithaler, J. Alloys Compd., 1998, 269, 92. 302 E. A. Axtell, J.-H. Liao and M. G. Kanatzidis, Inorg. Chem., 1998, 37, 5583. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 213.238 237303 J. A. Hanko and M.G. Kanatzidis, Chem. Commun., 1998, 725. 304 M. A. Mansour, W. B. Connick, R. L. Lachicotte, H. J. Gysling and R. Eisenberg, J. Am. Chem. Soc., 1998, 120, 1329. 305 P. F. Henry and M. T. Weller, Angew. Chem., Int. Ed., 1998, 37, 2855. 406 (a) M.C. Blanco, E. J. Ferna� ndez, P. G. Jones, A. Laguna, J. M. Lo� pez-de-Luzuriaga and M.E. Olmos, Angew. Chem., Int. Ed., 1998, 37, 3042; (b) R.E. Bachman and D. F. Andretta, Inorg. Chem., 1998, 37, 5657. 307 P. Braunstein, G. E. Herberich, M. Neuschu� tz, M.U. Schmidt, U. Englert, P. Lacante and A. Mosset, Organometallics, 1998, 17, 2177. 308 J. H. Telos, S. Brode and M. Chabanas, Angew. Chem., Int. Ed., 1998, 37, 1415. 309 J. Zank, A. Schier and H. Schmidbauer, J. Chem. Soc., Dalton Trans., 1998, 323. 310 M. Contel, J. Garrido, M.C. Gimeno and M. Laguna, J. Chem. Soc., Dalton Trans., 1998, 1083. 311 O.M. Abu-Salah, J. Organomet. Chem., 1998, 565, 211. 312 P. Schulte and U. Behrens, Chem. Commun., 1998, 1633. 313 T. J. Mathieson, A. G. Langdon, N. B. Milestone and B. K. Nicholson, Chem. Commun., 1998, 371. 314 H. Ecken, M.M. Olmstead, B. C. Noll, S. Attar, B. Schlyer and A. L. Balch, J. Chem. Soc., Dalton Trans., 1998, 3715. 315 G. A. Bowmaker, B. J. Kennedy and J. C. Reid, Inorg. Chem., 1998, 37, 3968. 316 H.-J. Haupt, D. Petters and U Flo� rke, J. Organomet. Chem., 1998, 553, 497. 317 J. Pethe, C. Maichle-Mo� ssmer and J. Stra� hle, Z. Anorg. Allg. Chem.,1998 , 624, 1207. 318 A. Burini, J. P. Fackler, R. Galassi, B. R. Pietroni and R. J. Staples, Chem. Commun., 1998, 95. 319 G. Schmid, J. Chem. Soc., Dalton Trans., 1998, 1077. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 213&n

ISSN:0260-1818    

DOI:10.1039/a805979i

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

16 Scandium, yttrium, the lanthanides and the actinides S. A. Cotton Uppingham School, Uppingham, Rutland, UK LE15 9QE 1 Introduction The available 1998 literature has been surveyed, together with late 1997 publications. A highlight is the discovery of the first dinitrogen complex of an actinide (Section 4.2). Another is the synthesis of 231Pu, the ‘missing’ isotope of plutonium.1 Attempts continue at the synthesis of elements 113 and 114 but so far without success.2 IUPAC has published their revised recommendations for the names of the transfermium elements.3 Molecular mechanics calculations have been applied to the extraction of lanthanides with organophosphates.4 Two new volumes of the Gmelin Handbook have appeared; one deals with the optical spectra of neodymium compounds, the other with alloys of uranium with transition metals of Groups 8–10.5,6 A volume on the organometallic chemistry of the lanthanides7 contains articles on general principles of organolanthanides,8a amides,8b complexes with heteroallylic ligands,8c monomeric alkoxides8d and metallocenes in homogeneous catalysis.8e More specifically, a review of the organometallic chemistry of the lanthanides and actinides for 1995 has appeared. 9 A review of ‘self-assembled’ rings and cages in organolanthanide chemistry has been published.10 A review on the lanthanide oxides has appeared.11 Structural aspects of lanthanide dipivaloylmethanides and their Lewis base adducts have been reviewed.12 A review on lanthanide amino acid complexes has appeared.13 Ternary and quaternary uranium and thorium chalcogenides have been reviewed.14 Interest grows in gadolinium-containing MRI agents, including Gadolite which is zeolite-based, used as a suspension for examination of the stomach and intestines (see also Section 3.7).15NMR biomedical applications of lanthanide(III) chelates have been reviewed.16 Reviews have appeared covering the co-ordination chemistry of scandium published in 199417a and 199517b and the co-ordination chemistry of yttrium for 1994,17c 199518 and 1996.19 An article has been published about the role of CeO 2 doped with ZrO 2 or lanthanide oxides in automobile exhaust complexes.20 A book on relativistic e§ects in chemistry includes a chapter on lanthanide and actinide compounds. 21 Kinetics of actinide complexation reactions have been reviewed.22 A review of sandwich-type phthalocyanine and porphyrin complexes includes a considerable number of lanthanide compounds.23 A short article on the bioinorganic chemistry of the actinides in blood has appeared.24 The proceedings of the 1994 Workshop on Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 239Actinide Solution Chemistry at Tokai, Japan includes material on both lanthanides and actinides.25 2 Scandium Laser-ablated Sc atoms react with O 2 in Ar matrices forming ScO, OScO (bent, 128°) and (O 2 )ScO with small amounts of ScOSc; on annealing, ScO 3 , (ScO) 2 and Sc(O 2 ) 2 also result.26 The new telluride Sc 8 Te 3 , isostructural with Y 8 Te 3 and Ti 8 Te 3 , has chains of trans-edge-sharing octahedra condensed into corrugated sheets.27 The new ternary phosphide ScNiP has Sc–Sc bonds.28 An X-ray and EXAFS study of aqueous solutions of scandium(III) salts indicates that around seven water molecules are bound to scandium, with a Sc–Odistance of 2.18Å, further indication that, compared with its transition metal successors, scandium does not form a hexaaqua ion.29 Thermal dehydration of ScCl 3 ·6H 2 O and various chloride complexes provided evidence for tetra- and di-hydrates, further heating being accompanied by hydrolysis.30 Reaction of lanthanide oxides with NH 4 Cl is a classic route to anhydrous lanthanide chlorides; DTA study of the reaction of Sc 2 O 3 with NH 4 Cl indicates that (NH 4 ) 3 ScCl 6 , (NH 4 ) 2 ScCl 5 (H 2 O) and (NH 4 ) 3 Sc 2 Cl 9 are formed as intermediates.31 A structural study of Ba 2 ScCl 7 shows it to be Ba 2 [ScCl 6 ]Cl.32 High-pressure studies of Na 3 ScF 6 (cryolite structure) indicate little change in the octahedral co-ordination of scandium up to 27.9 kbar.33 Cubic [Rb 3 Sc 2 (AsO 4 ) 3 ] is constructed of vertex-sharing ScO 6 and AsO 4 polyhedra.34 Sc 3 Ir 5 B 2 and quaternary derivatives Sc 2 MIr 5 B 2 (M\Be, Al, Si, Ti–Cu, Ga, Ge) have been synthesised.35 The new amide [ScMN(SiHMe 2 ) 2N3 (thf)] has distorted tetrahedral co-ordination of scandium, with short Sc · · · Si contacts in the solid state; this is in contrast to the five-co-ordinate [LnMN(SiHMe 2 ) 2N3 (thf) 2 ].36 A triamidoamine complex of scandium distils on heating the corresponding ‘ate’ complex [eqn. (1)].37 A mixture of scandium triflate and sodium dodecylsulfate catalyses three-component reactions of aldehydes, amines and allyltributylstannane in aqueous solution, giving good yields of homoallylic amines.38 Scandium triflate catalyses the Streckertype reactions of aldehydes, amines and tributyltin cyanide in both aqueous and organic solution; complete recovery of the tin compounds was achieved.39 In addition to the forest green triple-decker sandwich [(g5-Bu5 2 C 2 P 3 )Sc(l-g6:g6- Bu5 3 C 3 P 3 )Sc(g5-Bu5 2 C 2 P 3 )] described two years ago, co-condensation of Sc vapour with Me 3 CC–– –P also a§ords dark purple [Sc(g5-Bu5 3 C 3 P 2 ) 2 ] 1.It is the first stable scandocene complex to be characterised as well as being the first molecular scandium( II) compound. It is EPR active and has the expected magnetic characteristics for a d1 compound (k%&& \1.70 kB ).40 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 2403 Yttrium and the lanthanides 3.1 Binary and related compounds with non-metals The reaction of S 8 (g) with Ln` ions in a mass spectrometer a§ords a range of products, whose stoichiometry depends upon the lanthanide.41 Cerium reacts with 2- methoxyethanol at 250 °C forming ultrafine CeO 2 particles.42 Structures have been reported for the pentaphosphides MP 5 (M\Y,43a Dy,43b Ho,43b Tm,43c Lu43c).C-Type Ln 2 S 3 (Ln\Gd, Tb) have a cation-deficient Th 3 P 4 structure with eight-coordinate lanthanides.44 Ho 2 Se 3 , synthesised from HoSe 2~x and Ho using transport with AlCl 3 , has the Sc 2 S 3 structure.45 Rare earth transition metal borides such as Y 2 Co 14 B, LnCo 4 B and YCo 3 B 2 have been synthesised by Ca reduction of the rare earth oxide followed by di§usion of the lanthanide with the cobalt and boron at 1000 °C.This route is especially suitable for the borides of volatile lanthanides.46 3.2 Halides and complexes Rb 4 TmI 6 , synthesised by heating a mixture of RbI, Tm and HgI 2 , has the K 4 CdCl 6 structure with trigonal antiprismatic co-ordination of Tm.47 RbYbI 3 has a structure based on edge-sharing [YbI 6 ] octahedra.48 Gadolinium is eight-co-ordinate in BaGdCl 5 .49 Ba 2 [EuCl 7 ] is isostructural with Ba 2 [LnCl 7 ] (Ln\Gd–Lu, Y), but not with Ba 2 [ScCl 6 ]Cl, containing capped trigonal prismatic [EuCl 7 ]2~ ions.50 MCl 3 (M\Tb, Dy) react with [PPh 4 ]Cl in MeCN forming [PPh 4 ][MCl 4 (NCMe)] which contain dimeric [(MeCN)Cl 3 M(l-Cl) 2 MCl 3 (NCMe)]2~ anions.51 LaI 3 reacts withM (M\Cu, Ni) forming La 2 IM 2 , which have a new type of metal-rich layered structure. 52 3.3 Aqua-ions and salts Information from hydration studies of lanthanide- and actinide-(III) ions by laserinduced fluorescence spectroscopy has been combined with other techniques to indicate a change in hydration number from nine to eight in the Eu–Tb and Bk–Es regions of the series.53,54 EXAFS studies of aqua complexes and polyaminepolycarboxylate complexes have also been used to obtain co-ordination numbers.55 Interest continues in the anhydrous perchlorates.They exist in high- and low-temperature forms, both with nine-co-ordinate lanthanides.56 Stepwise thermal decomposition of several lan- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 241thanide triflates has been examined, with LnF 3 as the eventual product.57 Erbium is six-co-ordinate in Er 2 (SO 4 ) 3 , seven-co-ordinate in Er(SO 4 )(HSO 4 ) and eight-coordinate in Er(HSO 4 ) 3 .58 Other sulfate salts (H 5 O 2 )Ln(SO 4 ) 2 (Ln\Ho, Er, Y) contain lanthanides in dodecahedral co-ordination; on thermal decomposition [Ln(HSO 4 )(SO 4 )] and [Ln 2 (SO 4 ) 3 ] are successively formed.59 The oxamate [Ho(oxam) 3 (H 2 O) 3 ] 4 ·2.75H 2 O contains nine-co-ordinate holmium.60 [Ca(H 2 pic)(H 2 O) 3 ] [Ce(pic) 3 ] is a 1-D polymer with alternating CeN 3 O 6 and CaNO 7 polyhedra.61 Salts of 1-hydroxyethane-1,1-diphosphonic acid have been studied across the series.62 The heavier lanthanides (Tb–Lu, Y) are seven-co-ordinate, as in the chain structure of [Tb(H 3 hedp)(H 2 hedp)]·5H 2 O whilst lighter lanthanides are eightco- ordinate in [Nd(H 3 hedp)(H 2 hedp)]·7H 2 O and [H 3 O][Eu(H 2 hedp) 2 ]·12H 2 O. 3.4 Complexes The most comprehensive survey yet of complexes LnCl 3 (thf)x (e.g. x\2, 2.5, 3, 3.5, 4) has appeared. Structures have been determined for LnCl 3 (thf) 2 (Ln\La, Ce, Pr), LnCl 3 (thf) 3.5 (Ln\Gd, Er), YbCl 3 (thf) 3 and LaCl 3 (thf)(H 2 O).Most of these belong to known structural types, but LaCl 3 (thf) 2 represents a new type, a single-stranded polymer . . . (l-Cl) 3 (thf) 2 La(l-Cl) 3 . . . with cis thf molecules and square antiprismatic eight-co-ordinate lanthanum. Far-IR spectra of the complexes have been correlated with structural type.63 An independent report of the structure of ErCl 3 (thf) 3.5 showed64 it to be the expected salt [ErCl 2 (thf) 5 ][ErCl 4 (thf) 2 ]; the structure of [EuCl 3 (thf) 4 ] has been determined again.65 Two families of lactam complexes, [Ln(L1) 8 ][CF 3 SO 3 ] 3 (Ln\La–Eu, L1\e-caprolactam) and [Ln(L1) 7 ][CF 3 SO 3 ] 3 (Ln\Gd, Tb, Dy, Yb, Lu);66a [Ln(L2) 8 ][ReO 4 ] 3 (Ln\Pr, Nd, Sm and Eu, L2\d- valerolactam) and [Ln(L2) 7 ][ReO 4 ] 3 (Ln\Tb)66b whose stoichoiometries appear to reflect the lanthanide contraction have been synthesised.The cation in [Pr(L1) 8 ]- [CF 3 SO 3 ] 3 has slightly distorted dodecahedral geometry whilst in [Eu(L1) 8 ][ReO 4 ] 3 it is square antiprismatic. [Sm(NO 3 ) 3 (L3) 3 ] (L3\N-butylcaprolactam) contains samarium in a distorted tricapped trigonal prismatic environment.67 A number of lanthanide dithionate complexes have been studied.68 Nd 2 (S 2 O 6 ) 3 ·14H 2 O has each neodymium bound to six water molecules and to three oxygens from di§erent dithionates; in Nd 2 (S 2 O 6 ) 3 (OPPh 3 ) 4 ·8H 2 O, each neodymium is eight-co-ordinate, bound to two phosphine oxides, four water molecules and two dithionates (one monodentate, one a bridging ligand).Interest in lanthanide–transition metal heterometallics continues. [Ln 2 (dmf) 10MM(CN) 4N] = (Ln\Sm, Eu, Er, Yb; M\Ni, Pd, Pt), [Sm(dmf) 5MM(CN) 4NCl] = and [Yb(dma) 4MM(CN) 4NCl] = have 1-D chain structures where cyanide-bridged diamond-shaped Ln 2 M 2 cores are linked into infinite arrays through cyanide bridges by [M(CN) 4 ]2~ groups.69 Reaction of LnCl 3 and NiCl 2 with KNCO in dmf gives two di§erent complexes, depending upon crystallisation conditions.[Ln 2 (dmf) 6 Ni(NCO) 8 ] = (Ln\Sm, Eu) form 1-D extended arrays whilst [Ln 2 (dmf) 8 Ni(NCO) 8 ] are monomers with three bridging cyanates.70 The structure of [Gd(OSMe 2 ) 8 ][Fe(CN) 6 ] is reported.71 The 1,4-dioxane complex [Nd(C 4 H 8 O 2 )(NO 3 ) 3 (H 2 O) 2 ] contains zig-zag chains with bridging dioxanes.72 Ln(NO 3 ) 3 ·xH 2 O react with [Ni(en) 2 (NO 2 ) 2 ] in methanol forming [Ni(en) 2 (NO 2 )] 2 - [Ln(NO 3 ) 4 (MeOH) 2 ]NO 3 ·MeOH (Ln\La–Lu, Y) which contain chains of nickel ions with nitro–nitrito bridges and ten-co-ordinate lanthanides.73 LnI 2 (Ln\Sm, Yb) Annu. Rep.Prog. Chem., Sect.A, 1999, 95, 239–260 242reacts with substituted pyridines in thf forming [LnI 2 (py) 4 ]; the structures of [LnI 2 (3,5-dmpy) 4 ] (Ln\Sm, Yb) and [YbI 2 (4-Bu5py) 4 ] were determined, all have trans structures.74 [SmI 2 (thf) 2 ] recrystallises from py–dme as [SmI 2 (dme) 3 ], which occurs as two isomers in the same crystal;75 one has a linear I–Sm–I linkage, the other a bent I–Sm–I linkage.In contrast [but in keeping with the lower stability of Tm(II)] [TmI 2 (dme) 3 ] reacts with hmpa forming [TmI 3 (hmpa) 4 ]; this recrystallises from pyridine (depending on conditions) as [TmI 2 (hmpa) 4 ]I·5py or [TmI(py)(hmpa) 4 ]I 2 . Syntheses have been reported76 for MeCN complexes [Ln(NCMe)n]X 3 , as have the structures of [La(NCMe) 9 ][AsF 6 ] 3 ·MeCN, [Sm(NCMe) 9 ][AsF 6 ] 3 ·3MeCN, [Pr(NCMe) 9 ]- [AlCl 4 ] 3 ·MeCN and [Yb(NCMe) 8 ][AlCl 4 ] 3 .[Ce(phen) 4 (NCMe) 2 ][ClO 4 ] 3 ·3MeCN has ten-co-ordinate cerium in a bicapped square antiprismatic geometry.77 Solvothermal synthesis of [La(en) 4 Cl] In 2 Te 4 has been reported; the cation has monocapped square antiprismatic co-ordination.78 The 11-co-ordinate [Sm(terpy)(NO 3 ) 4 ]~ ion has been characterised79 as its [H 2 terpy]2` salt.Two reports show the tetradentate tripodal ligand ntb forming two strikingly di§erent types of complex. [Ln(ntb)(NO 3 ) 3 ]·H 2 O (Ln\La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Er) contains ten-co-ordinate monomers.80 With lanthanide perchlorates, the lanthanides bind two ntb ligands in a slightly distorted example of the rare cubic co-ordination geometry in [Ln(ntb) 2 ]3` ions (Ln\Pr, Eu) in 4,4@-bipyridyl adducts. 81 The complex [La(tbpa)(H 2 O)(g2-ClO 4 )][ClO 4 ] 2 ·MeOH contains ten-coordinate lanthanum.82 [Sm(OSCR) 3 (thf) 2 ] and [Na(thf) 4 ] [Sm(S 2 CR) 4 ] (R\4-MeC 6 H 4 ) are reported to be the first lanthanide chalcogenocarboxylate complexes.83 3.5 Diketonates A solid state synthesis has been reported84 for [Pr(acac) 3 ] from anhydrous PrCl 3 and Macac (M\Li, Na).Interest increases in glyme adducts of the lanthanide b-diketonates. La 2 O 3 and Hhfac react together with tetraglyme in hexane forming [La(hfac) 3MMe(OCH 2 CH 2 ) 4 OMeN] an air stable and volatile (95 °C, 10~4mmHg) potential MOCVD precursor.85 Similar compounds [La(hfac) 3 (MeOCH 2 CH 2 OMe)H 2 O], [La(hfac) 3MMe(OCH 2 CH 2 ) 2 OMeN] and [La(hfac) 3MMe(OCH 2 CH 2 ) 3 ] have also been prepared.86 A one-pot synthesis of [Eu(hfac) 3 L] (L\terpy, diglyme) from Eu 2 O 3 and Hhfac in the presence of L has been described,87a as has a one-step route87b to Ln(diketonate) 3 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 243(e.g. diketonate\acac, tfa, tmhd, etc.) via methyllanthanides prepared in situ from LaCl 3 and MeLi.[Y(hfac) 3 ] reacts with monoglyme and diglyme forming monomeric adducts [Y(hfac) 3 (MeOCH 2 CH 2 OMe)] which are eight- and nine-co-ordinate respectively. 88 In contrast, triglyme and tetraglyme form the ionic substances [Y(hfac) 2MMe(OCH 2 CH 2 )nOMe][Y(hfac) 4 ]. Sublimation of the compound where n\3 in the presence of ‘adventitious’ water yields the outer-sphere glyme complex [MY(hfac) 3 (OH 2 ) 2NMMe(OCH 2 CH 2 ) 3 OMeN] which has an infinite chain structure. [M(tmhd) 3 (H 2 O)] (M\Y, Gd) reacts with hmteta forming dimeric [(tmhd) 3 M(l- hmteta)M(tmhd) 3 ] in which only three of the four nitrogen atoms in the amine are bound to yttrium.89 The adducts [Eu(btfa) 3 (bipy)] and [Eu(bzac) 3 (bipy)] have been reported, as well as the structure of [Eu(btfa) 3 (bipy)]; the fluorinated compound shows a higher quantum yield in fluorescence.90 A new b-diketonate ligand, 1,3–bis(2–furyl)propane-1,3–dione, has been used to make the complex [Eu(dfp) 3 (phen)], a red emitter fabricated into a double layer electroluminescent device.91 The co-ordination geometry in [Ln(acac) 3 (phen)] (Ln\Ce, Pr) is described as slightly distorted square antiprismatic.92 [Eu(tan) 3 (bipy)] crystallises in two forms with slightly di§erent co-ordination polyhedra, one bicapped trigonal prismatic, the other square antiprismatic.93 Na[Er(pta) 4 ] contains tetragonally antiprismatic coordination of erbium.94 The co-ordination geometries in the air-stable potential CVD precursors [Ce(tmhd) 4 ] and [Ce(pmhd) 4 ] are distorted dodecahedral and square antiprismatic respectively; the former sublimes unchanged whilst the latter is involatile.95 On the other hand, [NH 4 ][Ce(etbd) 4 ], with distorted square antiprismatic co-ordination of Ce, was obtained under conditions expected to result in a Ce(IV) species.A number of binuclear tetraglyme complexes [Ce 2 (diketonate) 6MMe(OCH 2 CH 2 ) 4 OMeN] (diketonate\etbd; 1,1,1,5,5,5-hexa- fluoropentane-2,5-dionate; 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dionate) have also been made.96 EXAFS measurements on [Ln(hfac) 3 (H 2 O) 2 ] (Ln\Pr, Eu) indicate a co-ordination number of about 11, suggesting that some Ln · · ·F interactions are present.97 Lanthanide b-diketonates of fluorinated ligands form 1: 1 complexes with amino acids, enabling their extraction, transport and chiral recognition.98 Heterobimetallic compounds have been studied lately on account of their structures and magnetic properties.They are also potential MOCVD single-source precursors. The series [Ni(salen)La(hfa) 3 ] (Ln\Y, La–Yb) which have similar structures to several of the known [Cu(salen)La(hfa) 3 ] compounds sublime without decomposition in vacuo.99 3.6 Alkoxides, alkylamides, phosphides and thiolates Alcohol exchange between [Ce 2 (OPr*) 8 (Pr*OH) 2 ] and Hhfip a§ords [Ce(hfip) 4 (thf) 2 (Pr*OH)x], convertible into the stable adducts [Ce(hfip) 4 L 2 ] (L 2 \bipy; tmen; diglyme).Reaction with pmdien results in [Ce(hfip) 3 (OPr*)(pmdien)] and [Hpmdien] 2 [Ce(hfip) 6 ], the latter having octahedrally co-ordinated Ce.100 [Ce 2 (OPr*) 8 (Pr*OH) 2 ] reacts with Hthd and barium isopropoxide forming [Ba 4 Ce 2 (l6 -O)(thd) 4 (l3 -OPr*) 8 (OPr*) 2 ].101 Eu reacts with 2-methoxyethanol102 forming the hydrocarbon-soluble oligomer [Eu(OCH 2 CH 2 OMe) 2 ]n (n[10 in toluene).This reacts with 2,6-dimethylphenol or 2,6–diisopropylphenol forming the tetrametallic H 4 [MEu(l3 -g2-OCH 2 CH 2 OMe)(g2-OCH 2 CH 2 OMe)(OC 6 H 3 R 2 - Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 2442,6)N4 ] (R\Me, Pr*). These have a tetrahedron of seven-co-ordinate europium atoms, each bound to one terminal bidentate alkoxide, one bridging bidentate alkoxide, a terminal aryloxide and two bridging oxygens from other aryloxides. [Eu(OCH 2 CH 2 OMe) 2 ]n reacts with AlMe 3 forming the hexametallic [MMe 3 Al(l-g2- OCH 2 CH 2 OMe)Eu(l-g2-OCH 2 CH 2 OMe) 2 (AlMe 2 )N2 ].[LnMN(SiMe 3 ) 2N3 ] (Ln\La, Sm, Y) have been studied as highly active catalysts for the Tischenko reaction, dimerizing aldehydes to esters, e.g. converting benzaldehyde to benzyl benzoate.103 The amides [LnMN(SiHMe 2 ) 2N3 (thf) 2 ] (Ln\Y, La–Lu) are isostructural, with trigonal bipyramidal co-ordination; structures have now been determined for the La and Lu compounds, in addition to the Nd and Y analogues previously reported.36 Polynuclear lanthanide amides including [Ln 2 Br 4 (l- NHPh) 2 (thf) 5 ] (Ln\Sm, Gd) and [Ln 4 (l4 -O)(NHPh) 3 (OSiMe 2 NPh) 6 Na 5 (thf) 7 ]·thf (Ln\Gd, Yb) have been reported.104 The structure of trans- [Eu(PPh 2 ) 2 (meim) 4 ] has been determined.105 The N-substituted guanidinates [MMCyNC[N(SiMe 3 ) 2 ]- NCyN2 (l-Cl) 2 LiS 2 ] (M\Sm, Yb: S\Et 2 O, 0.5 tmen) have been synthesised and o§er a route to solvent-free alkyls and amides, of which [SmMCyNC[N(SiMe 3 ) 2 ]- NCyN2MCH(SiMe 3 ) 2N] and [YbMCyNC[N(SiMe 3 ) 2 ]NCyN2MN(SiMe 3 ) 2N] have been characterised.106 The first Ln(II) pyrazolate, [Yb(Ph 2 pz) 2 (dme) 2 ] has two chelating dimethoxyethane ligands and two g2 3,5-diphenylpyrazolates.107 [YMCH(SiMe 3 ) 2N3 ] reacts with HP(SiMe 3 ) 2 forming the dimeric [M(Me 3 Si) 2 PN2 YMl-[P(SiMe 3 ) 2 ] 2N- YMP(SiMe 3 ) 2N2 ].108 [Ln(SBu5) 3 ] (Ln\La, Ce, Pr, Nd, Eu, Yb, Y), made109 from [LnMN(SiMe 3 ) 2N3 ] and HSBu5, are intensively reactive, doubtless owing to co-ordinative unsaturation, and the adducts [(SBu5) 2 (bipy)Ln(l-SBu5) 2 Ln(bipy)(SBu5) 2 ] (Ln\Y, Yb) have been isolated.A series of thiophenolates and their selenium analogues have been synthesised110 and examined. [Ln(SPh) 3 (py) 3 ] 2 (Ln\Ho, Tm) have two thiolate bridges with sevenco- ordinate lanthanides; [Sm(SPh) 3 (py) 2 ] 4 has a linear arrangement of four seven-coordinate samariums with 3, 2 and 3 l-bridging thiolates; [Sm(SPh) 3 (thf)] 4n is a polymer. [Ln(SePh) 3 (thf) 3 ] (Ln\Tm, Ho, Er) have monomeric fac octahedral structures; [Sm(SePh) 3 (py) 3 ] 2 has two selenolate bridges with seven-co-ordinate samarium; and [Ln 3 (SePh) 9 (thf) 4 ]n (La\Pr, Nd, Sm) are polymeric with three doubly bridging selenolates.thf solutions of thiolates [Ln(SPh) 3 ] (Ln\Pr, Nd, Gd) dissolve sulfur, a§ording crystalline clusters [Ln 8 S 6 (SPh) 12 (thf) 8 ]; their structure is based on a cube of lanthanides, edge-bridged by mercaptides and face-bridged by sulfur.111 Clusters are also found in [Yb 4 Se 4 (SePh) 4 (py) 8 ] and in [Yb 6 S 6 (SPh) 6 (py) 10 ].112 A number of pyridinethiolate (2-SNC 5 H 4 ) complexes have been characterised.113 Ce(SNC 5 H 4 ) 3 reacts with [PEt 4 ][SNC 5 H 4 ] forming [PEt 4 ][Ce(SNC 5 H 4 ) 4 ], in which cerium is eight-co-ordinate; [PEt 4 ][Ln(SNC 5 H 4 ) 4 ] (Ln\Ho, Tm) were also reported.[Yb(SNC 5 H 4 ) 2 ] and [Yb(SNC 5 H 4 ) 3 ] crystallise from pyridine as seven-co-ordinate [Yb(SNC 5 H 4 ) 2 (py) 3 ] and eight-co-ordinate [Yb(SNC 5 H 4 ) 3 (py) 2 ] respectively. 3.7 Complexes of polyamine polycarboxylates, related complexes and NMR imaging agents The Eu(II) complex Na 3 [Eu(edta)]Cl·7H 2 O is in fact polymeric in the solid state with europium bound to two nitrogens and six carboxylate oxygens.114 A XAFS study of [Gd(dota)(H 2 O)]~ and [Gd(dtpa)(H 2 O)]2~ in the solid state and solution permits Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 245comparison with existing solid-state di§raction data.115 When binding to Gd3`, the tripodal ligand H 6 ttaha has one leg free, acting as a heptadentate ligand; two water molecules also co-ordinate, giving it a high relaxivity compared to many MRI agents.116 A new neutral potential MRI contrast agent, [Gd(dtpa-bmea)(H 2 O)] has very similar properties to the existing [Gd(dtpa-bma)(H 2 O)].117 Spin–lattice relaxation data for the Gd3` complex of 3,6,10-tris(carboxymethyl)- 3,6,10-triazadodecanedioic acid (see below) indicate that there is probably one water molecule co-ordinated.118 The solid state structure of [Gd(dtma)(H 2 O)]3` is a capped square antiprism.119 In solution the complex has only limited stability (logK\12.8). In the solid state, [La(pedta)(H 2 O)]·2H 2 O adopts a polymeric structure, giving ten-co-ordinate La; in solution, luminescence results for the Eu complex indicate three co-ordinated water molecules.120 The stability constants of [Ce(dota)]~ and [Yb(dota)]~ are reported as 1024.6 and 1026.4 respectively.121 Complexes [Ln(hedtra)(H 2 O)n] (Ln\most lanthanides) fall into three series; [M(hedtra)(H 2 O) 2 ]· 3H 2 O (M\Ho, Tm) have eight-co-ordinate square antiprismatic co-ordination in which the acid is co-ordinating through the hydroxo oxygen in addition to the two nitrogens and three carboxylate oxygen atoms.122 3.8 Some applications of lanthanides in organic chemistry The application of lanthanide metallocenes to the synthesis of small organic molecules has been reviewed123 as has SmI 2 as a reagent in polymer chemistry.124 Solutions of SmI 2 in tetrahydropyran reduce allylic, benzylic and alkyl halides forming stable Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 246organosamarium species.125 The e§ects of co-solvents upon the reducing power of SmI 2 in thf has been discussed.126 SmI 2 catalyses the reductive intramolecular cyclisation of a-bromo silyl ethers.127 Lanthanide triflates catalyse the highly stereoselective addition of chiral 3-(p-tolylsulfinyl)furfural with silyl ketene acetal128 whilst ytterbium triflate catalyses the addition of trimethylsilyl cyanide to many carbonyl compounds in high yield under mild conditions.129 [Sm(O 3 SCF 3 ) 2 (thf) 1.5 ] has a 1-D polymeric structure in the solid state; [Sm(O 3 SCF 3 ) 2 (NCMe) 1.5 ] and [Sm(O 3 SCF 3 ) 2 (NCBu5) 1.5 ] have similarly been prepared, the former being an excellent reagent for pinacol coupling reactions.130 Cerium(IV) ammonium nitrate and cerium(IV) sulfate act as oxidants in coupling reactions producing a-linked hexadecithiophene and tetracosithiophene derivatives.131 3.9 Poly(pyrazolyl)borates and related compounds [SmCl(HBpz 3 )L] (L\Hpz, N-methylpyrazol-1-yl) react with sodium b-diketonates forming [Sm(HBpz 3 )(acac)], [Sm(HBpz 3 )(tfac)] and [Sm(HBpz 3 )(hfac)].[SmCl(HBpz 3 )(Hpz)] reacts with K[H 2 Bpz 2 ] forming the bicapped trigonal prismatic [SmCl(HBpz 3 )(H 2 Bpz 2 )] whilst [SmCl(HBpz 3 )(Hpz)] is square-antiprismatic.132 3.10 Complexes of crown ethers and related ligands Lanthanides are nine-co-ordinate in [LnL 3 ][ClO 4 ] 3 ·3H 2 O (Ln\Nd, Ho; L\diethylene glycol).133 Complexes of lanthanide triflates with polyethene glycol MHO(CH 2 CH 2 O)nH; n\2,3,4N and polyethene glycol dimethyl ether MMeO(CH 2 CH 2 O)nMe; n\2,3,4N are e§ective Lewis acid catalysts for the Diels–Alder reaction and for the allylation of aldehydes with allyltributyltin.Structures have been reported for [La(OTf) 3 (thf)MHO(CH 2 CH 2 O) 4 HN],134a [Dy(OTf) 2MMeO(CH 2 CH 2 O) 4 MeN(H 2 O) 2 ][OTf]134a and [Eu(OTf) 3MMeO- (CHPhCHPhCH 2 (OCH 2 CH 2 ) 2 OCHPhCHPhOMeN].134b 2,2@-Bipyridyl complexes of Eu3` and Tb3` bound to polyethene glycol are strongly luminescent.135 The out-of-cavity hydroxide-bridged cationic complex [MY(OH)(benzo-15-crown- 5)(NCMe)N2 ]I 4 results from the reaction of YI 3 with the crown ether in MeCN.136 Yttrium is not bound to the crown ether in [Y(NO 3 ) 3 (H 2 O) 3 ]·Me 2 -16-crown- 5·H 2 O137 nor in [Yb(H 2 O) 8 ]Cl 3 ·15-crown-5.138 New oxonium complexes [H 9 O 4 ]- [LaCl 2 (H 2 O)(18-crown-6)]Cl 2 and [H 3 O][EuCl(H 2 O) 2 (18-crown-6)]Cl 2 have been reported.138 3.11 Complexes of macrocyclic ligands, particularly calixarenes, porphyrins and phthalocyanines p-Butylcalix[5]arene (H 5 L) forms dimeric lanthanide complexes [Ln 2 (H 2 L) 2 (dmso) 2 ] (Ln\Eu, Gd, Tb).139 The larger p-butylcalix[8]arene and p-nitrocalix[8]arene(H 8 L) rings each incorporate two lanthanides, forming [Ln 2 (H 2 L)(dmf) 5 ] (Ln\Eu, Lu).The structures of europium complexes of both p-butylcalix[5]arene and p-nitrocalix[8]- arene contain eight-co-ordinate europium.140 Calix[4]arenes substituted by acetamidophosphine oxide groups at the rim show selectivity, not just to trivalent ions but Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 247also to light lanthanides and actinides.141 Calix[4]arene podands and barrelands incorporating bipy groups form lanthanide complexes; their Eu3` and Tb3` complexes have high metal luminescence quantum yields.142 New routes have been described to unsymmetrical [Ln(pc)(pc@)] and [Ln(pc)(por)] systems.143 Heteroleptic triple deckers [Eu 2 (pc) 2 (por)] and [Eu 2 (pc)(por) 2 ] have also been synthesised.144 Syntheses of lipophilic lanthanide(III) bis(tetrapyridylporphyrinates) and their conversion into water-soluble N-methylated systems are reported.145 Gadolinium is eightco- ordinate in [Gd(tpp)(acac)(H 2 O) 2 ]·6H 2 O·3tcb.146 Remarkably, porphyrinogen complexes of neodymium and praseodymium fixN 2 and reduce it to theN 2 2~ anion in dimeric l-N 2 complexes.147 Two texaphyrin complexes are undergoing clinical trials; a gadolinium compound 2 is an e§ective radiation sensitiser for tumour cells, whilst the corresponding lutetium compound that absorbs light in the far-red end of the visible spectrum is in Phase II trials for photodynamic therapy for brain tumours and breast cancer.148 Europium complexes with a pendant-arm cyclen-based ligand in two stages, first by forming an external complex prior to encapsulation.149 3.12 Some spectroscopic studies A review of developments in luminescent materials for lighting and displays features rare earths prominently.150 Other reviews cover applications of lanthanide luminescence spectroscopy to solution studies151 and the luminescent properties of divalent europium complexes of crown ethers and cryptands.152 Another article details the synthesis and luminescence of lanthanide ions in nanoscale insulating hosts.153 Timeresolved chiroptical luminescence studies of mixtures of the enantiomers of [Eu(dipic) 2 ]3~ show solvent dependence in the rate of interconversion between the enantiomers.154 The solution luminescence spectra of 13 Eu(III) chelates have been examined155 and considerable variation in the 7F 0 ]5F 0 excitation spectra observed, depending upon the denticity of the ligand and the number and nature of co-ordinated nitrogen atoms.With additional information from excited-state lifetimes, solution structures were evaluated.Although it cannot be isolated in a pure state, a 1: 3 Eu(III) Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 248complex with diethylpyridine-2,6-dicarboxylate exhibits a very high quantum yield in CH 3 CN solution.156 Europium(III) complexes of calix[4]arenes incorporating bipyridine-N,N@-dioxide ligands have very high absorption coe¶cients and high luminescence quantum yields.157 Europium complexes of diphthalimidodiethylamine exhibit temperatureindependent luminescence.158 [1,4-dmpyH][Eu(ttfa) 4 ] exhibits triboluminescence (i.e.luminescence under pressure); europium has square antiprismatic co-ordination.159 [Eu(ttfa) 3 (phen)] is also triboluminescent.160 Sr 2 CeO 4 contains 1-D chains of CeO 6 octahedra. It exhibits blue-white emission at 485nm with a quantum yield of 0.48 owing to luminescence from a ligand-to-metal Ce4` charge transfer.161 3.13 Organometallics The three-co-ordinate r-alkyl [YMCH(SiMe 3 ) 2N3 ] is pyramidal in the solid state.108 Other new alkyls [LnMCH(SiMe 3 ) 2N3 ] (Ln\Pr, Nd) have been synthesised and their single-crystal absorption spectra recorded, along with those of [SmMCH- (SiMe 3 ) 2N3 ].162 Ligand-field splittings are similar to those in the analogous threeco- ordinate silylamides and aryloxides.The structure of the thermally unstable methyl-bridged compound [NdM(l-CH 3 ) 2 Al(CH 3 ) 2N3 ]·0.5[Al 2 (CH 3 ) 6 ] has been determined by neutron di§raction at 100 K. Hydrogens were located and a ‘tipped’ trigonal bipyramidal geometry at the bridging carbons characterised.163 The allyl [La(diox) 1.5 (g3-C 3 H 5 ) 3 ] reacts with various ligands forming adducts [LaL(g3-C 3 - H 5 ) 3 ] (L\dme, tmed, 2hmpa).164 [Ln(g3-C 3 H 5 )Cp* 2 ] react with [NHEt 3 ][BPh 4 ] to form [Ln(BPh 4 )Cp* 2 ] (Ln\Sm, Nd, Tm); in the solid state, the Sm compound has a bent SmCp* 2 unit that is also bound to two of the phenyl groups.165 This reacts with LiCH(SiMe 3 ) 2 to form [SmMCH(SiMe 3 ) 2NCp* 2 ] in high yield.[Nd(BPh 4 )Cp* 2 ] reacts with KCp* to form [NdCp* 3 ], another of the previously inaccessible LnCp* 3 systems. This reaction o§ers the hope of preparing more of these rare compounds, for the earlier lanthanides at least. Another route to cationic base-free ‘[LnCp* 2 ]`’ systems, albeit restricted to those lanthanides with an accessible divalent state, involves the oxidation of [LnMC 5 H 3 (SiMe 3 ) 2 -1,3N2 ] (Ln\Sm, Yb) by AgY (Y\CB 11 Br 6 H 6 , BPh 4 ) forming [LnMC 5 H 3 (SiMe 3 ) 2 -1,3N2 ]Y.A more general route, involving halide abstraction rather than electron transfer (Ln\Sm, Er, Yb), is shown in eqn. (2).[MLn[C 5 H 3 (SiMe 3 ) 2 -1,3] 2 IN2 ]]2AgY]2[LnMC 5 H 3 (SiMe 3 ) 2 -1,3N2 ]Y]2AgI (2) The [CB 11 Br 6 H 6 ]~ salts are more reactive; on recrystallisation from thf, ring-opening occurs, whilst [ErMC 5 H 3 (SiMe 3 ) 2 -1,3N2 ]` will abstract bromine from [CB 11 Br 6 H 6 ]~ or chlorine from CH 2 Cl 2 to form [MErX[C 5 H 3 (SiMe 3 ) 2 -1,3] 2N2 ] (X\Cl, Br). Structures are reported for the adducts [Sm(dme)MC 5 H 3 (SiMe 3 ) 2 -1,3N2 ][BPh 4 ], [Sm(thf) 2MC 5 H 3 (SiMe 3 ) 2 -1,3N2 ][CB 11 Br 6 H 6 ], [Er(thf) 2MC 5 H 3 (SiMe 3 ) 2 -1,3N2 ]- [CB 11 Br 6 H 6 ] and [MErBr[C 5 H 3 (SiMe 3 ) 2 -1,3) 2N2 ].166 A crown ether causes a displacement reaction167 when added to [LnMC 5 H 3 (SiMe 3 ) 2 -1,3N2 ] (Ln\Sm, Yb); the products are the salts [Sm(18-crown- 6)MC 5 H 3 (SiMe 3 ) 2 -1,3N][SmMC 5 H 3 (SiMe 3 ) 2 -1,3) 3 ] and [Yb(18-crown- 6)MC 5 H 3 (SiMe 3 ) 2 -1,3N][MC 5 H 3 (SiMe 3 ) 2 -1,3) 3 ].The [SmMC 5 H 3 (SiMe 3 ) 2 -1,3N3 ]~ ion, has also been isolated as the [K(18-crown-6)(g2-PhMe) 2 ]` salt. [YbMC 5 H 3 (Bu5) 2 - Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 2491,3N2 ] and its mono-adducts with Et 2 Oand dme have been synthesized, the latter both having the expected bent sandwich structures.168 The alkyls [(C 5 H 4 Bu5) 2 Ln(l- Me) 2 Ln(C 5 H 4 Bu5) 2 ] (Ln\Nd, Sm) have been synthesised; the corresponding hydrides cannot be isolated, though the samarium compound can be observed in solution.169 Hydrogenolysis of alkyls [NdR(C 5 H 4 CH 2 CH 2 OMe) 2 ] a§ords a transient [NdH(C 5 H 4 CH 2 CH 2 OMe) 2 ] which rearranges into [Nd(C 5 H 4 CH 2 CH 2 OMe) 3 ].The pentamethylcyclopentadienyl ligand has been responsible for many of the advances in f-block organometallic chemistry. Now two papers have been concerned with complexes of the tetramethylisopropylcyclopentadienyl analogue. Syntheses and structures are reported170 for [Sm(thf)(C 5 Me 4 Pr*) 2 ] and [(C 5 Me 4 Pr*) 2 Sm(l- Cl)Sm(C 5 Me 4 Pr*) 2 ].LnCl 3 (Ln\Y, Sm, Lu) react with two moles of NaC 5 Me 4 Pr* in thf forming [Ln(thf)Cl(C 5 Me 4 Pr*) 2 ] which can be alkylated to yield [Ln(thf)Me(C 5 Me 4 Pr*) 2 ] and [Ln(thf)MCH(SiMe 3 ) 2N(C 5 Me 4 Pr*) 2 ] which are e§ective precatalysts for the hydrosilylation of alkenes and alkynes. Structures of [Lu(thf)Me(C 5 Me 4 Pr*) 2 ] and [Lu(thf)Cl(C 5 Me 4 Pr*) 2 ] were reported.171 The alkyls [LnMCH(SiMe 3 ) 2NCp* 2 ] (Ln\La, Sm, Y, Lu) catalyse the hydroamination/cyclisation of aminoallenes.172 Treatment of [Sm(thf) 3 Cl 2 Cp] with hot toluene, followed by removal of the thf by distillation yields173 [SmCl 2 Cp]·0.16C 6 H 5 Me; this is in fact a cluster, [Sm 12 Cl 24 Cp 12 ], containing an icosahedron of samarium atoms.The similarly prepared [YbCl 2 Cp]·0.33thf·0.22toluene is [Yb 3 (thf) 3 Cl 5 Cp 3 ][Yb 6 Cl 13 Cp 6 ].[Yb(dme)Cp 2 ] reacts with perfluorodecalin or with perfluoromethylcyclohexane forming [MYb(thf)FCp 2N2 ], the first example of C–F activation of a saturated perfluoro compound by a lanthanide organometallic.174 A number of adducts of [Ln(OPR 3 )Cp 3 ] (Ln\La, Nd, Sm, Yb; R\Ph, o-tolyl, Bu/, etc.) have been synthesised and the structures of [Yb(OPR 3 )Cp 3 ] and [Nd(OPR 3 )Cp 3 ] determined; the former is tetrahedral and the latter has a geometry more typical of TBPY co-ordination. 175 [MLn(g-C 5 H 4 Me) 3N4 ] (Ln\Pr) has a structure similar to its Ln\La, Ce, Nd analogues.176 LnCl 3 reacts with excess Na[1,3-(Me 3 Si) 2 C 5 H 3 ] forming two series of complexes, [LnMg5-(Me 3 Si) 2 C 5 H 3N3 ] (Ln\La, Sm, Nd, Gd, Dy) (whose structures show pseudo-trigonal co-ordination of the lanthanide) and [MLnCl[(Me 3 Si) 2 C 5 H 3 ]N2 ] (Ln\Gd, Dy, Er, Y, Yb).177 Syntheses and structures are reported178 for the ytterbium(II) p-arene complexes [Yb(AlCl 4 ) 2 (g6-C 6 H 6 )]·C 6 H 6 , [Yb(AlCl 4 ) 2 (g6-C 6 H 3 Me 3 )] and Na[Yb 2 (AlCl 4 ) 5 (g6- C 6 H 6 )].The samarium(II) complexes [SmM(g6-C 6 H 5 Me)Sm(AlCl 4 ) 3N2 ], [Sm(AlCl 4 ) 2 ], [Sm(AlCl 4 ) 2 (g6-C 6 H 6 )], [Sm(AlCl 4 ) 2 (g6-C 6 H 3 Me 3 )], Na[Sm(AlCl 4 ) 3 (g6-C 6 H 6 )] and Na[Sm(AlCl 4 ) 3 (g6-C 6 H 3 Me 3 )] have been synthesised.179 Structures have been reported for [Pr(thf)Cl(ind) 2 ]180 and [Ln(thf)(ind) 3 ] (Ln\La,180,181 Pr,181 Nd,181 Sm181).This year there are numerous reports on (cot) complexes.[Nd(thf) 3 (BH 4 ) 3 ] reacts with K 2 cot forming [MNd(thf)(BH 4 )(cotN] 2 ]; with [NHEt 3 ][BPh 4 ], this a§ords the novel cationic [Nd(thf) 4 (BH 4 )(cot)][BPh 4 ]. Both of these react with KCp* yielding [Nd(thf)Cp*(cot)].182MO calculations on [Ln(cot) 2 ] and [Ln(cot) 2 ]~ (Ln\Ce, Nd, Tb, Yb) suggest that the neutral complexes are best regarded as Ln(III) systems.183 Compounds [Lnn(cot)m] [(n,m\(n, n]1) for n\1–5)] produced by laser vaporisation and molecular beam methods probably have multiple decker sandwich structures. 184 The anion in [Li(thf) 4 ][Sm(cot) 2 ] has a sandwich structure.185 [MSm(l-I)- (thf) 2 (C 5 Me 4 R)N2 ] reacts with K 2 cot forming [MSm(thf) 2 (C 5 Me 4 R)N2 (l-g8: 8-cot)] Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 250(R\Me, Et); [MSm[Me(OCH 2 CH 2 ) 2 OMe](C 5 Me 5 )N2 (l-g8: g8-cot)] has a bent triple-decker structure,186 as do the unsolvated compounds [MSm(C 5 Me 4 R)N2 (l- g8:g8-cot)] (R\Me, Et).Samarium reacts with C 8 H 8 in the presence of RSSR187 (R\2-pyridyl, 2,4,6-triisopropylphenyl) to form [Sm(thf) 0.5 (RS)(cot)], [Sm(hmpa) 2 (RS)(cot)] (four-legged piano stool structure when R\2-pyridyl) and [Sm(hmpa) 2 (RS)(cot)] (three-legged piano stool structure when R\2,4,6-triisopropylphenyl).Other triple deckers,188 as yet uncharacterised structurally, are [Ln 2MC 8 H 6 (SiMe 3 ) 2 -1,4N3 ]. Samarium reacts with C 8 H 8 and I 2 in thf to form [Sm(thf)I(cot)] which a§ords [Sm(hmpa) 3 (cot)] I when treated with excess hmpa.189 With a catalytic amount of iodine, La and Sm react with C 8 H 8 in the presence of hmpa to form [La(hmpa) 4 (cot)]- [La(cot) 2 ] and [Sm(hmpa) 3 (cot)][Sm(cot) 2 ], the latter structure confirmed by X-ray di§raction.Room- and low-temperature absorption spectra are reported for [Ln(thf) 3 I(cot)] (Ln\Pr, Nd, Sm).190 A novel compound 3 is the first complex of the pyrene trianion. [Cp*ClLa(l-Cl) 2 Li(thf) 2 ] reacts with pyrene and potassium to form [(LaClCp*) 3 (C 16 H 10 )(thf)].This contains two lanthanums g6-bonded to two of the rings; the third lanthanum is g2 bound to one of the middle rings, though it additionally co-ordinates a thf molecule.191 4 Actinides 4.1 Binary compounds and complexes An earlier claim for the existence of the Th3`(aq) ion has been questioned.192 SrTh 2 Se 5 has a structure based on U 3 S 5 whilst semiconducting SrTh 2 Te 6 contains layers of 2 = [Th 2 Te 6 ~] double chains joined by Cu` ions.193 A synchrotron X-ray di§raction study of [Th(S 2 PMe 2 ) 4 ] indicates the bonding is largely ionic with some 5d-like involvement,194 in contradistinction to some ab initio calculations, suggesting that these may overestimate the covalent nature of actinide bonding.Another application of the useful synthon [UI 3 (thf) 4 ] lies in the synthesis of a rare U(III) complex of an amine ligand, [U(tbpa)I 2 ]I·py, which has nine-co-ordinate uranium.82 Syntheses are reported of new chlorouranate(III) complexes SrUCl 5 ,195 Ba 2 UCl 7 ,195 CsUCl 4 ,196 and Cs 2 LiUCl 6 ,196 the last having the elpasolite structure.UCl 4 and certain phases (KCl)x(UCl 4 )y are selectively deposited inside carbon nanotubes by capillary action. 197 The complex[UO 2 (NO 3 ) 2 (tbp) 2 ] is very soluble in supercriticalCO 2 , suggesting an alternative to organic solvents for nuclear fuel processing.198 EXAFS spectra have been reported for [UO 2 (NO 3 ) 2 (tbp) 2 ], [UO 2 (NO 3 ) 2 (tibp) 2 ], [UO 2 (NO 3 ) 2MOP(OMe) 3N2 ] and [UO 2 (NO 3 ) 2MOP(OPh) 3N2 ].There are small differences in the U–O(P) bond lengths which may relate to di§erences in extraction Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 251e¶ciency.199 Camphene-derived organophosphorus compounds have been studied as potential extractants of uranium and the structure of [UO 2 (NO 3 ) 2 (RPO 3 Me 2 ) 2 ] (R\endo-8-camphanyl) determined.200 Relativistic density functional calculations on [UO 2 (OH) 4 ]2~ indicate that a trans structure is only slightly more stable than a cis one; a suggested mechanism for intramolecular ligand exchange in [UO 2 (OH) 4 ]2~ between uranyl and hydroxide involves a cis isomer.201 Activation parameters for ligand substitution reactions in ternary complexes of the type UO 2 LF 3 and UO 2 L 2 F (e.g.L\pyridinecarboxylate, oxalate) have been determined.202 2-D sheet structures have been found in [NHEt 3 ][(UO 2 ) 2 (PO 4 )(HPO 4 )] and [NPr 4 ]- [(UO 2 ) 3 (PO 4 )(HPO 4 ) 2 ].203 In a remarkable example of metal-ion control, [UO 2 Cl 4 ]2~ reacts with tert-butylcalix[ 6]arene (H 6 L) only in the presence of Cs` to form a trimetallic inclusion complex204 Cs[Hpy] 3 [UO 2 Cl 2 ] 2 [H 2 L].The crown ether does not co-ordinate to uranium in [UO 2 (CH 3 CO 2 )(H 2 O)(OH)] 2 ·18-crown-6 and [UO 2 (CH 3 CO 2 ) 2 (H 2 O) 2 ]· 2(H 2 O)·18-crown-6.205 The crown ether does not co-ordinate in either [UO 2 (NCS) 2 (H 2 O) 3 ]·1.5(18-crown-6)·MeCN or in [Th(NCS) 4 (H 2 O)(HOCH 2 - CH 2 OH)]·18-crown-6.206 A convenient microscale preparation of [UO 2 Cl 2 (OPPh 3 ) 2 ] has been described.207 Calixarenes have been suggested as uranophiles, the larger rings may act as receptors for multinuclear U(VI) species.208 A calix[4]arene with an acid and an amide group attached to the ring (L) forms a dimeric complex with the uranyl ion, [(UO 2 ) 2 L 2 ].209 The synthesis and structure of a uranyl monooxasapphyrin complex 4 is reported.210 The ring exhibits less deviation from planarity than the corresponding pentaphyrin.Hydrothermal synthesis of a number of new layered uranium(IV) fluoride species from UO 2 , HF and H 3 PO 4 additionally uses alkanediamines as templating agents. [H 3 N(CH 2 ) 3 NH 3 ][U 2 F 10 ]·2H 2 O, [H 3 N(CH 2 ) 4 NH 3 ] [U2 F 10 ]·3H 2 O, [H 3 N(CH 2 ) 6 NH 3 ] [U2 F 10 ]·2H 2 O and [HN(CH 2 CH 2 NH 3 ) 3 ][U 5 F 24 ] all contain negatively charged layers of uranium fluoride polyhedra (containing eight- and nineco- ordinate uranium) separated by the positively charged cations; the latter can be exchanged for a wide range of Group 1, Group 2 and transition metals.211 [NO]- [MF 6 ] (M\Np, Pu) are reported,212 as in the synthesis and structure of the first transactinide crown ether complex, [NpO 2 (18-crown-6)][ClO 4 ].213 Some more 237Np Mo� ssbauer studies have been reported, several this time on Np(V) compounds. 214 Analysis of Mo� ssbauer isomer shifts for Np(III–VII) compounds has been reported.215 A XANES study of plutonium aqua ions indicates that spectra are dependent upon, and characteristic of, the oxidation state.216 [Pu(CO 3 ) 5 ]6~ has been Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 252identified by EXAFS as the Pu(IV) species in solution at high carbonate concentration; the structure of crystalline [Na 6 Pu(CO 3 ) 5 ] 2 [Na 2 CO 3 ]·33H 2 O has also been determined. 217 Information from hydration studies of Cm(III) ions by laser-induced fluorescence spectroscopy indicates a co-ordination number of nine; hydration numbers have been given for other Cm(III) complex species.53 Carboxylate-derived calix[4]arenes218 show high selectivity for Am3`.Laser ablation of AmO 2 in polyimide219 produces organometallic ions including AmCN`, AmC 2 H` and AmC 4 H` as well as larger AmCxHyNz ` species, with x up to [12. 4.2 Alkoxides, amides and thiolates The importance of the choice of starting material in synthetic work is nicely illustrated by a study of aryloxides.220 UCl 4 and [UX 4 (NCMe) 4 ] (X\Br, I) react with two moles of KOR (R\2,6-di-tert-butylphenoxide) forming respectively [K(thf) 4 ][UCl 3 (OR) 2 ] (TBPY), [UBr 2 (OR) 2 (thf)] and [UI 2 (OR) 2 ].[UI 2 (OR) 2 ] and [K(thf) 4 ][UCl 3 (OR) 2 ] will react with a further mole of KORforming [UX(OR) 3 ] (X\Cl, I) whilst UCl 4 and [UI 4 (NCMe) 4 ] react with 4.2 moles of KOR forming [U(OR) 4 ].As anticipated, [UMN(SiMe 3 ) 2N3 ] has a pyramidal three-co-ordinate structure in the solid state, like the lanthanide analogues.221 [UHMN(SiMe 3 ) 2N3 ] reacts with B(C 6 F 5 ) 3 forming H 2 and [UMN(SiMe 3 ) 2N2MN(SiMe 3 )[SiMe 2 B(C 6 F 5 ) 3 ]N]. [UMC(Ph)(NSiMe 3 ) 2N2 Cl 2 ] reacts with NaBH 4 forming [UMC(Ph)(NSiMe 3 ) 2N2Mg3-BH 4N2 ] 5.Hydrogen atoms were located in both X-ray and neutron-di§raction studies.222 [MU(L)(l-Cl)N2 ] ML\N(CH 2 CH 2 NSiMe 3 ) 3N reacts with LiOR [R\Bu5, C(CF 3 ) 3 , Ph, 2,6-Bu5 2 -4- MeC 6 H 2 ] forming alkoxides and aryloxides [U(L)(OR)].223 Ate complexes [U(L)(OR)(OR@)Li(thf)n] (R, R@\Bu5, Ph), which have capped trigonal bipyramidal co-ordination of uranium, can be oxidized to neutral U(V) complexes [U(L)(OR) (OR@)].Potassium film reduction of [U(L@)Cl] [L@\N(CH 2 CH 2 NSiMe 2 Bu5) 3 ] gives [MU(L@)N2 (l-Cl)] and [U(L@)], separable on fractional sublimation. The latter reacts224 reversibly with N 2 forming the remarkable dinitrogen complex [MU(L@)N2 - (l-g2: g2-N 2 )].Density function calculations on the model compound [MU(NH 3 )- (NH 2 ) 3N2 (l-g2: g2-N 2 )] indicate significant U]N 2 p backbonding.225 On reduction in thf, [UI(NRR@) 3 ] (R@\3,5-dimethylphenyl; R\N-tert-butylanil- Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 253ide) forms [U(thf)(NRR@) 3 ] which reacts with [MoMNPh(Bu5)N3 ] underN 2 forming the end-on bridged compound [(NRR@) 3 U(l-N 2 )MoMNPh(Bu5)N3 ].[(NRR@) 3 U(l- N 2 )MoMNPh(Ad)N3 ] has also been synthesised.226 4.3 Organometallics Reductive coupling of acetone occurs in the presence of UCl 4 and Li–Hg. The carbon-based radical [UCl 3 (Me 2 C0 O)] dimerises to [MUCl 3 (thf) 2N2 (l- OCMe 2 CMe 2 O)] which reacted with LiCl forming [Li 2 (thf)][MUCl 4 (thf)N2 (l- OCMe 2 CMe 2 O)]; the last reacts with Li–Hg to form UCl 3 and [Li 2 (thf)]- [UCl 4 (OCMe 2 CMe 2 O)].The structure of [MUCl 3 (hmpa) 2N2 (l-OCMe 2 CMe 2 O)] was reported.227 A rare EPR study of U(V) compounds, including [U(NEt 2 ) 3 (cot)], [U(NEt 2 ) 3 Cp* 2 ][BPh 4 ] and [U(thf)(NEt 2 ) 2 (cot)][BPh 4 ] has been reported.228 An EPR and ENDOR study229 of [U(g7-C 7 H 7 ) 2 ]~ indicates an f1 ground state, largely made up of 5fn and 5fp uranium orbitals, with some admixture of 5f/.The cationic amide [U(thf)(NMe 2 )Cp* 2 ] [BPh 4 ] reacts with catalytic amounts of NR 2 H (R\Me, Et) forming a heterocyclic metallacycle 6.230 The amide forms an isocyanide adduct [U(CNBu5) 2 (NMe 2 )Cp* 2 ][BPh 4 ] with Bu5NC, but inserts MeCN, CO 2 and CO, forming [U(thf)MNC(Me)NMe 2NCp* 2 ][BPh 4 ], [U(thf)(O 2 CNMe 2 )Cp* 2 ] [BPh 4 ] and [U(thf)(g2-CONMe 2 )Cp* 2 ][BPh 4 ] respectively.The first uranium(IV) triflates, [U(OTf) 2 Cp* 2 ], [U(py)(OTf) 2 Cp* 2 ], [U(OTf)Cp* 3 ] and [U(py)(OTf) 2 (cot)] have been reported,231 as well as [U(py)(OTf) 4 ]. Structures have been determined for [U(H 2 O)(OTf) 2 Cp* 2 ] and [U(OTf)(CNBu5)Cp* 3 ]. A new route has been reported to the remarkable U(VI) imides232 [U(NR) 2 Cp* 2 ] (R\Ph, Ad) together with the structure of the adamantyl compound. MO calculations on [An(cot) 2 ] (An\Th, U) support the view that they are actinide(IV) systems.183 4.4 Chemistry of the post-actinides Although the synthesis of elements 113 and 114 is so far unsuccessful (see Section 1), there have been plenty of developments.Attempts of theoreticians to predict the future chemistry of the transactinides,233 suggest particular stability not just for elements around the Z\114 ‘magic island’ but also neutron-rich isotopes of element 110.Relativistic calculations continue to increase in importance, for example enabling prediction that the transactinide oxyhalides like DbOX 3 (X\Cl, Br), SgO 2 Cl 2 and SgOCl 4 will be less volatile than the halides of these elements.The volatility order RfCl 4[HfCl 4[ZrCl 4 has similarly been predicted. Supercomputer-facilitated calculations predict a Sg–Br bond length of 2.6Å for SgBr 6 . Fluoride complexation of Rf Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 254is very similar to Hf, with a complex ion [RfF 6 ]2~ proposed.234 Theoretical and experimental study of RfCl 4 has been reported.235 The increased volatility of RfCl 4 compared to HfCl 4 is ascribed to relativistic e§ects.Transport experiments suggest that RfOCl 2 only exists in the condensed phase. A comparative study of the extraction of Zr, Hf and Rf from HCl with tributylphosphate leads to an extraction order Zr[Rf[Hf, at variance with earlier studies.236 Study of the sorption of Rf from HF–HCl-containing aqueous solution indicates that its behaviour resembles Th rather than Hf.237MOcalculations have been applied238 to the electronic structure of hydrated and hydrolysed complexes of Nb, Ta, Pa and Db to obtain values for free energy changes aonstants of hydrolysis reactions, predicting hydrolysis to decrease in the order Nb[Ta[DbAPa.Calculations for the chloro complexes239 of these elements gives an order of complex formation (for [HCl][4M) of PaANb[Db[Ta; the hydrolysis order is the reverse, Ta[Db[NbAPa, significantly di§erent to that for the aqua ions. Study of the extraction of fluoro, chloro and bromo complexes of Nb, Ta, Pa and Db into aliphatic amines has been reported. 240 Dubrium shows a distribution coe¶cient in 6MHCl similar to Nb leading to an extraction sequence Pa[Nb[\Db[Ta.Gas phase and solution studies on seaborgium using 265Sg(t "[7 s) and 266Sg(t "[21 s) indicate that it behaves similarly to Mo and W.241 Oxychlorination is believed to produce SgO 2 Cl 2 . It is suggested that volatile species of Bh and Hs, HBhO 4 and HsO 4 , are potentially separable. Oxychlorination of 263Sg enabled its separation242 from Rf, Db and from heavy actinides, probably as [SgO 2 Cl 2 ].Separations of Sg in aqueous solution243 indicate ]6 to be the most stable oxidation state and that it forms neutral or ionic oxo and oxohalide compounds, possibly [SgO 4 ]2~, [SgO 3 F]~, [SgO 2 F 3 ]~ or [SgO 2 F 4 ]2~. There is evidence for strong complexation with F~. Sg is believed not to form [SgO 2 ]2`.Relativistic coupled cluster calculations suggest considerable stability for [(111)F 6 ]~. A trend in bond distances for the difluorometallates in [CuF 2 ]~ \[AuF 2 ]~\[(111)F 2 ]~\[AgF 2 ]~ is predicted (as usual the order is a§ected by the inclusion of relativistic corrections).244 Relativistic calculations on the compounds (114)X 2 and (114)X 4 (X\H, F, Cl) indicate that the inert pair e§ect is highly intensified by relativistic e§ects.245 (114)H 4 is predicted to be highly thermodynamically unstable, whilst (114)F 4 although kinetically stable will have marginal thermodynamic stability; (114)X 2 (X\F, Cl) are stable with respect to decomposition to the elements, but (114)H 2 is not.Bond energies in (114)X 2 are predicted to be similar to those in the lead analogues.References 1 R.F. Service, Science, 1998, 281, 1783. 2 P. Armbruster and F. P. Hessberger, Scientific American, September 1998, 50. 3 Pure Appl. Chem., 1997, 69, 2471. 4 P. Comba, K. Gloe, K. Inoue, T. Krueger, H. Stephan and K. Yoshizuka, Inorg. Chem., 1998, 37, 3310. 5 Gmelin Handbook of Inorganic and Organometallic Chemistry, Springer-Verlag, Heidelberg, 1997, vol.E2a. 6 Gmelin Handbook of Inorganic and Organometallic Chemistry, Springer-Verlag, Heidelberg, 1997, suppl. vol. B5. 7 W.A. Herrmann (Editor), Organolanthanoid Chemistry: Synthesis, Structure, Catalysis, Topics in Current Chemistry, Springer-Verlag, Berlin, 1996, vol. 179. 8 (a)R. Anwander and W. A. Herrmann, in ref. 7, p. 1; (b)R. Anwander, in ref. 7, p. 33; (c) F.T. Edelmann, in ref. 7, p. 113; (d) R. Anwander, in ref. 7, p. 149; (e) F.T. Edelmann, in ref. 7, p. 247. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 2559 F.T. Edelmann and Yu. K. Gun’ko, Coord. Chem. Rev., 1997, 165, 163. 10 R. Anwander, Angew. Chem., Int. Ed., 1998, 37, 599. 11 G. Adachi and N. Imanaka, Chem. Rev., 1998, 98, 1479. 12 L. I. Martynenko, N.P. Kuz’min and A. N. Grigor’ev, Zh. Neorg. Khim., 1998, 43, 1131; Russ. J. Inorg. Chem. (Transl. of Zh. Neorg. Khim.), 1998, 43, 1038. 13 S. Gao, Z. Li, M. Ji, J. Liu, X. Yang and D. Ren, Xibei Daxue Xuebao, Ziran Kexueban, 1997, 27, 489; Chem. Abstr., 1998, 129, 103 309. 14 A. A. Narducci and J. A. Ibers, Chem. Mater., 1998, 10, 2811. 15 H. Carmichael, Chem. Brit., August, 1998, 31. 16 S. Aime, M. Botta, M. Fasano and E. Terreno, Chem. Soc. Rev., 1998, 27, 19. 17 C. E. Housecroft, Coord. Chem. Rev., (a) 1996, 152, 467; (b) 1997, 164, 183; (c)1997, 162, 241. 18 Z. Pikramenou, Coord. Chem. Rev., 1997, 164, 189. 19 Z. Pikramenou, Coord. Chem. Rev., 1998, 172, 99. 20 A. Trovarelli, C. de Leitenburg and G. Dolcetti, CHEMTECH, 1997, 32. 21 K. Balasbramanian, Relativistic E§ects in Chemistry, Part B, Applications, John Wiley, New York, 1997. 22 K. L. Nash and J. C. Sullivan, J. Alloys Compd., 1998, 271–273, 712. 23 D. K. P. Ng and J. Jiang, Chem. Soc. Rev., 1997, 26, 433. 24 D.M. Taylor, J. Alloys Compd., 1998, 271–273, 6. 25 Recent Progress in Actinides Separation Chemistry, eds. Z. Yoshida, T. Kimura and Y. Meguro, World Scientific, Singapore, 1997. 26 G. V. Chertihin, L. Andrews, M. Rosi and C. W. Bauschlicher, J. Phys. Chem. A, 1997, 101, 9085. 27 P. A. Maggard and J. D. Corbett, Inorg. Chem., 1998, 37, 814. 28 H. Kleinke and H. F. Franzen, J. Solid State Chem., 1998, 137, 218. 29 T. Yamaguchi, M. Nihara, T. Takamuru, H. Wakita and H. Kanno, Chem. Phys. Lett., 1997, 274, 485. 30 S. V. Aleksandrovskii, Zh. Prikl. Khim (S.-Petersberg), 1997, 70, 1761; Chem.Abstr., 1998, 128, 187 879. 31 A. F. Gutsol, V. Ya. Kuznetsov, M.P. Rys’kina, E. L. Tikhomirova and V. T. Kalinnikov, Zh. Prikl. Khim (S.-Petersberg), 1998, 71, 543; Chem. Abstr., 1998, 129, 156 119. 32 S. Masselmann and G. Meyer, Z. Anorg. Allg. Chem., 1998, 624, 551. 33 S. Carlson, Y. Xu and R. Norrestam, J. Solid State Chem., 1998, 135, 116. 34 W.T.A. Harrison, M. L. F. Phillips, W. Clegg and S. J. Teat, J. Solid State Chem., 1998, 139, 299. 35 E. A. Nagelschmitz and W. Jung, Chem. Mater., 1998, 10, 3189. 36 R. Anwander, O. Runte, J. Eppinger, G. Gerstberger, E. Herdtweck and M. Spiegler, J. Chem. Soc., Dalton Trans., 1998, 847. 37 P. Roussel, N. W. Alcock and P. Scott, Chem. Commun., 1998, 801. 38 S. Kobayashi, T. Busujima and S.Nagayama, Chem. Commun., 1998, 18. 39 S. Kobayashi, T. Busujima and S. Nagayama, Chem. Commun., 1998, 981. 40 P. L. Arnold, F. G. N. Cloke and J. F. Nixon, Chem. Commun., 1998, 797. 41 K. J. Fisher, I. Dance and G. Willett, J. Chem. Soc., Dalton Trans., 1998, 975. 42 M. Kimura, M. Inoue and T. Inui, Kidorui, 1998, 32, 36. 43 (a) H.G. Von Schnering, D. Vu and K. Peters, Z.Kristallogr.-New Cryst. Struct., 1998, 213, 459; (b) H.G. Von Schnering, M. Wittmann and K. Peters, Z. Kristallogr.-New Cryst. Struct., 1998, 213, 463; (c)H.G. Von Schnering, D. Vu and K. Peters, Z. Kristallogr.-New Cryst. Struct., 1998, 213, 467. 44 T. Schleid and F. A. Weber, Z. Anorg. Allg. Chem., 1998, 624, 557. 45 W. Urland and H. Person, Z. Naturforsch., Teil B, 1998, 53, 900. 46 S. Kramp, M. Febri and J. C. Joubert, J. Solid State Chem., 1997, 133, 145. 47 G. Miller, M. Smith, M. Wang and S. Wang, J. Alloys Compd., 1998, 265, 140. 48 M.T. Wang and S. H. Wang, J. Rare Earths, 1997, 15, 246. 49 S. Masselmann and G. Meyer, Z. Anorg. Allg. Chem., 1998, 624, 357. 50 S. Masselmann and G. Meyer, Z. Kristallogr.-New Cryst. Struct., 1998, 213, 690. 51 G. Crisci and G.Meyer, Z. Anorg. Allg. Chem., 1998, 624, 927. 52 S. T. Hong, J. D. Martin and J. D. Corbett, Inorg. Chem., 1998, 37, 3385. 53 T. Kimura, Y. Kato and G. R. Choppin, in ref. 25, p. 149. 54 T. Kimura and Y. Kato, J. Alloys Compd., 1998, 278, 92. 55 T. Yamaguchi, K. Nakamura, H. Wakita and M. Nomura, in ref. 25, p. 165. 56 F. Favier, J.-L. Pascal, F. Cunin, A. N. Fitch and G. Vaughan, Inorg.Chem., 1998, 37, 1776; J. Solid State. Chem., 1998, 139, 259. 57 N. Yanagihara, S. Nakamura and M. Nakayama, Polyhedron, 1998, 17, 3625. 58 M.S. Wickleder, Z. Anorg. Allg. Chem., 1998, 624, 1347. 59 M.S. Wickleder, Chem. Mater., 1998, 10, 3212. 60 C. Papadimitriou, P. Veltsistas, J. Marek and J. D. Woollins, Inorg. Chim. Acta, 1988, 267, 299. 61 G. Swarnbala and M. V. Rajasekharan, Inorg.Chem., 1998, 37, 1483. 62 K. L. Nash, R. D. Rogers, J. Ferraro and J. Zhang, Inorg. Chim. Acta, 1998, 269, 211. 63 G. B. Deacon, T. Feng, P. C. Junk, B. W. Skelton, A. N. Sobolev and A. H. White, Aust. J. Chem., 1998, 51, 75. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 25664 G. R. Willey, T. J. Woodman and W. Errington, J. Indian Chem. Soc., 1998, 75, 435. 65 D.Y. Kong, S. W. Wang, Q. Zhu, Y. Y. Xie and X. Y. Huang, Jiegou Huaxue, 1998, 17, 61; Chem. Abstr., 1998, 128, 175 353. 66 (a)H.A. Alvarez, J. R. Matos, P. C. Isolani, G. Vincentini, E. E. Castellano and L. Zukerman-Schpector, J. Coord. Chem., 1998, 43, 349; (b) C. Munhoz, P. C. Isolani, G. Vincentini and L. Zukerman-Schpector, J. Alloys. Compd., 1998, 275–277, 782. 67 J. Dai, Q. F. Xu, R. Nukada, P. Qian, H. Z. Wang, M. Mikuriya and M. Munakata, J. Coord. Chem., 1998, 43, 13. 68 J. Fawcett, A. W. G. Platt and D. R. Russell, Inorg. Chim. Acta, 1998, 274, 177. 69 D.W. Knoeppel, J. Liu, E. A. Meyers and S. G. Shore, Inorg. Chem., 1998, 37, 4828. 70 J. Liu, E. A. Meyers, J. A. Cowan and S. G. Shore, Chem. Commun., 1998, 2043. 71 M. Klinga, R. Cuesta, J.M. Moreno, J. M. Dominguez-Vear, E. Colacio and R. Kivekas, Acta Crystallogr., Sect. C, 1998, 54, 1275. 72 Yu. N. Medvedev, M. L. Kuznetsov, K. A. Lysenko, M. Yu. Antipin and B. V. Lokshin, Zh. Neorg. Khim., 1998, 43, 430; Russ. J. Inorg. Chem. (Transl. of Zh. Neorg. Khim.), 1998, 43, 368. 73 T. M. Rajendiran, O. Kahn, S. Golhen, L. Ouahab, Z. Honda and K. Katsumata, Inorg. Chem., 1998, 37, 5693. 74 G. H. Maunder and A. Sella, Polyhedron, 1998, 17, 63. 75 W. J. Evans, R. N. R. Broomhall-Dillard and J. W. Ziller, Polyhedron, 1998, 17, 3361. 76 G. B. Deacon, B. Go� rtler, P. C. Junk, E. Lork, R. Mews, J. Petersen and B. Zemva, J. Chem. Soc., Dalton Trans., 1998, 3887. 77 L. Kh. Mincheva, L. S. Skogareva, G. A. Razgonyaeva, V. G. Sakharova and V. S. Sergienko, Russ.J. Coord. Chem. (Transl. of Koord. Khim.), 1997, 42, 1828. 78 Z. Chen, J. Li, F. Chen and D. M. Proserpio, Inorg. Chim. Acta, 1998, 273, 255. 79 M. G. B. Drew, M.J. Hudson, P. B. Iveson, M.L. Russell, J.-O. Liljenzin, M. Sklberg, L. Spjuth and C. Madic, J. Chem. Soc., Dalton Trans., 1998, 2973. 80 C. Y. Su, B. S. Kang, X. Q. Mu, J. Sun, Y. X. Tong and Z. N. Chen, Aust. J. Chem., 1998, 51, 565. 81 C. Y. Su, B. S. Kang, H. Q. Liu, Q. G. Wang and T. C.W. Mak, Chem. Commun., 1998, 1551. 82 R. Wietzke, M. Mazzanti, J.-M. Letour and J. Pe� caut, J. Chem. Soc., Dalton Trans., 1998, 4087. 83 T. Kanda, M. Ibi, K.-I. Mocizuki and S. Kato, Chem. Lett., 1998, 957. 84 I. G. Zaityseva, N. P. Kuz’mina, L. I. Martynenko, V. D. Makhaev and A. P. Borisov, Zh. Neorg. Khim., 1998, 43, 805. 85 G. Malandrino, I. L. Fragala` , S. Aime, W. Dastru` , R. Gobetto and C. Benelli, J. Chem. Soc., Dalton Trans, 1998, 1508. 86 G. Malandrino, C. Benelli, F. Castelli and I. L. Fragala` , Chem. Mater., 1998, 10, 3434. 87 (a) S.-J. Kang, Y. S. Jung and Y. S. Sohn, Bull. Korean Chem. Soc., 1997, 18, 75; (b) J.T. Lim, S. T. Hong, J. C. Lee and I.-M. Lee, Bull. Korean Chem. Soc., 1996, 17, 1023. 88 K. D. Pollard, J. J. Vittal, G. P. A. Yap and R. J. Puddephatt, J. Chem. Soc., Dalton Trans., 1998, 1264. 89 I. Baxter, S. R. Drake, M. B. Hursthouse, J. McAleese, K. M. A. Malik, D.M. P. Mingos, D. J. Otway and J. C. Plakatouras, Polyhedron, 1998, 17, 3777. 90 H. J. Batista, A. V.M. de Andrade, R. L. Longo, A. M. Simas, G. F. de Sa, N. K. Ito and L. C. Thompson, Inorg.Chem., 1998, 37, 3542. 91 K. Okada, M. Uekawa, Y. F. Wang, T. M. Chen and T. Nakaya, Chem. Lett., 1998, 801. 92 P. C. Christidis, I. A. Tossidis, D. G. Paschalidis and L. C. Tzavellas, Acta Crystallogr., Sect. C, 1998, 54, 1233. 93 L. C. Thompson, F. W. Atchison and V. G. Young, J. Alloys Compd., 1998, 275–277, 765. 94 T. M. Polyanskaya, G. V. Romanenko and N. V. Podberezskaya, J.Struct. Chem. (Eng. Transl.), 1997, 38, 637; Chem. Abstr., 1998, 128, 161 181. 95 I. Baxter, J. A. Darr, M. B. Hursthouse, K. M.A. Malik, D.M. P. Mingos and J. C. Plakatouras, J. Chem. Crystallogr., 1998, 28, 267. 96 I. Baxter, J. A. Darr, M. B. Hursthouse, K.M. A. Malik, J. Mcaleese and D.M. P. Mingos, Polyhedron, 1998, 17, 1329. 97 Y. Tao, X. Shao, G. Zhao and X. Jiu, Huaxue Tongbao, 1997, 39; Chem.Abstr., 1998, 128, 186 071. 98 H. Tsukube, S. Shinoda, J. Uenishi, T. Kanatani, H. Itoh, M. Shiode, T. Iwachido and O. Yonemitsu, Inorg. Chem., 1998, 37, 1585. 99 A. Gleizes, M. Julve, N. Kuzmina, A. Alikhanyan, F. Lloret, I. Malkerova, J. L. Sanz and F. Senocq, Eur. J. Inorg. Chem., 1998, 1169. 100 L. G. Hubert-Pfalzgraf, V. Abada and J. Vaissermann, J.Chem. Soc., Dalton Trans., 1998, 3437. 101 L. G. Hubert-Pfalzgraf, C. Sirio and C. Bois, Polyhedron, 1998, 17, 821. 102 W. J. Evans, M. A. Greci and J. W. Ziller, Inorg. Chem., 1998, 37, 5221. 103 H. Berberich and P. W. Roesky, Angew. Chem., Int. Ed., 1998, 37, 1569. 104 S. Kraut, J. Magull, U. Schaller, M. Karl, K. Harms and K. Dehnicke, Z. Anorg. Allg. Chem., 1998, 624, 1193. 105 G.W.Rabe, G. P. A. Yap and A. L. Rheingold, Inorg. Chim. Acta, 1998, 267, 309. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 257106 Y. Zhou, G. P. A. Yap, D. S. Richardson, Organometallics, 1998, 17, 4387. 107 G. B. Deacon, E. E. Delbridge, B. W. Skelton and A. H. White, Eur. J. Inorg. Chem., 1998, 543. 108 M. Westerhausen, M. Hartmann and W. Schwarz, Inorg. Chim. Acta, 1998, 269, 91. 109 H. C. Aspinall, S. A. Cunningham, P. Maestro and P. Macaudiere, Inorg. Chem., 1998, 37, 5396. 110 J. Lee, D. Freedman, J. H. Melman, M. Brewer, L. Sun, T. J. Emge, F. H. Long and J. G. Brennan, Inorg. Chem., 1998, 37, 2512. 111 J. M. Melman, T. J. Emge and J. G. Brennan, Chem. Commun., 1997, 2268. 112 D. Freedman, J. H. Melman, T. J. Emge and J. G. Brennan, Inorg.Chem., 1998, 37, 4162. 113 M. Berardini, J. Lee, D. Freedman, J. Lee, T. J. Emge and J. G. Brennan, Inorg. Chem., 1997, 36, 5772. 114 P. Starynowicz, J. Alloys Compd., 1998, 269, 67. 115 S. Be� nazeth, J. Purans, M.-C. Chalbot, M. K. Nguyen-van-Duong, L. Nicholas, F. Keller and A. Gaudemer, Inorg. Chem., 1998, 37, 3667. 116 R. Rulo§, R. N. Muller, D. Pubanz and A. E. Merbach, Inorg.Chim. Acta., 1998, 275–276, 15. 117 E. To� th, F. Connac, L. Helm, K. Adamli and A. E. Merbach, Eur. J. Inorg. Chem., 1998, 2017. 118 Y.M. Wang, C. H. Lee, G. C. Liu and R. S. Sheu, J. Chem. Soc., Dalton Trans., 1998, 4113. 119 L. Alderighi, A. Bianchi, L. Calabi, P. Dapporto, C. Giorgi, P. Losi, L. Paleari, P. Paoli, P. Rossi, B. Valtancoli and M. Virtuani, Eur. J. Inorg. Chem., 1998, 1581. 120 R. Rulo§, R. Rainer and L. Beyer, Z. Anorg. Allg. Chem., 1998, 624, 902. 121 L. Burai, I. Fabian, R. Kiraly, E. Szilagyi and E. Bruchner, J. Chem. Soc., Dalton Trans., 1998, 243. 122 K. Yamaguchi, Y. Inomata and F. S. Howell, Kidorui, 1998, 32, 280; Chem. Abstr., 1998, 129, 239 043. 123 G. A. Molander, Chemtracts: Org. Chem., 1998, 11, 237. 124 R. Nomura and T. Endo, Chem.Eur. J., 1998, 4, 1605. 125 B. Hamann-Gaudinet, J.-L. Namy and H. B. Kagan, J. Organomet. Chem., 1998, 567, 39. 126 M. Shabangi, J. M. Sealy, J. A. Fuchs and R. A. Flowers, Tetrahedron Lett., 1998, 39, 4429. 127 H. S. Park, I. S. Lee, D. W. Kwon and Y. H. Kim, Chem. Commun., 1998, 2745. 128 Y. Arai, T. Masuda and Y. Masaki, Synlett, 1997, 1459. 129 Y. Yang and D. Wang, Synlett, 1997, 1379. 130 K. Mashima, T. Oshiki and K. Tani, J. Org. Chem., 1998, 63, 7114. 131 A. H. Mustafa and M.K. Shepherd, Chem. Commun., 1998, 2743. 132 M. Onishi, K. Itoh, K. Hiraki, R. Oda and K. Aoki, Inorg. Chim. Acta, 1998, 277, 8. 133 J. Gu, X. Hu, Q. Li and L. Chen,Wuji Huaxue Xuebao, 1998, 14, 313; Chem. Abstr., 1998, 129, 283 762. 134 (a) H.C. Aspinall, J. L. M. Dwyer, N. Greeves, E. G.McIver and J. C. Woolley, Organometallics, 1998, 17, 1884; (b) H.C. Aspinall, N. Greeves and E. G. McIver, J. Alloys Compd., 1998, 275–277, 773. 135 V. Bekiari and P. Lianos, Adv. Mater., 1998, 10, 1455. 136 C. Runschke and G. Meyer, Z. Anorg. Allg. Chem., 1998, 624, 1243. 137 T. Lu, X. Peng, Y. Inoue, M. Ouchi, K. Yu and L. Ji, J. Chem. Crystallogr., 1998, 28, 197; Chem.Abstr., 1998, 129, 156 017. 138 H. Hassaballa, J. W. Steed, P. C. Junk and M. R. J. Elsegood, Inorg. Chem., 1998, 37, 4666. 139 L. J. Charbonnie` re, C. Balsiger, K. J. Schenk and J.-C. G. Bu� nzli, J. Chem. Soc., Dalton Trans., 1998, 505. 140 J.-C. G. Bu� nzli, F. Ihringer, P. Dumy, C. Sager and R. D. Rogers, J. Chem. Soc., Dalton Trans., 1998, 497. 141 L. H. Dekmau, N. Simon, M.-J.Schwing-Weill, F. Arnaud-Neu, J.-F. Dozol, S. Eymard, B. Tournois, V. Bo� hmer, C. Gru� ttner, C. Musigmann and A. Tunayar, Chem. Commun., 1998, 1627. 142 G. Ulrich, R. Ziessel, I. Manet, M. Guardigli, N. Sabbatini, F. Fraternali and G. Wip§ (sic), Chem. Eur. J., 1997, 3, 1815. 143 J. Jiang, W. Liu, W.-F. Law, J. Lin and D. K. P. Ng, Inorg. Chim. Acta, 1998, 268,M.T.M. Choi, W.-F. Law, J. Chen and D. K. P. Ng, Polyhedron, 1998, 17, 3903. 144 J. Jiang, W. Liu, W.-F. Law and D. K. P. Ng, Inorg. Chim. Acta, 1998, 268, 49. 145 G. A. Spyroulias, D. de Montauzon, A. Maisonat, R. Poilblanc and A. G. Coutsolelos, Inorg. Chim. Acta, 1998, 275–276, 182. 146 J. Z. Jiang, T. D. Hub, J. L. Xie, and J. Z. Zhang, Kidorui, 1998, 32, 278; Chem. Abstr., 1998, 129, 239 042. 147 E. Campazzi, E. Solari, C. Floriani and R. Scopelliti, Chem. Commun., 1998, 2603. 148 Chem. Br., May, 1998, 18; L. Milgrom and S. MacRobert, Chem. Br., May, 1998, 45; A. Adams, Science, 1998, 279, 1307; A. M. Rouhi, Chem. Eng. News., Nov. 2, 1998, 22. 149 P. Valente, S. F. Lincoln and K. P. Wainwright, Inorg. Chem., 1998, 37, 2846. 150 T. Ju� stel, H. Nikol and C.Ronda, Angew. Chem., Int. Ed., 1998, 37, 3084. 151 G. R. Choppin and D. R. Peterman, Coord. Chem. Rev., 1998, 174, 283. 152 J. Jiang, N. Higashiyama, K. Machida and G. Adachi, Coord. Chem. Rev., 1998, 170, 1. 153 B. M. Tissue, Chem. Mater., 1998, 10, 2837. 154 D. P. Glover-Fischer, D. H. Metcalf, T. A. Hopkins, V. J. Pugh, S. J. Chsdes, J. Kankare and F. S. Richardson, Inorg. Chem., 1998, 37, 3026. 155 M. Latva, H. Takalo, V.-M. Mukkala and J. Kankare, Inorg. Chim. Acta, 1998, 267, 63. 156 F. Renaud, C. Piguet, G. Bernardinelli, J.-C. G. Bunzli and G. Hopfgartner, Chem. Eur. J., 1997, 3, 1660. 157 L. Prodi, S. Pivari, F. Bolletta, M. Hissler and R. Ziessel, Eur. J. Inorg. Chem., 1998, 1959. 158 D.M. Y. Barrett, I. A. Kahwa, B. Raduchel, A. J. P. White and D. J.Williams, J. Chem. Soc., Perkin Trans. 2, Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 2581998, 1851. 159 X.-F. Chen, S.-H. Liu, C.-Y. Duan, Y.-H. Xu, X.-Z. You, J. Ma and N.-B. Min, Polyhedron, 1998, 17, 1883. 160 N. Takada, J. Sugiyama, N. Minami and S. Hieda, Mol. Cryst. Liq. Cryst. Sci. Technol., Sect. A, 1997, 295, 369. 161 E. Danielson, M. Devenney, D. M. Giaquinta, J.H. Golden, R. C. Haushalter, E. W. McFarland, D.M. Poojary, C. M. Reaves, W.H. Weinberg and X. D. Wu, Science, 1998, 279, 837. 162 C. Guttenberger and H.-D. Amberger, J. Organomet. Chem, 1997, 545–546, 601. 163 W. T. Klooster, R. S. Lu, R. Anwander, W. J. Evans, T. F. Koetzle and R. Bau, Angew Chem., Int. Ed., 1998, 37, 1268. 164 R. Taube, H. Windisch, H. Weissenborn, H. Hemling and H.Schumann, J. Organomet. Chem., 1997, 548, 229. 165 W. J. Evans, C. A. Seibel and J. W. Ziller, J. Am. Chem. Soc., 1998, 120, 6745. 166 Z. Xie, Z. Liu, Z.-Y. Zhou and T. C. W. Mak, J. Chem. Soc., Dalton Trans., 1998, 3367. 167 Y. K. Gun’ko, P. B. Hitchcock and M. F. Lappert, Chem. Commun., 1998, 1843. 168 A. A. Khvostov, A. I. Sizov, B. M. Bulychev, S. Ya. Knjazhanski and V.K. Belsky, J. Organomet. Chem., 1998, 559, 97. 169 M. Visseaux, N. Andre� , D. Baudry, A. Dormond and C. Pardes, J. Alloys. Compd., 1998, 275–277, 891. 170 W. J. Evans, K. J. Forrestal and J. W. Ziller, Polyhedron, 1998, 17, 4015. 171 H. Schumann, M. R. Keitsch, J. Winterfeld, S. Muhle and G. A. Molander, J. Organomet. Chem., 1998, 559, 181. 172 V.M. Arredondo, F. E. McDonald and T.J. Marks, J. Am. Chem. Soc., 1998, 120, 4871. 173 W. P. Kretschmer, J. H. Teuben and S. I. Troyanov, Angew. Chem., Int. Ed., 1998, 37, 88. 174 G. B. Deacon, C. Harris, G. Meyer, D. Stellfeldt, D. L. Wilkinson and G. Zelesny, J. Organomet. Chem., 1998, 552, 159. 175 G. B. Deacon, G. D. Fallon, C. M. Forsyth, B. M. Gatehouse, P. C. Junk, A. Philosof and P. A. White, J. Organomet.Chem., 1998, 565, 201. 176 X.-G. Zhou, Z.-E. Huang, R.-F. Cai, S.-N. Yu and X.-Y. Huang, Jiegou Huaxue, 1997, 16, 384. 177 Z. Xie, K. Chui, Z. Liu, F. Xue, Z. Zhang, T. C. W. Mak and J. Sun, J. Organomet. Chem., 1997, 549, 239. 178 S. I. Troyanov, Koord. Khim., 1998, 24, 373; Russ. J. Coord. Chem. (Transl. of Koord. Khim), 1998, 24, 351. 179 S. I. Troyanov, Koord. Khim., 1998, 24, 632; Russ.J. Coord. Chem. (Transl. of Koord. Khim.), 1998, 24, 591; S. I. Troyanov, Koord. Khim., 1998, 24, 381; Russ. J. Coord. Chem. (Transl. of Koord. Khim.), 1998, 24, 359. 180 J. Guan, Q. Shen and R. D. Fischer, J. Organomet. Chem., 1997, 549, 203. 181 Q. Shen, M. Qi, S. Song, L. Zhang and Y. Lin, J. Organomet. Chem., 1997, 549, 95. 182 S. M. Cendrowski, M. Nierlich, M.Lance and M. Ephritikhine, Organometallics, 1998, 17, 786. 183 W. Liu, M. Dolg and P. Fulde, Inorg. Chem., 1998, 37, 1067; M. Dolg and P. Fulde, Chem. Eur. J., 1998, 4, 200. 184 T. Kurikawa, Y. Negishi, F. Hayakawa, S. Nagao, K. Miyajima, A. Nakajima and K. Kaya, J. Am. Chem. Soc., 1998, 120, 11 766. 185 S. Anfang, G. Seybert, K. Harms, G. Geiseler, W. Massa and K. Dehnicke,Z.Anorg. Allg. Chem., 1998, 624, 1187. 186 W. J. Evans, R. D. Clark, M. A. Ansari and J. W. Ziller, J. Am. Chem. Soc., 1998, 120, 9555. 187 K. Mashima, T. Shibahara, Y. Nakayama and A. Nakamura, J. Organomet. Chem., 1998, 559, 197. 188 P. Poremba and F. T. Edelmann, J. Organomet. Chem., 1998, 553, 393. 189 K. Mashima, H. Fukumoto, Y. Nakayama, K. Tani and A. Nakamura, Polyhedron, 1998, 17, 1065. 190 H.-D. Amberger, S. Jank and F. T. Edelmann, J. Organomet. Chem., 1998, 559, 209. 191 K.-H. Thiele, S. Bambirra, J. Sieler and S. Yelonek, Angew. Chem. Int., Ed., 1998, 37, 2886. 192 G. Ionova, C. Madic and R. Guillaumont, Polyhedron, 1998, 17, 1991. 193 A. A. Narducci and J. A. Ibers, Inorg. Chem., 1998, 37, 3798. 194 B. B. Iversen, F. K. Larsen, A. A. Pinkerton, A. Martin, A.Darovsky and P. A. Reynolds, Inorg. Chem., 1998, 37, 4559. 195 M. Karbowiak and J. Drozdzynski, J. Alloys Compd., 1998, 271–273, 863. 196 M. Karbowiak and J. Drozdzynski, J. Alloys Compd., 1998, 275–277, 848. 197 J. Sloan, J. Cook, A. Chu, M. Zwiefka-Sibley, M.L. H. Green and J. L. Hutchison, J. Solid State Chem., 1998, 140, 83. 198 M. J. Carrott, B. E. Waller, N. G. Smart and C.M. Wai, Chem. Commun., 1998, 372. 199 C. D. Auwer, M.C. Charbonnel, M.T. Presson, C. Madic and R. Guillaumont, Polyhedron, 1998, 17, 4507. 200 W. Henderson, M.T. Leach, B. K. Nicholson, A. L. Wilkins and P. A. T. Hoye, Polyhedron, 1998, 17, 3747. 201 G. Schreckenbach, P. J. Hay and R. L. Martin, Inorg. Chem., 1998, 37, 4442. 202 Z. Szabo� and I. Grenthe, Inorg. Chem., 1998, 37, 6214. 203 R. J. Francis, M.J. Drewitt, D. S. Halasayamani, C. Ranganathachar, D. O’Hare and W. Clegg, Chem. Commun., 1998, 279. 204 P. C. Leverd, P. Berthault, M. Lance and M. Nierlich, Eur. J. Inorg. Chem., 1998, 1859. 205 Yu. N. Mikhailov, A. S. Kansihcheva, Yu. E. Gorbunova, V. I. Belomestnykh and L. B. Sveshnikova, Russ. J. Inorg. Chem. (Transl. of Zh. Neorg. Khim.), 1997, 42, 1817.Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 239–260 259206 R. D. Rogers, J. Zhang and D. T. Campbell, J. Alloys Compd., 1998, 271–273, 133. 207 F. J. Arnaiz and M. J. Miranda, J. Chem. Educ., 1998, 75, 1457. 208 J. Harrowfield, Gazz. Chim. Ital., 1997, 127, 663. 209 P. D. Beer, M.G. B. Drew, D. Hesek, M. Kan, G. Nicholson, P. Schmitt, P. D. Sheen and G. Williams, J. Chem.Soc., Dalton Trans., 1998, 2783. 210 J. L. Sessler. A. Gebauer, M.C. Hoehner and V. Lynch, Chem. Commun., 1998, 1835. 211 R. J. Francis, P. S. Halasayamani and D. O’Hare, Chem. Mater., 1998, 10, 3131; Angew. Chem., Int. Ed., 1998, 37, 2214. 212 P. G. Eller, J. G. Malm, B. I. Swanson and L. R. Morss, J. Alloys Compd., 1998, 269, 50. 213 D. L. Clark, D. W. Keogh, P. D. Palmer, B.L. Scott and C. D. Tait, Angew. Chem., Int. Ed., 1998, 37, 164. 214 M. Saeki, M. Nakada, T. Nakamoto, N. M. Masaki and T. Yamashita, J. Alloys Compd., 1998, 271–273, 176; M. Saeki, M. Nakada, T. Yamashita, T. Nakamoto and N. N. Krot, Radiochim. Acta, 1998, 80, 89. 215 G. V. Ionova, J. Jove and V. K. Mikhalko, Zh. Neorg. Khim., 1998, 43, 592; Russ. J. Inorg. Chem. (Transl. of Zh.Neorg. Khim.), 1998, 43, 522. 216 S. D. Conradson, I. Al Mahamid, D. L. Clark, N. J. Hess, E. A. Hudson, M. P. Neu, P. D. Palmer, W.H. Runde and C. D. Tait, Polyhedron, 1998, 17, 599. 217 D. L. Clark, S. D. Conradson, D. W. Keogh, P. D. Palmer, B. L. Scott and C. D. Tait, Inorg. Chem., 1998, 37, 2893. 218 X. Chen, M. Ji, D. R. Fisher and C. M. Wai, Chem. Commun., 1998, 376. 219 J. K. Gibson, J. Phys. Chem. A, 1998, 102, 4501. 220 S. D. McKee, C. J. Bnd L. R. Avens, Inorg. Chem., 1998, 37, 4040. 221 J. L. Stewart and R. A. Andersen, Polyhedron, 1998, 17, 953. 222 M.Mu� ller, V. C. Williams, L. H. Doerrer, M. A. Leech, S. A. Mason, M. L. H. Green and C. K. Prout, Inorg. Chem., 1998, 37, 1315. 223 P. Roussel, P. B. Hitchcock, N. D. Tinker and P. Scott, Inorg. Chem., 1997, 36, 5716. 224 P. Roussel and P. Scott, J. Am. Chem. Soc., 1998, 120, 1070; J. Alloys Compd., 1998, 271–273, 150. 225 N. Kaltsoyannis, Chem. Commun., 1998, 1665. 226 A. L. Odom, P. L. Arnold and C. C. Cummins, J. Am. Chem. Soc., 1998, 120, 5836. 227 M. Ephritikhine, O. Maury, C. Villiers, M. Lance and M. Nierlich, J. Chem. Soc., DaltonTrans., 1998, 3021. 228 D. Gourier, D. Caurant, J. C. Berthet, C. Boisson and M. Ephritikhine, Inorg. Chem., 1997, 36, 5931. 229 D. Gourier, D. Caurant, T. Arliguie and M. Ephritikhine, J. Am. Chem. Soc., 1998, 120, 6084. 230 C. Boisson, J. C. Berthet, M. Lance, M. Nierlich and M. Ephritikhine, J. Organomet. Chem., 1997, 548, 9. 231 J. C. Berthet, M. Lance, M. Nierlich and M. Ephritikhine, Chem. Commun., 1998, 1373. 232 B. P. Warner, B. L. Scott and C. J. Burns, Angew. Chem., Int. Ed., 1998, 37, 959. 233 For a summary see, M. Jacoby, Chem. Eng. News., 1998, March 23, 48. 234 G. Pfrepper, R. Pfrepper, D. Krauss, A. B. Yakushev, S. N. Timokhiin and I. Zvara, Radiochim. Acta, 1998, 80, 7. 235 A. Tu� rler, G. V. Buklanov, B. Eichler, H.W. Ga� ggeler, M. Krantz, S. Hu� bener, D. T. Jost, V. Ya. Lebedev, D. Piguet, S. N. Timokhin, A. B. Yakuschev and I. Zvara, J. Alloys Compd., 1998, 271–273, 287. 236 R. Gunther, W. Paulus, J. V. Kratz, A. Seibert, P. Tho� rle, S. Zauner, W. Bru� chle, E. Ja� ger, V. Pershina, M. Scha� del, B. Schausten, D. Schumann, B. Eichler, H.W. Ga� ggeler, D. T. Jost and A. Tu� rler, Radiochim. Acta, 1998, 80, 121; W. Bru� chle, E. Ja� ger, V. Pershina, M. Scha� del, B. Schausten, R. Gunther, J. V. Kratz, W. Paulus, A. Seibert, P. Tho� rle, S. Zauner, D. Schumann, B. Eichler, H.W. Ga� ggeler, D. T. Jost and A. Tu� rler, J. Alloys Compd., 1998, 271–273, 300. 237 D. Schumnann, H. Nitsche, St. Taut, D. T. Jost, H. W. Ga� ggeler, A. B. Yakushev, G. V. Buklanov, V. P. Domanov, D. T. Lien, B. Kubica, R. Misiak and Z. Szeglowski, J. Alloys Compd., 1998, 271–273, 307. 238 V. Pershina, Radiochim. Acta, 1998, 80, 65. 239 V. Pershina, Radiochim. Acta, 1998, 80, 75. 240 W. Paulus, J. V. Kratz, E. Strub, S. Zauner, W. Bru� chle, V. Pershina, M. Scha� del, B. Schausten, J. L. Adams, K. E. Gregorich, D. C. Ho§man, M.R. Lane, C. Laue, D.M. Lee, C. A. McGrath, D. K. Shaughnessy, D. A. Strellis and E. R. Sylwester, J. Alloys Compd., 1998, 271–273, 292. 241 H.W. Gaggeler, J. Alloys Compd., 1998, 271–273, 277. 242 I. Zva� ra, A. B. Yakushev, S. N. Timokhin, X. Honggui, V. P. Perelygin and Yu. T. Chuburov, Radiochim. Acta, 1998, 81, 179. 243 M. Scha� del, J. Alloys Compd., 1998, 271–273, 312. 244 M. Seth, F. Cooke, P. Schwerdtfeger, J.-L. Heully and M. Pelissier, J. Chem. Phys., 1998, 109, 3935. 245 M. Seth, K. Faegri and P. Schwerdtfeger, Angew. Chem., Int. Ed., 1998, 37, 2493. Annu. Rep. Prog. C

ISSN:0260-1818    

DOI:10.1039/a804896g

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

17 The co-ordination chemistry of open-chain polydentate ligands† M.D. Ward School of Chemistry, University of Bristol, Cantock’s Close, Bristol, UK BS8 1TS 1 Bidentate ligands Nitrogen-donor ligands Attachment of guanidinium, amido or amino groups (e.g. L1) to a bipy nucleus allows Rh(III) complexes intercalated to DNA to be stabilised by site-specific secondary interactions between the pendant group and the DNA exterior.1 The second-order hyperpolarisabilities of bipy derivatives with electron-donor substituents (L2) are enhanced on co-ordination to a metal, as zin [MX 2 (L2)] (M\Hg, Zn; X\halide) and [ReX(CO) 3 (L2)].2 Binding of monosaccharides to the pendant boronic acid groups of [ReCl(CO) 3 (L3)] causes a change in the UV/VIS spectrum of the complex.3 [Ru(bipy) 2 (L4)]2` is a monomer unit for incorporation into photorefractive polymers. 4 Homoleptic Fe(II) and Ru(II) complexes of bipy-5,5@-(CH 2 CH 2 CO 2 Ph) 2 are folded in solution such that the pendant phenyl groups undergo both face-to-face and edge-to-face stacking interactions with the co-ordinated bipy fragments.5 The 1H NMR spectrum and luminescence properties of [Ru(bipy) 2 (L5)]2` are concentrationdependent due to dimerisation of the ‘molecular clips’ incorporated in to L5.6 [CuCl 2 L] [L\bipy-6-CH(OMe)-6@-Bu5; the two chiral centres are homochiral] has a compressed tetrahedral structure; Cu(I) and Cu(II) complexes of the C 2 -symmetric ligand catalyse asymmetric cyclopropanation of alkenes.7 New annelated bipy derivatives have been prepared, with [Ru(bipy) 2 (L6)]2` being only poorly luminescent because of elongation of one Ru–N bond.8 [CuL 2 ]` [L\2,9-bis(tri- fluoromethyl)phenanthroline] has a very positive Cu(I)–Cu(II) redox potential; its MLCT excited state is emissive and is a powerful photooxidant.9 Bidentate tetraazatriphenylenes such as L7 and its substituted analogues are very e¶cient antenna groups for sensitisation of luminescent excited states of lanthanides.10 Cu(II) complexes of C 2 -symmetric chiral bis(oxazolines) continue to be popular for asymmetric catalysis, including addition of olefins to glyoxylate esters11 and Diels–Alder reactions.12,13 The Cu(I) complexes of the C 2 -symmetric ligands L8 (which has planar chirality),14 the diiminophosphoranes L9 and L10,15 and the † For this chapter only, py\2-pyridyl.Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 261–312 261N N R1 R2 N N I C10H21 C10H21 I C10H21 C10H21 N N O R R R R O L1 R1 = Me; R2 = (CH2) nNH–C(=NH2 +)–NH2 L2 R1 = various; R2 = –CH=CH–(1,4-C6H4)X ( X = electron-donor group) L3 R1 = R2 = –C(O)NH–(1,3-C6H4)–B(OH)2 L4 L5 2R = 2H or fused C6H4 N N (CH2)3OBut N N N N L6 L7 N N Fe C5Me5 Fe C5Me5 N N PPh3 PPh3 N N PPh3 PPh3 L8 L9 L10 N N N N OR Ph Ph Ph Ph L11 (R = H, CH2Ph) bis(sulfonamide) of cyclohexane-1,2-diamine,16 all catalyse asymmetric cyclopropanation of olefins.Cr(III) complexes of bulky anionic N-donor chelates based on b-diketimate and pyrollide/imine donor sets catalyse ethene polymerisation.17 The reversible Cu(I)–Cu(II) redox couple of [Cu(L11) 2 ]z` (z\1, 2) reflects the ease of interconversion of the donor set between near-planar [for Cu(II)] and pseudo- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 262tetrahedral [for Cu(I)].18 The anion of di(2-pyridyl)amine acts as a bidentate chelate via the pyridyl rings in complexes with Co(II) and Co(III).19 Unsymmetrical bis(pyrazolyl) borates, with two di§erently-substituted pyrazolyl rings, were prepared from a 1: 1 mixture of the two pyrazoles with LiBH 4 .20 In [Ru(PPh 3 ) 2 (CO)Cl(L·~)], where L is a chelating phenyl(azo)pyridine pyN––NC 6 H 4 X, L co-ordinates as a radical anion with an N–N bond order of 1.5 (confirmed crystallographically).21 Sulfur- and antimony-donor ligands The bis(thiophosphinyl)amine Ph 2 P(––S)–NH–PPh 2 (––S) (HL) is an acac-like S,Schelate with an acidic central NH proton; CoL 2 is pseudo-tetrahedral.22 The bis(thiophosphinyl)ferrocene [FeMC 5 H 4 PPh 2 (––S)N2 ] can act as either a cis or trans S,S-chelate in Ag(I) complexes, or can act as a bridging ligand to give a 1-D polymer.23 Ir(I) complexes of the chiral dithioethers L12 are asymmetric hydrogenation catalysts. 24 The ligands Ph 2 Sb(CH 2 )nSbPh 2 (n\1, 2) are Sb-donor analogues of dppm and dppe, and act as monodentate or bridging bidentate ligands to Cr-, Mo- and W-carbonyl fragments, e.g.in [MW(CO) 4N2 (l-L) 2 ], with no chelation occurring.25 In contrast Ph 2 Sb(CH 2 ) 3 SbPh 2 (L) is an Sb,Sb-chelate in trans-[RuL 2 X 2 ]z` (X\halide; z\0, 1) whose electrochemical interconversion was studied.26 N SR SR Ph L12 (R = Me, Pri, Ph) Phosphorus-donor ligands Chiral diphosphines are still of intense interest in asymmetric homogeneous catalysis.Examples include L13, in which the chirality is at the P centres rather than more remote from the metal on the carbon backbone;27 L14, for Rh-catalysed hydrogenation of ketones;28 and the bis(aminophosphine) L15, for Rh-catalysed hydrogenation of imines.29 Syntheses were described for numerous C 2 -symmetric derivatives of dppf30 and the ligands L16 for which complexes [MX 2 (L16)] (M\Ni, Pd, Pt; P Ph2P EtO2C Ph L13 P P L14 NH PPh2 NH PPh2 L15 X\halide) were prepared.31 The P,P-chelates L17, which have large bite angles, were used for Rh-catalysed hydroformylation32 and Ni-catalysed hydrocyanation,33 and in each case the e§ects of the steric and electronic properties of the aryl substituents on Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 263P P L16 ( n = 5, 6, 7, 8) CH (CH2) n CH (CH2) n H H O S (XH4C6)2P P(C6H4X)2 L17 (R = NMe2, OMe, Me, H, F, Cl, CF3) O X R P P L18 (R = Me, H; X = S, CMe2) the reaction were evaluated. Likewise a series of dppf derivatives was prepared, in which the e§ects of varying the phenyl substituents on the e¶ciency of Pd-catalysed amination were examined.34 Ligands L18, chiral analogues of L17, were e§ective in Pd-catalysed allylic alkylation.35 Mixed phosphine–phosphite [e.g.PPh 2 (1,2- C 6 H 4 )OP(OPh) 2 ]36 and chiral bis(phosphonite) ligands37 were also developed, for Pd-catalysed copolymerisation of CO–propene and Rh-catalysed hydrogenation of olefins, respectively. Structural and solution NMR spectroscopic studies revealed both bridging and chelating co-ordination modes of Ph 2 POCH(R)CH 2 PPh 2 (R\Et), which has two inequivalent donors and a chiral centre.38 Similar non-symmetric ligands were used to prepare the dihydrides [PtH 2 L], for which 1H NMR spectroscopic studies using para-hydrogen-induced polarisation revealed the mechanism ofH 2 addition.39 Monomeric and dimeric Ag(I) complexes of the dppe analogues R 2 PCH 2 CH 2 PR 2 (R\2- pyridyl, 3-pyridyl or 4-pyridyl) are water-soluble because of the hydrophilic pyridyl substituents.40 The diphosphine Ph 2 P(1,2-C 6 H 4 )Hg(1,2-C 6 H 4 )PPh 2 can be either a cis or trans chelate in [MCl 2 L] (M\Pd, Pt), and can undergo loss of Hg to give co-ordinated 2,2@-bis(diphenylphosphino)biphenyl.41 Ph 2 PCH 2 (2,5-C 4 H 2 S)- CH 2 PPh 2 , which has an even larger separation between the phosphine groups, spans two separate metal ions in the cluster [Cu 3 (l3 -X)(l-X) 2 (l-L) 2 ] (X\halide).42 The diphosphine L19 behaves similarly to dmpe in its complexes P P P P S S S S PPh2 PPh2 L19 L20 L21 with Fe(II), such as [FeX 2 (L19) 2 ] (X\halide) and [FeCl(CO)(L19) 2 ]`.43 [M(L20) 3 ] (M\Cr, Mo, W) have an unusual trigonal prismatic geometry.44 Co-ordination of the two phosphine termini of Ph 2 P(CH 2 CH 2 O) 4 CH 2 CH 2 PPh 2 to a Pd centre results in the ligand backbone forming a crown-ether-like cavity.45 Ligand L21 contains a chelating diphosphine group attached to a redox-active tetrathiafulvalene fragment; the electrochemical, magnetic and EPR spectroscopic properties of the complex [ReIIICl 2 (L21)][ReIIReIIICl 6 L] were determined (cf.ref. 210).46 Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 264Mixed-donor ligands The pseudo-tetrahedral complex [CuL 2 ] [HL is the chiral salicylaldimine derivative C 6 H 4MC––NC(Me)PhN-2-OH-1] catalyses ring-closure of 1,2-bis(ketenes).47 ‘Hemilabile’ pyridyl ligands such as pyCH(Me)P(––O)Ph 2 can be monodentate Ndonor ligands or N,O-chelates in complexes with Pd(II) and Pt(II).48 Co-ordination of the N,O-chelating pyridyl–nitrone ligand pyC–– N(O)Bu5 to first-row transition metal ions results in increased localisation of the C––N double bond.49 Metal N N+ R O O– L22 R = 2-pyridyl L23 R = 2-imidazolyl L24 R = 2-benzimidazolyl L25 R = 3,4-dimethyl-1,2,4-triazol-5-yl complexes of N,O-chelating ligands based on paramagnetic nitroxide donors have been prepared; in [MnL 3 ]2` and [NiL 3 ]2` (L\L22–L24) the metal and ligands are antiferromagnetically coupled,50 whereas lanthanide complexes of L25 are ferromagnetically coupled such that [Gd(L25) 2 (NO 3 ) 3 ], for example, has an S\9/2 ground state.51 Ar2P N O R L26 Chiral phosphine–oxazoline N,P-chelates such as L26 are of interest for asymmetric homogeneous catalysis.For example, Ir(I) complexes catalyse enantioselective olefin hydrogenation,52 and Pd(II) complexes catalyse enantioselective allylic substitution. 53,54 The homochiral form of [Ni(L26) 2 ]2` (with Ar\Ph, R\Bu*) is stabilised over the achiral form by intramolecular interlocking of ligand substituents.55 Pd complexes of the iminophosphine ligands R 2 P(1,2-C 6 H 4 )CH––NAr catalyse ethene oligomerisation, with the size of the resultant oligomer being controlled by the substituents on the aromatic ring Ar.56 Imine–thiol chelates HS(1,2-C 6 H 4 )N––Ar (HL; Ar\substituted phenyl ring, or ferrocenyl group) form square-planar complexes [NiL 2 ] and [PtL 2 ] which show helical distortions and a variety of intermolecular aromatic stacking interactions.57,58 The chiral amino–thiol ligands R1R2NCH(Pr*)CH 2 SR3, derived from S-valine, catalyse asymmetric addition of diethylzinc to aromatic aldehydes.59 The syntheses, structures and reactions of Pd(II) complexes of the chiral P,S-chelate L27 were studied.60 [M(L28) 2 ] (M\Zn, Cd, Hg) have an unusual N 2 Se 2 co-ordination environment. 61 Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 265P Ph SH Se– N O HL27 [L28]– 2 Tridentate ligands Nitrogen-donor ligands Attachment of terpy to the end of a DNA strand which is complementary to a specific RNA strand allows precise site-specific cleavage of the target RNA in the presence of Cu(II).62 The UV/VIS and luminescence properties of Zn(II), Ru(II) and Os(II) complexes of 4@-anthracenyl-2,2@: 6@,2A-terpyridine have been examined.63 Terpy groups have been covalently attached to C 60 fragments with a variety of spacers, and the properties of the resulting Ru(II) complexes evaluated.64 Attachment of four terpy groups to a pentaerythritol core results in a dodecadentate ligand with four terpy sites, N N N O R1 R2 N O O RO OR L29 R1 = H, R2 = L30 R2 = H, R1 = L31 R2 = H, R1 = which is used as the core of metallodendrimers containing up to 16 MRu(terpy) 2N2` fragments.65 Whereas [Ag(NCMe)(L29)]` is a four-co-ordinate monomer, [MAg 2 (L29) 2N2 ]4` contains two binuclear double helicates held together by weak Ag· · ·Ag interactions and aromatic p-stacking.66 [M(L30) 2 ]2` (M\Mn, Co, Ni, Cu, Zn) show weak antiferromagnetic metal–ligand exchange.67 The e§ects of oxidising the pendant aromatic group of complexes [M(L31) 2 ]2` to a quinone on the magnetic and redox properties of the complexes were evaluated.68 The redox and spectroelectrochemical properties of [Ru(L32) 2 ]2` were examined; L32 is a strong p-acceptor ligand.69 The ability of tridentate chelates such as terpy, and its more rigid annelated derivatives such as L33, to co-ordinate in a bidentate manner is crucial for allowing insertion reactions in Pd(II) complexes such as [PdMe(L33)]`.70 Exchange of co-ordinated and pendant N atoms of the ligand in [PdL(R)]` [L\2,6- bis(pyrimidin-2-yl)pyridine] proceeds via dissociation of a pyrimidine ring, rotation, and re-attachment via the alternate N atom.71 Annu.Rep.Prog. Chem., Sect. A, 1999, 95, 261–312 266X N N N L32 X = N L33 X = CH N N HN HN N N N N N N N N N N N Et Et OR RO L34 L35 R = H L36 R = mesityl L37 R = long-chain group Deprotonation of the imidazole groups of [Fe(L34) 2 ]2` results in a shift in the Fe(II)–Fe(III) redox potential from ]0.92 to [0.46 V.72 Whereas [Cu(L35) 2 ]2` has a dx»~y» ground state [Cu(L36) 2 ]2` has a dz» ground state, illustrating steric control of the magnetic properties of the complex.73 The free bis(benzimidazolyl)pyridines L37 have extensive mesogenic properties which are lost on co-ordination to lanthanides, due to the change in ligand conformation on binding to a metal ion.74 Fe, Co and Al complexes of simple 2,6-bis(imino)pyridines (from condensation of 2,6-diacetylpyridine with aromatic amines) are e§ective homogeneous catalysts for ethene polymerisation. 75–78 In octahedral [Ni(L38) 2 ]2` the peripheral phenolic groups of each ligand are directed appropriately for catenate formation.79 The bipyridyl–thiazole ligands L39 have a similar ligand-field strength to terpy, but when the thiazole ring is central the ligand-field strength is reduced and the Fe(II) complex becomes high-spin.80 The imidazole groups of mononuclear Cu(II) complexes of HL40 can be deprotonated, leading to self-assembly of oligomeric and polymeric complexes via imidazolate bridging; for example [MCu(hfac)(L40)N2MM(hfac) 2N] (M\Mn, Co, Ni, Zn) display antiferromagnetic coupling.81 The new chiral ligand L41 allows Ru-catalysed asymmetric ketone hydrogenation.82 Reaction of Cu(I) and Cu(II) complexes of L42 withO 2 results in regiospecific transfer of anOatom to the benzylic C–Hposition of the indane ligand (shown in diagram) via a binuclear peroxo-bridged intermediate.83 The structures, stabilities and spectroscopic properties of Cu(I) and Cu(II) complexes of L43 were systematically studied as a function of the number of methoxy substituents.84 Reactions of multinuclear Cu(I) complexes of (bridging) L44 with CO and O 2 were examined. 85 [Co(L45) 2 ]3` is a useful starting material for preparing a range of macrocycle Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 267N N N HO OH N N N S R N N HN HN N L38 L39 R = H, Me HL40 and sarcophagane complexes.86 The complexes [MPd(en)N6 (l3 -L) 4 ]12` [L\1,3,5- tris(4-pyridyl)triazine or 1,3,5-tris(3-pyridyl)triazine] contain an octahedral array of MPd(en)N2` fragments with a ligand L capping alternate faces of the octahedron;87,88 large guest molecules such as o-carboranes or substituted aromatic molecules can fit in the 2.0 nm-diameter cavity.88 O N HN N O Ph Ph L41 N py py H N OMe N OMe N N NH RO OR OR N N N L42 x 3– x L43 ( x = 0, 1, 2, 3) HL44 L45 For tris(pyrazolyl)borate ligands we use here Trofimenko’s notation Tp3R,4R,5R where 3R, 4R and 5R denote the pyrazolyl C3, C4 and C5 substituents.In [CuL(NO)], where L\TpCF’,H,CH’ or Tp.%4,H,H, a small change in the nature of the NO binding pocket has drastic consequences on the spectroscopic properties and reactivity of the complexes.89 Reaction of [M(TpM%,M%,M%)MIIN2 (l-OH) 2 ] (M\Co, Ni) with H 2 O 2 affords [M(TpM%,M%,M%)MIIIN2 (l-O) 2 ] in which the ligand methyl substituents prevent decomposition viaH· abstraction and subsequent ligand oxygenation.90 The tetrahedral complexes [(TpB65,H,P3*)Mn(OOR)] include the first structurally characterised alkylperoxo –Mn(II) complex.91 [Cu(Tp4-P3*@CŸH×,H,M%)(o-OC 6 H 4 SMe)] is a model for the galactose oxidase active site, with the ancillary ligand mimicking the co-ordinated cysteinyl–tyrosine residue.92 In [Ag 3 (TpR,H,H) 2 ]` (R\2-anisyl) each tris(pyrazolyl) borate ligand is co-ordinated in the hitherto unseen triply-bridging mode, with one pyrazolyl donor of each ligand co-ordinated to each two-co-ordinate Ag(I) centre.93 The phenyltris(pyrazolyl)borate [PhB(3-Bu5pz) 3 ]~ (L), with the usual B–H cap replaced by B–Ph, a§ords the reactive alkyl complex [FeIIMeL] which in turn a§ords numerous products such as [FeI(CO)L].94 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 268Oxygen-, sulfur- and phosphorus-donor ligands Electrochemical and spectroscopic studies on complexes of the face-capping tripod [L46]2~ reveal that it is close to fluoride in the spectrochemical series.95 Four-coordinate complexes such as [MCl(L47)] (M\Co, Ni) were prepared in which the tetrahedral geometry is imposed by tripodal [L47]~;96 in contrast the less hindering analogue [L48]~ forms octahedral complexes [M(L48) 2 ] (M\Fe, Co, Ni) as well as a cyclic tetramer [Cu 4 (L48) 4 ].97 Ru (RO)2P P(OR)2 P(OR)2 O O O R B SR1 SR1 SR1 [L46]2– [L47]– R = Ph, R1 = But [L48]– R = ferrocenyl, R1 = Me P Me2Si P SiMe2 P Ph Ph Ph Ph SiMe3 Me3Si Ph2P PPh2 PPh2 O OMe O MeO O OMe L49 L50 The triphosphine L49 forms planar complexes [MCl(L49)] (M\Rh, Ir);98 in contrast five-co-ordinate Rh(I) complexes of the new tripodal phosphine MeC(CH 2 PR 2 ) 3 (L; R\C 6 H 4 CF 3 -3), such as [RhCl(CO)L] were prepared.99 The triphosphine (HOH 2 C) 2 P(CH 2 CH 2 )PPh(CH 2 CH 2 )P(CH 2 OH) 2 forms complexes, with Pt(II), Rh(I) and Re(V) for example, which are water-soluble due to the hydroxymethyl substituents on the ligand;100 similarly [RhH(CO)(L50)] is a water-soluble hydroformylation catalyst.101 Mixed N,O-, N,S- and N, Se-donor ligands Cu(II) complexes of the ‘scorpionate’ ligands HL51 are possible models for the active site of galactose oxidase.102 Six-co-ordinate [M(L51) 2 ] (M\Co, Ni) undergo cistrans isomerisation in solution; the cis isomers can react with a second metal ionM2 to form linear trimetallic complexes [MM1(L51) 2N2 M2] in which the central metal ionM2 is pseudo-tetrahedral via phenolate bridges, and which show moderate magnetic exchange couplings.103,104 Insertion of CO 2 into one of the B–H bonds of a Zn(II)- bound bis(pyrazolyl)borate a§ords [ZnCl(L52)], in which L52 mimics the biological donor set of glutamate and two histidine residues.105 The dianionic O,N,O-chelate Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 269N N N N R1 R2 R1 R2 OH R3 R4 N N N N HB O H O Pri But But Pri N HO O HO N OH HO Ph Ph Ph Ph N R R N HO OH OH HL51 [L52]– H2L53 H2L54 HL55 L53 is a good ligand for both first-row transition-metal ions, as in [MIII(L53) 2 ]~ (M\Fe, Cr) and [Cu 2 (L53) 2 ], and lanthanide ions.106 The complex [TiCl 2 (L54)] is the basis of an a-olefin polymerisation catalyst.107 Binuclear phenolate-bridged complexes with a MMII 2 (L55) 2N2` core (M\Co, Ni, Cu) display antiferromagnetic exchange. 108 Some of the tautomeric forms of [CuII 2 (L56) 2 ], in which X, Y or Z are long-chain alkyl substituents, can form smectic mesophases.109 The tridentate Schi§- base L57 was developed by a combinatorial method for the asymmetric hydrocyanation of imines (Strecker reaction).110 The new mixed N,O- and N,S-donor ligands L58 O R N HO X Y Z N NH HO OMe But NH S O HN Ph N N X N N R1 R2 R2 R1 R3 R4 R3 R4 N N X N N R1 R2 R3 H2L56 HL57 L58 X = S, O, OCH2CH2O, OC6H4O R1, R2 = long alkyl chains R3, R4 = short alkyl chains or H L59 X = S, O, S(CH2) nS [ n = 2 or 3] R1, R2, R3 = H or Me Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 270transport various metal ions (NiII, CdII, ZnII, CuII) across organic membranes.111 Structural and solution NMRspectroscopic studies show that the asymmetric ligands L59 can be N,N-bidentate or N,O,N-tridentate chelates, but that the thioether groups do not co-ordinate.112 SH N X SH N O HN HS SH N NH S S Ph But H2N SH NH2 N N C N N SH N N Se Se H2L60 X = CH2CH2, 1,2-C6H4 H2L61 H2L62 HL63 H HL64 (CH2) n (CH2) n – – [L65]2– n = 4, 5, 6 Protonation and/or alkylation of the co-ordinated thiolates of the thiolate-bridged dimer [Ni 2 L 2 ] [H 2 L\MeN(CH 2 CH 2 SH) 2 ] modulates the redox properties of the complex without significantly a§ecting the structure; this behaviour mimics that of Ni-hydrogenases.113 Dinuclear thiolate-bridged complexes of L60 are also structural models for the Ni-hydrogenases.114 Oligonuclear thiolate-bridged Zn(II) complexes were prepared with mixed-donor ligands such as py(CH 2 )nNHCH 2 CH 2 SH; various structural types such as Zn 3 L 4 and MZnLN= were observed.115 The structures and spectroscopic properties of Ru(II) complexes with N,S,N-chelates of the type C 5 H 3 N(CH 2 SR) 2 -2,6 were determined.116 The ]3 metal oxidation state in [FeIII(L61) 2 ]~ is strongly stabilised by the unusual pyridine–carboxamide–thiolate donor set.117 The electrochemical, spectroscopic and reactivity properties of MMoO 2N2` and MMoON3` complexes with the N,S,S chelate L62 were examined.118 [M 2 (L63) 2 ]2` (M\Ni, Pd), with two thiolate bridges, undergo two stepwise M2`–M` redox couples; replacement of the bridging S by Se does not a§ect these much.119 [Ni 2 (L63) 3 ]2` has a bioctahedral, trapped-valence NiIINiIII(l-S) 3 core which can be electrochemically converted to the NiIINiII and NiIIINiIII forms, all of which were characterised by EPR and UV/VIS spectroscopy.120 [MIII(L64) 2 ]` were prepared and their electronic spectra assigned; the Fe(III) complex is a structural model for the active site of nitrile hydratase.121 [Pd(PR 3 )(L65)] are unusual examples of complexes based on Se,N,Se chelates.122 Other mixed-donor ligands Binuclear Cu(I) complexes of L66 such as [Cu 2 (NCMe) 2 (L66) 2 ]2`, in which L66 acts as an N,N-chelate to one metal and a P-donor to the other, were prepared.123 Ligand L67 adopts the same co-ordination mode (N,N-chelating and P-monodentate) in Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 271N Ph2P N N N N N N PPh2 L66 L67 PPh2 N N Ph2P L68 [Ag 2 (L67) 2 ]2` which has a box-like structure with p-stacking between the ligands.124 Tripodal N-donor and N,P-donor ligands of the type MeC(CH 2 X)(CH 2 Y)(CH 2 Z), based on the neopentyl core (X, Y, Z\pyrazol-1-yl, PPh 2 , NMe 2 , imidazolyl, etc.), co-ordinate to molybdenum–carbonyl fragments.125 Mixed azine–phosphine ligands containing chiral camphor groups, such as L68, act as tridentate P,N,P-chelates in [M(CO) 3 (L68)] (M\Mo, W).126 In [PtCl(L69)] the ligand series L69 is always a tridentate N,N,C (cyclometallated) chelate, irrespective of the degree of steric strain arising from the polymethylene chain X.127 The complex [MCuII(L70)N2 Cl 2 ], where the ligands L70 are co-ordinated as radical monoanions, is a model for the galactose oxidase active site and catalyses aerobic oxidation of alcohols to aldehydes or ketones.128 The ligands MeC(CH 2 X)(CH 2 SR)(CH 2 SR@) (X\PPh 2 or SRA) are potential S 2 P- or S 3 -donors which exhibit a range of co-ordination modes.129 Pd(II) complexes of the P,O,PN N H X S OH HO But But But But O NaO3S SO3 Na PPh2 Ph2P PPh2 X Y OH NH N S CO2 H HL69 H2L70 L71 HL72 X = CH, Y = N HL73 X = N, Y = CH HL74 chelate L71 are water-soluble catalysts for alkene hydroxycarbonylation.130 [RuCl 2 (PPh 3 )L] [HL\Ph 2 P(1,2-C 6 H 4 )C––NCH 2 CH 2 OH] exhibits reversible photochromism, with the trans-axial chlorides being replaced by MeCN in the dark and the chloride ligands re-attaching on photo-irradiation.131 The P,N,O-chelates L72 and L73 contain mixtures of hard and soft donor atoms and form mononuclear square planar complexes with Ni(II), Pd(II) and Pt(II).132 The donor set of L74 mimics the histidine–methionine–glutamate biological ligand set; whereas [Cu(L74) 2 ] has a trans,cis,cis-S 2 N 2 O 2 donor set, [Ni(L74) 2 ] is the cis,cis,cis isomer.133 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 2723 Tetradentate ligands Nitrogen-donor ligands Complexes with ‘back-to-back’ bridging ligands.The complex [MFe(CN) 4N2 (l- L75)]z~ (z\2 to 6) exists as a five-membered redox chain; the FeII–FeIII form is a Class III, strongly-delocalised mixed-valence species.134 Similarly [MRuCl([9]aneS 3 )N2 (l- L75)]z` (z\2, 3, 4) are electrochemically accessible and the RuII–RuIII mixed-valence form is also strongly delocalised (Class III).135 Spectroelectrochemical studies on binuclear [MRu(phen) 2N2 (l-L76)]4` and tetranuclear [M(phen) 2 Ru(l-L76)N3 Ru]8` revealed inter-valence charge transfer bands in the mixed-valence RuII–RuIII species.136 Whereas mononuclear [Cu(PPh 3 ) 2 (L77)]` undergoes metal-centred reduction followed by de-chelation, binuclear [MCu(PPh 3 ) 2N2 (l-L77)]2` undergoes bridging-ligand centred reduction to give a radical anion.137 N N N N N N N N N N N N N N X X L75 L76 L77 X = H, Me, Cl The luminescence and electrochemical properties of polynuclear RuII and mixed RuII–PtII complexes incorporating L78 as a bridging ligand were examined,138,139 as were the e§ects of bridging ligand length in the photophysical and electrochemical properties of [MRu(bipy) 2N2 (l-L79)]4`.140 The optically pure, C 2 -symmetric rod-like complexes [MRu(phen) 2N2 (l-L80)]4` were prepared.141 [MRu(bipy) 2N2 (l-L81)]4` associates via p-stacking to form dimers in solution.142 The Ru-centred emission from one positional isomer of [MRu(bipy) 2N(l-L82)MPtCl 2N]2` is much weaker than from the other isomer, due to the di§ering steric and electronic properties of the two inequivalent bipyridyl sites.143 [Ru(bipy) 2 (L83)]2` and [MRu(bipy) 2N2 (l-L83)]4` catalyse electrochemical reduction of CO 2 to formic acid.144 The sign and magnitude of magnetic exchange in binuclear Cu(II) complexes of L84 depends on the twist between the two CuNN planes, which is determined by the bulk of the co-ligands.145 [M 2 (L84) 3 ]n` (M\MnII, FeII, NiII, n\4;M\CoIII, FeIII, n\6) have triple helical structures, with the MnII 2 complex showing weak ferromagnetic exchange.146 In [MCu(PPh 3 ) 2N2 (l-L85)] the bridging ligand is co-ordinated as a radical anion, which is stabilised by the presence of two metal centres.147 In [MCu(PPh 3 ) 2N(l- L86)(FBF 3 )] the bridging ligand is the non-symmetrical tautomer with a quinone–diimine site co-ordinated to Cu(I) and a diamine site hydrogen-bonded to tetrafluoroborate.148 Bridging ligands such as L87 contain two chiral oxazoline groups linked to a 4,4@-bipyridyl core;149 their Rh(I) complexes are enantioselective hydrosilylation catalysts.150 2,2@-Biimidazole joins two MM(bipy) 2N2` fragments Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 273N N N N N N N N N X N N N N N N N N N N N N N N N L78 L79 X = (C6H4) n, n = 1 or 2 L81 n L80 ( n = 1, 2) N N N N N N N N N N L82 L83 N Y X N N Y N R R N N Cl N N N N Cl PhN PhN NHPh NHPh N N N O N O R R R' R' L84 (R = H or NH2; X = H or Me; Y = CH or N) L85 L86 L87 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 274(M\Ru, Os) to give complexes with metal-centred oxidations and ligand-centred reductions.151 Helicates and related complexes. [Ag(L88)] = has a single-stranded helical polymeric structure.152 Reaction of the double helicate [Zn 2 (L89) 2 ]4` with a dinaphthocrown ether results in five-component assembly of a [2]-catenane.153 Binding of the complexes [MRu(phen) 2N2 (l-L90)]4` to DNA is sensitive to the length of the polymethylene spacer group between the two metal termini.154 A detailed comparison of N N N N N N (CH2) n N N N N N O O N N O O N L88 L90 ( n = 5, 7, 10) L91 ( n = 2, 3, 4) L89 thermal and optical inter-valence charge transfer in the mixed-valence complexes [FeIIFeIII(L91) 3 ]5`, which have triple helical structures, was carried out.155 The ‘chiragen’ bridging ligands L92 and L93 allow stereospecific assembly of the circular double helicate [Ag 6 (L92) 6 ]6`,156 and dinuclear triple helicates [M 2 (L93) 3 ]4` (M\Cd, Fe, Zn).157 [Co 4 (L94) 6 (BF 4 )][BF 4 ] 7 consists of a MCo 4 (L94) 6N8` tetrahedral core, with one bridging ligand along each edge, encapsulating a [BF 4 ]~ anion which is presumed to act as a template; in contrast [Ni 2 (L94) 3 ]4` has an open-chain structure with one bridging ligand and no templating anion (cf.refs. 195, 196).158 The ligand L94 also forms a dinuclear double helicate with Cu(I), and mononuclear complexes with Cu(II) in which it acts as a tetradentate chelate.159 Whereas [Ag 2 (L95) 2 ]2` is a double helicate, [Ag(L96)(NO 3 )] = is a homochiral infinite polymer; the ligands are bridging in each case.160 Homochiral ligand–ligand recognition occurs during the assembly of [Cu 2 (L96) 2 ]2`, such that use of the racemic ligand a§ords only the DD and KK complexes.161 [Cu 2 (L97) 2 ][BF 4 ] 2 is a double helicate with a columnar liquid crystalline phase; co-ordination to the metal alters the ligand conformation to favour mesophase formation (cf. ref. 74 in which the reverse e§ect occurs).162 The structures and magnetic and electrochemical properties of the binuclear triple helicates of Co(III) and Fe(II) with L98 were determined.163 Ligand L99 forms a binuclear double helicate with Cu(I) in the solid state but a monomer in solution; the redox potential of the ferrocene–ferrocenium couple is shifted to a more positive potential on Cu(I) coordination. 164 Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 275Y X Y X X Y X Y N N N N N N N N R R N N L92 X = N; Y = CH L93 X = CH; Y = N L95 R = H L96 2R = cyclo –(CH2)4– L94 N N N N R R OC16H33 OC16H33 OC16H33 O O N N N N N N R3 R3 R2 R1 R1 R2 O O N N O O N N L97 R = L98 Fe L99 Other open-chain N-donor ligands Complexes of L100 with Cu(I) and Cu(II) are e§ective at cleaving DNA in the presence of O 2 .165,166 Binuclear Cu(I) complexes of L101 and L102 are models for tyrosinase; reaction with O 2 can result in hydroxylation of the phenyl ring to give a bridging phenolate group.167,168 The fluorescence intensity of the anthracenyl unit of L103 is di§erent for the ‘closed’ [Cu 2 (L103) 2 ]4` and ‘open’ [Cu 2 (L103) 2 ]2` species, allowing easy determination of structural type from the emission properties.169 Structure –property correlations were determined for Cu(II) complexes of poly(imidazole) ligands such as L104, which are models for the active sites of various copper proteins. 170 In lanthanide complexes of the new aminotroponimine ligand L105, the Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 276N N N N O O NH2 N N (CH2) x N (CH2) x N N N N N L100 L101 x = 1, 2 L102 NH N HN N N N N NH N N NH N X NH HN N N Pri Pri N N N N NH HN NH N N HN L103 H H L104 X = O or 2H H2L105 – [L106]– L107 ligand can be a tetradentate chelate to give e.g.[MLaIIICl(thf)(L105)N2 ] or a bis(bidentate) bridge to give e.g. [MLaIII 2 (thf)(L105) 3N2 ].171 In [CuII 3 (L106) 4 ]2` each tetradentate ligand spans the linear Cu–Cu–Cu chain, giving a propeller-like structure in which the metal centres are strongly antiferromagnetically coupled.172 The planar MCu(L107)N core undergoes monomer–dimer equilibrium in solution; in [Cu(NO 3 )(L107)]Cl the chloride anion is hydrogen-bonded to both pyrazolyl NH groups in a ‘chelating’ interaction.173 Deprotonation of the imidazole termini of [Cu(H 2 L108)]2` gives polymeric [Cu(L108)]n in which the metals are linked by imidazolate bridges, and the antiferromagnetically coupled trinuclear complexes [MCu(L108)(H 2 O)NMNi(hfac) 2 (H 2 O)N2 ] were also prepared.174 [Cu(H 2 L109)]2` likewise assembles into infinite chains or cyclic tetramers on deprotonation.175 Ligand L110 acts as a tetradentate chelate in [Pb(L110) 2 ]2` but as a bridging ligand in the ‘face-to-face’ dinuclear complexes [MII 2 (l-X) 2 (l-L110) 2 ]2` (M\Co, Cu, X\OH; M\Ni, X\OAc);176 in contrast L111 invariably acts as a tetradentate chelate in complexes with Fe(III), Zn(II), Cu(II), Ag(I) or Pb(II).177 Complexes of the C 2 -symmetric ligand L112 with Ru(II) catalyse enantioselective alkene epoxidation;178 those with first-row transition-metal ions catalyse other processes such as asymmetric Michael additions.179 Complexes containing the MFeIII 2 (L113) 2 (l-O)N4` core (with additional Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 277bridging ligands such as acetate, sulfate, carbonate, etc.) are models for non-heme iron proteins.180 Polymeric co-ordination complexes of Ag(I) with multinucleating bridging ligands such as C 6 H 2 (CH 2 5py) 4 -1,2,4,5 were prepared; an N,S-chelating co-ordination mode of each ’arm’ is also possible.181 The combination of chelating and bridging co-ordination modes of L114 results in its complexes with Co(II), Zn(II) and Cd(II) having interpenetrated 2-D network structures and its Cu(I) complex having a helicoidal chain structure.182 N N R R N N N N NH O O HN O N N O R R N NR RN N R1 R2 N N N N N N H2L108 n = 3; R = 2-imidazolyl H2L109 n = 4; R = 4-imidazolyl (CH2) n (CH2) n L110 n = 1 L111 n = 3 L112 R = H, Me, Pri, But, Ph, CH2Ph L113 L114 Tripodal tetradentate ligands.The conversion between j3 and j4 co-ordination modes of L115 to MHgCl 2N fragments was studied by 1H NMR spectroscopy, and the results obtained in solution correlated with crystallographic studies.183 Lanthanide( III) complexes of L116 and L117 (such as seven-co-ordinate [MCl 3 L]) were prepared as structural models for species involved in solvent extraction; L117 selectively binds to actinides in solution in preference to lanthanides.184 Reversible Cu(I)–Cu(II) interconversion in [Cu(SCN)(L118)]z` (z\0, 1) causes a conformational change which triggers a very large change in the chiroptical properties of the complex, and is therefore the basis of an optically-read molecular switch.185 The crystal structures,CD spectra, and solution dynamic behaviour of Zn(II) and Cu(II) complexes with a range of conformationally mobile, chiral tripodal ligands of the type L119 were determined.186 N N R 3 L115 R = Me L116 R = H L120 R = NH–CH2–But L121 R = NH–C(O)–But N N N 3 L117 N R Me H R R L118 R = 2-quinolinyl L119 R = 2-pyridyl Annu.Rep. Prog. Chem., Sect.A, 1999, 95, 261–312 278Covalent attachment of the tris(2-pyridylmethyl)amine (L116) group to the peripheries of porphyrin cores allows the preparation of cytochrome c oxidase models containing FeIII–O–CuII and FeIII–O–O–CuII cores, in which the Fe(III) is porphyrin-bound and the Cu(II) is L-bound.187,188 The complex cis-[FeIII(OH)(O 2 CPh)(L120)]`, with an unusual FeIII–OH core, is a model for the active site of soybean lipoxygenase; the hydroxyl ligand is stabilised by hydrogen-bonding to the ligand NH groups.189 The structures and electrochemical properties of several complexes of the type [CuIIX(L121)]` were determined (X\ anion), including [CuII(O 2 )(L121)]` in which the superoxide is stabilised by the protective cavity provided by the Bu5 groups of L121.190 The co-ordinated hydroperoxide in [CuII(OOH)(L122)]` is stabilised by hydrogen-bonding to the pivalamido NH groups,191 and other complexes [CuIIX(L122)]` were prepared and structurally characterised as models for copper protein active sites.192 [MIIL]~ [M\Co, Ni, Zn; H 3 L\N(CH 2 CONHBu5) 3 ] have a trigonal monopyramidal geometry imposed by the bulky ligand and are all high spin.193 The ligand L123, based on the bispidine backbone, occupies four sites of the octahedral complexes cis-[MnX 2 (L123)] (X\Cl, I).194 N N N HN But O 2 L122 O N CO2Me N N N MeO2C L123 Oxygen-, sulfur- and phosphorus-donor ligands [Ti 2 (L124) 3 ]4~ is a triple helicate, which associates with K` cations to give a dimer in the solid state.195 [FeIII 4 (L125) 6 ]12~ is tetrahedral with one bridging ligand along each edge and an [NEt 4 ]` counter ion trapped inside the cavity (cf.ref. 158);196 with chiral analogues such as L126 the assembly is self-selective, with all six ligands in each complex cation necessarily having the same chirality even when a racemic mixture of ligand is used.197 [MMoO 2N2 (l-L127) 2 ]4~ is a chiral ‘2]2’ molecular square in which the chirality of the tris(chelate) metal centres is determined by the chirality of the ligands.198 The bulky substituents of L128 cause twisting between the two rings such that the two spins cannot pair and the ligand is a diradical; it forms a polymeric chain with MTlIIIMe 2 (thf)N` fragments in which there is strong magnetic coupling between the ligand radical centres.199 In [MRu(bipy) 2N2 (l-L129)]2` the ligand is a diradical because the meta substitution pattern of the bridging ligand prevents the two semiquinone spins from pairing; in contrast [MRu(bipy) 2N2 (l-L130)]2` (in the same oxidation state) is diamagnetic with the two spins paired across the para-substituted bridge.200 Metallomacrocyclic complexes with MV 2 (l-L131) 2Nz` [z\0, V(II); z\2, V(III)] cores have box-like structures with each bis(acetylacetonate) ligand bridging both metal centres.201 The bridging behaviour of the bis(acetylacetonate) ligands L132 results in high nuclearity complex formation, exemplified by [MnII 8 L 8 ] and Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 279HO OH HO OH O HN X NH O HO OH HO OH HO HO OH OH O –O O O– But But R R O O O O H4L124 H4L125 X = 1,5-naphthalenediyl H4L126 X = –CH(Me)–CH(Me)– H4L127 • • [L128]2– – – [L129]2– meta-substituted at central C6H4 [L130]2– para-substituted at central C6H4 • • [Mg 4 L 6 ]2~.202 Ligands of the type L133 (where X is a large spacer such as a phenyl ring or a porphyrin core) are designed to hold two carboxylate donors (L) close together in the correct orientation to bridge two metal ions, and as such have been used to prepare several MFeIII 2 (l-L) 2N complexes as models for non-heme iron protein active sites.203,204 [MMn(hfac) 2N2 (l-L134)], which contains two high-spin S\5/2 metal ions and a ligand diradical, has a spin-frustrated ground state.205 O O O O O O O O R R R R N O O R CO2H R R N O O R HO2C X H2L131 – – [L132]2– H2L133 N N N N O• O •O O L134 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 280O NH HN O SH SH HS HS S S S S PPh2 PPh2 Ph2P Ph2P H4L135 L136 The bis(dithiol) H 4 L135 acts as an S 4 -donor chelate in [Ti(L135)Cp]~ but as a bis(bidentate) bridging ligand in [MCp 2 TiN2 (l-L135)].206 The bridging ligand C 6 H 2 (PPh 2 ) 4 -1,2,4,5, L, has two P,P-chelating sites; in the trinuclear chain complex [(bipy) 2 Os(l-L)Ni(l-L)Pd(dppb)]6`, photoinduced Os(II)]Pd(II) electron transfer is switchable according to the oxidation state of the central Ni fragment.207 The ligand C 6 H 2 (CH 2 PPh 2 ) 4 -1,2,4,5 also has two P,P-chelating sites in [MRuCl 2 (PPh 3 )N2 (l-L)].208 The cumulenic bridging ligands (Ph 2 P) 2 C––C––C(PPh 2 ) 2 and (Ph 2 P) 2 C––C––C––C(PPh 2 ) 2 , with a P,P-chelating site at each end, were used to link MRu(bipy) 2N2` and MOs(bipy) 2N2` fragments; the complexes are strongly luminescent and the metal–metal interaction depends on the length of the cumulene bridge.209,210 Binuclear Pd(II) and Pt(II) complexes of L136, which is designed to allow attachment of metal fragments to a tetrathiafulvalene core, were prepared and their FAB mass spectra studied (cf.ref. 46).211 Mixed N,O-donor ligands ‘Salen’-type ligands. Chiral ligands based on the ‘salen’ core continue to be popular for asymmetric catalysis: examples include [AlCl(L137)] for the Strecker reaction; 212 [TiCl 2 (L137)] for addition of Me 3 SiCN to benzaldehyde;213 and [MnCl(L138)] for epoxidation in perfluorocarbon solvents.214 The crystal structure of [MnN(L139)] was related to its catalytic activity.215 The electronic e§ects of the substituents X on enantioselectivity of epoxidation catalysed by [MnIII(L140)]` were investigated in detail.216 Mn(III) and Ni(II) complexes of the chiral ligand L141 show modest second-order non-linear optical activity.217 On heating, oxidation of [VO(L142)] gives a double bond between the phenyl rings, facilitated by the cis-arrangement of the two H atoms that are eliminated.218 [UO 2 (L143)] catalyses nucleophilic attack of benzenethiolate on cyclopent-1-en-3-one in two ways: (i) co-ordination of the substrate to the MUO 2N2` centre is assisted by aromatic p-stacking with the phenyl substituents, and (ii) after the reaction the product is too bulky for the restricted binding pocket and dissociates quickly.219 The tetrahedral distortion around the metal centre of [Cu(L144)] reduces the steric barrier to lanthanide binding to the phenolates, allowing preparation of [Cu(L144)Gd(hfac) 3 ] for example.220 The relationship between structure and spin-state (high-spin, low-spin or spin-crossover) of several Fe(III)–salen derivatives with axial imidazole ligands was investigated.221 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 281OH N N HO R1 R2 X Y Y X Z Z H2L137 R1 + R2 = cyclo –(CH2)4–; X = Y = But; Z = H H2L138 R1 + R2 = cyclo –(CH2)4–; X = Y = C8F17; Z = H H2L139 R1 = R2 = Ph; X = Me; Y = But; Z = H H2L140 R1, R2 = Ph or cyclo –(CH2)4–; X = various; Y = But; Z = H H2L141 R1 + R2 = cyclo –(CH2)4–; X = Y = H; Z = NEt2 OH N N HO Ph Ph X X OH N N HO (CH2) n X X H2L142 (X = various) H2L143 X = Ph n = 0 H2L144 X = H, n = 1 Other ‘linear’ N,O-donor ligands.[Cu(L145)] is a functional model for galactose oxidase.222 The structures and N-atom transfer reactions of nitrido–Os(VI) and –Ru(VI) complexes with N,O-chelating ligands such as L146 were determined.223 In [Cu(L146)M(bipy) 2 ] the MM(bipy) 2N2` fragments (M\Co, Ni, Zn) are attached to the (bridging) phenolates of the MCu(L146)N2~ fragment; the complexes withM\Co and Ni are antiferromagnetically coupled.224 K[MIII(L146)(pyridine) 2 ] (M\Mn, Co) form extended polymeric networks in the solid state via association of phenolate oxygen atoms with K` ions.225 Magnetic exchange interactions between metal and ligand were evaluated for several first-row transition-metal complexes of the diradical ligand L147.226,227[MnIV 2 (l-O) 2 (l-L148) 2 ], in which each L148 acts as a bis(bidentate) bridging ligand, catalyses aerobic oxidation of alcohols and aldehydes.228 Cu(II) complexes of planar bis(oxamate) ligands can be easily oxidised to the Cu(III) form; this oxidation is reversible for [Cu(L149)]2~ but irreversible for [Cu(L150)]2~.229 Protonation of the pendant pyridyl group of [Cu(L151)] perturbs the spectroscopic and electrochemical properties of the Cu(II) centre via a through-space electronic interaction. 230 The phenolate-bridged dinuclear complex [MNi(HL152)(MeOH)N2 ]2` rearranges to give a cyclic imidazolate-bridged tetramer [MNi(L152)N4 ] on deprotonation of the imidazole group, in contrast to [Cu(L152)] = which is a linear chain polymer.231 Cu(II) complexes of L153, such as square pyramidal [CuCl(L153)], may be suitable for radiopharmaceutical applications.232 The structures and spin-states of first-row transition- metal complexes of L154 were determined.233 Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 261–312 282OH NH HN HO But But But But OH NH O HN O HO N N N N N N O O• •O O H2L145 H4L146 L147 NH HN O O O OH HO O O OH NH HN O HO N R OH N N R OH N HN N H4L148 X = 1,2-C6H4 H4L149 X = (CH2)3 H4L150 X = 1,8-naphthdiyl X H2L151 H2L152 R = 2-phenylimidazol-4-yl H2L154 R = 2-aminophenyl HL153 R = 3- or 4-pyridyl Ligands with two bidentate compartments. [Cu 4 (l-L155) 4 ] is a tetranuclear double helicate containing two planar and two pseudo-tetrahedral Cu(II) centres.234 In the metallomacrocyclic complexes [Cu 2 (HL156) 2 ]2`, both ligands act as an N,O-chelate to each metal ion and the edifice is stabilised by inter-ligand hydrogen-bonding involving the oxime OH groups; alternatively L156 can co-ordinate as N 4 -donor chelates to give mononuclear complexes.235,236 The paramagnetic bridging ligand L157 forms 1-D237 and 2-D238 polymeric complexes with Mn(II) which display a range of interesting magnetic properties such as ferro- and ferri-magnetism.The complexes [MM(bipy) 2N2 (l-L158)]2` (M\Ru, Os) display both metal-centred and ligand-centred redox activity, with ligand-centred oxidations giving a bridging quinone; the mixed-valence M(II)–M(III) forms of the complexes are strongly interacting.239 In [MRu(bipy) 2N(l-L159)MCu(phen)(H 2 O)N]3` the luminescence of the MRu(bipy) 3N2` Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 283fragment is quenched by the Cu(II) at the amino acid site, despite negligible electronic coupling between the metals in their ground states.240 OH N S O O N HO N O NH OH HN O N HO N N N N O O• N OH HO N N N N N O N (CH2) n NH2 OH O H2L155 (CH2) n H2L156 n = 2, 3, 4 H HL157 H2L158 H HL159 Tripodal ligands.Vanadyl complexes of the amine–carboxylate tripodal ligands L160 and L161 are models for halogenoperoxidases; reaction with H 2 O 2 a§ords peroxo–V(V) complexes.241 Binuclear Mn(II) complexes such as [Mn 2 (H 2 O) 4 - (L160) 2 ]2` and Mn(IV) complexes such as [Mn 2 (l-O) 2 (L162) 2 ]2` are derived from interconnected monomeric MMnLN units.242 Monomeric and O-bridged dimeric complexes of Zn(II) with L160 or L163 were prepared and characterised.243 The trigonal bipyramidal complexes [CuX(L164)] (X\acetate, SCN) have phenolate in the axial position and are structurally reminiscent of the galactose oxidase active site; their anion-binding properties (e.g.with azide, cyanide) were studied.244 Square pyramidal FeIII complexes with mixed-donor tripods such as L165–L168 were prepared as models N N O OH (CH2) n R N X HO 3–m m HL160 m = 2, n = 1 H2L161 m = 1, n = 1 HL162 m = 2, n = 2 m 3–m HL163 m = 2, R = 2-pyridyl, X = H HL164 m = 2, R = 2-pyridyl, X = NO2 H2L165 m = 1, R = 2-pyridyl, X = NO2 HL166 m = 2, R = 2-benzimidazolyl, X = NO2 H2L167 m = 1, R = 2-benzimidazolyl, X = NO2 HL168 m = 2, R = 2-pyridyl, X = Br Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 284HO O N N NH N N HN HN N CO2H N OH OH R2 R1 R3 R4 NMe2 2 HL169 HL170 HL171 for catechol-1,2-dioxidase and do show some catalytic activity.245 [CuCl(HL163)Cl]` has an apical (protonated) phenol at the axial site and is a structural model for galactose oxidase.246 The O-atom transfer reactivity and electrochemical properties of [MMVIO 2NL] (M\Mo, W; L\a tripodalN 2 O 2 donor such as L165) were studied; the complexes catalyse oxidation of benzoin by dmso.247 [Zn(H 2 O)(L169)]` is a zinc peptidase model and catalyses amide hydrolysis.248 The structural characterisation of oxo–Re(V) complexes with ligands such as N(CH 2 py) 2 (CH 2 CH 2 OH) was used to visualise the mechanism of stepwise chelation of the multidentate ligand.249 In [CuII 2 Cl 2 (L170) 2 ] both ligands are bridging.However, EPR spectroscopic studies reveal a monomer–dimer equilibrium in solution.250 The nuclearity and hence magnetic properties of phenolate-bridged polynuclear Mn(II) and Mn(III) complexes with L171 depend on the steric properties of the ligand substituents.251 Mixed N,S-donor ligands [NiII(H 2 O) 2 (NSSN)]2` [NSSN\py(CH 2 ) 2 S(CH 2 ) 2 S(CH 2 ) 2 py] is a model for nickel metalloprotein active sites; its Ni(I) analogue was also characterised.252 The squarepyramidal complex [FeIIICl(L172)], which has a spin of S\3/2, was characterised by UV/VIS and EPR spectroscopy and electrochemistry; reaction with OH~ a§ords [MFe(L172)N2 (l-O)].253 Reaction of the thiolate-bridged dimers [M 2 (L173) 2 ] (M\Zn, Cd) with MeI a§ords mononuclear complexes [MI 2 (L174)] in which L174 is N,Nbidentate.This behaviour models that of Zn-dependent methylation enzymes.254 Reaction of [FeII 2 (L173) 2 ] with O 2 a§ords [MFeIII(L173)N2 (l-O)], in which two of the bridging thiolates of the starting material are replaced by the oxo ligand.255 Hexanuclear Fe–S clusters containing L175 have ‘nest-like’ and ‘stair-like’ structures.256 The electrochemical properties of [MII(L176)] (M\Ni, Cu), which may have squareplanar or flattened tetrahedral structures depending on the length of the linking group between the two halves of the ligand, were determined.257 First-row transition-metal complexes of ferrocenyl–Schi§ base ligands with N,S donor sets, such as L177, were prepared.258 [Ni(L178)]z~ (z\1, 2) was structurally characterised in both Ni(II) and Ni(III) oxidation states, the latter being unusual with thiolate ligands.The structures reveal a slight shortening of the metal–ligand bonds on oxidation.259 [MII(L179)] (M\Cu, Ni, Pd) can have 5,5,5- or 5,6,4-membered chelate rings, depending on which N atoms are used to complete the SNNS donor set.260 Alkyl substituents on the [Cu(L180)] core control the Cu(I)–Cu(II) redox potential, which Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 285N N SH HS Ph Ph Ph Ph N N SR SR N N SH SH SH N R MeS N HS R SMe H2L172 H2L173 R = H L174 R = Me H2L175 L H2L176 S NHPh S PhHN NH HN HS SH O O N N N SH HS N R3 2N NR3 2 R1 R2 SH S HN HS O R R SH S N O O HN O OC6F5 SH N HN HS O O CO2 Me H+ N HN Fe H2L177 H4L178 H2L179 R1 = Ph; R2 = H; R3 = Et H2L180 R1, R2, R3 various H3L181 R = H H3L182 R = Me H H3L183 H3L184 – allows optimisation of the uptake of 64Cu-labelled complexes in hypoxic cancer cells.261 Whereas [ReO(L181)] decomposes on reaction with tertiary phosphines by loss of the CH 2 CH 2 SH group, stable six-co-ordinate phosphine adducts [ReO(PR 3 )(L182)] can be isolated.262 The reactive pendant ester group of L183, an N,N,S,S-donor, should allow covalent attachment of radiolabelled [ReO(L183)] to proteins.263 Two isomers of the square-pyramidal complex [ReO(L184)], having di§erent orientations of the oxo group, were separated by HPLC.264 Fe(III) complexes of the NS 3 -donor podand [N(CH 2 CH 2 S) 3 ]3~ are models for sulfur-rich Fe metalloproteins.265 The tetrahedral complexes [Ga(L185)] and [In(L185)] show less tendency to expand their co-ordination sphere than do the complexes with the phenolate-based analogues, which influences their utility as in vivo diagnostic imaging agents.266 Monomeric and thiolate-bridged dimeric complexes of Zn(II) with L186 were prepared.267 Cu(I) and Cu(II) complexes of Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 286N(CH 2 CH 2 py) 2 (CH 2 CH 2 SMe), L, are models for the Cu B centre of dopamine b- hydroxylase; reaction of [CuL(NCMe)]2` with H 2 O 2 results in oxidation of the thioether group of L to a sulfoxide.268 N N HS n m H3L185 n = 0, m = 3 HL186 n = 2, m = 1 Other mixed-donor ligands Photosubstitution of axial monodentate ligands (e.g.halide, phosphine) in Ru(II) and Ru(III) complexes of L187 (an N 2 S 2 donor) and L188 (an N 2 P 2 donor) was examined. 269 The 31P NMR spectra and Cu(I)–Cu(II) redox potentials were examined for the series [Cu(L189)]z` (z\1, 2) as a function of the length of the polymethylene chain in the ligand.270 3,6-Bis(diphenylphosphino)pyrazine (L) acts as a tetranucleating bridging ligand in the polymeric chain complex [MAg 2 (NCMe) 2 (l-L) 2N2`] = .271 Ni(II), Pd(II) and Pt(II) complexes of the P,N,N,P-donor ligands L190 display a variety of ligand co-ordination modes including N 2 P 2 chelating to one metal ion and N,Pchelating to each of two metal ions.272 [ReVL 2 ]~ [H 3 L\P(C 6 H 4 SH-2) 3 ] is eightco- ordinate with a P 2 S 6 ligand set.273 The new ligand Ph 2 P(CH 2 ) 2 S(CH 2 ) 3 S(CH 2 ) 2 PPh 2 , L, is a P,S,S,P-chelate in trans-[CoIIICl 2 L]`, but only P,P-chelating in [CoIII(dtc) 2 L]`.274 R N N R PPh2 NH HN Ph2P X X Y Y Ph2P PPh2 X L187 R = SBut L188 R = PPh2 (CH2) n L189 n = 2, 3, 4, 5 L190 X = CH, Y = N L191 X = N, Y = CH Ni(II) complexes with the N 2 SO ligand series L192 have basically planar geometries with varying degrees of tetrahedral distortion; they undergo metal-centred reduction to Ni(I), and the EPR and UV/VIS spectroscopic properties of the reduced complexes were determined.275,276 Complexes of L193 display a variety of di§erent co-ordination Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 287S MeS NH HO R1 N R2 OH N SH SH (CH2) n H2L192 H3L193 modes, including tetradentate to MVON3` and MMoO 2N2` fragments and N,S,Stridentate to Ni(II); ligand-centred oxidation a§ords co-ordinated g2-sulfenate groups.277 4 Pentadentate ligands Nitrogen-donor ligands In the solid state [MCo 2 (L194) 2N2 (l-OAc) 2 ]6` contains two double helical MCo 2 (L194) 2N4` units of opposite chirality linked by the two bridging acetate groups; this association does not persist in solution.278 In [Cu 2 (L195) 2 ]2`, which is a chiral metallocyclophane, the bridging ligand L195 adopts a bis(bidentate) co-ordination mode with one of the pyrazine N atoms not co-ordinated.279 [Ni 5 X 2 (l5 -L196) 4 ] (X\terminal monodentate anion) have linear chain structures; the two terminal octahedral Ni(II) centres with S\1 are weakly antiferromagnetically coupled through the three intervening planar (S\0) Ni(II) centres.280 [Cu(L197)] has a distorted square pyramidal structure with an axial pyrazole group.281 The alkylperoxo-complexes [CoIII(OOR)L] (L\L197, L198) are intermediates in the Co-catalysed oxidation of hydrocarbons by ROOH.282 The ligand L199 co-ordinates to five sites of an octahedron in mononuclear [NiX(L199)]` (X\monodentate anion) and dinuclear [MNi(L199)N2 (l-X)]3` which have weak antiferromagnetic coupling across the single bridge.283 In [(H 2 O)Cu(l-L)(l-OAc)CuCl]2` (L\pyCH 2 NH- (CH 2 ) 3 NH(CH 2 ) 3 NHCH 2 py) the two Cu(II) centres are bound at tridentate and bidentate sites of L, and are ferromagnetically coupled across the acetate bridge because of the accidental orthogonality of their magnetic orbitals.284 The double helical core of [Cu 2 (L200) 2 ]z` (z\2, 3, 4) is retained in all three oxidation states Cu(I)–Cu(I), Cu(I)–Cu(II) and Cu(II)–Cu(II), with each bridging ligand being either tetradentate or pentadentate according to the requirements of the Cu(I) or Cu(II) centres.285 Mixed N,O-donor ligands The crystal lattice packing of trigonal bipyramidal [Cu(L201)] and squareplanar [Ni(L201)] are very di§erent, because the non-co-ordinated acetyl group of [Ni(L201)] allows formation of hydrogen-bonded columns.286 Trigonal bipyramidal [Co(L202)] binds O 2 reversibly in solution.287 The heteronuclear triple helicate [LnIIICoII(L203) 3 ]5` (Ln\a lanthanide), which contains nine-co-ordinate lanthanide and six-co-ordinate Co(II) may be oxidised to the kinetically inert [LnIIICoIII(L203) 3 ]6` form with Br 2 ; removal of the labile lanthanide ion a§ords the complex fac- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 288N N N N N R R N N N N N N O HN O NH R R N H2N NH2 H2N NH2 N N N N N L194 R = 4-chlorophenyl L195 H2L197 R = pyrazol-1-yl H2L198 R = 2-pyridyl L199 H H H2L196 N N N N N R R L200 R = 4-MeOC6H4 N O HN O NH O O OH N N N HO But But N N N N N N O Et2N N N N CO2H HO2 C R1 R1 R2 R2 H2L201 H2L202 L203 H2L204 R1 = H, R2 = Me H2L205 R1 + R2 = cyclo-(CH2)3 [Co(L203) 3 ]3` in which the three pendant tridentate sites form a preorganised nonadentate cavity.288 The chiral complexes [CoIIIXL]` (X\neutral monodentate ligand; L\L204, L205) exhibit stereoselectivity in their inner-sphere redox reactions with chiral Fe(II) complexes.289 Multinuclear cryptates and triple helicates are formed by L206 with a wide range of metal ions, in which each ligand bridges three metal centres.290,291 [Mn 2 (l-L207) 2 ]z~ (z\0, 1, 2) are e¶cient catalase models, and catalyse H 2 O 2 disproportionation.292 Tri- and tetra-nuclear complexes of Mn(II) with the flexible bridging ligand L208, such Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 289R O O N O R O OH N OH N HO X X R1 N N OH OH HO R2 R2 R3 R3 R3 R3 OH N N NMe2 Me2N Br OH N N NMe2 Me2N H2L206 n n H3L207 n = 1 H3L208 n = 2 H3L209 HL210 HL211 OH HO N N OH N N N N OH OH O NH N N O H3L212 H2L213 H2L214 as [Mn 3 (L208) 2 (l-OAc)]~, were prepared.293 [CuIIX(L209)] (X\OMe, OH, Br) is antiferromagnetically coupled and undergoes two reversible reductions to the Cu(I)–Cu(I) state.294 Phenolate-bridged dinuclear Ni(II) complexes of L210 and L211 were prepared as models for the active site of urease.295 In the hexameric cluster [MnIII 6 (MeOH) 6 (L212) 6 ] the ligand L212 has one O,N,Otridentate and one N,O-bidentate binding pocket.296 In [VO(HL213)]` the hydroxyethyl arm is not co-ordinated; comparison of the V(IV)–V(V) redox potential with other related complexes shows a linear relationship with the number of co-ordinated phenolates.297 The four-co-ordinate complexes [M(L214)] (M\Ni, Cu) can co-ordinate other metal ions via the oximate and ketonic O-donors to form dinuclear and trinuclear complexes; antiferromagnetic exchange was detected in various mixedmetal dinuclear complexes.298 The potentially hexadentate ligand L215 binds strongly to lanthanides (Ln) in water to give either [Ln(L215) 2 ]3`, in which the ligand is neutral and pentadentate with one pendant hydroxyl group, or [Ln(L215)(H 2 O)n]3` which shows strong phosphodiesterase activity.299 The structures, spectroscopic properties and stability constants of oxovanadium(V) and dioxomolybdenum(VI) complexes with Schi§-base ligands such as L216, containing multiple alkoxide donors, were examined. 300 Cu(II) complexes of L217 form polymeric networks, via the externally-directed carboxylate group which links monomer fragments together.301 The N,N,N-tridentate and O,O-bidentate binding pockets of L218 allow preparation of trinuclear complexes [(hfac) 2 MnII(L218)MII(L218)MnII(hfac) 2 ] (M\Mn, Fe) in which the central metalMis Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 290N 6 co-ordinated; the complexes display antiferromagnetic exchange.302 Several C 2 - symmetric binucleating ligands, of which L219 is a representative example, were prepared for possible use in asymmetric homogeneous catalysis;303 the crystal structures of several binuclear complexes of Ni(II), Cu(II) and Zn(II) with these ligands having both exogenous and endogenous bridging ligands were determined.304 N HO HO OH OH OH OH N OH OH OH R1 R2 R3 N HN H2N OH N N O O N OH N O O N N N N N HO2C L215 H4L216 H2L217 H HL218 HL219 Other mixed-donor ligands [MCuII 2 (H 2 PO 4 ) 2 (HL220)N2 ]2` has a ‘dimer of dimers’ structure with S and [H 2 PO 4 ]~ bridging ligands; there are three inequivalent antiferromagnetic exchange interactions within the tetranuclear unit.305 Whereas [M(L221)]` (M\Cu, Ag, Au) are four-coordinate with the ligand acting as a P 2 S 2 -chelate, [Cd(CF 3 SO 3 ) 2 (L221)] is seven-coordinate with the ligand pentadentate.306 The five-co-ordinate, low-spin complex [FeIIIL]` [where H 2 L is the S 2 N 3 -chelate HSC(Me) 2 C(Me)–– N(CH 2 ) 3 NH(CH 2 ) 3 N–– C(Me)C(Me) 2 SH] is a model for the active site of nitrile hydratase; reaction with azide forms the adduct [Fe(N 3 )L] which mimics the azide-inhibited form of the active site.307 Crystal structures of five-co-ordinate [MIIL] [where H 2 L are the S 2 N 3 - chelates HSCR 2 CH(Me)NH(CH 2 ) 3 NH(CH 2 ) 3 NHCH(Me)CR 2 SH, R\H or Me; M\Fe, Co, Ni, Zn] reveal a helical co-ordination mode of the ligand.308 5 Hexadentate ligands Nitrogen-donor ligands Ligands with two tridentate compartments.In binuclear [MRu(terpy)N2 (l-L222)]4` the electronic interaction across the bridging ligand is moderately strong, leading to a clear inter-valence charge transfer transition for the Ru(II)–Ru(III) state;309,310 the Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 291N N N N N N N py N py py py N py N py N N py py py N HN S HN N py N S S PPh2 Ph2P L222 L223 + + (L224)2+ H2L220 L221 N py py N O O N O O N py py N N N N N N R1 R1 R3 R2 R2 L225 L226 R1 = SPr; R2 = R3 = H L227 R1 = H; R2 = Me; R3 = Ph electrochemical and luminescence properties of trinuclear [(ttpy)Ru(l-L222)Ru(l- L222)Ru(ttpy)]6` were also determined.310 [(terpy)Ru(l-tppz)RhCl 3 ]2` undergoes photoinduced Ru]Rh electron-transfer after excitation.311 Attachment of a Zn(II) ion to the pendant terpyridyl site of [Ru(ttpy)(L223)]4` results in the Ru-based luminescence intensity being increased by an order of magnitude.312 [FeII 2 (L224) 2 ]8` has a box-like structure containing two MFe(terpy) 2N2` units.313 The bridging ligand L225 gives linear trinuclear complexes [(terpy)Ru(l-L225)M(l-L225)Ru(terpy)]6` (M\Fe, Ni) which were shown by electrospray mass spectrometry to undergo multiple protonations at the basic macrocyclic sites.314 Tetranuclear 2]2 molecular grids [M1(M2) 2 M3(L226) 4 ]8` could be prepared with up to three di§erent metal ions at specific locations in the grid, by a stepwise ‘toposelective’ method.315 Grid-like complexes such as [Cd 4 (L227) 4 ]8` were incorporated into monolayers.316 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 292N N N N B N N N N H H B B N N N N N N N N N N N N R R R R R R B B N N N N N N N N N N N N R R R R R R O N N py py py py Ph Ph Ph Ph N N py py py py N N H2N H2N NH2 NH2 [L228]– Fe [L229]– R = H, Me, Ph [L230]– R = H, Me DNA L231 Fe L232 L233 Whereas [CuII 2 (L228) 2 ]2` and [K 2 (L228) 2 ] are conventional double helicates, in [Gd(NO 3 ) 2 (L228)] the ligand L228 is a pseudo-equatorial hexadentate chelate.317 ‘Back-to-back’ attachment of two tris(pyrazolyl)borates gives dinucleating bridging ligands: Tl(I) complexes of L229 and nitrosyl–Mo(I) complexes of L230 were prepared and characterised.318,319 Sequence-specificRNA cleavage using the dizinc(II) complex of L231 requires cooperation of both Zn(II) ions in the dinuclear complex.320 Coordination of Zn(II) to [L232]` (in the ferrocenium form) increases the redox potential of the Fe(II)–Fe(III) couple, triggering oxidation of another substrate which could not be oxidised by free [L232]` alone.This is the basis of a Zn(II)-controlled regulatory system for redox reactions.321 [CuII 2 (L233)(l-OH)(l-OAc) 2 ]2` is strongly antiferromagnetically coupled.322 Binuclear Ni(II) complexes of L234 and L235 with endogenous pyrazolate and exogenous hydroxide bridges were investigated as urease models; all are strongly antiferromagnetically coupled.323 Recrystallisation of binuclear complexes such as [Ni 2 Cl 2 (l-Cl)L] (L\L235, L236) can result in the formation of infinite 1-D chains in which two chloride bridges link adjacent dinuclear complex units; antiferromagnetic coupling occurs both within the dimer and between dimer units in the chain.324 Whereas [Cu(HL237)]3` is five-co-ordinate with one pendant arm protonated, [(H 2 O)CuII(L238)CuII(OH)]3` is dinuclear with L238 acting as a bis(tridentate) bridge.325 [Cu(L239)]2` is also five-co-ordinate with one pendant arm, irrespective of the length of the bridging group in the ligand.326 Mononuclear complexes of L240 with Zn(II), Pd(II) and Ru(II), in which one tridentate pocket is vacant, are good building blocks for 1-D oligomers.327 [CuII 2 (L241)(l-OH) 2 ]2` catalyses oxidation of phenol by Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 293N NH N N Me2N NMe2 R R R R N R R N (CH2) n N N py py py py N N py py py py HL234 R = (CH2)3NMe2; x = 3 HL235 R = Me; x = 3 HL236 R = Me; x = 2 (CH2) x (CH2) x L237 n = 2; R = NH2 L238 n = 2; R = NMe2 L239 n = 2 to 5; R = 2-pyridyl L240 L241 N N N OH N N N N N OH L242 H 2 O 2 , probably via a l-1,1-superoxo-bridged intermediate which was characterised. 328,329 The ligand L242 is linear when free in solution; on metal-ion co-ordination, e.g. in [MCo(NO 3 ) 2N(L242)], each tridentate site creates a chiral pocket around the metal to give a meso-helical structure.330 Ligands with three bidentate compartments. NMR and mass spectrometric measurements as a function of time showed how mixtures of L243 with Ni(II) or Fe(II) first form a triple helicate [M 3 (L243) 3 ]6` (the kinetic product), followed by slow rearrangement to the circular helicate [M 5 Cl(L243) 5 ]9` with an anion in the central cavity (the thermodynamic product).331 The imino-bridged oligo(bipyridyl) ligand L244 gives double helicates with Ag(I) and Cu(I).332 The mixed-metal Ru(II)–Os(II)–Ru(II) and Os(II)–Ru(II)–Os(II) complexes with L245 were prepared by Pd-catalysed cross-coupling reactions of functionalised metal monomer units.333 The dipyrromethene trimer L246 forms a trinuclear double helicate with Zn(II).334 The high-spin six-co-ordinate complex [Fe(L247)]2` forms an adduct with superoxide despite the steric congestion around the metal centre.335 Deprotonation of the imidazole groups of the low-spin six-co-ordinate complex [Fe(L248)]3` allows it to associate with metalloporphyrin and MM(hfac) 2N fragments to give polynuclear adducts. 336 [Cu(H 3 L249)]2` is chiral due to the skew of the ligand; partial deprotonation of the imidazole groups results in assembly of a hydrogen-bonded network of homochiral complex units in the crystal.337 Luminescence from the Ru(II) complexes of tris(bipyridyl) podands such as L250 is enhanced compared to that of [Ru(bipy) 3 ]2`, and the podand complexes have greater photochemical inertness.338 Removal of the ester head-group of optically pure [Ru(L251)]2` by hydrolysis gives specifically the fac-[Ru(bipy) 3 ]2` derivative; the head-group can therefore be used as a template to orient the three ligand strands and prevent formation of the more usual mer tris(chelate).339 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 294N N N N N N N N N N N N N N N N N N N N N N N N N N Et Et Et Et Et Et L243 L244 L245 – – – [L246]3- N N NH N N N R2 N N Me O O NH O N N NHCO2Et C6H3 N N R1 3 3 L247 R1 = H, R2 = CPh3 L248 R1 = Me, R2 = H H3L249 3 3 L251 L250 -1,3,5 Other N-donor ligands.The stability constants of the octahedral complexes [ML]2` were determined as a function of chelate ring size for M\Co, Ni, Cu, Zn [L\pyCH 2 NH(CH 2 )nNH(CH 2 )mNH(CH 2 )nNHCH 2 py; n\2 and m\3, or n\3 and m\2].340 Oxygen-donor ligands 1H NMR spectroscopy shows that the trinuclear triple helicate [Ti 2 (L252) 3 ]6~ undergoes racemisation by consecutive inversion of the three centres.341 In the tetrahedral complex [Ti 4 (l3 -L253) 4 ]8~ each ligand caps one triangular face of the metal tetahedron. 342 [MRu(bipy) 2N3 (L254)]z` is part of a seven-membered redox chain based on ligand-centred interconversions between the tris(catecholate) (z\0) and tris(quinone) Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 295HO OH HO OH HO OH C6H3 NH O HO OH H6L252 3 H6L253 HO OH OH OH OH HO H6L254 HO OH OH OH HO HO H6L255 O NH N –O3S SO3 – SO3 – HO OH 3 H6L256 O N N OH O Me 3 H3L257 –1,3,5 (z\6) states, and has a very strong low-energy MLCT transition which is tuneable over a wide range according to oxidation state.343 [MPt(P–P) 2N3 (L255)] (where P–P is a diphosphine) is bowl-shaped, and undergoes three well-separated reversible redox interconversions.344 New tripod ligands containing three 2,2@-dihydroxybiphenyl345 or hydroxamate346,347 units, for example L256 and L257, have very high binding constants with Fe(III).Mixed N,O-donor ligands The neutral triple helicates [Ln 2 (L258) 3 ] [Ln\lanthanide(III) ion] are thermodynamically very stable in aqueous solution and luminescent for Ln\Eu.348 In the triple helicates [Ln 2 (L259) 3 ]6` the carboxamide groups contribute to the e¶cient ligand-to-metal energy transfer, which results in strong luminescence for the Eu complex, and are also resistant to hydrolysis.349 The compartmental ligands L260 and L261 were used to prepare heterodinuclear complexes containing a transition-metal ion in the inner N 2 O 2 -donor compartment and a lanthanide in the outer O 4 -donor compartment, linked by phenolate bridges; there is usually weak magnetic exchange between the two metal ions.350–352 Oxamide-based bridging ligands such as L262 can have either a cis conformation with separate N 4 - and O 2 -donor compartments, or a trans conformation with two N,N,O-donor compartments, allowing the build-up of multinuclear transition-metal complexes (from dinuclear to infinite polymeric networks) which generally display strong antiferromagnetic coupling across the oxamide Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 296N N N N N N R2 O O R2 R1 R1 OH N N OMe HO MeO NH2 NH HN H2N O O N O N N N O N N H2L258 R1 = Et, R2 = OH L259 R1 = NEt2, R2 = Me or Et R H2L260 R = CH2CMe2 H2L261 R = CH2CMe2CH2 H2L262 H H R H2L264 R = (CH2)2, (CH2)3, 1,2-C6H4 N N OH HO HO OH R1 R1 R2 R2 H4L263 bridge.353–356 Two equivalents of [M(H 2 L263)] (M\Mn, Fe, Co, Ni, Cu), in which the metal ion is in the inner N 2 O 2 -donor compartment, can be attached via the pendant catechol site to a MMo 2 O 5N2` unit such that the two MM(H 2 L263)N units are confacial; this allows cooperative binding of small molecules between the two metals M.357 The dinuclear complexes [CuII 2 X 2 (L264)]2` (X\Cl, Br) are antiferromagnetically coupled and catalyse oxidation of catechol to quinone.358 Binuclear Cu(II) complexes of the compartmental bis(hydrazones) L265 are possible antitumour agents; phenolate-bridged polymers can also form.359 The ligand L266 contains an edta-type backbone with pendant uracil fragments, allowing its complexes to associate with other hydrogen-bonding receptors.360 The stability constants of Cu(II) and Ni(II) complexes of the podand L267 were determined by potentiometry; a wide range of 1: 1 complexes can form.361 The cytotoxicity of octahedral [Mg(L268)], which is structurally similar to the Ga(III) analogue, was investigated in drug-sensitive and multidrug- resistant cells.362 The crystal structures and spin states of Fe(III) complexes with the open-chain ligand L269 and the podand L270 were investigated.363 The asymmetry of the bridging ligand L271 allows the preparation of complexes such as [Fe 4 (l-O) 2 (l- OAc) 2 (L271) 2 ]4` where the metals have di§erent co-ordination numbers (five and six), which are models for non-heme iron protein models containing inequivalent metal centres.364 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 297OH N N O O N N HO (CH2) n N N O O CO2H HO2C NH HN HN NH HN NH O X O X R R N HO SO3 – Me N N N N OH HO R R Me N HO N OH N Me R R R H H H4L265 H2L266 X = O, S; R = H, CO2H, NH2 H2 + 3 H3L267 H H H2L268 R = OMe H2L269 R = H 3 H3L270 HL271 R = 2-benzimidazolyl Other mixed-donor ligands The electronic couplings in mixed-valence Ru(II)–Ru(III) complexes across the cyclometallated bridging ligands L272 and L273 were measured, as a function of the length and substitution pattern (para or meta) of the bridging ligand and the position of the cyclometallated sites.365 Octahedral [Ni(L274)], with anN 2 S 2 O 2 donor set, undergoes metal-centred oxidation.366 The electrochemical properties of octahedral [Ni(L275)], with an N 4 S 2 donor set, and pseudo-tetrahedral [Cu(L275)], with an N 4 donor and the thioether groups pendant, were investigated.367 6 Ligands of higher denticity Nitrogen-donor ligands The emission properties of [MRu(terpy)N2 (l-L276)]4` may be modulated by protonation, alkylation or metal-ion co-ordination at the central bipyridyl site.368 [MCoII(NCS)N2 (l-L277)] contains two trigonal bipyramidal Co(II) centres with no magnetic interaction between them.369 U(III) and La(III) complexes of the heptadentate podand L278 were prepared;370 the Cd(II) complex of the structurally very similar podand L279 was also investigated by solution NMR spectroscopy.371 Polynuclear Cu(II) complexes of multidentate amine–benzimidazolyl ligands, such as L280 and L281, were prepared as models for tyrosinase; some show catechol oxidase activ- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 298py py py py H H N N py py H H OH N S S N OH N O NH S S HN O N n H2L272 H2L273 H2L274 (CH2) n H2L275 n = 2, 3 N py py N N N py py N N N N py py py py N N N N N N L276 L277 3 L278 L279 ity.372,373 In [Zn 2 (H 2 O)(OH)(L282)]2` the H 2 O and OH~ ligands are hydrogenbonded together to give e§ectively an [H 3 O 2 ]~ bridge, which acts as a ‘protected’ source of hydroxide; this complex shows more activity to CO 2 hydration than do complexes with a MZn 2 (l-OH)N3` core.374 Ligand L282 was also used to prepare dinuclear Ni(II) complexes containing deprotonated urea or carbamate ion as bridging ligands, which thereby model the substrate-bound and product-bound forms of urease.375 In binuclear Co(II) complexes of L282 and L283 the presence or absence of an exogenous bridge, and its co-ordination mode, depend on the lengths of the ligand arms.376 The dodecadentate ligand L284, which contains two hexadentate podand cavities linked by a B–B bond, was used to prepare dinuclear lanthanide complexes with one metal ion in each hexadentate cavity.319 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 299N N R N R R R R N N N R R R R N N NH N N NR2 NR2 R2N R2N B B N N N N N N N N N N N N N N N N N N L280 R = N-methyl-2-benzimidazolyl L281 R = N-methyl-2-benzimidazolyl n n n n HL282 n = 2, R = Et HL283 n = 3, R = Me 2– [L284]2– Mixed N,O-donor ligands [RuIII 2 (l-O 2 CR) 2 (l-L285)]~ (R\Me, Ph) are strongly antiferromagnetically coupled and can be reversibly converted to all oxidation states from Ru(II)–Ru(II) to Ru(III)–Ru(IV).377 [CuII 2 (py) 2 (l-L285)]~, containing two square pyramidal Cu(II) centres, is strongly antiferromagnetically coupled in the solid state but only weakly so in solution because of a geometric change.378 An Fe(III) ion co-ordinates to the non-symmetrical ligand L286 at the ‘hard’ carboxylate-rich site; reduction to Fe(II) causes translocation of the metal ion to the softer pyridine-rich binding site.379 [MnII 2 (MeOH) 2 (l-L287)]` is a model for the catalase active site.380 The multiplybridged tetranuclear Fe(III) cluster [Fe 4 (l-O)(l-OH)(O 2 CR) 2 (L288) 2 ]~ is a non-haem iron protein structural model,381 and [NiII 2 (l-O 2 CR)(l-L289)]2` (R\Me, Et) are models for the urease active site.382 In [CuII 2 (l-OAc)(H 2 O) 2 (H 2 L290)]2` the coordinated phenol groups, unusually, retain their protons.383 Asymmetric dinuclear iron complexes [FeIIFeIII(l-L)(l-O 2 CPh) 2 ]2` (L\L291, L292) show inter-valence charge transfer transitions in their electronic spectra and can be electrochemically converted between the Fe(II)–Fe(II) and Fe(III)–Fe(III) states.384 Lanthanide and transition-metal complexes of numerous multidentate Schi§-base podands such as L293 and L294 were prepared.385 Heterodinuclear lanthanide complexes [Ln!Ln"(NO 3 ) 2 (L294)]` were prepared in which the lanthanide ions in the ‘inner’ N 4 O 3 -donor and ‘outer’ O 6 -donor compartments are linked by bridging phenolates; the Gd(III)–Gd(III) complex shows very weak antiferromagnetic exchange.386 In contrast [FeIIIGdIII(L294)]3` is ferromagnetically coupled with an S\12/2 ground state.387 In [Pb 2 (L294)] the two Pb(II) ions are likewise linked by phenolate bridges although the ‘outer’ Pb(II) ion is only three-co-ordinate, with a stereochemically active lone pair, because the methoxy groups are not co-ordinated.388 The formation constants of lanthanide complexes with podands such as L295 having flexible backbones were determined; in the 1: 1 complexes the ligand is heptadentate, but in the 1: 2 metal: ligand complexes the ligand is O,O,O-tridentate only.389 The dodecadentate Annu.Rep.Prog. Chem., Sect. A, 1999, 95, 261–312 300OH N N R2 R2 R1 R1 N N OH R1 R1 R2 R2 N OH R R N R R H5L285 R1 = R2 = CO2H H3L286 R1 = CO2H; R2 = 2-pyridyl HL287 R1 = R2 = 2-pyridyl H5L288 R1 = R2 = CO2H HL289 R1 = R2 = N-methyl-2-imidazolyl H3L290 R1 = 2-pyridyl; R2 = C6H4OH-2 HL291 R = 2-pyridyl HL292 R = 6-methyl-2-pyridyl N N HO O Cl N HO MeO N HN P Ph O– O N N N O N N HN O NH O HO 3 H3L293 3 H3L294 + 3 H3L295 3 H3L296 tripodal ligand L296 has 2,2@-bipyridyl sites [for Fe(II)] and salicylamide sites [for Fe(III)] and is one of an extensive series of related ligands.390 Two tetradentate ‘Cr(III)–salen’ units may be linked by flexible chains either ‘backto- back’, as in L297, or ‘side-by-side’; co-operative asymmetric catalysis is an order of magnitude more e¶cient than with monomeric complexes, because the flexible linkers allow easy formation of the required transition state.391 Binuclear Eu(III) complexes of dinucleating ‘bis(salen)’ ligands such as L298 are strongly luminescent, because of e¶cient ligand-to-Eu energy transfer.392 The three binding pockets of L299 allow stepwise preparation of heterotrinuclear complexes such as [(Me 3 tacn)(FeIIICl 2 )MCuII(MeOH)NNiII(L299)] in which the ‘inner’ and ‘outer’ N 2 O 2 sites are occupied by Ni(II) and Cu(II) respectively, and the two oximate O-donors bind Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 301But But OH N N HO But O O But OH N N HO But But OH N N OH H2C OH N N OH N HO N HO OH N N OH O O py py n H4L297 n = 2 to 10 2 H4L298 H4L299 (CH2) n H2L300 N HN O O NH N R R NH HN O O X O Y O HN HN NH NH OH OH HO HO O O O O H2L301 R = 2-pyridyl H4L302 R = 2-pyrrolyl H4L303 X = Y = OH H4L304 X = OH, Y = NMeH H4L305 X =Y = NHMe H8L306 to Fe(III).393 New syntheses of compartmental ligands L300, with pyridyl pendant arms, have been developed and some complexes structurally characterised.394 The binuclear Cu(II) complexes of L301 and L302 are strongly antiferromagnetically coupled across the oxamate bridges.395 Assembly of MCuIILN2~ units (L\L303, L304, L305) around Mn(II) ions via their external O,O-chelating sites results in 2-D ferrimagnetic networks with alternating S\1/2 and S\5/2 centres.396 Whereas [(VO) 2 (l- L306)]4~ has no significant magnetic coupling between the metals, [CoIII 2 (l-L306)]2~ is strongly antiferromagnetically coupled; ligand-centred oxidation of the latter results in a ferrimagnetic species containing a ligand radical (S\1/2) connecting the two S\1 metal centres.397 The stability constants of numerous complexes of the dtpa-analogue L307 were measured; the co-ordinated water ligand in [Gd(H 2 O)(L307)]2~ means that the complex is an e§ective water relaxation agent.398 Hydrogen-bonding of water molecules to Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 302N N N CO2 H CO2H CO2H HO2C CO2H O N N N O HN OMe NH MeO CO2H CO2 H CO2 H N N N CO2H CO2 H CO2 H N CO2H O R O R H5L307 H3L308 H6L309 R = OH H6L310 R = NHC4H9 N O O N CO2H CO2H HO2C HO2C N N N N OH HO HO N N OH OH HO NH NH2 HN H2N H4L311 H3L312 H2L313 N O O N N N N L314 N NH N N R R EtS EtS HL315 R = NEt2 HL316 R = SEt pendant amide and ether groups of [Gd(H 2 O)(L308)] in solution increases the rotational correlation time, and gives the complex favourable properties for use as an MRI contrast enhancement agent.399 The structures, stability constants and NMR properties of Ga(III) and In(III) complexes of L309 and L310 were determined to evaluate the Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 303utility of the ligands for radiopharmaceutical applications.400 In [MCu(en)N2 (l-L311)] there is weak antiferromagnetic exchange via N–H· · ·O hydrogen bonds between the dinuclear units.401 The luminescence properties of the water-stable complexes [LnIII 2 (L312) 2 ] (Ln\Tb, Eu), in which the metal ions are eight-co-ordinate, were examined.402 [CuII 3 Cl 2 (L313)]` has a triangular CuII 3 core with chloride and alkoxide bridges, which remains intact in solution; the complex is a possible structural model for ascorbate oxidase.403 [M(L314)]2` (M\Cd, Hg) have seven-co-ordinate mono-helical structures.404 [NiII 2 Cl 3 (L315)] and [NiII 2 Cl 3 (L316)], both of which have chloride and pyrazolate bridges between the metals, can be oxidised to the Ni(II)–Ni(III) states and are antiferromagnetically coupled; the former is a rare example of a dinuclear complex with ligand-imposed asymmetry.405 References 1 R.H.Terbrueggen, T. W. Johann and J. K. Barton, Inorg. Chem., 1998, 37, 6874. 2 M. Bourgault, K. Baum, H. Le Bozec, G. Pucetti, I. Ledoux and J. Zyss, New J. Chem., 1998, 22, 517. 3 V. W.-W. Yam and A. S.-F. Kai, Chem. Commun., 1998, 109. 4 Q. Wang, L. Wang and L. Yu, J. Am. Chem. Soc., 1998, 120, 12 860. 5 G.A. Breault, C. A. Hunter and P. C. Mayers, J. Am. Chem. Soc., 1998, 120, 3402. 6 J.A.A.W. Elemans, R. de Gelder, A. E. Rowan and R. J. M. No� lte, Chem. Commun., 1998, 1553. 7 H.-L. Kwong, W.-S. Lee, H.-F. Ng, W.-H. Chiu and W.-T. Wong, J. Chem. Soc., Dalton Trans., 1998, 1043. 8 E. Amouyal, F. Penaud-Berruyer, D. Azhari, H. Aý� t-Haddou, C. Fontenas, E. Bejan, J.-C. Daran and G. G. A. Balavoine, New J. Chem., 1998, 22, 373. 9 M.T. Miller, P. K. Gantzel and T. B. Karpishin, Angew. Chem., Int. Ed., 1998, 37, 1556. 10 E. B. van der Tol, H. J. van Ramesdonk, J. W. Verhoeven, F. J. Steemers, E. G. Kerver, W. Verbood D. N. Reinhoudt, Chem.Eur. J., 1998, 4, 2315. 11 D. A. Evans, C. S. Burgey, N. A. Paras, T. Vojkovsky and S. W. Tregay, J. Am. Chem. Soc., 1998, 120, 5824. 12 D. A. Evans, E. J. Olhava, J. S. Johnson and J. M. Janey, Angew. Chem., Int. Ed., 1998, 37, 3372. 13 J. Thorhauge, M. Johannsen and K. A. Jørgensen, Angew. Chem., Int. Ed., 1998, 37, 2404. 14 M.M.-C. Lo and G. C. Fu, J. Am. Chem. Soc., 1998, 120, 10 270. 15 M.T. Reetz, E. Bohres and R. Goddard, Chem. Commun., 1998, 935. 16 S. E. Denmark, S. P. O’Connor and S. R. Wilson, Angew. Chem., Int. Ed., 1998, 37, 1149. 17 V. C. Gibson, P. J. Maddox, C. Newton, C. Redshaw, G. A. Solan, A. J. P. White and D. J. Williams, Chem. Commun., 1998, 1651. 18 R. Bhalla, M. Helliwell, R. L. Beddoes, D. Collison and C. D. Garner, Inorg. Chim.Acta, 1998, 273, 225. 19 F. A. Cotton, L.M. Daniels, G. T. Jordan IV and C. A. Murillo, Polyhedron, 1998, 17, 589. 20 P. Ghosh, T. Hascall, C. Dowling and G. Parkin, J. Chem. Soc., Dalton Trans., 1998, 3355. 21 M. Shivakumar, K. Pramanik, P. Ghosh and A. Chakravorty, Inorg. Chem., 1998, 37, 5968. 22 C. Silvestru, R. Ro� sler, J. E. Drake, J. Yang, G. Espinosa-Pe� rez and I. Haiduc, J.Chem. Soc., Dalton Trans., 1998, 73. 23 M.C. Gimeno, P. G. Jones, A. Laguna and C. Sarroca, J. Chem. Soc., Dalton Trans., 1998, 1277. 24 M. Die� guez, A. Ruiz, C. Claver, M. M. Pereira and A. M.d’A. R. Gonsalves, J. Chem. Soc., Dalton Trans., 1998, 3517. 25 A.M. Hill, N. J. Holmes, A. R. J. Genge, W. Levason, M. Webster and S. Rutschow, J. Chem. Soc., Dalton Trans., 1998, 825. 26 N. J. Holmes, W. Levason and M. Webster, J. Chem. Soc., Dalton Trans., 1998, 3457. 27 Y. Song, K. F. Mok, P.-H. Leung and S.-H. Chan, Inorg. Chem., 1998, 37, 6399. 28 Q. Jiang, Y. Jiang, D. Xiao, P. Cao and X. Zhang, Angew. Chem., Int. Ed., 1998, 37, 1100. 29 F.-Y. Zhang, C.-C. Pai and A. S. C. Chan, J. Am. Chem. Soc., 1998, 120, 5808. 30 L. Schwink and P. Knochel, Chem. Eur. J., 1998, 4, 950. 31 L. Dahlenburg and V. Kurth, Eur. J. Inorg. Chem., 1998, 1, 597. 32 L. A. van der Veen, M. D. K. Boele, F. R. Bregman, P. C. J. Kamer, P. W. N.M. van Leeuwen, K. Goubitz, J. Fraanje, H. Schenk and C. Bo, J. Am. Chem. Soc., 1998, 120, 11 616. 33 W. Goertz, W. Keim, D. Vogt, U. Englert, M.D. K. Boele, L. A. van der Veen, P. C. J. Kamer and P.W. N. M. van Leeuwen, J. Chem. Soc., Dalton Trans., 1998, 2981. 34 B. Hamann and J. F. Hartwig, J. Am. Chem. Soc., 1998, 120, 3694. 35 P. Dierkes, S. Ramdeehul, L. Barloy, A. De Cian, J. Fischer, P. C. J. Kamer, P. W. N. M. van Leeuwen and Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 304J. A. Osborn, Angew. Chem., Int. Ed., 1998, 37, 3116. 36 K. Nozaki, M. Yasutomi, K. Nakamoto and T. Hiyama, Polyhedron, 1998, 17, 1159. 37 M.T. Reetz, A. Gosberg, R. Goddard and S.-H. Kyung, Chem. Commun., 1998, 2077. 38 A. Bayler, A. Schier and H. Schmidbauer, Inorg. Chem., 1998, 37, 4353. 39 S. P. Millar, M. Jang, R. J. Lachiotte and R. Eisenberg, Inorg. Chim. Acta, 1998, 270, 363. 40 S. J. Berners-Price, R. J. Bowen, P. J. Harvey and P. C. Healy, J. Chem. Soc., Dalton Trans., 1998, 1743. 41 M.A. Bennett, M.Contel, D. C. R. Hockless and L. L. Welling, Chem. Commun., 1998, 2401. 42 B.-L. Chen, K. F. Mok and S.-C. Ng, J. Chem. Soc., Dalton Trans., 1998, 2861. 43 L. D. Field, I. P. Thomas, T. W. Hambley and P. Turner, Inorg. Chem., 1998, 37, 612. 44 P. Rosa, L. Ricard, P. Le Floch, F. Mathey, G. Sini and O. Eisenstein, Inorg. Chem., 1998, 37, 3154. 45 D. C. Smith, Jr., C. H. Lake and G.M. Gray, Chem. Commun., 1998, 2771. 46 C. E. Uzelmeier, S. L. Bartley, M. Fourmigue� , R. Rogers, G. Grandinetti and K. R. Dunbar, Inorg. Chem., 1998, 37, 6706. 47 M.J. Dejmek and R. Selke, Angew. Chem., Int. Ed., 1998, 37, 1540. 48 G. Minghetti, S. Stoccoro, M. A. Cinellu, A. Zucca, M. Manassero and M. Sansoni, J. Chem. Soc., Dalton Trans., 1998, 4119. 49 F. A. Villamena, M. H.Dickman and D. R. Crist, Inorg. Chem., 1998, 37, 1446. 50 K. Fegy, N. Sanz, D. Luneau, E. Belorizky and P. Rey, Inorg. Chem., 1998, 37, 4518. 51 J.-P. Sutter, M. L. Kahn, S. Golhen, L. Ouahab and O. Kahn, Chem. Eur. J., 1998, 4, 571. 52 A. Lightfoot, P. Schnider and A. Pfalz, Angew. Chem., Int. Ed., 1998, 37, 2897. 53 S. Kudis and G. Helmchen, Angew. Chem., Int. Ed., 1998, 37, 3047. 54 A.M. Porte, J. Reibenspies and K. Burgess, J. Am. Chem. Soc., 1998, 120, 9180. 55 K. L. Bray, C. P. Butts, G. C. Lloyd-Jones and M. Murray, J. Chem. Soc., Dalton Trans., 1998, 1421. 56 E. K. van den Beuken, W. J. J. Smeets, A. L. Spek and B. L. Feringa, Chem. Commun., 1998, 223. 57 T. Kawamoto and Y. Kushi, Inorg. Chim. Acta, 1998, 282, 71. 58 I. Nagasawa, T. Kawamoto, H. Kuma and Y.Kushi, Bull. Chem. Soc. Jpn., 1998, 71, 1337. 59 J. C. Anderson and M. Harding, Chem. Commun., 1998, 393. 60 P.-H. Leung, S.-Y. Siah, A. J. P. White and D. J. Williams, J. Chem. Soc., Dalton Trans., 1998, 893. 61 G. Mugesh, H. B. Singh, R. P. Patel and R. J. Butcher, Inorg. Chem., 1998, 37, 2663. 62 A. T. Daniher and J. K. Bashkin, Chem. Commun., 1998, 1077. 63 G. Albano, V.Balzani, E. C. Constable, M. Maestri and D. R. Smith, Inorg. Chim. Acta, 1998, 277, 225. 64 D. Armsprach, E. C. Constable, F. Diederich, C. E. Housecroft and J.-F. Nierengarten, Chem. Eur. J., 1998, 4, 723. 65 E. C. Constable, C. E. Housecroft, M. Cattalini and D. Phillips, New J. Chem., 1998, 22, 193. 66 G. Baum, E. C. Constable, D. Fenske, C. E. Housecroft and T. Kulke, Chem. Commun., 1998, 2659. 67 M.A. Halcrow, E. K. Brechin, E. J. L. McInnes, F. E. Mabbs and J. E. Davies, J. Chem. Soc., Dalton Trans., 1998, 2477. 68 G. D. Storrier, S. B. Colbran and D. C. Craig, J. Chem. Soc., Dalton Trans., 1998, 1351. 69 R. R. Ruminski, S. Underwood, K. Vallely and S. J. Smith, Inorg. Chem., 1998, 37, 6528 70 J. H. Groen, A. de Zwart, M.J. M. Vlaar, J. M. Ernsting, P.W. N.M. van Leeuwen, K. Vrieze, H. Kooijman, W.J. J. Smeets, A. L. Spek, P. H. M. Budzelaar, Q. Xiang and R. P. Thummel, Eur. J. Inorg. Chem., 1998, 1, 1129. 71 J. H. Groen, P. W. N.M. van Leeuwen and K. Vrieze, J. Chem. Soc., Dalton Trans., 1998, 113. 72 R. F. Carina, L. Verzegnassi, G. Bernardinelli and A. F. Williams, Chem. Commun., 1998, 2681. 73 N. K. Solanki, E. J. L. McInnes, F.E. Mabbs, S. Radojevic, M. McPartlin, N. Feeder, J. E. Davies and M.A. Halcrow, Angew. Chem., Int. Ed., 1998, 37, 2221. 74 H. Nozary, C. Piguet, P. Tissot, G. Bernardinelli, J.-C. G. Bu� nzli, R. Deschenaux and D. Guillon, J. Am. Chem. Soc., 1998, 120, 12 274. 75 G. J. P. Britovsek, V. C. Gibson, B. S. Kimberley, P. J. Maddox, S. J. McTavish, G. A. Solan, A. J. P. White and D. J.Williams, Chem. Commun., 1998, 849. 76 B. L. Small, M. Brookhart and A.M. A. Bennett, J. Am. Chem. Soc., 1998, 120, 4049. 77 B. L. Small and M. Brookhart, J. Am. Chem. Soc., 1998, 120, 7143. 78 M. Bruce, V. C. Gibson, C. Redshaw, G. A. Solan, A. J. P. White and D. J. Williams, Chem. Commun., 1998, 2523. 79 A. L. Vance, N. W. Alcock, J. A. Heppert and D. H. Busch, Inorg. Chem., 1998, 37, 6912. 80 B. J. Childs, D. C. Craig, M.L. Scudder and H. A. Goodwin, Inorg. Chim. Acta, 1998, 274, 32. 81 E. Colacio, J.-M. Dominguez-Vera, M. Ghazi, R. Kiveka� s,M. Klinga and J. M. Moreno, Inorg. Chem., 1998, 37, 3040. 82 Y. Jiang, Q. Jiang and X. Zhang, J. Am. Chem. Soc., 1998, 120, 3817. 83 I. Blain, P. Bruno, M. Giorgi, E. Lojou, D. Lexa and M. Re� glier, Eur. J. Inorg. Chem., 1998, 1, 1297. 84 R. T. Jonas and T. D. P. Stack, Inorg. Chem., 1998, 37, 6615. 85 K. Singh, J. R. Long and P. Stavropoulos, Inorg. Chem., 1998, 37, 1073. 86 K. Hegetschweiler, M. Weber, V. Huch, R. J. Geue, A. D. Rae, A. C. Willis and A. M. Sargeson, Inorg. Chem., 1998, 27, 6136. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 30587 M. Fujita, S.-Y. Yu, T. Kusukawa, H. Funaki, K.Ogura and K. Yamaguchi, Angew. Chem., Int. Ed., 1998, 37, 2082. 88 T. Kusukawa and M. Fujita, Angew. Chem., Int. Ed., 1998, 37, 3142. 89 J. L. Schneider, S. M. Carrier, C. E. Ruggiero, V. G. Young, Jr. and W.B. Tolman, J. Am. Chem. Soc., 1998, 120, 11 408. 90 S. Hikichi, M. Yoshizawa, Y. Sasakura, M. Akita and Y. Moro-oka, J. Am. Chem. Soc., 1998, 120, 10 567. 91 H. Komatsuzaki, N.Sakamoto, M. Satoh, S. Hikichi, M. Akita a, Inorg. Chem., 1998, 37, 6554. 92 M. Ruf and C. G. Pierpont, Angew. Chem., Int. Ed., 1998, 37, 1736. 93 E. R. Humphrey, N. C. Harden, L. H. Rees, J. C. Je§ery, J. A. McCleverty and M. D. Ward, J. Chem. Soc., Dalton Trans., 1998, 3353. 94 J. L. Kisko, T. Hascall and G. Parkin, J. Am. Chem. Soc., 1998, 120, 10 561. 95 T.Ru� ther, U. Englert and U. Koelle, Inorg. Chem., 1998, 37, 4265. 96 P. J. Schebler, C. G. Riordan, I. A. Guzei and A. L. Rheingold, Inorg. Chem., 1998, 37, 4754. 97 P. J. Schebler, C. G. Riordan, L. Liable-Sands and A. L. Rheingold, Inorg. Chim. Acta, 1998, 270, 543. 98 N. Me� zailles, N. Avarvari, L. Ricard, R. Mathey and P. Le Floch, Inorg. Chem., 1998, 37, 5313. 99 M. Su� lu� , L.M. Venanzi, T. Gerfin and V. Gramlich, Inorg. Chim. Acta, 1998, 270, 499. 100 C. J. Smith, V. S. Reddy and K. V. Katti, J. Chem. Soc., Dalton Trans., 1998, 1365. 101 P. Sto� ßel, H. A. Mayer and F. Auer, Eur. J. Inorg. Chem., 1998, 1, 37. 102 T. C. Higgs, D. Ji, R. S. Czernuscewicz and C. J. Carrano, Inorg. Chim. Acta, 1998, 273, 14. 103 T. C. Higgs, K. Spartalian, C. J. O’Connor, B.F. Matzanke and C. J. Carrano, Inorg. Chem., 1998, 37, 2263. 104 T. C. Higgs, N. S. Dean and C. J. Carrano, Inorg. Chem., 1998, 37, 1473. 105 P. Ghosh and G. Parkin, J. Chem. Soc., Dalton Trans., 1998, 2281. 106 S. M. Couchman, J. C. Je§ery, P. Thornton and M. D. Ward, J. Chem. Soc., Dalton Trans., 1998, 1163. 107 H. Mack and M. S. Eisen, J. Chem. Soc., Dalton Trans., 1998, 917. 108 D. Black, A. J. Blake, K. P. Dancey, A. Harrison, M. McPartlin, S. Parsons, P. A. Tasker, G. Whittaker and M. Schro� der, J. Chem. Soc., Dalton Trans., 1998, 3953. 109 C. K. Lai, R. Lin, M.-Y. Lu and K.-C. Kao, J. Chem. Soc., Dalton Trans., 1998, 1857. 110 M. S. Sigman and E. N. Jacobsen, J. Am. Chem. Soc., 1998, 120, 4901. 111 C. J. Matthews, T. A. Leese, D. Thorp and J. C.Lockhart, J. Chem. Soc., Dalton Trans., 1998, 79. 112 C. J. Matthews, W. Clegg, S. L. Heath, N. C. Martin, M. N. S. Hill and J. C. Lockhart, Inorg. Chem., 1998, 37, 199. 113 C. B. Allan, G. Davidson, S. B. Choudhury, Z. Gu, K. Bose, R. O. Day and M.J. Maroney, Inorg. Chem., 1998, 37, 4166. 114 E. Bouwman, R. K. Henderson, A. K. Powell, J. Reedijk, W. J. J. Smeets, A. L. Spek, N.Veldman and S. Wocadlo, J. Chem. Soc., Dalton Trans., 1998, 3495. 115 M. Mikuriya, X. Jian, S. Ikemi, T. Kawahashi and H. Tsutsumi, Bull. Chem. Soc. Jpn., 1998, 71, 2161. 116 C. Vin8 as, P. Angle` s, G. Sa� nchez, N. Lucena, F. Teixidor, L. Escriche, J. Casabo� , J. F. Piniella, A. Alvarez-Larena, R. Kiveka� s and R. Sillanpa� a� , Inorg. Chem., 1998, 37, 701. 117 J. C. Novaron, M.M.Olmstead and P. K. Mascharak, Inorg. Chem., 1998, 37, 1138. 118 L. Stelzig, S. Ko� tte and B. Krebs, J. Chem. Soc., Dalton Trans., 1998, 2921. 119 B. Kersting, Eur. J. Inorg. Chem., 1998, 1, 1071. 120 B. Kersting and D. Siebert, Inorg. Chem., 1998, 37, 3820. 121 T. C. Higgs, D. Ji, R. S. Czernuszewicz, B. F. Matzanke, V. Schunemann, A. X. Trautwein, M. Helliwell, W. Ramirez and C.J. Carrano, Inorg. Chem., 1998, 37, 2383. 122 S. Ford, C. P. Morley and M. Di Vaira, Chem. Commun., 1998, 1305. 123 S.-M. Kuang, Z.-Z. Zhang, Q.-G. Wang and T. C. W. Mak, J. Chem. Soc., Dalton Trans., 1998, 1115. 124 S.-M. Kuang, Z.-Z. Zhang, Q.-G. Wang and T. C. W. Mak, J. Chem. Soc., Dalton Trans., 1998, 2927. 125 A. Jacobi, G. Huttner, U. Winterhalter and S. Cunskis, Eur.J. Inorg. Chem., 1998, 1, 675. 126 B. L. Shaw, N. Iranpoor, S. D. Perera, M. Thornton-Pett and J. D. Vessey, J. Chem. Soc., Dalton Trans., 1998, 1885. 127 Y. Jahng and J. G. Park, Inorg. Chim. Acta, 1998, 267, 265. 128 P. Chaudhuri, M. Hess, U. Flo� rke and K. Wieghardt, Angew. Chem., Int. Ed., 1998, 37, 2217. 129 R. Soltek, G. Huttner, L. Zsolnai and A. Driess, Inorg. Chim. Acta, 1998, 269, 143. 130 M. C. Goedheijt, J. N. H. Reek, P. C. J. Kamer and P. W.N. M. van Leeuwen, Chem. Commun., 1998, 2431. 131 K. Nakajima, S. Ishibashi and M. Kojima, Chem. Lett., 1998, 997. 132 P. Bhattacharyya, J. Parr and A. M. Z. Slawin, J. Chem. Soc., Dalton Trans., 1998, 3609. 133 C. J. Matthews, S. L. Heath, M. R. J. Elsegood, W. Clegg, T. A. Leese and J. C. Lockhart, J. Chem. Soc., Dalton Trans., 1998, 1973. 134 M. Ketterle, J. Fiedler and W. Kaim, Chem. Commun., 1998, 1701. 135 S. Roche, L. J. Yellowlees and J. A. Thomas, Chem. Commun., 1998, 1429. 136 R. R. Ruminski, P. T. Deere, M. Olive and D. Serveiss, Inorg. Chim. Acta, 1998, 281, 1. 137 S. E. Page, K. C. Gordon and A. K. Burrell, Inorg. Chem., 1998, 37, 4452. 138 W. Paw, W. B. Connick and R. Eisenberg, Inorg.Chem., 1998, 37, 3919. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 306139 E. Ishow, A. Gourdon, J.-P. Launay, P. Lecante, M. Verelst, C. Chiorboli, F. Scandola and C.-A. Bignozzi, Inorg. Chem., 1998, 37, 3603. 140 Y. Wang, W. J. Perez, G. Y. Zheng, D. P. Rillema and C. L. Huber, Inorg. Chem., 1998, 37, 2227. 141 K. Wa� rnmark, P. N. W. Baxter and J.-M. Lehn, Chem.Commun., 1998, 993. 142 E. Ishow, A. Gourdon and J.-P. Launay, Chem. Commun., 1998, 1909. 143 A.M. Barthram, M. D. Ward, A. Gessi, N. Armaroli, L. Flamigni and F. Barigelletti, New J. Chem., 1998, 22, 913. 144 M. M. Ali, H. Sato, T. Mizukawa, K. Tsuge, M. Haga and K. Tanaka, Chem. Commun., 1998, 249. 145 L. K. Thompson, Z. Xu, A. E. Goeta, J. A. K. Howard, H. J. Clase and D. A.Miller, Inorg. Chem., 1998, 37, 3217. 146 Z. Xu, L. K. Thompson, D. O. Miller, H. J. Clase, J. A. K. Howard and A. E. Goeta, Inorg. Chem., 1998, 37, 3620. 147 N. Doslik, T. Sixt and W. Kaim, Angew. Chem., Int. Ed., 1998, 37, 2403. 148 J. Rall, A. F. Stange, K. Hu� bler and W. Kaim, Angew. Chem., Int. Ed., 1998, 37, 2553. 149 H. Brunner, R. Sto� riko and F. Rominger, Eur. J. Inorg.Chem., 1998, 1, 771. 150 H. Brunner and R. Sto� riko, Eur. J. Inorg. Chem., 1998, 1, 783. 151 P. Majundar, S.-M. Peng and S. Goswami, J. Chem. Soc., Dalton Trans., 1998, 1569. 152 C. Kaes, M.W. Hosseini, C. E. F. Rickard, B. W. Skelton and A. H. White, Angew. Chem., Int. Ed., 1998, 37, 920. 153 A. C. Try, M. M. Harding, D. G. Hamilton and J. K.M. Sanders, Chem. Commun., 1998, 723. 154 F. M. O’Reilly and J. M. Kelley, New J. Chem., 1998, 22, 215. 155 C.M. Elliott, D. L. Derr, D. V. Matyushov and M. D. Newton, J. Am. Chem. Soc., 1998, 120, 11 714. 156 O. Mamula, A. von Zelewsky and G. Bernardinelli, Angew. Chem., Int. Ed., 1998, 37, 290. 157 H. Mu� rner, A. von Zelewsky and G. Hopfgartner, Inorg. Chim. Acta, 1998, 271, 36. 158 J. S. Fleming, K. L. V. Mann, C.-A.Carraz, E. Psillakis, J. A. McCleverty and M. D. Ward, Angew. Chem., Int. Ed., 1998, 37, 1279. 159 J. S. Fleming, K. L. V. Mann, S. M. Couchman, J. C. Je§ery, J. A. McCleverty and M.D. Ward, J. Chem. Soc., Dalton Trans., 1998, 2047. 160 P. K. Bowyer, K. A. Porter, A. D. Rae, A. C. Willis and S. B. Wild, Chem. Commun., 1998, 1153. 161 M. A. Masood, E. J. Enemark and T. D. P. Stack, Angew.Chem., Int. Ed., 1998, 37, 928. 162 A. El-ghayoury, L. Douce, A. Skoulios and R. Ziessel, Angew. Chem., Int. Ed., 1998, 37, 2205. 163 L. J. Charbonnie` re, A. F. Williams, C. Piguet, G. Bernardinelli and E. Rivara-Minten, Chem. Eur. J., 1998, 4, 485. 164 M. Buda, J.-C. Moutet, E. Saint-Aman, A. De Cian, J. Fischer and R. Ziessel, Inorg. Chem., 1998, 37, 4146. 165 M. Pitie� , B.Sudres and B. Meunier, Chem. Commun., 1998, 2597. 166 M. Pitie� , B. Donnadieu and B. Meunier, Inorg. Chem., 1998, 37, 3486. 167 D. Ghosh and R. Mukherjee, Inorg. Chem., 1998, 37, 6597. 168 S. Ryan, H. Adams, D. E. Fenton, M. Becker and S. Schindler, Inorg. Chem., 1998, 37, 2134. 169 V. Amendola, L. Fabbrizzi, P. Pallavicini, L. Parodi and A. Perotti, J. Chem. Soc., Dalton Trans., 1998, 2053. 170 C. Place, J.-L. Zimmermann, E. Mulliez, G. Guillot, C. Bois and J.-C. Chottard, Inorg. Chem., 1998, 37, 4030. 171 P. W. Roesky, Inorg. Chem., 1998, 37, 4507. 172 G. A. van Albada, I. Mutikainen, U. Turpeinen and J. Reedijk, Eur. J. Inorg. Chem., 1998, 1, 547. 173 R. Deters and R. Kra� mer, Inorg. Chim. Acta, 1998, 269, 117. 174 J.-M. Dominguez-Vera, F. Camara, J. M.Moreno, E. Colacio and H. Stoeckli-Evans, Inorg. Chem., 1998, 37, 3046. 175 M. Mimura, T. Matsuo, T. Nakashima and3. 176 K. L. V. Mann, J. C. Je§ery, J. A. McCleverty, P. Thornton and M.D. Ward, J. Chem. Soc., Dalton Trans., 1998, 89. 177 K. L. V. Mann, J. C. Je§ery, J. A. McCleverty and M. D. Ward, J. Chem. Soc., Dalton Trans., 1998, 3029. 178 N. End and A. Pfalz, Chem. Commun., 1998, 589. 179 N. End, L. Macko, M. Zehnder and A. Pfalz, Chem. Eur. J., 1998, 4, 755. 180 J. Glerup, K. Michelsen, N. Arulsamy and D. J. Hodgson, Inorg. Chim. Acta, 1998, 274, 155. 181 C.M. Hartshorn and P. J. Steel, J. Chem. Soc., Dalton Trans., 1998, 3935. 182 H.-P. Wu, C. Janiak, L. Uehlin, P. Klu� fers and P. Mayer, Chem. Commun., 1998, 2637. 183 D. C. Bebout, J. F. Bush II, K. C. Crahan, M. E. Kastner and D. A. Parrish, Inorg. Chem., 1998, 37, 4641. 184 R. Wietzke, M. Mazzanti, J.-M. Latour, J. Pe� caut, P.-Y. Cordier and C. Madic, Inorg. Chem., 1998, 37, 6690. 185 S. Zahn and J. W. Canary, Angew. Chem., Int. Ed., 1998, 37, 305. 186 J. W. Canary, C. S. Allen, J. M. Castagnetto, Y.-H. Chiu, P. J. Toscano and Y. Wang, Inorg.Chem., 1998, 37, 6255. 187 H. V. Obias, G. P. F. van Strijdonck, D.-H. Lee, M. Ralle, N. J. Blackburn and K. D. Karlin, J. Am. Chem. Soc., 1998, 120, 9696. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 307188 T. Sasaki, N. Nakamura and Y. Naruta, Chem. Lett., 1998, 351. 189 S. Ogo, S. Wada, Y. Watanabe, M. Iwase, A. Wada, M. Harata, K. Jitsukawa, H. Masuda and H. Einaga, Angew.Chem., Int. Ed., 1998, 37, 2102. 190 M. Harata, K. Jitsukawa, H. Masuda and H. Einaga, Bull. Chem. Soc. Jpn., 1998, 71, 637. 191 A. Wada, M. Harata, K. Hasegawa, K. Jitsukawa, H. Masuda, M. Mukai, T. Kitagawa amd H. Einaga, Angew. Chem., Int. Ed., 1998, 37, 798. 192 M. Harata, K. Hasegawa, K. Jitsukawa, H. Masuda and H. Einaga, Bull. Chem. Soc. Jpn., 1998, 71, 1031. 193 M.Ray, B. S. Hammes, G. P. A. Yap, A. L. Rheingold and A. S. Borovik, Inorg. Chem., 1998, 37, 1527. 194 P. Comba, B. Kanellakopoulos, C. Katsichtis, A. Lienke, H. Pritzkow and F. Romiger, J. Chem. Soc., Dalton Trans., 1998, 3997. 195 M. Albrecht, M. Schneider and R. Fro� hlich, New J. Chem., 1998, 22, 753. 196 D. L. Caulder, R. E. Powers, T. N. Parac and K. N. Raymond, Angew. Chem., Int.Ed., 1998, 37, 1840. 197 E. J. Enemark and T. D. P. Stack, Angew. Chem., Int. Ed., 1998, 37, 932. 198 A.-K. Duhme, S. C. Davies and D. L. Hughes, Inorg. Chem., 1998, 37, 5380. 199 G. A. Abakumov, V. K. Cherkasov, V. I. Nevodchikov, V. A. Kuropatov, B. C. Noll and C. G. Pierpont, Inorg. Chem., 1998, 37, 6117. 200 A.M. Barthram, R. L. Cleary, J. C. Je§ery, S. M. Couchman and M.D.Ward, Inorg. Chim. Acta, 1998, 267, 1. 201 P. J. Bonitatebus, Jr., S. K. Mandal and W. H. Armstrong, Chem. Commun., 1998, 939. 202 R.W. Saalfrank, N. Lo� w, B. Demleitner, D. Stalke and M. Teichert, Chem. Eur. J., 1998, 4, 1305. 203 D. D. Le Cloux, A. M. Barrios, T. J. Mizoguchi and S. J. Lippard, J. Am. Chem. Soc., 1998, 120, 9001. 204 X.-X. Zhang, P. Fuhrmann and S. J. Lippard, J.Am. Chem. Soc., 1998, 120, 10 260. 205 M. Tanaka, K. Matsuda, T. Itoh and H. Iwamura, Angew. Chem., Int. Ed., 1998, 37, 810. 206 W. W. Seidel, F. E. Hahn and T. Lu� gger, Inorg. Chem., 1998, 37, 6587. 207 E. Zahary and M.A. Fox, Chem. Eur. J., 1998, 4, 1647. 208 P. Steenwinkel, S. Kolmschot, R. A. Gossage, P. Dani, N. Veldman, A. L. Spek and G. van Koten, Eur. J. Inorg.Chem., 1998, 1, 477. 209 B. Hong, S. R. Woodcock, S. K. Saito and J. V. Ortega, J. Chem. Soc., Dalton Trans., 1998, 2615. 210 B. Hong and J. V. Ortega, Angew. Chem., Int. Ed., 1998, 37, 2131. 211 J. M. Asara, C. E. Uzelmeier, K. R. Dunbar and J. Allison, Inorg. Chem., 1998, 37, 1833. 212 M. S. Sigman and E. N. Jacobsen, J. Am. Chem. Soc., 1998, 120, 5315. 213 V. I. Tararov, D. E.Hibbs, M.B. Hursthouse, N. S. Ikonnikov, K. M.A. Malik, M. North, C. Orizu and Y. N. Belokon, Chem. Commun., 1998, 387. 214 G. Pozzi, F. Cinato, F. Montanari and S. Quici, Chem. Commun., 1998, 877. 215 A. S. Jepsen, M. Roberson, R. G. Hazell and K. A. Jørgensen, Chem. Commun., 1998, 1599. 216 M. Palucki, N. S. Finney, P. J. Pospisil, M. L. Gu� ler, T. Ishida and E. N. Jacobsen, J.Am. Chem. Soc., 1998, 120, 948. 217 G. Lenoble, P. G. Lacroix, J. C. Daran, S. Di Bella and K. Nakatani, Inorg. Chem., 1998, 37, 2158. 218 G. Hoshina, M. Tsuchimoto, S. Ohba, K. Nakajima, H. Uekasa, Y. Ohashi, H. Ishida and M. Kojima, Inorg. Chem., 1998, 37, 142. 219 V. van A. Castelli, A. D. Cort, L. Mandolini and D. N. Reinhoudt, J. Am. Chem. Soc., 1998, 120, 12 688. 220 M. Sasaki, H.Horiuchi, M. Kumagai, M. Sakamoto, H. Sakiyama, Y. Nishida, Y. Sadaoka, M. Ohba and H. Okawa, Chem. Lett., 1998, 911. 221 R. Herna� ndez-Molina, A. Mederos, S. Dominguez, P. Gili, C. Ruiz-Pe� rez, A. Castin8 eiras, X. Solans, F. Lloret and J. A. Real, Inorg. Chem., 1998, 37, 5102. 222 E. Saint-Aman, S. Me� nage, J.-L. Pierre, E. Defrancq and G. Gellon, New J. Chem., 1998, 22, 393. 223 P.-M.Chan, W.-Y. Yu, C.-M. Che and K.-K. Cheung, J. Chem. Soc., Dalton Trans., 1998, 3183. 224 Y. Sunatsuki, T. Matsuo, M. Nakamura, F. Kai, N. Matsumoto and J.-P. Tuchagues, Bull. Chem. Soc. Jpn., 1998, 71, 2611. 225 Y. Sunatsuki, M. Mimura, H. Shimada, F. Kai and N. Matsumoto, Bull. Chem. Soc. Jpn., 1998, 71, 167. 226 F. M. Romero, D. Luneau and R. Ziessel, Chem. Commun., 1998, 551. 227 D. Luneau, F. M. Romero and R. Ziessel, Inorg. Chem., 1998, 37, 5078. 228 R. Ruiz, A. Aukaloo, Y. Journaux, I. Ferna� ndez, J. R. Pedro, A. L. Rosello� , B. Cervera, I. Castro and M.C. Mun8 oz, Chem. Commun., 1998, 989. 229 B. Cervera, J. L. Sanz, M.J. Iba� n8 ez, G. Vila, F. Lloret, M. Julve, R. Ruiz, X. Ottenwaelder, A. Aukaloo, S. Prossereau, Y. Journeaux and M.C.Mun8 oz, J. Chem. Soc., Dalton Trans., 1998, 781. 230 N. D. Villanueva, M.Y. Chiang and J. R. Bocarsly, Inorg. Chem., 1998, 37, 685. 231 M. Mimura, T. Matsuo, N. Matsumoto, S. Takamizawa, W. Mori and N. Re, Bull. Chem. Soc. Jpn., 1998, 71, 1831. 232 H. Luo, P. E. Fanwick and M.A. Green, Inorg. Chem., 1998, 37, 1127. 233 G. Brewer, P. Kamaras, L. May, S. Prytkov and M. Rapta, Inorg.Chim. Acta, 1998, 279, 111. 234 N. Yoshida, H. Oshio and T. Ito, Chem. Commun., 1998, 63. 235 I. O. Fritsky, H. Kozlowski, E. V. Prisyazhnaya, A. Karaczyn, V. A. Kalibabchuk and T. Glowiak, J. Chem. Soc., Dalton Trans., 1998, 1535. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 308236 I. O. Fritsky, H. Kozlowski, E. V. Prisyazhnaya, Z. Rzaczynska, A. Karaczyn, Y. T. Sliva and T.Glowiak, J. Chem. Soc., Dalton Trans., 1998, 3629. 237 K. Fegy, D. Luneau, E. Belorizky, M. Novac, J.-L. Tholence, C. Paulsen, T. Ohm and P. Rey, Inorg. Chem., 1998, 37, 4524. 238 K. Fegy, D. Luneau, T. Ohm, C. Paulsen and P. Rey, Angew. Chem., Int. Ed., 1998, 37, 1270. 239 T. E. Keyes, R. J. Forster, P. M. Jayaweera, C. G. Coates, J. J. McGarvey and J. G. Vos, Inorg.Chem., 1998, 37, 5925. 240 B. Geißer and R. Alsfasser, Eur. J. Inorg. Chem., 1998, 1, 957. 241 B. J. Hamstra, G. J. Colpas and V. L. Pecoraro, Inorg. Chem., 1998, 37, 949. 242 H. Iikura and T. Nagata, Inorg. Chem., 1998, 37, 4702. 243 A. Tro� sch and H. Vahrenkamp, Eur. J. Inorg. Chem., 1998, 1, 827. 244 M. Vaidyanathan, R. Viswanathan, M. Palaniandavar, T. Balasubramanian, P. Prabhaharan and T.P. Muthiah, Inorg. Chem., 1998, 37, 6418. 245 R. Viswanathan, M. Palaniandavar, T. Balasubramanian and T. P. Muthiah, Inorg. Chem., 1998, 37, 2943. 246 S. Ito, S. Nishino, H. Itoh, S. Ohba and Y. Nishida, Polyhedron, 1998, 17, 1637. 247 Y.-L. Wong, Y. Yan, E. S. H. Chan, Q. Yang, T. C. W. Mak and D. K. P. Ng, J. Chem. Soc., Dalton Trans., 1998, 3057. 248 K. Ogawa, K.Nakata and K. Ichikawa, Chem. Lett., 1998, 797. 249 J. M. Botha, K. Umakoshi, Y. Sasaki and G. J. Lamprecht, Inorg. Chem., 1998, 37, 1609. 250 C. J. Campbell, W.L. Driessen, J. Reedijk, W. Smeets and A. L. Spek, J. Chem. Soc., Dalton Trans., 1998, 2703. 251 M. Hirotsu, M. Kojima, W. Mori and Y. Yoshikawa, Bull. Chem. Soc. Jpn., 1998, 71, 2873. 252 V. V. Pavlishchuk, S. V. Kolotilov, E.Sinn, M. J. Prushan and A. W. Addison, Inorg. Chim. Acta, 1998, 278, 217. 253 M.-A. Kopf, D. Varech, J.-P. Tuchagues, D. Mansuy and I. Artaud, J. Chem. Soc., Dalton Trans., 1998, 991. 254 C. A. Grapperhaus, T. Tuntulani, J. H. Reibenspienorg. Chem., 1998, 37, 4052. 255 G. Musie, C.-H. Lai, J. H. Reibenspies, L. W. Sumner and M.Y. Darensbourg, Inorg.Chem., 1998, 37, 4086. 256 F. Osterloh, W. Saak, S. Pohl, M. Kroeckel, C. Meier and A. X. Trautwein, Inorg. Chem., 1998, 37, 3581. 257 E. Benoist, J.-F. Gestin, J.-F. Chatal, G. Charbonnel-Jobic, J.-L. Parrain, J.-P. Quintard and C. Courseille, New J. Chem., 1998, 22, 615. 258 O. Seidelmann, L. Beyer, R. Richeter and T. Herr, Inorg. Chim. Acta, 1998, 271, 40. 259 J. Hanss and H.-J.Kru� ger, Angew. Chem., Int. Ed., 1998, 37, 360. 260 A. Castin8 eiras, E. Bermejo, D. X. West, A. K. El-Sawaf and J. K. Swearingen, Polyhedron, 1998, 17, 2751. 261 J. L. J. Dearling, J. S. Lewis, D. W. McCarthy, M. J. Welch and P. J. Blower, Chem. Commun., 1998, 2531. 262 M. J. Al-Jeboori, J. R. Dilworth and Y. Zheng, J. Chem. Soc., Dalton Trans., 1998, 3215. 263 M. Glaser, M.J. Howard, K. Howland, A. K. Powell, M. T. Rae, S. Wocadlo, R. A. Williamson and P. J. Blower, J. Chem. Soc., Dalton Trans., 1998, 3087. 264 R. A. Bell, B. E. McCarry and J. F. Valliant, Inorg. Chem., 1998, 37, 3517. 265 S. C. Davies, D. L. Hughes, R. L. Richards and J. R. Sanders, Chem. Commun., 1998, 2699. 266 R. J. Motekaitis, A. E. Martell, S. A. Koch, J. Hwang, D. A. Quarless, Jr.and M.J. Welch, Inorg. Chem., 1998, 37, 5902. 267 R. Burth, A. Stange, M. Scha� fer and H. Vahrenkamp, Eur. J. Inorg. Chem., 1998, 1, 1759. 268 F. Champloy, N. Benali-Che� rif, P. Bruno, I. Blain, M. Pierrot and M. Re� glier, Inorg. Chem., 1998, 37, 3910. 269 K. Nakajima, Y. Ando, H. Mano and M. Kojima, Inorg. Chim. Acta, 1998, 274, 184. 270 F. Tisato, G. Pilloni, F. Refosco, G.Bandoli, C. Corvaja and B. Corain, Inorg. Chim. Acta, 1998, 275, 401. 271 S.-M. Kuang, Z.-Z. Zhang, Q.-G. Wang and T. C. W. Mak, Chem. Commun., 1998, 581. 272 A. G. J. Ligtenbarg, E. K. van den Beuken, A. Meetsma, N. Veldman, W. J. J. Smeets, A. L. Spek and B. L. Feringa, J. Chem. Soc., Dalton Trans., 1998, 263. 273 P. Perez-Lourido, J. Romero, J. Garcia-Vazquez, A. Sousa, K.P. Maresca, D. J. Rose and J. Zubieta, Inorg. Chem., 1998, 37, 3331. 274 K. Kashiwabara, T. Naguchi, H. D. Takagi, K. Nakajima and T. Suzuki, Polyhedron, 1998, 17, 1817. 275 E. Pereira, L. Gomes and B. de Castro, J. Chem. Soc., Dalton Trans., 1998, 629. 276 E. Pereira, L. Gomes and B. de Castro, Inorg. Chim. Acta, 1998, 271, 83. 277 C. R. Cornman, K. L. Jantzi, J. I. Wirgau, T.C. Stau§er, J. W. Kampf and P. D. Boyle, Inorg. Chem., 1998, 37, 5851. 278 E. C. Constable, M. Neuburger, L. A. Whall and M. Zehnder, New J. Chem., 1998, 22, 219. 279 T. Bark, T. Weyhermu� ller and F. Heirtzler, Chem. Commun., 1998, 1475. 280 C.-C. Wang, W.-C. Lo, C.-C. Chou, G.-H. Lee, J.-M. Chen and S.-M. Peng, Inorg. Chem., 1998, 37, 4059. 281 F. A. Chavez, M. M. Olmstead and P.K. Mascharak, Inorg. Chim. Acta, 1998, 269, 269. 282 F. A. Chavez, J. M. Rowland, M. M. Olmstead and P. K. Mascharak, J. Am. Chem. Soc., 1998, 120, 9015. 283 C. Dietz, F. W. Heinemann, J. Kuhnigk, C. Kru� ger, M. Gerdan, A. X. Trautwein and A. Grohmann, Eur. J. Inorg. Chem., 1998, 1, 1041. 284 S. Tirada-Guerra, N. A. Cuevas-Garibay, M. E. Sosa-Torres and R. Zamorano-Ulloa, J. Chem.Soc., Dalton Trans., 1998, 2431. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 309285 A. El-ghayoury, A. Harriman, A. De Cian, J. Fischer and R. Ziessel, J. Am. Chem. Soc., 1998, 120, 9973. 286 T. Kawamoto, B. S. Hammes, R. Ostrander, A. L. Rheingold and A. S. Borovik, Inorg. Chem., 1998, 37, 3424. 287 R. Boca, H. Elias, W. Haase, M. Hu� ber, R. Klement, L.Mu� ller, H.Paulus, I. Svoboda and M. Valko, Inorg. Chim. Acta, 1998, 278, 127. 288 S. Rigault, C. Piguet, G. Bernardinelli and G. Hopfgartner, Angew. Chem., Int. Ed., 1998, 37, 169. 289 H. J. Hilgers and K. Bernauer, Inorg. Chim. Acta, 1998, 275, 9. 290 R.W. Saalfrank, V. Seitz, D. L. Caulder, K. N. Raymond, M. Teichert and D. Stalke, Eur. J. Inorg. Chem., 1998, 1, 1313. 291 R.W. Saalfrank, N.Lo� w, S. Trummer, G.M. Sheldrick, M. Teichert and D. Stalke, Eur. J. Inorg. Chem., 1998, 1, 559. 292 A. Gelasco, S. Bensiek and V. L. Pecoraro, Inorg. Chem., 1998, 37, 3301. 293 L. Stelzig, A. Steiner, B. Chanson and J.-P. Tuchagues, Chem. Commun., 1998, 771. 294 P. Amudha, M. Kandaswamy, L. Govindasamy and D. Velmurugan, Inorg. Chem., 1998, 37, 4486. 295 T. Koga, H. Furutachi, T.Nakamura, N. Fukita, M. Ohba, K. Takahashi and H. Okawa, Inorg. Chem., 1998, 37, 989. 296 B. Kwak, H. Rhee, S. Park and M. S. Lah, Inorg. Chem., 1998, 37, 3599. 297 A. Neves, S. M. de M. Romanowski, I. Vencato and A. S. Mangrich, J. Chem. Soc., Dalton Trans., 1998, 617. 298 J.-P. Costes, F. Dahan, A. Dupuis and J.-P. Laurent, J. Chem. Soc., Dalton Trans., 1998, 1307. 299 S.J. Oh, Y.-S. Choi, S. Hwangbo, S. C. Bae, J. K. Ku and J. W. Park, Chem. Commun., 1998, 2189. 300 C. P. Rao, A. Sreedhara, P. V. Rao, M. B. Verghese, K. Rissanen, E. Kolehmainen, N. K. Lokanath, M.A. Sridhar and J. S. Prasad, J. Chem. Soc., Dalton Trans., 1998, 2383. 301 R. Sakamoto, M. Ohba, N. Fukita, K. Takahashi, H. Okawa and L. K. Thompson, Bull. Chem. Soc. Jpn., 1998, 71, 2365. 302 T. Kajiwara and T. Ito, J. Chem. Soc., Dalton Trans., 1998, 3351. 303 C. J. Fahrni and A. Pfaltz, Helv. Chim. Acta, 1998, 81, 491. 304 C. J. Fahrni, A. Pfaltz, M. Neuberger and M. Zehnder, Helv. Chim. Acta, 1998, 81, 507. 305 B. Moubaraki, K. S. Murray, J. D. Ranford, X. Wang and Y. Xu, Chem. Commun., 1998, 353. 306 S.-M. Kuang, Z.-Z. Zhang and T. C.W. Mak, J. Chem. Soc., Dalton Trans., 1998, 317. 307 J. J. Ellison, A. Nienstedt, S. C. Shoner, D. Barnhart, J. A. Cowen and J. A. Kovacs, J. Am. Chem. Soc., 1998, 120, 5691. 308 S. C. Shoner, A. M. Nienstedt, J. J. Ellison, I. Y. Kung, D. Barnhart and J. A. Kovacs, Inorg. Chem., 1998, 37, 5721. 309 A. Gourdon and J.-P. Launay, Inorg. Chem., 1998, 37, 5336. 310 P. Bonho� te, A. Lecas and E. Amouyal, Chem. Commun., 1998, 885. 311 J.-D. Lee, L. M. Vrana, E. R. Bullock and K. J. Brewer, Inorg. Chem., 1998, 37, 3575. 312 F. Barigelletti, L. Flamigni, G. Calogero, L. Hammarstro� m, J.-P. Sauvage and J.-P. Collin, Chem. Commun., 1998, 2333. 313 E. C. Constable and E. Schofield, Chem. Commun., 1998, 403. 314 K. L. Bushell, S. M. Couchman, J. C. Je§ery, L. H. Rees and M.D. Ward, J. Chem. Soc., Dalton Trans., 1998, 3397. 315 D.-M. Bassani, J.-M. Lehn, K. Fromm and D. Fenske, Angew. Chem., Int. Ed., 1998, 37, 2364. 316 T. Salditt, Q. An, A. Plech, C. Eschenbaumer and U. S. Schubert, Chem. Commun., 1998, 2731. 317 J. S. Fleming, E. Psillakis, S. M. Couchman, J. C. Je§ery, J. A. McCleverty and M. D. Ward, J. Chem. Soc., Dalton Trans., 1998, 537. 318 E. Herdtweck, F. Peters, W. Scherer and M.Wagner, Polyhedron. 1998, 17, 1149. 319 N. C. Harden, J. C. Je§ery, J. A. McCleverty, L. H. Rees and M.D. Ward, New J. Chem., 1998, 22, 661. 320 S. Matsuda, A. Ishikubo, A. Kuzuya, M. Yoshiro and M. Komiyama, Angew. Chem., Int. Ed., 1998, 37, 3284. 321 H. Plenio and C. Aberle, Angew. Chem., Int. Ed., 1998, 37, 1397. 322 C. J. Boxwell, R. Bhalla, L. Cronin, S. S. Turner and P. H. Walton, J.Chem. Soc., Dalton Trans., 1998, 2449. 323 F. Meyer, A. Jacobi, B. Nuber, P. Rutsch and L. Zsolnai, Inorg. Chem., 1998, 37, 1213. 324 F. Meyer, U. Ruschewitz, P. Schober, B. Antelmann and L. Zsolnai, J. Chem. Soc., Dalton Trans., 1998, 1181. 325 P. V. Bernhardt and E. J. Hayes, J. Chem. Soc., Dalton Trans., 1998, 1037. 326 N. Marisch, G. Nardin, L. Randaccio and A. Camus, Inorg. Chim.Acta, 1998, 278, 237. 327 A. Hazell, C. J. McKenzie and L. P. Nielsen, J. Chem. Soc., Dalton Trans., 1998, 1751. 328 M. Kodera, Y. Tachi, S. Hirota, K. Katayama, H. Shimakoshi, K. Kano, K. Fujisawa, Y. Moro-oka, Y. Naruta and T. Kitagawa, Chem. Lett., 1998, 389. 329 M. Kodera, H. Shimakoshi, Y. Tachi, K. Katayama and K. Kano, Chem. Lett., 1998, 441. 330 K. Airola, J.Ratalainen, T. Nyro� nen and K. Rissanen, Inorg. Chim. Acta, 1998, 277, 55. 331 B. Hasenknopf, J.-M. Lehn, N. Boumediene, E. Leize and A. van Dorsselaer, Angew. Chem., Int. Ed., 1998, 37, 3265. 332 R. Stiller and J.-M. Lehn, Eur. J. Inorg. Chem., 1998, 1, 977. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 310333 P. J. Connors, Jr., D. Tzalis, A. Lorg.Chem., 1998, 37, 1121. 334 Y. Zhang, A. Thompson, A. J. Rettig and D. Dolphin, J. Am. Chem. Soc., 1998, 120, 13 537. 335 I. Morgenstern-Badarau, F. Lambert, A. Deroche, M. Cesario, J. Guilhem, B. Jeita and L. Nadjo, Inorg. Chim. Acta, 1998, 275, 234. 336 C. T. Brewer, G. Brewer, M. Shang, W.R. Scheidt and I. Muller, Inorg. Chim. Acta, 1998, 278, 197. 337 M. Mimura, T. Matsuo, Y.Motoda, N. Matsumoto, T. Nakashima and M. Kojima, Chem. Lett., 1998, 691. 338 R. F. Beeston, W. S. Aldridge, J. A. Treadway, M. C. Fitzgerald, B. A. de Gra§ and S. E. Stitzel, Inorg. Chem., 1998, 37, 4368. 339 H. Weizman, J. Libman and A. Shanzer, J. Am. Chem. Soc., 1998, 120, 2188. 340 S.-D. Kim, J.-K. Kim and W.-S. Jung, Polyhedron, 1998, 17, 1223. 341 M. Albrecht and M.Schneider, Chem. Commun., 1998, 137. 342 C. Bru� ckner, R. E. Powers and K. N. Raymond, Angew. Chem., Int. Ed., 1998, 37, 1837. 343 A.M. Barthram, R. L. Cleary, R. Kowallick and M.D. Ward, Chem. Commun., 1998, 2695. 344 D. S. Bohle and D. Stasko, Chem. Commun., 1998, 567. 345 P. Baret, V. Beaujolais, C. Be� guin, D. Gaude, J.-L. Pierre and G. Serratrice, Eur. J. Inorg. Chem., 1998, 1, 613. 346 Y. Sun, R. J. Motekaitis and A. E. Martell, Inorg. Chim. Acta, 1998, 281, 60. 347 A. Katoh, Y. Hida, J. Kamitani and J. Ohkanda, J. Chem. Soc., Dalton Trans., 1998, 3859. 348 M. Elhabiri, R. Scopelliti, J.-C. G. Bu� nzli and C. Piguet, Chem. Commun., 1998, 2347. 349 N. Martin, J.-C. G. Bu� nzli, V. McKee, C. Piguet and G. Hopfgartner, Inorg. Chem., 1998, 37, 577. 350 J.-P.Costes, A. Dupuis and J.-P. Laurent, J. Chem. Soc., Dalton Trans., 1998, 735. 351 J.-P. Costes, F. Dahan, A. Dupuis and J.-P. Laurent, Chem. Eur. J., 1998, 4, 1616. 352 J.-P. Costes, F. Dahan, A. Dupuis and J.-P. Laurent, New J. Chem., 1998, 22, 1525. 353 J. M. Dominguez-Vera, J. M. Moreno, N. Galvez, J. Suarez-Varela, E. Colacio, R. Kivekas and M. Klinga, Inorg. Chim. Acta, 1998, 281, 95. 354 J. Ribas, C. Diaz, R. Costa, J. Tercero, X. Solans, M. Font-Bardia and H. Stoeckli-Evans, Inorg. Chem., 1998, 37, 233. 355 Z.-N. Chen, H.-X. Zhang, K.-B. Yu, B.-S. Kang, H. Cai, C.-Y. Su, T.-W. Wang and Z.-L. Lu, Inorg. Chem., 1998, 37, 4775. 356 G.-M. Yang, J. Shi, S.-P. Yan, D.-Z. Liao, Z.-H. Jiang and G.-L. Wang, Polyhedron, 1998, 17, 1587. 357 S. M. Malinak, D. T. Rosa and D.Coucouvanis, Inorg. Chem., 1998, 37, 1175. 358 S. Parimala, K. N. Gita and M. Kandaswamy, Polyhedron, 1998, 17, 3445. 359 J. D. Ranford, J. J. Vittal and Y.M. Wang, Inorg. Chem., 1998, 37, 1226. 360 S. Ulvenlund, A. S. Georgopoulou, D. M. P. Mingos, I. Baxter, S. E. Lawrence, A. J. P. White and D. J. Williams, J. Chem. Soc., Dalton Trans., 1998, 1869. 361 A. K. W. Stephens and C. Orvig, J. Chem. Soc., Dalton Trans., 1998, 3049. 362 V. R. Polyakov, V. Sharma, C. L. Crankshaw and D. Piwnica-Worms, Inorg. Chem., 1998, 37, 4740. 363 F. A. Deeney, C. J. Harding, G. G. Morgan, V. McKee, J. Nelson, S. J. Teat and W. Clegg, J. Chem. Soc., Dalton Trans., 1998, 1837. 364 J. H. Satcher, Jr., M. M. Olmstead, M. W. Droege, S. R. Parkin, B. C. Noll, L. May and A. L. Balch, Inorg. Chem., 1998, 37, 6751. 365 C. Patoux, J.-P. Launay, M. Beley, S. Chodorowski-Kimmes, J.-P. Collin, S. James and J.-P. Sauvage, J. Am. Chem. Soc., 1998, 120, 3717. 366 S. Pal, S. Ghosh, G. Mukherjee and A. K. Nandi, Polyhedron, 1998, 17, 3439. 367 Y. Sunatsuki, T. Matsumoto, Y. Fukushima, M. Mimura, M. Hirohata, N. Matsumoto and F. Kai, Polyhedron, 1998, 17, 1943. 368 M. Hissler, A. El-ghayoury, A. Harriman and R. Ziessel, Angew. Chem., Int. Ed., 1998, 37, 1717. 369 A. Døssing, P. Engberg and R. Hazell, Inorg. Chim. Acta, 1998, 268, 159. 370 R. Wietzke, M. Mazzanti, J.-M. Latour and J. Pe� caut, J. Chem. Soc., Dalton Trans., 1998, 4087. 371 A. Ja� ntti, M. Wagner, R. Suontamo, E. Kolehmainen and K. Rissanen, Eur. J. Inorg. Chem., 1998, 1, 1555. 372 E. Monzani, L. Quinti, A. Perotti, L. Casella, M. Gullotti, L. Randaccio, S. Geremia, G. Nardin, P. Faleschini and G. Tabbi, Inorg. Chem., 1998, 37, 553. 373 E. Monzani, L. Casella, G. Zoppellaro, M. Gullotti, R. Pagliarin, R. P. Bonomo, G. Tabbi, G. Nardin and L. Randaccio, Inorg. Chim. Acta, 1998, 282, 180. 374 F. Meyer and P. Rutsch, Chem. Commun., 1998, 1037. 375 F. Meyer and H. Pritzkow, Chem. Commun., 1998, 1555. 376 F. Meyer, K. Heinze, B. Nuber and L. Zsolnai, J. Chem. Soc., Dalton Trans., 1998, 207. 377 Y. Mikata, N. Yakeshita, T. Miyazu, Y. Miyata, T. Tanase, I. Kinoshita, A. Ichimura, W. Mori, S. Takamizawa and S. Yano, J. Chem. Soc., Dalton Trans., 1998, 1969. 378 R. C. Holz, J. M. Bradshaw and B. Bennett, Inorg. Chem., 1998, 37, 1219. 379 C. Belle, J.-L. Pierre and E. Saint-Aman, New J. Chem., 1998, 22, 1399. 380 Y. Sasaki, T. Akamatsu, K. Tsuchiya, S. Ohba, M. Sakamoto and Y. Nishida, Polyhedron, 1998, 17, 235. 381 T. Tanase, T. Inagaki, Y. Yamada, M. Kato, E. Ota, M. Yamazaki, M. Sato, W. Mori, K. Yamaguchi, M. Mikuriya, M. Takahashi, M. Takeda, I. Kinoshita and S. Yano, J. Chem. Soc., Dalton Trans., 1998, 713. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 261–312 311382 Y. Hosokawa, H. Yamone, Y. Nakao, K. Matsumoto, S. Takamizawa, W. Mori, S. Suzuki and H. Kimoto, Inorg. Chim. Acta, 1998, 283, 118. 383 A. Neves, L. M. Rossi, I. Vencato, V. Drago, W. Haase and R. Werner, Inorg. Chim. Acta, 1998, 281, 111. 384 M. Suzuki, S. Fujinami, T. Hibino, H. Hori, Y. Maeda, A. Uehara and M. Suzuki, Inorg. Chim. Acta, 1998, 283, 124. 385 N. Brianese, U. Casellato, S. Tamburini, P. Tomasin and P. A. Vigato, Inorg. Chim. Acta, 1998, 272, 235. 386 J.-P. Costes, F. Dahan, A. Dupuis, S. Lagrave and J.-P. Laurent, Inorg. Chem., 1998, 37, 153. 387 J.-P. Costes, A. Dupuis and J.-P. Laurent, Eur. J. Inorg. Chem., 1998, 1, 1543. 388 P. Bhattacharyya, J. Parr, A. T. Ross and A. M. Z. Slawin, J. Chem. Soc., Dalton Trans., 1998, 3149. 389 M. P. Lowe, P. Caravan, S. J. Rettig and C. Orvig, Inorg. Chem., 1998, 37, 1637. 390 A. Lutz and T. R. Ward, Helv. Chim. Acta, 1998, 81, 207. 391 R. G. Konsler, J. Karl and E. N. Jacobsen, J. Am. Chem. Soc., 1998, 120, 10 780. 392 R. D. Archer, H. Chen and L. C. Thompson, Inorg. Chem., 1998, 37, 2089. 393 C. N. Verani, T. Weyhermu� ller, E. Rentschler, E. Bill and P. Chaudhuri, Chem. Commun., 1998, 2475. 394 E. V. Rybak-Akimova, N. W. Alcock and D. H. Busch, Inorg. Chem., 1998, 37, 1563. 395 J. M. Dominguez-Vera, N. Galvez, J. M. Moreno and E. Colacio, Polyhedron, 1998, 17, 2713. 396 C. Surville-Barland, R. Ruiz, A. Aukaloo, Y. Journaux, I. Castro, B. Cervera, M. Julve, F. Lloret and F. Sapin8 a, Inorg. Chim. Acta, 1998, 278, 159. 397 S. W. Gordon-Wylie, B. L. Claus, C. P. Horwitz, Y. Leychkis, J. M. Workman, A. J. Marzec, G. R. Clark, C. E. F. Rickard, B. J. Conklin, S. Sellers, G. T. Yee and T. J. Collins, Chem. Eur. J., 1998, 4, 2173. 398 Y.-M. Wang, C.-H. Lee, G.-C. Liu and R.-S. Sheu, J. Chem. Soc., Dalton Trans., 1998, 4113. 399 E. To� th, F. Connac, L. Helm, K. Adzauli and A. E. Merbach, Eur. J. Inorg. Chem., 1998, 1, 2017. 400 B. Achour, J. Costa, R. Delgado, E. Garrigues, C. F. G. C. Geraldes, N. Korber, F. Nepveu and M. I. Prata, Inorg. Chem., 1998, 37, 2729. 401 E. Escriva, J. Server-Carrio� , J. Garcý� a-Lozano, J.-V. Folgado, F. Sapin8 a and L. Lezama, Inorg. Chim. Acta, 1998, 279, 58. 402 R. C. Howell, K. V. N. Spence, I. A. Kahwa and D. J. Williams, J. Chem. Soc., Dalton Trans., 1998, 2727. 403 P. V. Bernhardt and P. C. Sharpe, J. Chem. Soc., Dalton Trans., 1998, 1087. 404 N. Beynek, M. McPartlin, B. P. Murphy and I. J. Scowen, Polyhedron, 1998, 17, 2137. 405 M. Konrad, F. Meyer, K. Heinze and L. Zsolnai, J. Chem. Soc., Dalton Trans., 1998, 199. Annu. Rep. Prog. Chem., Sect. A, 1999, 9

ISSN:0260-1818    

DOI:10.1039/a804897e

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

18 The co-ordination chemistry of macrocyclic ligands I. A. Fallis Department of Chemistry, Cardi§ University, PO Box 912, Cardi§, UK CF10 3TB 1 Tridentate ligands N-Donor ligands Reaction of [FeIII(L1)Cl 3 ] with anhydrous disodium disulfide (Na 2 S 2 ) a§ords the unusual diamagnetic persulfide complex [(L1)FeIII(l-g1-S 2 ) 3 FeIII(L1)] 1.1 Two 13C NMRsignals for the macrocyclic ring methylene residues indicate that inversion at the tetrahedral sulfur centres was slow.The structure indicated a short metal–metal distance, consistent with an Fe–Fe bond, and stabilising hydrogen-bonds between the N N N PtIV O Cl O N N N PtIV O Cl O FeIII S N N S N S N N N FeIII S S S 2 1 H H H H H H 2+ H H H H H H terminal sulfur atoms and the ringNHgroups. The complex [Pt 2 IV(L1) 2 (l-O 2 ) 2 Cl 2 ]2` 2 was prepared by reduction of [PtCl 2 (dmso) 2 ] and L1 in aqueous methanol under aerobic conditions.2 This is a very rare example of a binuclear complex in which the metal centres are linked by two bridging peroxo groups and has been proposed as a Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 313model intermediate in the aerial oxidation of PtII complexes. Cluster complexes of CoIII and L1 in which the purine-thione co-ligands L2–L4 act as bridging ligands have been prepared.3 The trinuclear complex [Co 3 (L1) 3 (L2) 3 ]3` has C 1 symmetry and could be separated into its optical isomers and characterised byCDspectroscopy.Clusters with the general formula [Con(L1)n(L2–4)n]n` are very robust which permitted their nuclearity to be confirmed by mass spectrometry.The reaction of equimolar quantities of [Co(L1)(CN) 3 ] and [Co(L1)(H 2 O) 3 ]3` in water a§ords the elegant octanuclear cluster [CoIII 8 (L1) 8 (l-CN) 12 ]12`.4 Eight [CoIII(L1)] fragments are linked in a cube via linear cyanide bridges, a structure reminiscent of that of Prussian Blue. The analogous mixed metal cluster [CrIII 4 CoIII 4 (L1) 8 (l-CN) 12 ]12` could also be prepared in a similar manner by reaction of [CoIII(L1)(CN) 3 ] and [CrIII(L1)(H 2 O) 3 ]3`.The mixed ligand sandwich complex [NiII(L1)(L30)]2` has been prepared by successive addition of L1 and L30 to NiII salts in aqueous solutions.5 A monocyclic intermediate [NiII(L1)(MeNO 2 ) 3 ]2` was also identified. [NiII(L1)(L30)]2` shows a quasi-reversible NiII–NiIII couple at 0.86V (vs. ferrocene–ferrocenium) which is intermediate between the NiII–NiIII couples of [NiII(L1)]2` and [Ni(L30)].N N N R2 R3 R1 L1 R1 = R2 = R3 = H L5 R1 = R2 = R3 = Me L6 R1 = R2 = R3 = CH2CN L7 R1 = R2 = R3 = CH2CH2CN L8 R1 = R2 = R3 = CH2CONH2 L9 R1 = R2 = R3 = CH2CONHMe N HN N S R H H2L2 R = H H2L3 R = NH2 H2L4 R = OH Octahedral complexes of general formula [Ti(L1,5,30)(NBu5)Cl 2 ] are obtained by reaction of ligands L1,5,30 with [Ti(NBu5)Cl 2 (py) 3 ] in dichloromethane.6 These complexes are isolobal with Group IV metallocene complexes.The phosphorescence of complexes with the general formula [MoIII(L5)X 3 ] (X\Cl~, Br~, I~) in MeCN has been described.7 These complexes undergo reversible one-electron photooxidations in the presence of electron acceptors such as chloranil and TCNE.Where X\Br~ or I~ irreversible photooxidations are observed in the presence of tetranitromethane, C(NO 2 ) 4 , yielding the cationic MoIV species [Mo(L5)X 3 ]`. A two-electron oxidation was possible in aqueous acetonitrile, which proceeded via a primary MoIV photoproduct which spontaneously disproportionates to yield [MoV(L5)OX 2 ]`.The synthesis of two series of quasi-isostructural homo- and hetero-trinuclear complexes of general formula [(L5)MnIIIMMII(l-dmg) 3NMnIII(L5)][ClO 4 ] 2 and [(L5)MnIVMMII(l- dmg) 3NMnIV(L5)] has been described.8 Two exchange pathways were identified with Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 314distinct coupling pathways between adjacent and terminal metal centres.In a separate study the analogous series of CrIII complexes, [(L5)CrMMII(l-dmg) 3NCr- (L5)]`1@`2@`3@`4 [M\absent, (H`) 2 , LiI, MgII, CuII, NiII, NiIV, CoIII, FeII, FeIII] was prepared; two exchange pathways were also found.9 Treatment of a mixture of [RuIII(L5)Cl 3 ] and Ag(CF 3 SO 3 ) with cyclohexa-1,3-diene in ethanol yields the p-arene complex [Ru(L5)(g6-C 6 H 6 )]2`.10 In the presence of zinc dust with 1-(trimethylsilyl) cyclopentadiene, 1-(trimethylsilyl)indene, cyclohexa-1,3-diene or cycloheptatriene this reaction yielded [Ru(L5)(g5-C 5 H 5 )]`, [Ru(L5)(g5-C 9 H 7 )]`, [Ru(L5)(1–5- g)-C 6 H 7 )]` and [Ru(L5)(1–5-g-C 7 H 9 )]` respectively.The r-bonded vinyl complexes [RhIII(L5)(CH––CH 2 ) 3 ], [RhIII(L5)(Z-CH––CHMe) 3 ] and [RhIII(L5)Me(CH–– CH 2 ) 2 ] have been synthesised.11 Protonation of these complexes with triflic acid, [H(OEt 2 ) 2 ] [B(C 6 H 3 R 2 -3,5)] (R\CF 3 ) or HCl was performed in a number of solvents, [RhIII(L5)(CH––CH 2 ) 3 ] a§ording [RhIII(L5)(CH––CH 2 )(g3-E-CH 2 CH––CHMe)]`.Reaction of [RhIII(L5)(CH––CH 2 ) 3 ] using CD 3 OD as solvent and acid source yielded [RhIII(L5)(CH––CH 2 )(g3-E-CH 2 CH––CHCH 2 D)]` as the only isotopically substituted product, which suggests a [RhIII(L5)(CH––CH 2 ) 2 (––CHCH 2 D)]` intermediate.Reaction of SbCl 3 and SbCl 5 with L5 a§ords the ionic complex [SbCl 2 (L5)][SbCl 6 ] in which the [SbCl 2 (L5)]` cation contains a five-co-ordinate SbIII centre; a stereochemically active lone-pair is trans to a macrocyclic N-donor atom.12 The products of the photolysis of [MnIII(L5)(N 3 ) 3 ] in methanol or acetonitrile solution are sensitive to temperature and to the wavelength of the radiation used.13 At[35 °C and 350nm in acetonitrile the photooxidation product [MnV(L5)(N 3 ) 2 ] is observed, whilst irradiation at 20 °C and 253.7nm in methanol yielded the photoreduction product [MMnII(L5)(N 3 )N2 (l-N 3 )].The amidation of hydrocarbons has been achieved using cis-[RuII(L5)(TsNH)(H 2 O)] in the presence of AgClO 4 .14 The functionalised ligands L6 and L7 form polymeric networks with AgI salts, in which the pendant nitrile groups co-ordinate to adjacent metal centres within the lattice.15 The VIV––O, VIII, MnII, CoII, NiII, CuII and ZnII complexes of the tris(pendantarm amide) ligands L8 and L9 have been described.16 In each case the ligand presents a N 3 O 3 donor sphere, with the pendant donors binding via the oxygen atoms of the carboxamide groups.In the case of CrIII an N 4 O 2 donor sphere was possible with the pendant donors behaving as N- or O-donors. The co-ordinated amide groups were found to hydrolyse slowly. A resonance Raman and DFT study of the electrogenerated phenoxyl radicals of the ScIII, FeIII, and GaIII complexes of L10–13 permit17 a categorical distinction between co-ordinated and free radical species.The complex [GaIII(L14)F 3 ]·6MeOH·CH 2 Cl 2 contains cyclic hexamers of methanol supported within hydrophobic cavities created by two neighbouring [GaIII(L14)F 3 ] units.18 CuI and CuII complexes of the sterically demanding ligands L15 and L16 have been prepared.19 The CuI complexes [Cu(L15,16)(NCMe)]X (X\ClO 4 ~ or CF 3 SO 3 ~) display four-co-ordinate tetrahedral geometries in which the pendant donor is uncoordinated, whilst the CuII complexes [Cu(L15,16)X@]X (X@\Cl~ or CF 3 SO 3 ~; X\ClO 4 ~ or CF 3 SO 3 ~) are trigonal bipyramidal with the pendant amide group co-ordinated via the carbonyl oxygen atom.Complexes of the general formula [NiII(L17)(H 2 O) 2 ]2` form micelles in aqueous solutions, small angle neutron scattering showing an approximate aggregation number of fifty.20 The ligandH 4 L18 has been prepared as a potential 67,68Ga binding group for the labelling of bioactive molecules. 21 Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 315HO OMe But HO OMe But HO But But HO OMe But H2N But But N O H O N R' R" COOH COOH COOH n-alkyl OH L17 R1 = R2 = H ; R3 = H4L18 R1 = R2 = R3 = L15 R1 = R2 = Pri ; R3 = R¢ = H or Me ; R¢¢ = H or Me L16 R1 = R2 = Pri ; R3 = L14 R1 = R2 = R3 = H3L10 R1 = R2 = R3 = H3L11 R1 = R2 = R3 = H2L12 R1 = Et ; R2 = R3 = HL13 R1 = R2 = H ; R3 = Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 316The ditopic ligand HL19 forms mononuclear and binuclear CuII complexes in aqueous solution, with the pyrazole deprotonated complex [Cu 2 (L19)]3` able to bind additional ligands such as azide and additional pyrazole-based heterocyclic donors.22 N N N H H N N N H H N N H N N N N N N N N N R N N R N R R N N N R1 R1 R2 L20 R1 = H ; R2 = L21 R1 = ; R2 = H L22 R = HL19 The synthesis of three novel pendant-imidazole ligands L20–L22 has been described and their PbII complexes isolated as the tetraphenylborate salts.23 X-Ray crystallography of the complexes indicated the macrocycle in its typical face-capping mode with bound pendant donors.In all three structures one phenyl group of the counter ion strongly interacts in a face-on manner to complete the co-ordination sphere of the metal centre.N N N N N N N N N N OH R L23 R = (CH2)2 L24 R = (CH2)3 L25 R = (CH2)4 L26 R = L27 R = The NiII co-ordination chemistry of the series of ditopic ligands L23–L27 has been established.24 The crystal structure of [Ni 2 (H 2 O) 2 (L25)][ClO 4 ] 4 indicates that each metal centre has six-co-ordinate tetragonally distorted geometry with the co-ordination sphere completed by a water molecule.Electrochemical studies showed that oxidation to dinuclear [NiIIINiIII] species was possible. A kinetic study of the rates of hydrolysis of phenyl acetates by the ZnII complexes of L28 ([12]aneN 3 ) indicated that the esters were co-ordinated to the metal centre prior Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 317N N NH NH HN NH L29 H H L28 to hydroxide attack at the carbonyl group.25 An electrostatic interaction between the metal centre and hydroxide ions facilitated ester hydrolysis.The CoIII sandwich complex of L28 displays two electrochemical reductions in aqueous solution. The first is a reversible CoIII–CoII couple and the second is an irreversible CoII–CoI couple.26 The cryptand L29 forms unsymmetrical complexes with CuI and AgI ions.27 The mode of bonding in [MI(L29)]` is quite unusual, with the metal centre co-ordinated by two N-donors and displaying an interaction with the terminal aromatic rings described as a three-centre two-electron bond involving an aromatic C–H bond.S- and P-donor ligands The transport of metal cations (e.g. PbII, CdII, ZnII and CuII) across a polarised liquid–liquid (H 2 O–ClCH 2 CH 2 Cl) interface is facilitated by the thioether ligands [9]aneS 3 (L30), [10]aneS 3 (L31), [12]aneS 4 (L135) and [16]aneS 4 (L136), with PbII and CdII ion transport being electrochemically reversible.28 The vanadium complexes [VIIICl 3 (L30)] and [VIII 2 (thf)(L30)] have been prepared and structurally characterised. 29 The complexes [RuII(P––CHCMe 3 )L@(PPh 3 )(L30)]Cl (L@\CO or CS) have been prepared by the reaction of L30 with [RuII(P––CHCMe 3 )ClL@(PPh 3 ) 2 ].30 The tungsten carbyne complex [W(–– – CPh)(L30)(CO) 2 ][PF 6 ], prepared by the reaction of L30 and [W(–– – CPh)(CO) 2 (py) 2 Cl] in refluxing acetonitrile in the presence of Ag- [PF 6 ],31 displays an intense orange to red emission upon excitation at 330 nm.Reaction of [Mo(CO) 2 (NCMe)(g5-ind)]`with L30 results in the ‘ring-slipped’ product [Mo(CO) 2 (g3-ind)(L30)]`.32 The binuclear complex [RuII 2 (L30) 2 (L32)Cl 2 ]2` is prepared by the addition of L32 to [RuII(L30)(dmso)Cl 2 ];33 an electrochemical analysis indicated that the RuII oxidation state was strongly stabilised by p-back donation from L32.The di§erence between the potentials of the RuII 2 –RuIIIRuII and RuIIRuIII–RuIII 2 couples (0.48 V), indicated a moderately strong metal–metal interaction.AgI complexes of L30,161,191 have been used as templates for the preparation of polyiodide ions; the following complexes were structurally characterised [Ag(L30) 2 ]I 5 , [Ag 2 (L161) 2 ]I 12 , [Ag(L191)]I 7 , and [Ag(L191)]I 7 .34 S S S S S S N N N N N N P P P Et Et Et L33 L32 L30 L31 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 318The complex [NiIIBr(L33)]Br shows a very unusual structure in the solid state.35 The metal co-ordination geometry, which is best described as distorted square planar, is thought to be a consequence of the P-donors being constrained within the macrocyclic framework. Mixed donor ligands An extensive calorimetric study of the enthalpies of protonation of tridentate macrocyclic ligand (N-, P- and S-donors) complexes showed the ligand basicities to vary in the orderNAPqS, and that an increase in ligand basicity also caused an increase in metal basicity.Despite a large di§erence in ligand basicity for S- and P-donors, the metal basicities were very similar. This was attributed to non-bonding lone pair (on sulfur) d-orbital repulsion raising d-orbital energy and rendering the metal more basic.The crystal structures of the NiII and CuII complexes of HL35 have been determined.36 Ni(II) forms the mononuclear complex [Ni(HL35)(O 2 CMe)][BPh 4 ]·MeCN in which the metal centre is six-co-ordinate with the ligand acting as a tetradentate donor and a chelating acetate ligand completing the co-ordination sphere.With CuII, L35 forms a binuclear complex [Cu 2 (L35) 2 ][BPh 4 ] 2 in which the pendant alcohol ligands are deprotonated to form bridging alkoxo ligands. The structure and electrochemistry of the octahedral complex [Cu(L34) 2 ][PF 6 ] 2 was also described. An extensive study of the FeII and FeIII complexes of L34 and L36 included37 single-crystal electronic spectroscopy of [Fe(L34) 2 ][ClO 4 ] 2 and [Fe(L36) 2 ][ClO 4 ] 2 , which indicated a splitting of the parent octahedral 1A 1' ]1T 2' and 1A 1' ]1T 1' bands, but was finally attributed to a weak ligand (S-donor) to metal charge transfer band.The novel pendant-arm [9]aneN 2 S derivatives H 2 L37, H 2 L38 and H 2 L39 have been prepared and their CuII co-ordination chemistry explored.38 The bulk of the pendant-arm a§ected the mode of co-ordination of the ligand, with H 2 L37 forming the binuclear complex [Cu 2 (HL37) 2 ][PF 6 ] 2 and H 2 L39 forming only the mononuclear complex [Cu(H 2 L39)][PF 6 ] 2 .WithH 2 L38 both binuclear [Cu 2 (HL38) 2 ][PF 6 ] 2 and mononuclear [Cu(H 2 L38)][PF 6 ] 2 were isolated. SQUID magnetometry of [Cu 2 (HL37) 2 ]- [PF 6 ] 2 indicated that despite two alkoxo-bridges, the CuII centres were essentially non-interacting.Upon dissolution in CH 2 Cl 2 under a CO atmosphere [CuI(L40)(NCMe)]`forms [CuI(L40)]`39 in which the pendant naphthalene moiety is g2- bound, giving an approximate tetrahedral geometry at the metal. 2 Tetradentate ligands N-Donor ligands The kinetics of the reaction of [NiII(L41)]2` with phen, en and Gly~ ligands is first order in both [NiII(L41)]2`, and phen or en.40 The reaction was zero order in Gly~ at high concentrations, but reverted to first order in more dilute solutions.ZnII complexes of L42–44 are e§ective in the transport of imide-containing nucleotides and nucleosides from aqueous solution into chloroform.41 For example, [Zn(L44)]2` selectively extracted thymidine from a mixture of other nucleobases.The electronic spectrum of the 2,4-dinitrophenyl functionalised L45 is very sensitive to protonation or to metal Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 319OH N S S R OH S N N R R L36 R = H L37 R = CH2CH2OH L38 R = CH2C(CH3)2OH L39 R = L34 R = H HL35 R = S S N L40 binding.42 Upon co-ordination of divalent metal ions (ZnII, CdII, PbII) the electronic transition of the 2,4-dinitrophenyl moiety is shifted to lower wavelengths, whilst the binding of NiII or CuII e§ectively quenches this absorption band.The ZnII complex of L45 also binds the anion of 1-methylthymine (MT~), which is stabilised by p-interaction between the 2,4-dinitrophenyl moiety and the MT~ fragment. The protonation constants and the CaII and LnIII stability constants of L46 have been measured.43 The formation constants of lanthanide ions increased with atomic number for the lighter members of the series (LaIII–SmIII) and were essentially constant for the heavier members of the series.The number of co-ordinated water molecules in the complex [EuIII(L46)(H 2 O)x]` was determined to be 2.6–3.0 by laser excited luminescence spectroscopy at a range of pH values.Optimised conditions (37 °C and ammonium acetate bu§er) for the high-yield complexation of 90Y by H4 L47 immunoconjugates have been established.44 In an XAFS study of [Gd(L47)]~ in aqueous solution the local environment and complex dynamics remained constant (up to a radius of 4.5Å) down to pH 1.5 and the metal centre remained nine-co-ordinate; [L47]4~ binds through all eight donor atoms and a water molecule completes the co-ordination sphere.45 At lower pH values complex dissociation occurred.The Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 320N N Me N N N N R2 R2 R1 R1 H2L46 R1 = H ; R2 = CH2CO2H H4L47 R1 = R2 = CH2CO2H L48 R1 = R2 = CH2CO2NH2 H2L49 R1 = CH2CO2H ; R2 = proton/solvent relaxivity of [GdIII(L48)(H 2 O)]3` is constant over the pH range 3–8, and higher outside this range.46 A single crystal X-ray study indicated a nine-coordinate monocapped square antiprismatic geometry with the water molecule occupying the apical site.The rate of exchange of the co-ordinated water molecule in [EuIII(L48)(H 2 O)]3` is sensitive to ligand conformation; the two possible diasteromeric forms have significantly di§erent rates.47 The NiII and ZnII co-ordination chemistry of the potentially octadentate ligand L49 has been investigated.48 NiII forms two complexes [Ni(L49)]·6.5H 2 O and [Ni(H 1.5 L49)][ClO 4 ] 1.5 ·2H 2 O in which the metal centres are approximately octahedral with the macrocycle binding via all four N-donors. In the former complex the pendant carboxylate donors co-ordinate to the metal centre whilst in the latter the imidazole donor completes the metal co-ordination sphere.The structure of the trinuclear complex [Zn 3 (L49) 2 ][ClO 4 ] 2 ·3H 2 Ohas peripheral seven-co-ordinate [Zn(L49)] fragments binding a tetrahedral ZnII centre via one bridging carboxylate and a free pendant imidazole donor per terminal unit.The pendant phosphate and phosphate ester ligands H 4 L50 and H 2 L51 form stable 1: 1 complexes with a range of di- and tri-valent metal ions, with ZnII forming the most stable complexes.49 The stability constants for the complexes [LnIII(L51)]` increased by two orders of magnitude along the lanthanide series (LaIII to LuIII), whilst those of [LnIII(L50)]` increased by three orders of magnitude for the same series.A mechanism for the encapsulation of EuIII ions by H 4 L52 has been proposed, in which two molecules of H 4 L52 bind to a single EuIII centre via eight hydroxyl donors prior to the complete encapsulation of the metal ion by H 4 L52 via four N- and four O-donors.50 A 13C NMR spectroscopic study of alkali metal complexes of H 4 L52 indicated eight-coordinate structures in dmf with the ‘basket’, as defined by the four phenyl rings, becoming increasingly shallow with an increase in ionic radius of the metal.51 Chiral lanthanide complexes of ligands such as H 3 L53 have been examined by NMR spectroscopy, relaxometry and circularly polarised luminescence.52 The chirality of the remote amido pendant-arm group determined the overall sense of helicity in the complex as defined by the pendant arms and the conformation of the macrocyclic chelate rings.The metal- and ligand-based fluorescence of [TbIII(L54)] have been monitored as a function of pH and partial oxygen pressure (pO 2 ).53 The ligand fluorescence was enhanced by a factor of three upon protonation of the pendant Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 313–351 321N N N N HO OH OH HO P O OH OEt P O OH OH H4L50 R1 = R2 = H2L51 R1 = R2 = N N N N P P P O O HO HO O OH Me Me Me R N O Me N N O H H H3L53 R = H3L54 R = phenanthridyl groups whilst the metal-based fluorescence was diminished by a factor of 125. The triplet state of the pendant phenanthridyl groups is quenched by O 2 , and thus at low pO 2 values the quantum yield and luminescence lifetime of the metal centre are increased.Cyclam (L55) forms the octahedral CoIII acetylacetonate complexes [Co(L55)(acac)]- [BF 4 ] 2 and [Co(L55)(acac)][acac] 2 in which the macrocycle adopts a folded cis conformation with a bidentate acac completing the co-ordination sphere.54 The synthesis of MnV–nitrido complexes of L55 has been reported.Photolysis of trans- [MnIII(L55)(N 3 ) 2 ][ClO 4 ] yields the binuclear complex [Mtrans-(L55)MnVNN(l-N 3 )]- [ClO 4 ] and dinitrogen whilst treatment of trans-[Mn(L55)Cl 2 ]` with aqueous ammonia and sodium hypochlorite a§ords [MnV(L55)NCl]`.13 Reaction of L55 and K 3 [Fe(CN) 6 ] yields [FeIII(L55)][Fe(CN) 6 ]·6H 2 O55 which has infinite chains of [FeIII(L55)]3` linked via [Fe(CN) 6 ]3~ units which co-ordinate via trans bridging cyanide ligands.Magnetic studies indicated a strong interchain ferromagnetic coupling of adjacent metal centres, and a weak antiferromagnetic interchain interaction. The ZnII complexes trans-[Zn(L56)(H 2 O) 2 ]Cl 2 and trans-[Zn(L56)X 2 ] (X\N 3 ~ or NCS~) have been structurally characterised.56 The oxidation of the RhIII hydride complexes [RhH(L55)]2` and [RhH(L57)]2` by Bu5OOH in aqueous solution is catalysed by FeII ions.57 The products of the reaction are [RhIII(L55,57)]3` species, methane and acetone.The reaction is also initiated by [CoII(L57)]2`, although this complex is required in stoichiometric amounts for complete peroxide decomposition. NiII and CuII form square planar complexes with the isomeric cyclohexyl cyclam derivatives L58 and L59.58 L60 forms octahedral complexes [MII(L60)][ClO 4 ] 2 (M\NiII, CuII).The CuII species was crystallographically characterised which indicated a trans disposition of the Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 322N N N N N N N N H H N N N N H H H H L56 L57 H H H H L55 N N N N H H H H L58 rac L59 meso pendant pyridyl donors.59A short synthesis of the mono-pendant armH 2 L61 has been reported.60 The CuII complexes [Cu(HL61)][ClO 4 ] 2 ·0.5H 2 O and [Cu(L61)][ClO 4 ]· 5H 2 O were isolated; the former at acidic pH values, the latter at basic pH values.The metal centre in [Cu(HL61)]2` is five-co-ordinate with the pendant carboxylate group bound via the carbonyl oxygen. The pendant group remains protonated in aprotic media and dilute aqueous acid, but is deprotonated at neutral pH values.Very short metal–ligand distances and a very high ligand field strength (Dq\1785 cm~1) are observed in the low spin, distorted octahedral complex [FeII(L62)]2`.61 Owing to the short bond lengths, the FeII–FeIII couple occurs at a very low potential (0.45Vvs. SHE). Reaction of [CoIII(L63)]3` with formaldehyde in methanol a§ords the bis(imine) complex [CoIII(L64)]3`. Subsequent tetrahydroborate reduction yields [CoIII(L65)]3` as a mixture of meso and rac forms as defined by the configuration of the N-methyl groups.62 N N N N N R R H H N N N N R2 R1 R2 R1 H H H H L62 R1 = H ; R2 = NH2 L63 R1 = Me ; R2 = NH2 L64 R1 = Me ; R2 = N=CH2 L65 R1 = Me ; R2 = NHMe L60 R = H2L61 R = CH2CO2H The synthesis of the ‘trans’ functionalised ligands L66–71 and their NiII and CuII co-ordination chemistry have been reported.63 The complexes of L68 and L69 displayed pH-sensitive co-ordination numbers, consistent with protonation/deprotonation of the pendant amine donors.The NiII complex of HL72 displays a distorted octahedral geometry with the co-ordination sphere consisting of four amine and one sulfonate donor and a co-ordinated water molecule.64 The macrocycle adopts a folded cis conformation about the metal centre.At low pH values [NiII(L73)]2` displays an intense fluorescence due to the anthracene moiety.65 At higher pH values the pendant Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 323arm becomes deprotonated and co-ordinates the metal centre to yield [Ni(L73)- (H 2 O)]2` which displays a lower fluorescence intensity. The addition of further base results in deprotonation of the co-ordinated water molecule and a further reduction in fluorescence.The two-component ligand L74 forms binuclear complexes with general formula [MII(L74)MReCl(CO) 3N]2` (M\Ni, Cu, Zn) in which the first row metal ion occupies the macrocyclic cavity.66 The oxidation potential of the ReI centre is essentially una§ected by the presence of CuII or ZnII within the macrocyclic cavity.However, this oxidation is significantly altered by the presence of NiII, due to a NiII oxidation process preceding the ReI oxidation. The fluorescence of the ReI(bipy) component is quenched in the NiII and CuII complexes, but not in the ZnII case. N N N N R1 R2 R2 R1 L66 R1 = Me ; R2 = CH2CN L67 R1 = Me ; R2 = CH2CH2CN L68 R1 = Me ; R2 = CH2NH2 L69 R1 = Me ; R2 = CH2CH2NH2 L70 R1 = Me ; R2 = CH2CO2NH2 L71 R1 = Me ; R2 =CH2CO2H N N N N N N N R1 R1 R3 R2 HL72 R1 = Me ; R2 = H ; R3 = CH2CH2SO3H L73 R1 = R2 = H ; R3 = L74 R1 = R2 = H ; R3 = H Vigorously aprotic conditions were required for transition metal complex formation with the ‘proton-sponge’ ligand L75;67 stable complexes are formed with CrII, MnII, MnIII, FeII, FeIII, CoII, NiII, CuI, CuII and ZnII ions.As an indication of the stability of these complexes the electronic spectrum of [CuII(L75)]2` remains unchanged in 1M HClO 4 solution after several weeks at 40 °C. The tricyclic bis(cyclam) ligands L76 and L77 and their NiII and CuII complexes have been synthesised.68 EPR spectroscopy of the binuclear complex of L76 indicates a significant interaction between the metal centres.The complex [HgII 3 (L78)]6` selectively binds tris(imidazole)-based ligands (in this case a trihistidine tripeptide) over unidentate imidazole-containing ligands.69 The trinuclear complex [Cu 3 L79]- [ClO 4 ] 6 ·5H 2 O was prepared in a template synthesis by reacting 232-tet, formaldehyde, melamine and Cu(NO 3 ) 2 in aqueous methanol.70 The complex has a syn,anti relative stereochemistry of the macrocyclic subunits with reference to the central melamine core.The EPR spectrum of [Cu 3 L79][ClO 4 ] 6 ·5H 2 O indicates that the metal centres are only weakly interacting via a dipole–dipole mechanism.NiIII complexes of general formula [Ni(L80–82)X 2 ]` (X\Cl~, Br~ and NO 3 ~) are formed by oxidation of the parent NiII complex by (NH 4 ) 2 S 2 O 8 , FeCl 3 or HNO 3 .71 In all cases where potential pendant donors were present they remained unco-ordinated. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 324N N N N Me Me H2C CH2 CH2 H2C N N N N X X N N N N H H H H L76 X = L77 X = L75 N H N H N H N N H N H N H N N N N N H H H N N N N N N N N N N N N N N N N N N H H H H H H H H H H H H L79 L78 N N N N N N R R H H H H L80 R = CH2CH2OH L81 R = CH2CH2CN L82 R = Me Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 325L83 is stereospecifically formed upon condensation of 1,2-diaminopropane monohydroperchlorate and acetone.72 Reduction of L83 yields a mixture of three saturated isomeric ligands (L83@) which form CrIII complexes of general formula [CrXY(L83@)]` (X, Y\H 2 O, Cl~).The novel ligand L84 forms stable CuII, NiII and ZnII complexes, and also forms trans complexes of general formula [CoIII(L84)X 2 ]` (X\Cl~, Br~, NCS~, N 3 ~, CH 3 CO 2 ~, NO 2 ~).73 CuII complexes of L85 are four-co-ordinate at low pH and five-co-ordinate at higher pH due to deprotonation and subsequent coordination of the pendant amine group.74 N N N N N N N N Et Et N N N N H H H H N N N N H H H H L86 L85 H H L84 L83 H H The decarboxylation of cis-[CoIII(L85)(CO 3 )]` has been resolved into two steps; the cleavage of the carboxylate ring with rapid decarboxylation, followed by cis to trans rearrangement.75 Treatment of trans-[RuIII(L86)Cl 2 ]Cl with zinc dust under a dinitrogen atmosphere a§ords trans-[RuII(L86)(N 2 )Cl][PF 6 ] in which the monodentate N 2 ligand is bound end-on.76 The NiII and CuII co-ordination chemistry of the dioxo –tetraaza ligands L87–93 has been described.77 The NiII complex of H 2 L90 has a distorted octahedral geometry with two amine N-donors, two carboxylate O-donors, one amide O-donor and a water molecule.The degree of deprotonation of the macrocyclic amide groups is a function of ring size and the ability of the pendant donors to co-ordinate to the metal centre. The bis(hydroxamate) dioxocyclam ligand L94 forms the dinuclear FeIII complex [Fe 2 (L94) 3 ], the structure of which was postulated from a series of molecular mechanics calculations.78 The acid dissociation kinetics of the CuII complexes of L95–98 have been interpreted as proceeding via a protonated carbonyl intermediate with the rate determining step being the tautomerism of this enolic form to protonated imine.79 An electroabsorption spectroscopy and near infrared resonance Raman study of [ML99]n` (M\Fe, Ru) type complexes has provided evidence in support of the assignment of an absorption band in the near infrared region as a delocalised intervalence transition.80 The binding of carbon monoxide by [FeII(L100)][PF 6 ] 2 has large negative values for both the entropy and volume of activation.81 These observations are consistent with a mechanism in which a CO molecule enters the ligand chamber prior to Fe–CObond formation.The metal centre subsequently undergoes a high-spin to low-spin transition in which the metal centre moves towards the plane of the ligand (as defined by the N donor atoms), e§ectively causing a further reduction in volume.H 2 L101 forms the eight-co-ordinate unsymmetrical sandwich complex [YIII(L101)(HL101)]·2thf.82 The solid-state supramolecular interactions of the nonplanar NiII complex [Ni(L101)] and a range of main group cluster compounds have been investigated.83 With buckminsterfullerene the 1: 1 complex [Ni(L101)][C 60 ] is Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 326N N N N O O R2O2C R2O2C N N N N O O R R N N N N O O R1 R2 H H H H R1 H2L87 R1 = (CH2)2 ; R2 = H H2L88 R1 = (CH2)3 ; R2 = H H2L89 R1 = CH2CH(OH)CH2 ; R2 = H H2L90 R1 = (CH2)4 ; R2 = H H2L91 R1 = cis-(CHCH=CHCH2) ; R2 = H L92 R1 = (CH2)2 ; R2 = Et L93 R1 = (CH2)3 ; R2 = Et L95 R1 = OCH3 ; R2 = H L96 R1 = R2 = H L97 R1 = OCH3 ; R2 = Br L98 R1 = R2 = Br H H H H H2L94 R = CH2CON(OH)CH3 formed whilst a 2: 1 stoichiometry is observed in materials of the general formula [Ni(L101)][X] 2 (X\P 3 S 4 or o-C 2 B 10 H 12 ).The crystal structures of these materials were described in detail.The binuclear RuII complex [MRu(L101)N2 (l-cod)] reacts with substituted diazomethanes (RR@CN 2 ) to yield stable carbene complexes of general formula [Ru(L101)(––CRR@)] which, depending upon the nature of R and R@, yield carbonyl complexes or carbene migration upon exposure to an atmosphere of carbon monoxide.84 In the case of R\R@\Ph, [Ru(L101)(––CRR@)(CO)] was obtained, whilst in the case where R\H and R@\Ph metal-to-macrocycle carbene migration occurred, subsequently followed by isomerisation to the ring-expanded product [RuII(L102)(CO) 2 ].A series of 6,13-disubstituted tetraaza[14]annulene NiII complexes with the general formula [NiII(L103–107)] have been prepared by coupling [NiII(L101)] with the appropriate para substituted diazonium salts.85 The r-bonded CoIII–porphycene metal alkyls [Co(L108–111)R] (R\CH 3 or C 6 H 5 ) undergo a metal-to-ligand alkyl migration upon electrogeneration of [Co(L108–110)R]`· to yield N-substituted CoII species.86 The FeIII complex [Fe(L109)Cl] is reduced in three (reversible) one-electron steps and oxidised in two (reversible) one-electron steps; the l-oxo dimer [MFe(L109)N2 O] undergoes four oneelectron oxidations and four one-electron reductions.87 It was also noted that the reduction of [Fe(L109)Cl] under an atmosphere of carbon monoxide yields the stable carbonyl complex [FeII(L109)(CO)].Reaction of L112 with FeII salts and di-tert-butylbenzoquinone yields the FeIII–semiquinonate complex [FeIII(L112)(dbsq)][ClO 4 ] 2 ·2.5H 2 O, the first example of its kind.88 The low spin FeIII centre and the semiquinonate free radical are antiferromagnetically coupled.The complex is stable to oxidation by molecular oxygen, but is reduced to the corresponding catecholate species by superoxide ions, which has important implications in the mechanism of C–C bond cleavage processes in cat- Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 327N N N N N N N N Ph Ph N N Ph Ph N N N N N N N N N N N N H H Ph N N N N R R N N X L100 L99 H H H H R = H2L103 X = H H2L104 X = NO2 H2L105 X = Cl H2L106 X = CH3 H2L107 X = OCH3 H H H2L102 H2L101 H H echolate systems.The protonation and stability constants of H 2 L113 and H 3 L114 with a range of d- and p-block metal ions have been determined.89 These ligands selectively bind CuII and NiII but interact more weakly with the other metal ions examined.A synthesis of the ditopic cyclophane-based ligands L115–117 and a preliminary account Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 328N N N N Me Me N N N N R1 R1 R2 N N N N H H H 2 L115 ortho isomer L116 meta isomer L117 para isomer H2L113 R1 = CH2CO2H ; R2 = H H3L114 R1 = R2 = CH2CO2H L112 of their mononuclear and dinuclear CuII complex formation has been reported.90 O-Donor ligands The structure of the air- and moisture-stable octahedral WVI complex [W(L118)(OCH 2 CH 2 O)] has been crystallographically determined.91H 4 L118 initially reacts with [M 2 (NMe 2 ) 6 ] to yield [NH 2 Me 2 ] 2 [M 2 (l-g2:g2-L118) 2 ] (M\Mo, W) in which each L118 bridge is bidentate at each metal centre.92 On heating this complex in pyridine it isomerises to [NH 2 Me 2 ] 2 [M 2 (g4-L118) 2 ] in which each molecule of L118 cups a single metal centre.The partially protonated materials [NH 2 Me 2 ][W(g4- L118)(g4-HL118)] were also crystallographically characterised; a bridging hydrogen bond is indicated between the two L118 ligands. It is worth noting that [NH 2 Me 2 ] 2 - [M 2 (l-g2:g2-L118) 2 ] was also described independently.93 The allyl substituted L119 exhibited excellent selectivity for Ag` over sodium ions when employed as a neutral carrier in an ion selective electrode.94 The related tetraester L120 displayed a relatively poor selectivity in similar experiments.The calix(4)arene sulfonyl carboxamide ligands L121–124 extract HgII ions from acidic nitrate solutions with very good selectivity over alkali, alkaline earth, PbII, AgI and PdII ions.95 The sulfur functionalised calix[4]arene derivatives L125–130 selectively extract heavy metal ions (HgII, AgI, PdII, AuIII) from water into chloroform.96 The relative e§ectiveness for a particular ligand for a given metal is a complex function of ionic radius, polarisability, and kinetic factors.A dimeric [UVIO 2 ]2` complex of H 3 L131 has been structurally characterised.97 This ligand quantitatively extracts [UVIO 2 ]2`, LaIII, LuIII, HgII, SrII, PbII and BiII at pH 7, and was also successfully immobilised on a resin support. The complexes [AuI(L132)Cl] and trans-[Pd(L132) 2 Cl 2 ]·2CH 2 Cl 2 are prepared by the addition of HL132 to [Au(tht)Cl] and [PdCl 2 (NCPh) 2 ] respectively.98 Reaction of L133 with [PdCl 2 (NCPh) 2 ] yields oligomeric material.The calix-quinone H 3 L134 shows a marked selectivity towards Ca2` ions, even against an interfering background of a 1000-fold excess of Na` ions.99 S and Se-donor ligands The thioether hydrazone ligands L139 and L140 have been prepared by the reaction of 2,4-dinitrophenylhydrazine under acidic conditions with the keto-macrocycles L137 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 329O O R1 R2 O O R2 R1 But But But But H4L118 R1 = R2 = H L119 R1 = R2 = CH2CH=CH2 L120 R1 = R2 = CH2CO2CH2CH=CH2 L121 R1 = OMe, R2 = OCH2C(O)NHSO2CF3 L122 R1 = OMe, R2 = OCH2C(O)NHSO2CH3 L123 R1 = OMe, R2 = OCH2C(O)NHSO2Ph L124 R1 = OMe, R2 = OCH2C(O)NHSO2C6H4NO2-4 O O R1 R1 R2 R2 O O R1 R1 R2 R3 S NMe2 S S NMe2 S O S O L125 R1 = But; R2 = R3 = L126 R1 = H; R2 = R3 = L127 R1 = But; R2 = R3 = CH2CH2SH L128 R1 = But; R2 = R3 = CH2CH2SMe L129 R1 = H; R2 = R3 = CH2CH2SMe L130 R1 = But; R2 = R3 = H3L131 R1 = But ; R2 = CH2CO2H ; R3 = CH2CONH2 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 330O O R1 R1 R2 R4 O O R1 R1 R2 R3 O O R O O O R R H3L134 R = CH2CO2H H132 R1 = But ; R2 =CH2CO2Et ; R3 = PPh2 ; R4 = H H133 R1 = But ; R2 =CH2CO2Et ; R3 = R4 = PPh2 S S S S S S S S L135 L136 and L138 respectively.100 In the solid state the structures of these ligands and their square-planar PdII complexes are dominated by p-stacking interactions of the pendant aryl moieties.The disulfide-containing macrocycles L141 and L142 form complexes with CuI.That with L141 consists of infinite ladders of CuI bridged by L141, whilst L142 bridges discrete (CuI) 2 units.101 Reaction of NiX 2 (X\Cl, Br or I) with L143 in n-butanol yields the complexes trans-[NiII(L143)X 2 ] which have been investigated by EXAFS.102 A comparative study with analogous tetradentate 16-membered complexes indicated that the ligand field strength decreased along the series N 4[S 4[Se 4 .Mixed donor ligands In a potentiometric and electrochemical study the ferrocene-substituted ligand L144 selectively binds HgII over PbII, CuII and ZnII ions in aqueous solution.103 The bicyclic ligands L147–150 are prepared by the reaction of the complexes [NiII(L145,146)] with the appropriate a.x-dibromo electrophile.The resulting complexes [NiII(L147–150)]- Br 2 contain square planar NiII centres and display an anodic shift in the NiII–NiI couple with increasing ring size. The complex cation [NiII(H 2 L151)]2` has also been prepared by the reaction of [NiII(L145)] withH 2 L152. [NiII(L151)]2` could be demetallated to a§ord the parent ligand.104 Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 331S S S S X S S S X Se Se Se Se S S S S S S S S S S L143 L142 L141 L137 X = O L139 X = NNHC6H3(NO2)2-2,4 L138 X = O L140 X = NNHC6H3(NO2)2-2,4 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 3323 Pentadentate ligands The FeII complexes of a range of pentacyclen (e.g. L153–155) derivatives disproportionate superoxide species in aqueous solution.105 The crystal structure of [Fe(L155)Cl 2 ] showed a seven-ordinate metal centre with pentagonal bipyramidal geometry with chloride donors occupying the axial positions.The structure of the InIII complex of H 3 L156 indicated a mononuclear capped trigonal prismatic structure.106 This is in contrast to related YIII, GdIII and LaIII complexes which were previously shown to have binuclear nine-co-ordinate structures.The MnII complex [Mn(L157)(H 2 O) 2 ]- Cl 2 ·4H 2 O, characterised by X-ray crystallography, has a pentagonal pyramidal geometry with L157 occupying equatorial sites and two water molecules occupying axial sites.107 Analysis of the zero-field splitting parameters from a variable temperature EPR study indicated that the complex undergoes an increasing rhombic distortion with decreasing temperature.N N N N N N N N N N R R R R R N HO2C HO2C CO2H N N O O N N N H3C N CH3 N N N H H L157 H H H3L156 L153 R = H L154 R = Me H H H H H L155 H H H H H The unusual 15-crown-5 (L158)-containing cation [MNa(L158)N4 Br]3` has an approximately tetrahedral array of four [Na(L158)]` fragments arranged about a central bromide anion.108 The cations are located within a folded network of [TlBr 4 ]~ anions which is stabilised by weak van der Waals Br · · ·Br interactions.The lipophilic colorimetric agent HL159 displays a selective colour change in aqueous solution upon complexation of sodium ions in the presence of an anionic surfactant.109 Reaction of p-tert-butylcalix[5]arene with P(NMe 2 ) 3 a§ords the ligand H 3 L160. Subsequent reaction with [WVI(NBu5) 2 (NHBu5) 2 ] yields [W(NBu5)(NHBu5)(L160)] in which the metal centre adopts a distorted square pyramidal structure with only a weak long range interaction with the P donor.Treatment of this complex with triflic acid yields [W(NBu5)(O 3 SCF 3 )(L160)] in which the metal centre displays an almost octahedral Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 333co-ordination geometry, albeit with a moderately long W–P bond distance of 2.743(2)Å.O O O O O O O O O O O H21C10 NO2 HO HL159 L158 HO But But O But O But OH But HO P Me2N H3L160 The novel polymeric thia crown L162 is extremely e§ective ([99% e¶ciency) in removing HgII ions from aqueous solutions.110 The CuI complexes of a series of ditopic crown ligands L163–166 have the general formula [Cu(PPh 3 ) 2 (L163–166)][BF 4 ]; the metal is bound only by the chelating pyridyl imine unit.111 The electronic spectra of these complexes were insensitive to the addition of alkali metal ions but showed significant shifts in the metal-to-ligand charge-transfer band with the addition of softer metal ions (ZnII and CdII), consistent with metal binding within the crown cavity.Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 334H H H2L170 L169 L167 L168 N N N O O H H N N N O O O H H O O N N N O N N N N The mixed donor ligands L167 and L168 form mononuclear complexes with lanthanide( III) ions.112 L169 has been prepared by the template reaction of 2,6-diacetylpyridine and the appropriate diamine in the presence of YIII and LnIII ions (Ln–La, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu).113 The extended ‘porphyrin’ H 2 L170 (oxasapphyrin) forms the stable pentagonal bipyramidal uranyl complex [UO 2 (L170)]2` in which the metal centre lies in the ‘plane’ of a slightly saddle-shaped ligand array.114 4 Hexadentate ligands N-Donor ligands The ferrocene-substituted ligand L171 and its CdII complex have been structurally characterised.115 L171 is e§ective in metal extraction processes but back extraction into a water phase via oxidation of the ferrocenyl units was unsuccessful due to the instability of the oxidised form of the ligand.The potentially octadentate bis(nitrophenol)- containing ligand L172 forms a binuclear CuII complex and a range of partially protonated mononuclear complexes.116 The related ligand L173 forms a mononuclear complex.The binuclear CuII complex of L174 can be isolated as two hydrate isomers of general formula [Cu 2 (L174)(O 2 CMe)(H 2 O)n][ClO 4 ] 2 ·mH 2 O (m\0, n\2 or m\2, n\0).117 One isomer contains four-co-ordinate metal centres (three amine and one acetate donor) whilst the other contains five-co-ordinate metal centres (three amine and one acetate donor and an additional co-ordinated water molecule).The binuclear CuII complexes of L175 form 1: 1 ternary adducts with a range of guest species including maleate, malonate, fumarate and orthophosphate.118 A comparative study of a range of molecular mechanics programs has been published based upon several hexaamine cage compounds of which L176 is typical.119 In this work it was found that Molmec, Momec91(H), Momec92(C) and Xnviron reliably Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 335Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 336reproduced crystallographically determined bond lengths although some systematic errors were present in each system. The lifetimes of the 2E state of [CrIII(L177)]3` have been measured at 235 ls inH 2 Oand 1.5 ls inD 2 O, which represent the longest known lifetimes for a saturated CrIIIN 6 chromophore.120 An extensive range of novel homocalixpyridines (L178–187) has been prepared and shown to extract ‘soft’ transition metal ions (e.g.AgI, PdII, HgII and AuIII) selectively.121 The complexation behaviour can be easily modified by adjusting the ligand ring size and the peripheral substitution pattern.Also included in this study was a comparison with a series of analogous open chain ligands and the incorporation of the homocalixpyridines into ion-selective electrodes. O-Donor ligands In an extensive crystallographic study (nine structures) the interactions between [18]aneO 6 (L188) and a series of p-, d- and f-block hydrated metal salts have been described.122 In some cases complexes of the general formula [M(H 2 O) 6 ]- [ClO 4 ] 2 ·L188 (M\NiII, CoII, CuII and ZnII) are isolated.In the case of NiII and CuII the unusual species [Ni(H 2 O) 6 ] 3 [NiBr 2 (H 2 O) 4 ]Br 6 ·L188 4 ·2H 2 Oand [Cu(H 2 O) 3 (L188)] 2 - [ClO 4 ] 4 could also be prepared. Here, the latter complex contains both co-ordinated and purely H-bonded crown ether units.The conclusion was that the overall stability of the structure governs crystal packing, as opposed to the co-ordination preferences of the individual components of the system. The interaction of L188 withMIV-containing species (M\Ti, Zr, Hf) has also been examined.123 Treatment of a mixture of [TiCl 3 Cp] and L188 with HCl gas a§ords [H 3 O·L188][TiCl 5 (H 2 O)] in which L188 binds an oxonium ion, whilst a similar reaction mixture when treated with AlMe 3 O O O O O O L188 yields the TiIII complex [TiCl(L188)Cp][AlCl 2 Me 2 ] in which L188 is tridentate.Reaction of L188 with ZrCl 4 resulted in ring cleavage to yield the alkoxo complex [ZrCl 2 ·(OCH 2 CH 2 ) 5 OCH 2 CH 2 Cl][ZrCl 5 (thf)] in which the metal centre (alkoxide) has a seven-co-ordinate distorted pentagonal bipyramidal structure.In a similar reaction with HfCl 4 in the presence of NaCl the complex [Na(L188)][HfCl 5 (thf)] was isolated. L188 reacts with BaCO 3 in the presence of carboxylic acids to form a range of hydrated complexes with the general formulae [Ba(O 2 CMe)(L188)]·nH 2 O and [BaMO 2 C(CH 2 ) 4 CO 2N(L188)]·nH 2 O, which decompose on heating to 200 °C to evolve intact L188.124 The structurally characterised complexes [Sr(L188)(hmpa) 2 ][SMes*] 2 and [Ba(L188)(hmpa)(SMes*)][SMes*] are rare examples of thiolate species with zero or one cation interactions respectively.The metal centres are bound by all six crownether donor atoms and by two or one molecules of hmpa, and by zero or one Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 337[SMes*]~ anions.125 The first structurally characterised neptunium crown ether complex, [NpO 2 (L188)][ClO 4 ], is readily prepared126 by simply adding L188 to the appropriate metal salt, in sharp contrast to the synthesis of the analogous uranyl complex which requires rigorously anhydrous conditions.The eight-co-ordinate cation has approximately hexagonal bipyramidal geometry with the O-donor atoms of L188 occupying the ‘equatorial’ sites.O O O O O O O N N O N N R1 R1 OH But But N N But OH But O O O O O O H2L190 L189 R1 = H H Novel pyridine–crown ether receptor molecules, of which L189 is representative, have been described.127 Chloride ion binding by [ReCl(CO) 3 (L189)] is greatly enhanced by the presence of K` within the 18-crown-6 compartment of the ligand, and occurred exclusively within the amide ‘cavity’ of the ligand.The complex [NiII(L190)], and adducts with alkali metal halides with the general formula [NiII(L190)MI]X·nH 2 O (M\K, Cs; X\I~),128 show preferential transport of hydrophobic amino acids from acidic solutions to pure water. The MnIII complex of H 2 L190 selectively transports zwitterionic species such as tryptophan, serotonin and dopamine through a CHCl 3 liquid membrane.129 S-Donor ligands A structural and 99Tc NMR spectroscopic study of the thioether complexes fac- [Tc(CO) 3 (L30)]Br, fac-[Tc 2 (O 3 SC 6 H 4 Me) 2 (CO) 6 (L191)] and [Tc 2 (CO) 6 (L192)]- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 338[O 3 SC 6 H 4 Me] 2 has been reported.130 The NMR spectra indicate that L191 and L192 can also form 1: 1 complexes depending on the metal: ligand ratio.The L191 complex crystallises with the metal centres trans with respect to the ligand and L192 crystallises in a cis fashion. Theoretical and electrochemical studies of the transport of PbII ions facilitated by L191 across a nitrobenzene–water interface in the presence of hydrophilic ligands such as acetate, tartrate and citrate have been published.131,132 In a study of the macrocyclic thioether chemistry of CoIII the crystal structure of [Co(L193)][BF 4 ] 3 was determined.133 The metal centre is octahedral with the trimethylene bridges of the macrocycle occupying cis positions. 13C and 59Co NMR spectroscopic studies of [Co(L191,193)]3` cations in solution indicated that only one possible diastereomer of each was present.S S S S S S OH S S S S S S S S S S S S L193 L191 L192 Mixed donor ligands The reaction of L194 with [RuIIICl 3 (terpy)] a§ords [Ru(terpy)(L194)][PF 6 ] 2 which subsequently reacts with 4@-[4-(bromomethyl)phenyl]-2,2@: 6@,2A-terpyridine to yield [Ru(terpy)(L195)][PF 6 ] 2 .134 The latter complex was used in the synthesis of the trinuclear complexes [MMRu(terpy)(L195)N2 ][PF 6 ] 6 (M\Fe or Ni) which consist of two terminal ‘Ru(terpy) 2 ’ fragments linked via [18]aneN 2 O 4 macrocycles to a central ‘M(terpy) 2 ’ fragment.Electrochemical and electronic spectroscopy measurements indicate that the metal centres were essentially non-interacting. An acid-promoted rearrangement of the co-ordination sphere of [PdII(L196)]2` has been described.135 This complex has an N 2 S 2 co-ordination sphere (with two further long range interactions with S donors) which upon the addition of HBF 4 rearranges to an S 4 coordination sphere as confirmed in the crystal structure of the salt [PdII(H 2 L196)]- [BF 4 ] 4 .Schi§-base ligands The co-ordination polymer [Ni 2 (L197)Ml-H 2 N(CH 2 ) 3 NH 2N2 (H 2 O) 2 ][ClO 4 ] 2n·nH 2 O is formed in the NiII templated condensation of 2,6-diformyl-4-methylphenol and an excess of 1,3-diaminopropane.136 The NiII centres show an intramolecular antiferromagnetic coupling (J\[30^4 cm~1) and a weak intermolecular ferromagnetic coupling (J\2^1 cm~1).The unsymmetrical compartmental ligand L198 displays a wide range of co-ordination behaviour, forming the mononuclear complexes Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 339N N N O O N O O N R2 R1 N S S N S S H H L196 L194 R1 = H; R2 = Ar L195 R1 = R2 = Ar Ar = [MII(H 2 L198)][ClO 4 ] (M\Mg, Cu, Ni, Co, Fe, Mn), the homo- and hetero-binuclear complexes [M! IIM" II(L198)][ClO 4 ] 2 (M! \M" \Cu, Ni; M! \Ni, M" \Cu, Co; M! \Mn, M" \Cu) and a tetranuclear complex [MNiIIFeII(L198)(H 2 O) 2N2 ]- [ClO 4 ] 4 .137 The ethylenediamine derived compartment shows a strong a¶nity for NiII metal centres.The unsymmetrical compartmental ligandsH 2 L199–201 and their binuclear MnIII complexes, of general formula [Mn 2 (L199–201)X 2 ]·nH 2 O (X\Cl~ or Br~), have been synthesised.138 Electrochemical studies showed that the first one-electron reduction, to a [MnIIIMnII] species, depends on ring size, the substituent at the position para to the phenoxide donor and the nature of axial halide donors (Cl~ or Br~).Oneelectron oxidation to [MnIIIMnIV] species is largely only sensitive to the identity of the axially bound halide ion. NiII and CuII binuclear complexes of [H 2 L202,203]2~ are prepared by the reaction of the non-macrocyclic complexes [M 2 (HL204,205) 2 ] with BF 3 ·OEt 2 .139 In [CuII 2 (L202,203)] there is strong antiferromagnetic coupling between the metal centres.The magnetochemistry of a series of the heteronuclear complexes [VIVO(L206,207)MII(l-O 2 CMe)L@][ClO 4 ]·nH 2 O (M\Ni, Co, Fe, Mn; L@\H 2 O, MeOH; n\0, 1) has been described.140 In the [VIVO,CuII] system there is a linear correlation between the dihedral angle of the metal planes (as defined by the macrocyclic donor atoms) and the magnetic exchange constants.All of the complexes (except the [VIVO,MnII] system) displayed ferromagnetic exchange between the metal centres. Reduction of [Ni 2 (L208)][ClO 4 ] 2 with NaBH 4 in methanol a§ords the saturated ligand complex [Ni 2 (L209)][ClO 4 ] 2 .141 The latter complex shows two oxidations and two reductions all of which are one-electron, reversible processes.Carbon-substituted L210 has been prepared as a mixture of stereo- and constitutional- isomers by condensation of 2,6-diacetylpyridine and racemic or optically pure 1,2-diaminopropanes in the presence of LnIII ions.142ABaII templated synthesis of the unsymmetrical Schi§-base ligand L211 has been reported.143 L211 forms the low-spin FeII complex [Fe(L211)][ClO 4 ] 2 , which is somewhat surprising given the relative inflexibility of the ligand system.The formation of ligands L212 and L213 has been achieved by the template condensation of 2,6-diformylpyridine and the appropriate diamine in the presence of LnIII ions (Ln\La, Ce, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu).144 Attempts to prepare these ligands in metal-free syntheses were unsuccessful.Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 340OH N N N N OH H2L197 n = 1 H2L198 n = 0 n OH N N N OH N X X OH N N O N B O O B O N OH R R F F F F OH N N HO OH R H3L204 R = Me H3L205 R = But (H2L203)2- R = Me (H2L204)2- R = But (CH2) n X = Br or Me L199 n = 2 L200 n = 3 L201 n = 4 SH N N N N SH SH N N N N SH OH N N OH N N H2L206 n = 1 H2L207 n = 0 H H H H H2L208 H H H H H2L209 n Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 3415 Macrocycles of higher denticity An NMR spectroscopic analysis of the conformation of the novel phosphahemispherand L214 and its binding properties with alkali metal and ammonium ions have been described.145 The highest binding coe¶cients were observed for K` and Rb`.The photophysical properties of the xanthone-containing crown ethers L215–217 are very sensitive to the presence of a divalent metal ion within the macrocyclic cavity.146 Thus L217 displays a strong luminescence enhancement upon binding BaII ions, attributed to the stabilisation of a di§erent ground-state conformer of the dioxyxanthone luminophore.The selectivity of L218 for rubidium salts has been analysed in a molecular mechanics calculation and crystallographic study.147 Complexation of sodium by L218 resulted in a higher energy conformation and RbI binding is favoured over CsI binding due to stronger metal–ligand interactions. The photochemistry and acid–base properties of supramolecular complexes of K 4 [Co(CN) 5 (SO 3 )] with the protonated form of ligands such as L219 have been investigated.148 The quantum yield for the photoaquation of the sulfite ion decreases upon binding the complex within the cavity of [H 8 L219]8`; it is likely that cyanide ligands are involved in hydrogen bonding to the host framework but that sulfite does not participate in such an interaction.The novel ‘triple-cyclam’ compartmental ligandsL220 and L221 have been prepared in a modified Richman–Atkins synthesis.149 In [CuCl 2 (L220)]Cl 2 ·2H 2 O the ligand binds two metal centres in the terminalN 4 sites with each metal adopting a five-co-ordinate distorted square pyramidal geometry; chloride donors occupy the apical positions.Potentiometric measurements with a wide range of metal salts indicated that L220 and L221 can bind one or two metal centres and that the overall formation constants of binuclear complexes with these tricyclic ligands were not dissimilar to those of octaaza monocyclic ligands.The binuclear Schi§-base complex [CoII 2 (L222)(NCMe) 4 ]4` displays two reversible Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 342P N N O O O Me O O O O O O O O O O O O O O O O L218 L215 n = 3 L216 n = 4 L217 n = 5 n L214 Me Me N N N N N N N N N N N N N N N N H H H H (CH2) n (CH2) n L220 n = 0 L221 n = 1 H H H H H H H H L219 oxidations and two reversible reductions (all one-electron processes).150 The first reduction yields a [CoICoII(L222)]3` species which exhibits an intervalence charge transfer band at 965 nm.The crystal structure of the GdIII complex of the cryptate ligand L223 has been determined.151 The complex crystallises as [GdIII(H 2 O) 2 (L223)]- [NO 3 ] 3 and displays a pH-sensitive proton relaxivity over a range of 4–9.In a resonance Raman and structural study of several binuclear CuI and CuII–CuI complexes of L224–226 Cu–Cu bond formation was proposed. The Cu–Cu distance is 2.928(4)Å in [CuI 2 (L225)]2`.152 A pure Cu–Cu stretching mode could not be assigned from the Raman spectrum but 63Cu–65Cu isotopic substitution experiments indicated significant Cu–Cu character in the stretching mode at 250 cm~1.The cryptand ligand L227 unexpectedly forms a mononuclear high spin (S\2) FeII complex; it is thought Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 343that the constraints imposed by the ligand structure prevent low-spin or binuclear complex formation.153 However, the saturated ligands L228 and L229 support binuclear FeII complex formation, as indicated by the isolation of the hydroxy complexes [FeII 2 (OH)(L228)][PF 6 ] 2 ·4H 2 Oand [FeII 2 (OH)(L229)][O 3 SCF 3 ][BPh 4 ] 2 .This study also included an examination of the magnetic properties and Mo� ssbauer spectra of these complexes and related podand ligand systems.The crystal structures of the CdII, BiIII, PbII and TlI complexes of the large ring thiamacrocycles L230 and L231 have been determined.154 In all cases the macrocycles bind two metal ions which, for TlI, involved metal centres bridging adjacent ligands and thus forming a chain structure.A simple synthesis of the lariat crown L232 has been described.155 The ligand was isolated directly from the reaction mixture as a complex of general formula [M 2 (H 2 O)(L232)]I 2 ·H 2 O (M\NaI, KI) in which two seven-co-ordinate metal ions are bound within the macrocyclic cavity with five Odonors and one N-donor derived from L232 and one O-donor from a bridging water molecule.A thermodynamic study of the complexation of alkali metal, SrII and BaII ions in methanol by the benzene-containing cryptands L233–236 showed that these ligands form stable complexes with all metals except Li`, and that K` is preferentially bound over all other cations.156 The stability constants for the complexes of alkali and alkaline earth cations decreased with an increase in the number of benzo-substituents along the series of ligands L237[L238[L239.157 The two cryptands L240 and L241 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 344Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 345form mononuclear NiII and CuII complexes in which the metal ion occupies the tetraaza site within the ligand cavity.158 These complexes are good hosts for water molecules.The catalytic hydroxylation of alkane substrates (e.g. adamantane, cyclohexane) has been achieved by using the binuclear FeII complexes of H 2 L242 and H 2 L243 and H 2 S as a two-electron reductant.159 The active species has been proposed as a diiron peroxide which decomposes to a binuclear FeIII species bearing an oxo bridge which releases an oxygen atom for substrate hydroxylation.The synthesis of the large-ring Schi§-base ligand L244 is e§ected by the condensation of 2,6-bis(2-formylphenoxymethyl)pyridine and 1,5-bis(2-aminophenoxy)-3- oxapentane in the presence of a wide range of template LnIII ions (Ln\La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb and Lu).160 Air-stable binuclear CuI complexes of L245 and L246 have been isolated.161 The structure of [Cu 2 L245][ClO 4 ] 2 ·0.5CH 3 OH·2.5H 2 has two tetrahedral metal centres bound withinN 2 S 2 donor atom arrays.The ligand adopts a helical structure stabilised by a p-stacking interaction of the central para-substituted phenylene rings. Cyclic voltammetry indicated a single quasi-reversible CuI–CuII couple, the reversibility of which was increased by the addition of ferrocene.N N N OH N X N N N X OH Me Me H2L242 X = H2L243 X = Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 346Si(Pri)3 O O N N Si(Pri)3 N N O O O O O O L247 L248 N N N N N N N N N N N N N N L249 Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 347The photophysics of the fullerene-capped rotaxane [CuI(L247)(L248)][BF 4 ] has been compared to those of the individual components.162 Both the fullerene first excited state and the metal bis(phenanthroline) MCLT band were quenched, the former being attributed to energy transfer from the CuI complex and the latter by electron transfer from the metal to the fullerene to form a charge separated CuII–fullerene radical anion species. It was also observed that whilst both individual rotaxane components could sensitise the formation of singlet oxygen the assembled rotaxane displayed no such activity.The novel macrobicyclic cryptophane L249 forms mononuclear and binuclear CuII complexes.163 Electronic spectroscopy indicates that the metal centres are bound within tren-like co-ordination environments. An NMR spectroscopic study of the binding of aromatic arene sulfonate substrates by protonated L249 species was also described.References 1 A.C. Morland and T. B. Rauchfuss, J. Am. Chem. Soc., 1998, 120, 9376. 2 M. S. Davies and T. W. Hambley, Inorg. Chem., 1998, 37, 5408. 3 K. Yamanari, I. Fukuda, T. Kawamoto, Y. Kushi, A. Fuyihiro, N. Kubota, T. Fukuo and R. Arakawa, Inorg. Chem., 1998, 37, 5611. 4 J.L. Heinrich, P. A. Berseth and J.R. Long, Chem. Commun., 1998, 1231. 5 A. McAuley, S. Subramanian, M. J. Zaworotko and R. Atencio, Inorg. Chem. 1998, 37, 4607. 6 P. J. Wilson, A. J. Blake, P. Mountford and M. Schro� der, Chem. Commun., 1998, 1007. 7 A.K. Mohammed, R. A. Isovitsch and A. W. Maverick, Inorg. Chem., 1998, 37, 2779. 8 F. Birkelbach, U. Flo� rke, H.-J. Haupt, C. Butzla§, A. X. Trautwein, K. Wieghardt and P.Chaudhuri, Inorg. Chem., 1998, 37, 2000. 9 D. Burdinski, F. Birkelbach, T. Weyhermu� ller, U. Flo� rke, H.-J. Haupt, M. Lengen, A. X. Trautwein, E. Bill, K. Wieghardt and P. Chaudhuri, Inorg. Chem., 1998, 37, 1009. 10 S.-M. Yang, M. C.-W. Chan, S.-M. Peng and C.-M. Che, Organometallics, 1998, 17, 151. 11 H. S. Zhen, C. M. Wang, Y. H. Yu and T. C. Flood, Organometallics, 1998, 17, 5397. 12 G. R. Willey, M. P. Spry and M. G. B. Drew, Polyhedron, 1998, 17, 4497. 13 K. Meyer, J. Bendix, N. Metzler-Nolte, T. Weyhermu� ller and K. Weighardt, J. Am. Chem. Soc., 1998, 120, 7260. 14 S.-M. Au, S.-B. Zhang, W.-H. Fung, W.-Y. Yu, C.-M. Che and K. K. Cheung, Chem. Commun., 1998, 2677. 15 T. Tei, V. Lippolis, A. J. Blake, P. A. Cooke and M. Schro� der, Chem. Commun., 1998, 2633. 16 T. Weyhermu� ller, K. Weighardt and P. Chaudhuri, J. Chem. Soc., Dalton Trans., 1998, 3805. 17 R. Schnepf, A. Sololowski, J. Mu� ller, V. Bachler, K. Wieghardt and P. Hildebrandt, J. Am. Chem. Soc., 1998, 120, 2352. 18 F. N. Penkert, T. Weyhermo` ller and K. Wieghardt, Chem. Commun., 1998, 557. 19 L.M. Berreau, J. A. Halfen, V. G. Young, Jr. and W.B. Tolman, Inorg. Chem., 1998, 37, 1091. 20 I. A. Fallis, P. C. Gri¶ths, P. M. Gri¶ths, D. E. Hibbs, M. B. Hursthouse and A. L. Winnington, Chem. Commun., 1998, 665. 21 J. P. Andre� , H. R. Maecke, M. Zehnder, L. Macko and K. G. Akyel, Chem. Commun., 1998, 1301. 22 H. Weller, T. A. Kaden and G. Hopfgarten, Polyhedron, 1998, 17, 4543. 23 M. Di Vaira, F. Mani and P. Stoppioni, J. Chem. Soc., Dalton Trans., 1998, 3209. 24 S. J. Brudenell, L. Spiccia, A. M. Bond, P. C. Mahon and D. C. R. Hockless, J. Chem. Soc., Dalton Trans., 1998, 3919. 25 J. Suh, S. J. Son and M. P. Suh, Inorg. Chem., 1998, 37, 4872. 26 R. Abdel-Hamid, H. M. El-Sagher, A. M. Abdel-Mawgoud and A. Nafadu, Polyhedron, 1998, 17, 4535. 27 M. Mascal, J. Hansen, A. J. Blake and W.-S. Li, Chem. Commun., 1998, 355. 28 G. Lagger, L.Tomaszewski, M. D. Osborne, B. J. Seddon and H. H. Girault, J. Electroanal. Chem, 1998, 451, 29. 29 S. Davies, M. Durrant, D. L. Hughes, C. Le Floc’h, S. J. A. Pope, G. Reid, R. L. Richards and J. R. Rodgers, J. Chem. Soc., Dalton Trans., 1998, 2185. 30 R. B. Bedford, A. F. Hill, C. Jones, A. J. P. White, D. J. Williams and J. D. E. T. Wilton-Ely, Organometallics, 1998, 17, 4744. 31 F.W. Lee, M. C. W. Chan, K. K. Cheung and C.M. Che, J. Organomet. Chem., 1998, 563, 191. 32 M.J. Calhorda, C. A. Gamelas, I. S. Goncalves, E. Herdtweck, C. C. Romao and L. F. Veiros, Orgonometal- Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 348lics, 1998, 17, 2597. 33 S. Roche, L. J. Yellowlees and J. A. Thomas, Chem. Commun., 1998, 1429. 34 A. J. Blake, R. O. Gould, W.-S.Li, V. Lippolis, S. Parsons, C. Radek and M. Schro� der, Inorg. Chem., 1998, 37, 5070. 35 P. G. Edwards, F. Ingold, S. J. Coles and M. B. Hursthouse, Chem. Commun., 1998, 545. 36 A. J. Blake, J. P. Danks, I. A. Fallis, A. Harrison, W.-S. Li, S. Parsons, S. A. Ross, G. Whittaker and M. Schro� der, J. Chem. Soc., Dalton Trans., 1998, 3969. 37 V. A. Grillo, L. R. Gahan, G. R. Hansom, R.Stranger, T. W. Hambley, K. S. Mur D. Cashion, J. Chem. Soc., Dalton Trans., 1998, 2341. 38 A. J. Blake, J. P. Danks, A. Harrison, S. Parson, P. Schooler, G. Whittaker and M. Schro� der, J. Chem. Soc., Dalton Trans., 1998, 2335. 39 W.S. Striejewske and R. R. Conry, Chem. Commun., 1998, 555. 40 C.-Y. Lai, W. J. Lau, C. Wang and C.-S. Chung, Polyhedron, 1998, 17, 2127. 41 S. Aoki, Y. Honda and E. Kimura, J. Am. Chem. Soc., 1998,120, 10 018. 42 T. Koike, T. Gotoh, A. Aoki, E. Kimura and M. Shiro, Inorg. Chim. Acta, 1998, 270, 424. 43 C. A. Chang, Y.-H. Chen, H.-Y. Chen and F.-K. Shieh, J. Chem. Soc., Dalton Trans., 1998, 3243. 44 D. L. Dukis, S. J. DeNardo, G. L. DeNardo, R. T. O’Donell and C. F. Meares, J. Nucl. Med., 1998, 39, 2105. 45 S.Be� nazeth, J. Purans, M.-C. Chalbot, M.K. Nguyen-van-Duong, L. Nicolas, F. Keller and A. Gaudemer, Inorg. Chem., 1998, 37, 3667. 46 L. Alderighi, A. Bianchi, L. Calabi, P. Dapporto, C. Giorgi, P. Losi, L. Paleari, P. Paoli, P. Rossi, B. Valtancoli and M. Virtuani, Eur. J. Inorg. Chem., 1998, 1581. 47 S. Aime, A. Barge, M. Botta, A. S. De Souza and D. Parker, Angew. Chem., Int.Ed., 1998, 37, 2673. 48 M. Di Vaira, F. Mani and P. Stoppioni, J. Chem. Soc., Dalton Trans., 1998, 1879. 49 L. Burai, J. Ren, Z. Kovacs, E. Bu� cher and A. D. Sherry, Inorg. Chem., 1998, 37, 69. 50 P. Valente, S. F. Lincoln and K. P. Wainwright, Inorg. Chem., 1998, 37, 2848. 51 S. L. Whirbread, P. Valente, M.A. Buntine, P. Clements, S. F. Lincoln and K. P. Wainwright, J. Am. Chem.Soc., 1998, 120, 2862. 52 S. Aime, M. Botta, R. S. Dickins, C. L. Maupin, D. Parker, J. P. Riehl and J. A. G. Williams, J. Chem. Soc., Dalton Trans., 1998, 881. 53 D. Parker and J. A. G. Williams, Chem. Commun., 1998, 245. 54 E. Simon, P. L. Haridon, R. Pichon and M. L’Her, Inorg. Chim. Acta, 1998, 282, 172. 55 E. Colacio, J. M. Domý� nguez-Vera, M. Ghazi, R. Kiveka� s, M. Klinga and J.M. Moreno, Chem. Commun., 1998, 1071. 56 K.-Y. Choi, Polyhedron, 1998, 17, 1975. 57 A. Bakac, Inorg. Chem., 1998, 37, 3548. 58 K. Sakata, T. Odumura, Y. Kanbara, T. Nibu, M. Hashimoto, A. Tsuge and Y. Moriguchi, Polyhedron, 1998, 17, 1463. 59 S.-G. Kang, S.-J. Kim and J. H. Jeong, Polyhedron, 1998, 17, 3227. 60 S.-G. Kang, S.-J. Kim, K. Ryu and J. Kim, Inorg. Chim. Acta, 1998, 274, 24. 61 H. Bo� rzel, P. Comba, H. Pritzkow and A. F. Sickmu� ller, Inorg. Chem., 1998, 37, 3853. 62 P. V. Bernhardt and L. A. Jones, J. Chem. Soc., Dalton Trans., 1998, 1757. 63 A. Comparone and T. A. Kaden, Helv. Chim. Acta, 1998, 81, 1765. 64 C. Schmid, M. Neuburger, M. Zehnder, T. A. Kaden and T. Hu� bner, Polyhedron, 1998, 17, 4065. 65 L. Fabrizzi, M. Licchelli, P. Palavicini and L.Pardoi, Angew. Chem., Int. Ed., 1998, 37, 800. 66 I. Costa, L. Fabbrizzi, P. Pallavicini, A. Poggi and A. Zani, Inorg. Chim. Acta, 1998, 275–276, 117. 67 T. J. Hubin, J. M. McCormick, S. R. Collinson, N. W. Alcock and D. H. Busch, Chem. Commun., 1998, 1675. 68 M. Lachkar, R. Guilard, A. Atmani, A. D. Cian, J. Fisher and R. Weiss, Inorg. Chem., 1998, 37, 1575. 69 S. Sun, J.Saltmarsh, S. Malik and K. Thomasson, Chem. Commun., 1998, 519. 70 P. V. Bernhardt and E. J. Hayes, J. Chem. Soc., Dalton Trans., 1998, 3539. 71 M.P. Suh, E. Y. Lee and B. Y. Shim, Inorg. Chim. Acta, 1998, 269, 337. 72 R.W. Hay and I. Fraser, Polyhedron, 1998, 17, 1931. 73 R.W. Hay, I. Fraser and N. C. Owen, Polyhedron, 1998, 17, 1611. 74 R.W. Hay, E. Kiss, C. Loechel and T. Cli§ord, Polyhedron, 1998, 17, 2167. 75 R.W. Hay and A.M. Danby, Polyhedron, 1998, 17, 3795. 76 W.H. Chin, C.-M. Choi and T. C. W. Mak, Polyhedron, 1998, 17, 4421. 77 M.B. Inoue, R. E. Navarro, I. O. Landin, D. M. Lo� pez, M. Inoue and Q. Fernandez, Inorg. Chim. Acta, 1998, 269, 224. 78 M.A. Santos, M. Gaspar, M.L. S. S. Gonc�alves and M. T. Amorim, Inorg. Chim. Acta, 1998, 278, 51. 79 H. Liu, S.Zhu, A. B. Kondiano, X. Su, E. Kun and Y. Chen, Polyhedron, 1998,17, 4331. 80 L. Korki, R. D. Williams, J. T. Hupp, C. B. Allan and L. O. Speer, Inorg. Chem., 1998, 37, 2837. 81 M. Buchalova, D. H. Busch and R. van Eldik, Inorg. Chem., 1998, 37, 1116. 82 Z. Wang, K. Sakuta and M. Hashimoto, Polyhedron, 1998,17, 4451. 83 P. C. Andrews, J. L. Atwood, L. J. Barbour, P. J. Nichols and C.L. Raston, Chem. Eur. J., 1998, 4, 1384. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 34984 A. Klose, E. Solari, C. Floriani, S. Geremia and L. Randaccio, Angew. Chem., Int. Ed., 1998, 37, 148. 85 K. Sakata, J. Yamashita, M. Hashimoto, T. Moriguchi and A. Tsuge, Inorg. Chim. Acta, 1998, 281, 190. 86 K.M. Kadiah, P. L. Boulas, M. Kisters, E. Vogel, A.M. Aukauloo, F.D’Souza and R. Guilard, Inorg. Chem., 1998, 37, 2693. 87 C. Bernard, Y. Le Mest and J. P. Gisselbrecht, Inorg. Chem., 1998, 37, 181. 88 W. O. Koch, V. Schu� nemann, M. Gerdan, A. X. Trautwein and H.-J. Kru� ger, Chem. Eur. J., 1998, 4, 1255. 89 J. Costa, R. Delgado, M. G. B. Drew and V. Felix, J. Chem. Soc., Dalton Trans., 1998, 1063. 90 M. I. Burguete, E. Garcý� a-Espan8 a, S.V. Luis, J. F. Miravet, L. Paya� , M. Querol and C. Soriano, Chem. Commun., 1998, 1823. 91 A. Lehtonen and R. Sillanpa� a� , Polyhedron, 1998, 17, 3327. 92 M. H. Chisholm, K. Folting, W. E. Streib and D.-D. Wu, Chem. Commun., 1998, 379. 93 U. Radius and J. Attner, Eur. J. Inorg. Chem., 1998, 299. 94 K. Kimura, K. Tatsumi, F. Yajima, F. Miyaki, H. Sakamoto and M. Yokohama, Chem.Lett., 1998, 833. 95 G. G. Talanova, H.-S. Hwang, V. S. Talanov and R. A. Bartsch, Chem. Commun., 1998, 1329. 96 A. T. Yordanov, B. R. Whittlesey and D. M. Roundhill, Inorg. Chem., 1998, 37, 3526. 97 P. D. Beer, M.G. Drew, D. Hesek, M. Kan, G. Nicholson, P. Schmitt, P. D. Sheen and G. Williams, J. Chem. Soc., Dalton Trans., 1998, 2783. 98 P. Faidherbe, C. Wieser, D. Matt, A. Harriman, A.De Cian and J. Fisher, Eur, J. Inorg. Chem., 1998, 451. 99 T. A. Chong, S. K. Kang, H. Kim, J. R. Kim, W. S. Oh and S.-K. Chang, Chem. Lett., 1998, 1225. 100 L. R. Sutton, A. J. Blake, W.-S. Li and M. Schro� der, J. Chem. Soc., Dalton Trans., 1998, 279. 101 R. D. Adams, M. Huang and S. Johnson, Polyhedron, 1998, 17, 2775. 102 M. K. Davies, W. Levason and G. Reid, J. Chem.Soc., Dalton Trans., 1998, 2185 103 J. M. Lloris, R. Martý� nez-Ma� n8 ez, T. Pardo, J. Soto and M. E. Padilla-Tosta, Chem. Commun., 1998, 837. 104 B. Tomapatanaget, B. Pulpoka and T. Tuntulani, Chem. Lett., 1998, 1037. 105 D. Zhang, D. H. Busch, P. L. Lennon, R. H. Weiss, W. L. Neumann and D. P. Riley, Inorg. Chem., 1998, 37, 956. 106 M. B. Inoue, M. Inoue and Q. Fernando, Inorg.Chim. Acta, 1998, 271, 207. 107 O. Jime� nez-Sandoval, D. Ramirez-Rosales, M.-del-J. Rosales-Hoz, M. E. Sosa-Torres and R. Zamorano- Ulloa, J. Chem. Soc., Dalton Trans., 1998, 1551. 108 N. S. Fender, I. A. Kahwa, A. J. P. White and D. J. Williams, J. Chem. Soc., Dalton Trans., 1998, 1729. 109 T. Kuboyama, S. Nakamura, M. Takagi, J. C. Lee and T. Hayashita, Chem. Lett., 1998, 373. 110 T. F. Baumann, J. G. Reynolds and G. A. Fox, Chem. Commun., 1998, 1637. 111 V. W.-W. Yam, Y.-L. Pui, W.-P. Li, K. K.-W. Lo and K.-K. Cheung, J. Chem. Soc., Dalton Trans., 1998, 3615. 112 L. Valencia, R. Bastida, A. de Blas, D. E. Fenton, A. Macias, A. Rodrý� guez-Blas and A. Castin8 eras, Inorg. Chim. Acta, 1998, 282, 42. 113 W. Radecka-Paryzek, V. Patroniak-Krzyminiewska and H. Litkowska, Polyhedron, 1998, 17, 1477. 114 J. L. Sessler, A. Gebauer, M.C. Hoehner and V. Lynch, Chem. Commun., 1998, 1835. 115 J. M. Lloris, R. Martinez-Ma� n8 ez, T. Pardo, J. Soto and M. E. Padilla-Tosta, J. Chem. Soc., Dalton Trans., 1998, 2635. 116 P. Dapporto, V. Fusi, M. Micheloni, P. Palma, P. Paoli and R. Pontellini, Inorg. Chim. Acta, 1998, 275–276, 168. 117 H.-L. Zhu, L.-M. Zhang, C.-Y.Duan, X.-Y.Huang, W.-M. Bu, M.-F. Wu and W. X. Tang, Polyhedron, 1998, 17, 3909. 118 T. F. Pauwels, W. Lippens, G. G. Herman and A. M. Goeminne, Polyhedron, 1998, 17, 1715. 119 A.M. T. Rygott and A. M. Sargeson, Inorg. Chem., 1998, 37, 4795. 120 K. N. Brown, R. J. Geue, G. Moran, S. F. Ralph, H. Riesen and A. M. Sargeson, Chem. Commun., 1998, 2291. 121 H. Stephan, T. Kru� ger-Rambusch, K.Gloe, W. Hasse, B. Ahlers, K. Cammann, K. Rissananen, G. Brod 434. 122 J. W. Steed, B. J. McCool and P. C. Junk, J. Chem. Soc., Dalton Trans., 1998, 3417. 123 A. Alvanipour, J. L. Atwood, S. G. Bott, P. C. Junk, U. H. Kynast and H. Prinz, J. Chem. Soc., Dalton Trans., 1998,1223. 124 L. Archer, M.J. Hampden-Smith and E.Duesler, Polyhedron, 1998, 17, 713. 125 S. Chadwick, U. Englich and K. Ruhlandt-Senge, Chem. Commun., 1998, 2149. 126 D. L. Clark, D. W. Keogh, P. D. Palmer, B. L. Scott and C. D. Tait, Angew. Chem., Int. Ed., 1998, 37, 164. 127 J. E. Redman, P. D. Beer, S. W. Dent and M. G. B. Drew, Chem. Commun., 1998, 231. 128 D. T. Rosa and D. Coucouvanis, Inorg. Chem., 1998, 37, 2328. 129 D.T. Rosa, V. G. Young and D. Coucouvanis, Inorg. Chem., 1998, 37, 5042. 130 R. Schibli, R. Alberto, U. Abram, A. Abram, A. Egli, P. A. Schubiger and T. A. Kaden, Inorg. Chem., 1998, 37, 3509. 131 H. Katano and M. Senda, Bull. Chem. Soc. Jpn., 1998, 71, 2359. 132 H. Katano, K. Tanaka and M. Senda, Anal. Sci., 1997, 13, 299. 133 G. J. Grant, S. S. Shoup, C. E. Hadden and D. G. VanDerveer, Inorg. Chim. Acta, 1998, 274, 192. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313–351 350134 K. L. Busbell, S. M. Couchman, J. C. Je¡×rey, L. H. Rees and M.D. Ward, J. Chem. Soc., Dalton Trans., 1998, 3397. 135 A. J. Blake, R. O. Gould, G. Reid and M. Schro¡§ der, J. Chem. Soc., Dalton Trans., 1998, 2597. 136 A. Asokan, B. Varghese, A. Caneschi and P. T. Manooharan, Inorg. Chem., 1998, 37, 228. 137 S. Mohanta, S. Baitalik, S. K. Dutta and B. Adhikang, Polyhedron, 1998, 17, 2669. 138 M. Marappan, V. Narayanan and M. Kandaswamy, J. Chem. Soc., Dalton Trans., 1998, 3405. 139 K. K. Nanda, A.W. Addison, N. Paterson, E. Sinn, L. K. Thompson and U. Sakaguchi, Inorg. Chem., 1998, 37, 1028. 140 S. Mohanta, K. K. Nanda, L. K. Thompson, U. Flo¡§ rke and K. Nag, Inorg. Chem., 1998, 37, 1465. 141 S. Brooker, P. D. Croucher, T. C. Davidson, G. S. Dunbar, A. J. McQuillan and G. B. Jameson, Chem. Commun., 1998, 2131. 142 F. Benetollo, G. Bombieri, W. A. Gootee, K. K. Fonda, K.M. Samaria and L. M. Valarino, Polyhedron, 1998, 17, 3633. 143 S. Brooker and T. J. Simpson, J. Chem. Soc., Dalton Trans., 1998, 1151. 144 C. Platas, R. Bastida, A. de Blas, D. E. Fenton, A. Macias, A. Rodr©¥¢¥ guez and T. Rodr©¥¢¥guez-Blas, Polyhedron, 1998, 17, 1759. 145 P. Delangle, J.-P. Dutasts, J.-P. Declerq and B. Tinant, Chem. Eur. J., 1998, 4, 101. 146 L. Prodi, F. Bolletta, N. Zacheroni, C. I. F. Watt and N. J. Mooney, Chem. Eur. J., 1998, 4, 1090. 147 J.C Bryan, R. A. Sachleben, J. M. Lavis and M. C. Davis, Inorg. Chem., 1998, 37, 2749. 148 A. J. Parola, F. Pina, M.F. Manfrin and L. Moggi, J. Chem. Soc., Dalton Trans., 1998, 1005. 149 A. Damsyik, P. J. Davies, C. I. Keeble, M. R. Taylor and K. P. Wainwright, J. Chem. Soc., Dalton Trans., 1998, 703. 150 S. Brooker, R. J. Kelly and P. G. Plieger, Chem. Commun., 1998, 1079. 151 S. W. A. Bligh, M.G. B. Drew, N. Martin, B. Maubert and J. Nelson, J. Chem. Soc., Dalton Trans., 1998, 3711 152 A. Al-Obaidi, G. Baranovic¢§, J. Coyle, C. G. Coates, J. J. McGarvey, V. McKee and J. Nelson, Inorg. Chem., 1998, 37, 3567. 153 K. F. Deeney, C. J. Harding, G. G. Morgan, V. McKee, J. Nelson, S. J. Teat and W. Clegg, J. Chem. Soc., Dalton Trans., 1998, 1837. 154 A. J. Blake, D. Fenske, W.-S. Li, V. Lippolis and M. Schro¡§ der, J. Chem. Soc., Dalton Trans., 1998, 3961. 155 Z. Kilic¢�,M. Yildiz, T. Ho¡§ kelek and B. Erdogan, J. Chem. Soc., Dalton Trans., 1998, 3635. 156 X. X. Zhang, J. S. Bradshaw, A. V. Bordunov, V. N. Pastushok and R.M. Izatt, Inorg. Chim. Acta, 1998, 278, 6. 157 D. A. Dantz, H.-J. Buschmann and E. Schollmeyer, Polyhedron, 1998, 17, 1891. 158 D. K. Chand and P. K. Bharadwaj, Inorg. Chem., 1998, 37, 5050. 159 Z. Wang, A. E. Martell and R. J. Motekaitis, Chem. Commun., 1998, 1523. 160 C. Lodeiro, R. Bastida, A. de Blas, D. E. Fenton, A. Macias, A. Rodr©¥¢¥guez and T. Rodr©¥¢¥guez-Blas, Inorg. Chim. Acta, 1998, 267, 55. 161 G. Wei, G.A Lawrence, D. T. Richens, T. W. Hambley and P. Turner, J. Chem. Soc., Dalton Trans., 1998, 623. 162 N. Armaroli, F. Diederich, C. O. Dietrich-Buchecker, L. Flamigni, G. Marconi, J.-F. Nierengarten and J.-P. Sauvage, Chem. Eur. J., 1998, 4, 406. 163 A. Bencini, A. A. Bianchi, S. Brazzini, V. Fusi, C. Giorgi, P. Paoletti and B. Valtacoli, Inorg. Chim. Acta, 1998, 273, 326. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 313.351 3

ISSN:0260-1818    

DOI:10.1039/a804898c

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

19 Organometallic chemistry of monometallic species P. K. Baker Department of Chemistry, University of Wales, Bangor, Gwynedd, UK LL57 2UW 1 Introduction Important reviews have been published on transition-metal complexes containing allenylidene, cumulenylidene and related ligands,1 arynes, strained cyclic alkynes and strained cyclic cumulenes,2 heteroaldehydes and heteroketones,3 quantum mechanical exchange coupling in polyhydride and dihydrogen complexes,4 mixed cyclopentadienyl –dithiolene complexes,5 and organometallic complexes in non-linear optics.6,7 Reviews on the zirconocene [ZrCp 2 ] synthon and benzynezirconocene complexes as tools in main group element chemistry,8 the comparative chemistry of 18-electron Mo(II) and 17–electron Mo(III) compounds containing only carbon-based ligands,9 seven-co-ordinate halogenocarbonyl complexes of the type [MXY(CO) 3 (NCMe) 2 ] (M\Mo, W; X,Y\halide, pseudo-halide) as highly versatile starting materials,10 (g6-arene)tricarbonylchromium and (g5-cyclohexadienyl)tricarbonyl manganese complexes: indirect nucleophilic substitutions,11 the co-ordination chemistry of mononuclear iron carbonyl complexes,12 cis-octahedral iron complexes [FeM(CO)xRNM(CO)yR@N(CO) 4 ] (x]y\0, 1, 2, 3, 4) thermolysis and carbon–carbon coupling: a personal survey,13 and a new class of electron-rich organometallics; the C 3 , C 4 and C 5 metallacumulenes Ru––(C–– )nCR 2 ,14 have been published.Bent metallocenes, 15 homoleptic isocyanide metalates,16 transition metals in phosphinine chemistry, 17 the activation of g5-pyrrole complexes toward nucleophilic attack,18 and organometallic chemistry in the solid state19 have also been reviewed.A series of reviews has appeared concerned with photochemical aspects of monometallic organometallic complexes.20–26 Reviews on the applications of mononuclear organometallic complexes in catalysis include, Group 4 ansa-cyclopentadienyl–amido catalysts for olefin polymerisation,27 highly active metallocene catalysts for olefin polymerisation,28 fluorenyl complexes of zirconium and hafnium as catalysts for olefin polymerisation,29 enantio- and regio-control in palladium- and tungsten-catalysed allylic substitutions,30 smart ruthenium catalysts for the selective catalytic transformation of alkynes,31 the homogeneous oxidation of alkanes by electrophilic late transition- metals,32 and diaminoarylnickel(II) ‘pincer’ complexes: mechanistic considerations in the Kharasch addition reaction, controlled polymerisation, and dendrimeric Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 353transition-metal catalysts33 have appeared. Reviews on kinetic versus thermodynamic control in hydrozirconation reactions,34 asymmetric synthesis with Fischer carbene complexes: the development of imidazolidinone and oxazolidinone complexes,35 tungsten –alkynyl and –propargyl compounds for organic syntheses,36 tricarbonyliron complexes: an approach to acyclic stereocontrol,37 carbon–heteroatom bond-forming reductive eliminations of amines, ethers and sulfides,38 and regioselective additions to p-allyl metal complexes39 have also been published. 2 Titanium, zirconium and hafnium Agostic interactions have been characterised by a topological analysis of the experimental and theoretical charge densities in [Ti(Et)Cl 3 (dmpe)].40 Treatment of an imidotitanium complex, stabilized by a tridentate diamidopyridine ligand, with MeC 2 R (R\Me or Ph) gives, via C–H activation of the substrate and subsequent C–N coupling, the azatitanocycles 1, crystallographically characterised for R\Me.41 N Ti N N Me3Si Me3Si N But R H Me 1 Reactions of [Ti(CO) 6 ]2~ and Ph 3 CCl or (4-MeOC 6 H 4 ) 3 CCl a§ord the first examples of crystallographically characterised trityl titanium complexes [Ti(CO) 4Mg5- C(C 6 H 4 R-4) 3N]~ (R\H or OMe).42 Ti(IV) dimethyl complexes such as [TiMe 2 (OC 6 H 2 Bu5 2 -2,4-Np-6)Cp] react with [B(C 6 F 5 ) 3 ] to yield cationic methyl complexes which eliminate methane to give [TiMCH 2 B(C 6 F 5 ) 2N(C 6 F 5 )(OAr)Cp].43 The facile insertion of carbodiimides, R@N––C––NRA, into a Ti-C M% bond of [TiMe 3 (g5- C 5 R 5 )] (R\H or Me) in pentane at 25 °C gives a wide range of complexes of the type [TiMe 2MNR@C(Me)NRAN(g5-C 5 R 5 )] in high yield.44 The Group 4 mixed-ligand complexes [MCl 2MNC 5 H 4 (CR 2 O)-2NCp] (M\Ti, Zr; R\Pr* or Ph) have been prepared and structurally characterised for M\Ti, R\Pr* and M\Zr, R\Ph; they are all active catalysts for the polymerisation of ethene in the presence of methylaluminoxane. 45 The synthesis, catalytic activity and crystal structure (for R\Bu5) of the first examples of covalently bonded bridged-phospholyl complexes 2 (R\Me or Bu5), have been described.46 Titanium dialkyl complexes containing a linked cyclopentadienyl –alkoxide ancillary ligand of the type [TiR 2Mg5: g1-C 5 Me 4 (CH 2 ) 3 ON] (R\Cl, alkyl, benzyl) have been reported; for R\benzyl, treatment with B(C 6 F 5 ) 3 a§ords a cationic benzyl species active in catalytic olefin polymerisation, whereas for R\CH 2 SiMe 3 , Si–Me bond cleavage occurs to give a product where the alkoxide ligand participates.47 The zwitterionic zirconocene alkyl complex 3 is a highly selective single-component a-olefin dimerisation catalyst; it is thermolabile and decomposes in Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 354P Me2Si Ti N Cl Cl R 2 Zr B(C6F5)3 CH2CMe3 + 3 – bromobenzene at ambient temperature to give the zwitterionic 2-methallyl complex [Zr(g3-C 3 H 4 Me-2)Cp*(g5-C 5 H 4 Bu5)MCH 3 B(C 6 F 5 ) 3N].48 The phosphine-stabilized ethene complex [Zr(PPh 2 Me)(g2-C 2 H 4 )Cp 2 ] reacts with one equivalent of B(C 6 F 5 ) 3 to yield the girdle-type zwitterion [Zr`(PPh 3 Me)MCH 2 CH 2 B~(C 6 F 5 ) 3NCp 2 ], which is an ethene polymerisation catalyst either with or without added B(C 6 F 5 ) 3 .49 Several zirconocene-ate zwitterionic complexes have been prepared, including 4, which has been crystallographically characterised. 50 Benzylation of [ZrCl 2 CpMg5-C 5 H 4 SiMe 2 (CH 2 CH–– CH 2 )N] gives [Zr(CH 2 C 6 H 5 ) 2 CpMg5-C 5 H 4 SiMe 2 (CH 2 CH–– CH 2 )N], which reacts with either [CPh 3 ][B(C 6 F 5 ) 4 ] or B(C 6 F 5 ) 3 to a§ord the cation 5, which has been characterised by 1H, 13C and 1H DNMR spectroscopy.51 Treatment of [TiMe 2 Cp 2 ] with Zr H PPh2 H MeO O Cp2 – + 4 Si Me Me H H Zr+ C H Ph H H H H 5 2–SiHMe 2 (C 5 H 4 N) gives the first example of a chelating silyl, and a tertiary silyl complex of TiIIICp 2 , namely [TiM2-SiMe 2 (C 5 H 4 N)NCp 2 ], which has been characterised by X-ray crystallography and EPR spectroscopy; its reactions with PMe 3 and pyridine are also described.52 The first examples of d0 transition-metal complexes containing g5-germolyl and g5-silolyl ligands, [HfCl 2Mg5-C 4 Me 4 E(SiMe 3 )NCp*] (E\Ge or Si) have been prepared and crystallographically characterised; the g5- silolyl is the first such complex of any transition metal.53 The preparation, crystal structure and alkene co-polymerisation behaviour of both rac- and meso-[ZrCl 2 L] ML\1,2-CH 2 CH 2 [4-(7-Meind)] 2N have been described.54 The first examples of titanium 1–aza-1,3–diene complexes such as [TiMN(R)CH––C(R@)CHPhNCp 2 ] (R\Bu5, R@\H; R\C 6 H 4 Me-4, R@\H; R\c-C 6 H 11 , R@\Me), which has been crystallographically characterised for R\c-C 6 H 11 , R@\Me, have been reported.55 The structurally characterised g2-N,N-diazoalkane complex, [Ti(N 2 CHSiMe 3 )Cp* 2 ], undergoes thermolysis in the presence of 1-alkenes to yield the trans a-,b-disubstituted titanacyclobutanes [TiMCH(SiMe 3 )CH(R)CH 2NCp* 2 ] (R\H, Ph, Me or Et), crystallographically characterised for R\Me.56 Reaction of [Ti(––NPh)Cp* 2 ] with C 2 H 4 or C 2 H 2 gives the azametallacycles, [TiMN(Ph)CH 2 CH 2NCp* 2 ] and Annu.Rep.Prog. Chem., Sect. A, 1999, 95, 353–374 355[TiMN(Ph)CH––CHNCp* 2 ] respectively; thermolysis of [TiMN(Ph)CH––CHNCp* 2 ] affords the novel ring-activated complex, [TiMN(Ph)HN(g5:g1- C 5 Me 4 CH 2 CH––CH)Cp*].57 The cycloaddition and nucleophilic substitution reactions of the titanocene sulfido complex [Ti(––S)(NC 5 H 5 )Cp* 2 ] give a range of products including the thiametallacyclobutene [TiMSC(SiMe 3 )–– CHNCp* 2 ], which has been crystallographically characterised.58 The synthesis and molecular structure of the bis(amidinate) complex [TiMC 6 H 10 [NC(C 6 H 4 Me-4)NPh] 2 -transN(g6-C 6 H 5 Me)] have been described; the cyclohexa-1,4-diene dianion resonance structure makes a significant contribution.59 The preparation and structural characterisation of the bis(anthracene) complexes [Ti(g2-dmpe)(g4-C 14 H 10 )(g6-C 14 H 10 )] and [Ti(g2- C 14 H 10 )(g4-C 14 H 10 )Cp*]~ have been reported,60 as have the preparation, crystal structure and electronic structure of [Ti(NBu5)(g8-C 8 H 8 )].61 3 Vanadium, niobium and tantalum The preparation and crystal structures of the first 16-, 17- and 18-electron homoleptic isocyanide complexes [V(CNC 6 H 3 Me 2 -2,6) 6 ]z (z\1, 0, [1) have been reported.62 The first nitrosyl complexes of niobium and tantalum, namely [M(CO) 2 (NO)MBu5Si(CH 2 PMe 2 ) 3N] (M\Nb or Ta) have been prepared and crystallographically characterised.63 Treatment of [Ta(C–– – CPh)(g2-PrC 2 Pr)M2,6- (ArNCH 2 ) 2 NC 5 H 3N] (Ar\2,6-C 6 H 3 Pr* 2 ) with an equimolar amount of HC 2 Ph at 110 °C a§ords the crystallographically characterised metallacycle 6, via the N Ta NAr NAr Pr Pr Ph Ph 6 insertion of co-ordinated octyne into a Ta–CCPh bond, followed by a 2,1-insertion of phenylacetylene into the newly formed alkenyl unit.64 Theoretical and experimental results show an equilibrium between a- and b-agostic interactions in [NbCl(CHMe 2 )(g2-MeC 2 Ph)Tp@], whereas only a-agostic interactions were observed for the analogous ethyl complex.65 A series of tribenzylidenemethane complexes of high oxidation-state tantalum have been prepared including [TaClMe 2 (tbm)], [TaMe 2 (NPh 2 )(tbm)], [TaMe 2 (tmb)Cp], [TaMe 2 (tmb)Cp@] and [TaMe 2 (tmb)(Flu)] which have all been crystallographically characterised.66 The identification of [M(CO) 3 (g2-C 2 H 4 )Cp] (M\Nb or Ta), and the kinetics of the ethylene loss from [Nb(CO) 3 (g2-C 2 H 4 )Cp] in supercritical fluids have been described.67 The control of stereoselectivity in the ring-opening metathesis polymerisation of norbornene by the complexes [Ta(CH 2 Ph) 2 (g4-C 4 H 6 )Cp*] and [Ta(CH 2 Ph) 2Mg4-o-(CH 2 ) 2 C 6 H 4NCp*] has been described; the crystal structures of the carbene complexes [Ta(–– CHPh)(PMe 3 )(g4-C 4 H 6 )Cp*] and [Ta(––CHPh)Mg4-o-(CH 2 ) 2 C 6 H 4NCp*] are also described.68 The preparation and characterisation of the first niobocene germyl Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 356complexes [Nb(H) 2 (GeR 3 )(g5-C 5 H 4 SiMe 3 ) 2 ], crystallographically characterised for R\Ph, have been reported; the molecular structure of the analogous triphenylstannylniobocene complex [Nb(H) 2 (SnPh 3 )(g5-C 5 H 4 SiMe 3 ) 2 ] has been described and the reactivity of the complexes discussed.69 4 Chromium, molybdenum and tungsten The preparation and first structural characterisation of a homoleptic tetraorganochromate( III) salt, [Li(thf) 4 ][Cr(C 6 Cl 5 ) 4 ] have been described.70 Reaction of [Mo(NAr) 2 Cl 2 (dme)] (Ar\2,6-diisopropylphenyl) with LiOC(OCBu5)CMe 2 at low temperature gives the novel C-bonded Mo(VI) enolate complex [Mo(NAr) 2 ClMg2- C(Me 2 )CO 2 Bu5N], which has been crystallographically characterised; the unusual a-aminoenolate complex [Mo(NAr) 2 ClMg2-CH(NMe 2 )CO 2 EtN] was prepared under analogous conditions using LiNPr* 2 -Me 2 NCH 2 CO 2 Et.71 The neutron di§raction structure determination of [MoMe 2 (NC 6 H 3 Pr*) 2 ] shows two highly distorted methyl ligands, due to the presence of multiple C–H·· ·Ma-agostic interactions.72 A series of complexes, [MoMeM(ArNCH 2 CH 2 ) 3 NN] (Ar\Ph, C 6 H 4 F-4, C 6 H 4 Bu5-4, C 6 H 3 Me 2 - 3,5, C 6 H 4 Me-2 or mesityl) has been prepared and characterised.73 The d0 alkane complexes [W(––NSiBu5 3 ) 3 (RH)], prepared from the reactions of alkyl halides with K[(––NSiBu5 3 ) 3 WH], precede C–H activation and formation of [(–– NSiBu5 3 ) 2 (Bu5SiNH)WR/R@].74 An equilibrium between [W(–– – CBu5)(CH 2 Bu5) 2 - (SiBu5Ph 2 )] and [W(––CHBu5) 2 (CH 2 Bu5)(SiBu5Ph 2 )] has been directly observed; the reaction of [W(–– – CBu5)(CH 2 Bu5) 2 (SiBu5Ph 2 )] with one equivalent of O 2 at room temperature gives the crystallographically characterised complex [W(–– O)(CH 2 Bu5) 2M––C(Bu5)(SiBu5Ph 2 )N] via the first example of a silyl migration to an alkylidyne ligand.75 (OC)4Cr N N CH2Ph Me Me Me 7 N N R¢ H X (OC)5M H R + – 8 P (OC)5W Ph 9 The spectroscopic detection and kinetic characterisation of the intermediate in the nucleophilic substitution reactions of [CrM––C(OMe)PhN(CO) 5 ] with thiolate ions in aqueous acetonitrile have been reported.76 The first Fischer-type hydrazino(methyl) carbene complex [CrM––C(Me)N(CH 2 Ph)NMe 2N(CO) 5 ], has been prepared from the appropriate acetylhydrazine and Na 2 [Cr(CO) 5 ]; the first crystal structure of a chelate hydrazine complex 7, has also been described.77 Reaction of the carbene complexes [MM–– C(OEt)(C–– – CR)N(CO) 5 ] (M\Cr, W; R\Ph, Bu5, SiMe 3 ) with a series of 1,3- dinitrogen ligands (amidines, guanidines, ureas) gives two products; the major, 8 (R\Ph, Bu5, SiMe 3 ; R@\Me, CH 2 CH 2 S; X\Ph, NMe 2 , O, S), is a cycloadduct whose structure may be related to a pyrimidinic ring arising from a formal [3]3] Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 357cycloaddition between the dinitrogen systems and the metal carbene complexes.78 Treatment of [5]metacyclophane with the (intermediate) phenylphosphinidene complex, [W(CO) 5 (PPh)] yields the crystallographically characterised 7-phosphanorbornadiene 9.The reaction involves the first 1,4-addition of a phosphinidene complex to an unsaturated system, the first addition of a phosphinidene complex to a benzene ring, and the first example of a [4]1] cycloaddition to an aromatic compound.79 Quantitative inversion at the chiral sp3 hybridised carbon atoms in the C 2 -chiral diphosphine complex [W(CO) 4 L] [L\Ph 2 PCHArPPh 2 (Ar\2-pyridyl)] occurs at moderately elevated temperatures.80 Tridentate co-ordination of the potentially tetradentate ligand, N,N@-dimethyl-2,11-diaza[3,3](2,6)pyridinophane (L) has been established by the crystallographic characterisation of [Mo(CO) 3 L].81 Treatment of [WI(CO)(NCR)Tp@] with pyridine N-oxide results in the oxyfunctionalisation of the i2N,C-nitrile ligand and formation of the unusual arylimido complexes [WMNC(O)RNI(CO)Tp@]; one example, [WMNC(O)MeN(SPh)(CO)Tp@], displays a sixco- ordinate structure in which the orientation of the ligands is determined by p-orbital overlap considerations.82 Reaction of trans-[Mo(N 2 ) 2 (dppe) 2 ] with an excess of PhCH––NAr (Ar\Ph, p-MeC 6 H 4 , p-MeOC 6 H 4 ) in refluxing benzene under N 2 affords, via the unprecedented conversion of benzylideneanilines into aryl isocyanides, trans-[Mo(CNAr)(N 2 )(dppe) 2 ], crystallographically characterised for Ar\Ph.83 Treatment of [W(CN)(CO)(g2-RC 2 R@)Tp@] (crystallographically characterised for R\Me, R@\Ph) with methyltriflate or triflic acid gives cationic isocyanide complexes, whereas reaction with H[BF 4 ] a§ords neutral BF 3 adduct complexes.84 The synthesis, molecular structure and ligand exchange reactions of [W(CO)(OEt 2 )(g2- MeC 2 Ph)Tp@][BMC 6 H 3 (CF 3 ) 2 -3,5N4 ] have been described; in the absence of suitable ligands, the diethyl ether complex [W(CO)(OEt 2 )(g2-MeC 2 Ph)Tp@][BMC 6 H 3 (CF 3 ) 2 - 3,5N4 ] decomposes in CH 2 Cl 2 to give the crystallographically characterised metallacycle 10.85 Reaction of [Mo(CO) 2 (NCMe)(S 2 PX 2 )(g3-allyl)] (X\OEt or Ph; W O Ph Cl CH2Cl Me Tp¢ [B{C6H3(CF3)2–3,5}4] 10 allyl\C 3 H 5 ) with dimethylacetylenedicarboxylate gives [Mo(CO) 3 (S 2 PX 2 )- MOC(OMe)C(allyl)––CCO 2 MeN], via coupling of the allyl and alkyne which reacts further with PEt 3 to give 11 (crystallographically characterised for X\Ph).86 Treatment of [Mo(–– – CR)(CO)LTp] (R\C 6 H 4 Me-4; L\CO, PPh 3 ) with CS 2 gives the novel metallacyclic thioketene complex 12, which has been crystallographically characterised. 87 The one-electron oxidation of [Mo(–– – CCH 2 CH 2 CH 2 CH 3 )(CO)MP(OPh) 3NCp] in the presence of HC 2 Ph, results in H-abstraction and addition to the resulting metal carbene, to give the crystallographically characterised complex 13 as the final product. 88 The donor-stabilized silyl (silylene) complexes [W(SiMe 3 )(––SiMe 2 · Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 358C O Mo C C S Et3P CO CO CO2Me MeO H H H H H S P X X 11 Mo S C C C S Tp O R O 12 Mo H OC (PhO)3P H P(OPh)3 Bun Ph [BF4] 13 base)(CO) 2 Cp] [base\thf or hmpa (crystallographically characterised)] have been prepared by the photolysis of C 6 D 6 solutions containing [W(SiMe 2 SiMe 3 )(CO) 3 Cp] and bases; the double bond character of the tungsten–silylene linkage has been shown by the significant downfield shift of the 29Si NMR resonance as well as by the large 1J(WSi) coupling constant.89 Reaction of the g1-acetylide complexes [W(C–– – CR)(CO)(NO)Cp]~ (R\Bu5, Ph or C6 H 4 Me-4) with ethyliodoacetate at [78 °C gives, after protonation with dilute acids, the corresponding oxametallacyclopentadienyl complexes 14, crystallographically characterised for W O R OC2H5 O I N O 14 R\Bu5.90 Density functional calculations suggest that [W(NO)(PH 3 )Cp] has a planar triplet ground state, a result which has important implications for the inversion of configuration of 16-electron d6 ML 2 Cp species.91 The preparation and crystal structure (forM\W) of the stable paramagnetic cyclopentadienyl polyhydride complexes [MH 3 (dppe)Cp*][PF 6 ] (M\Mo or W) have been reported.92 The low temperature protonation of [MH 5 (PMe 3 )Cp*] (M\Mo or W) with H[BF 4 ]·OEt 2 affords the non-classical polyhydride complexes [M(H) 6 (PMe 3 )Cp*][BF 4 ]; theoretical studies indicate that they are dihydrogen complexes [M(H 2 )(H) 4 (PR 3 )Cp*]` having very low exchange barriers through a transition-state having a stretched trihydride anion as a ligand.93 The comparative reactivity of the isomeric complexes [Mo(g3- C 3 H 5 )(g4-C 4 H 6 )Cp], with either supine or prone allyl, and either s-cis-(supine) or s-trans butadiene ligands, towards protons has been studied in detail.94 The reactivity of the bis(butadiene) complex [Mo(s-cis-supine-g4-C 4 H 6 )(s-trans-g4-C 4 H 6 )Cp][BF 4 ] towards nucleophiles has been investigated; the reaction with PMe 3 gives the crystallographically characterised complex [Mo(s-cis-supine-g4-C 4 H 6 )Msyn-prone-g3- C 3 H 4 (CH 2 PMe 3 )NCp][BF 4 ].95 The preparation, molecular structure and reactivity of aldehyde-substituted g3-allyl complexes of molybdenum such as [Mo(CO) 2Mg3-exoanti- CH 2 CHCH(CHO)NCp*] have been described; X-ray crystallography shows a contribution from a zwitterionic form involving donation of electron density from the molybdenum to the aldehyde carbonyl group.96 Treatment of [Mo(CO) 3 (g2- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 359OC OC N O R R 15 Mo H 2 C––C––CHCPh 3 )Cp][BF 4 ] with secondary amines NHR 2 [NHR 2 \dimethylamine, piperidine or morpholine (product crystallographically characterised)] gives 15 via coupling of a p-co-ordinated tritylallene with an amido ligand, unexpectedly at the terminal carbon atom.97 Reaction of [W(CO) 2 (g4- C 6 H 8 )Cp][BF 4 ] with RMgBr (R\methylvinyl, phenyl, naphthyl) at [78 °C a§ords [W(CO) 2M(1,2,4-g)-1-CO-2-R-C 6 H 10NCp] as the major products, an example of a nucleophile attacking the internal carbon atom of a cationic g4-diene unit.98 Treatment of [Cr(CO) 2Mg2-CH 2 ––CH(CO 2 Me)N(g6-C 6 H 6 )] with cyclohexadiene at ambient temperature gives the highly unsaturated complex [Cr(CO) 2 (g4-C 6 H 8 ) 2 ] in high yield; this reaction suggests that both acrylate–chromium and arene–chromium bonds are labile.99 The nitrogen nucleophile HN(OH)C(O)OBu5 reacts with non-racemic chiral Cr(CO) 3 complexes of benzylic ethers with retention of configuration, giving a novel approach to non-racemic N-hydroxycarbamates and amines.100 5 Manganese, technetium and rhenium The preparation, structure and properties of the first paramagnetic tetrahedral cyanometalate complex, [N(PPh 3 ) 2 ] 2 [Mn(CN) 4 ] have been described.101 The first rhenium diethyl ether and CH 2 Cl 2 complexes, cis-[Re(CO) 4 (PPh 3 )L][BMC 6 H 3 (CF 3 ) 2 - 3,5N4 ] (L\Et 2 O or CH2 Cl 2 ) have been prepared and structurally characterised, together with the firstH 2 adduct of the simple M(CO) 4 (PPh 3 ) fragment; the heterolytic activation of H 2 is also discussed.102 Photolysis of the complexes [ReR(CO) 3 (dmb)] (R\CH 3 , CD 3 , Et, Pr* or benzyl) into their visible absorption bands gives rise to homolytic cleavage of the Re–R bond, a§ording the radicals [Re(CO) 3 (dmb)]· and R·.103 The luminescent Re(I) diynyl complexes [Re(C–– – CC–– – CR)(CO) 3 (Bu5 2 -bipy)] (R\H or Ph) have been prepared and structurally characterised and their photophysical properties studied.104 The photoassisted reactions of fac- [Re(CH 2 OR)(CO) 3 (bipy)] [R\H or OAc (crystallographically characterised)] in MeOH gives high yields of the structurally characterised complex fac- [Re(OMe)(CO) 3 (bipy)]; the reactions of fac-[Re(CH 2 OR)(CO) 3 (bipy)] (R\H or OAc) and fac-[Re(CH 2 Ph)(CO) 3 (bipy)] with and without oxygen have been compared. 105 The coupling of isocyanide with the diphosphinocarbene unit in the complexes fac-[Mn(CO) 3 (CNR)M(PPh 2 ) 2 CI)N] (R\Ph or Bu5) yields fac- [MnI(CO) 3M(PPh 2 ) 2 C––C––NRN] (crystallographically characterised for R\Bu5), which have the new ketenimine ligands. The coordinated N-phenylketenimine (R\Ph) undergoes a [4]1] cycloaddition upon reaction with CNPh to a§ord the Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 360crystallographically characterised complex 16, which has a unique 2-(diphosphinomethylidene)- 3-imino-2,3-dihydroindole ligand.106 A series of g2-co-ordinated alkene complexes of the type fac-[Re(PPh 3 )(L)(dien)L@]` (L\CO or PF 3 , L@\unsaturated organic molecule) includes the g2-furan, [Re(CO)(PPh 3 )(dien)(g2-C 4 H 4 O)]- [OTf], a rare example of a thermally stable g2-heterocycle complex.107 C N C N H C Ph2 P P Ph2 Mn OC OC I C O Ph 16 Boronic acids have been used in a convenient three-component preparation of carbon-substituted cyclopentadienyl tricarbonyl rhenium complexes.108 The transition- metal alkane complex, [Re(CO) 2 (C 5 H 10 )Cp] has been directly observed byNMR spectroscopy.109 Reaction of [Re(CO) 2 (g2-RC 2 R)Cp*] (R\Me or Ph) with H[BF 4 ] at [78 °C gives the hydride complexes [ReH(CO) 2 (g2-RC 2 R)Cp*][BF 4 ] in which proton migration (R\Me, [16 °C) furnishes the 1-metallacyclopropene complex [Re(CO) 2 (g2-CMeCHMe)Cp*][BF 4 ].This then rearranges to the g3-allyl complex [Re(CO) 2 (g3-exo,anti-MeHCCHCH 2 )Cp*][BF 4 ].For R\Ph, however, warming to room temperature gives the crystallographically characterised 1-metallacyclopropene complex [Re(CO) 2 (g2-CPhCHPh)Cp*][BF 4 ].110 The cationic complex [Re(NCMe)Cp 2 ][BF 4 ] reacts with an excess of benzene or thiophene under UV light to a§ord high yields of the C–H bond activation products [Re(H)PhCp 2 ][BF 4 ] and [ReH(2-C 4 H 3 S)Cp 2 ][BF 4 ] respectively; reaction of [Re(H)PhCp 2 ] with dbu gives [RePhCp 2 ], which upon protonation regenerates [Re(H)PhCp 2 ][BF 4 ].111 The preparation and reactivity of the cationic carbene complexes, [Re(––CHR)Cp 2 ]- [BMC 6 H 3 (CF 3 ) 2 -3,5N4 ] (R\H or Me) have been described.112 6 Iron, ruthenium and osmium The crystal structure previously reported as that of ‘[Li(OEt 2 )] 4 [FePh 4 ]’ has been reinterpreted as that of the dihydride complex [Li(OEt 2 )] 4 [trans-FeH 2 Ph 4 ].113 The preparation, molecular structure and reactivity of the complex [FeMeMphenyl-tris(3- tert-butylpyrazolyl)boratoN] have been reported; this complex reacts with CO to give the four-coordinate monovalent iron derivative, [Fe(CO)L] [L\phenyltris(3-tertbutylpyrazolyl) borato].114 The synthesis and reactions of the very acidic ruthenium dihydrogen complexes, trans-[Ru(H 2 )(CNH)MPh 2 P(CH 2 )nPPh 2N2 ][O 3 SCF 3 ] 2 (n\2 or 3) have been described.115 The first calix[4]arenes with organometallic fragments positioned in the larger opening of the cavity have been described, and 17 has been structurally characterised.116 The bis(carbamoyl)iron complexes [FeMC(O)NR 2N2 (CO) 4 ] have been prepared either by treatment of the carbamoyl anions, [FeMC(O)NR 2N(CO) 4 ]~ with half an equivalent of oxalyl chloride or by alkoxy/amine exchange from [Fe(CO 2 Me) 2 (CO) 4 ]; the complexes Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 361P Ru P C Cl Cl O O O O O 17 O C [FeMC(O)NR 2N2 (CO) 4 ] undergo rapid carbon–oxygen coupling of the two carbamoyl groups at low temperature to give, after decarbonylation, stable metallacyclic carbene complexes, [FeMC(NR 2 )OC(O)NR 2N(CO) 3 ].117 The 5-bromo-8-quinolyl (L) complexes [OsX(CO)(PPh 3 ) 2 (g2-L)] [X\Cl, Br, I (crystallographically characterised for X\I)] react (X\Cl) with electrophiles such as Me 2 NC(O)Me to give the crystallographically characterised product, [OsCl(CO)(PPh 3 ) 2 (g2-L@)] (L@\methyl-8-quinolyl ketone).118 Treatment of 1-methyl-2-(p-chlorophenylazo)imidazole (L) and 2- (phenylazo)pyridine (L@) with [RuH(X)(CO)(PPh 3 ) 3 ] (X\Cl or Br) yield the crystallographically characterised paramagnetic radical-anion complexes [Ru(L·~)Cl(CO)(PPh 3 ) 2 ] and [Ru(L@·~)Br(CO)(PPh 3 ) 2 ] respectively.119 Luminescent Ru(II) bipyridine complexes with orthometallated aminocarbene ligands, such as [RuM––C(CH 2 Ph)NHC 6 H 3 OMeN(bipy) 2 ][OTf], have been crystallographically characterised and their photophysical properties studied.120 The synthesis, molecular structures, solid-state NMR spectra and density functional theory calculations of the carbonyl complexes [M(CO)(tpp)(1-MeIm)] (M\Fe, Ru or Os) and the Os(II) pyridine adduct [Os(CO)(py)(tpp)] have been reported.121 Thermolysis of the crystallographically characterised complex [Os(SC 6 F 4 F-2)(SC 6 F 5 ) 2 (PMe 2 Ph) 2 ] in refluxing toluene gives the structurally characterised complexes [Os(SC 6 F 5 ) 2 (o- S 2 C 6 F 4 )(PMe 2 Ph)] and [Os(C 6 F 5 ) 2 (o-S 2 C 6 F 4 )(PMe 2 Ph) 2 ] via C–F cleavage and C–S bond formation.122 The first ruthenium complexes containing both alkylidene and N-heterocyclic carbene species, such as 18, which has been crystallographically characterised, are highly active alkene metathesis catalysts.123 Reaction of [Os(H) 2 Cl 2 (PPr* 3 ) 2 ] with propylene or styrene a§ords equimolar amounts of [OsHCl 2 (CCH 2 R)(PPr* 3 ) 2 ] and the hydrogenated alkenes; these are isomeric with the N N Ru Pri Pri CHC6H4Cl–4 Cl Cl N N Pri Pri 18 N N N N Ru C R¢ R 19 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 362ruthenium carbene complexes [RuCl 2MC(H)CH 2 RN(PPr* 3 ) 2 ], but are thermodynamically preferred redox alternatives.124 The materials RuCl 3 , P(C 6 H 11 ) 3 , alk-1-ynes, Mg, H 2 and H 2 O are the ingredients for an e¶cient one-pot synthesis of the highly active alkene metathesis catalysts, [RuM–– CH(CH 2 R)NCl 2MP(C 6 H 11 ) 3N2 ] (R\H, Ph).125 The synthesis and crystallographic characterisation (R\Ph, R@\H) of the ruthenium carbene complexes 19 (R\R@\Ph; R\Ph, R@\H; R\Ph, R@\CO 2 Me) have been described.In the presence of CO, the carbene unit migrates to the ancillary macrocycle, a process similar to the crucial step in metathesis mediated by ruthenium carbenes.126 The new vinyl carbene cation [Ru(–– CaHCbH–– CcPh 2 )(CO)(S 2 CNMe 2 )(PPh 3 ) 2 ][PF 6 ] reacts with F~, OR~, BH 4 ~ and OH~ at Cc, to yield c-functionalised r-vinyl complexes; with dithiocarbamate salts, attack at Ca occurs to give the crystallographically characterised metallacycle, 20.127 Treatment of [Ru(P––CHBu5)Cl(CO)(PPh 3 ) 2 ] or [Ru(P––CHBu5)Cl(CNBu5)(CO)(PPh 3 ) 2 ] with excess isocyanopivalic acid under aerobic conditions a§ords the metallacyclic k5-phos- S Ru PPh3 S C OC Me2N S CPh2 C S NMe2 20 PPh3 Ru ButNC ButNC PPh3 C O P But O 21 Cy3P Ru Cy3P H H C C H SiMe2 H H CH3 22 phaalkenyl-P complex 21.128 The complex [ReH 2 (H 2 ) 2MP(c-C 6 H 11 ) 3N2 ] reacts with SiHMe 2 (CH 2 CH––CH 2 ) to give the very reactive species 22, which is stabilized by co-ordination of a vinylsilane group via Ru–(g2-C––C) and Ru–(g2-H–Si) bonds.Complex 22 catalyses the dehydrogenative silylation of SiHMe 2 (CH 2 CH–– CH 2 ) and redistribution of silicon under ethene pressure.129 The reaction of [MRuCl 2 (cym)N2 ] and (S,S)-2,6-bis(oxazolin-2-yl)pyridines in the presence of a,b-unsaturated carbonyl compounds a§ords g2-alkene complexes such as 23, which has been structurally N O N N O Me Me Ru Cl CHO H Cl 23 characterised; these RuCl 2 (pybox) units not only discriminate the one enantioface (si-face) of the alkenes, but also fix the conformation of the carbonyl group s-trans.130 Three papers describing the synthesis and reactions of p-allyltricarbonyliron lactone and lactam complexes have been published.131–133 Three stereogenic centres, having azide, methoxy and ethylthio units, have been constructed stereoselectively using only the chirality of the Fe(CO) 3 group and concurrent 1,2-migration of the Fe(CO) 3 unit; the product was converted to an anti-aminoalcohol derivative to establish the absolute Annu.Rep.Prog. Chem., Sect. A, 1999, 95, 353–374 363stereochemistry.134 Treatment of [RuL(g4-C 5 H 4 O)Cp][CF 3 SO 3 ] (L\NCMe, pyridine or thiourea) with PMe 3 a§ords the unusual fluxional complexes [RuL(PMe 3 )(g3-C 5 H 5 )(g4-C 5 H 4 O)] in quantitative yield; the kinetics of these reactions have been studied in detail.135 The rapid exchange of hydrogen atoms between hydride and methyl groups in the cationic complex [OsH(CH 3 )(dmpm)Cp*]` has been described.136 Reaction of the iron–phosphorane complexes [FeMP(OC 6 H 4 Y )(OC 6 H 4 Z)N(CO) 2 Cp] (Y, Z\NMe or O) with lithium diisopropylamide followed by MeI a§ords [FeMe(CO) 2Mg5- C 5 H 4 P(OC 6 H 4 Y )(OC 6 H 4 Z)N], the first example of migration of a hypervalent phosphorus fragment; one of the migration products, 24 has been crystallographically characterised.137 The regioselective nucleophilic addition of lithium enolates, Li[CH 2 COR] to [RuM––C––C–– C(R@)PhN(PPh 3 ) 2 (g5-C 9 H 7 )][PF 6 ] (R@\H, Ph) yield the first chiral keto-functionalised r-alkynyl complexes of Ru(II), namely Fe OC OC CH2Ph O NMe P O NMe 24 Fe L (C6F5)2P P(C6F5)2 O O Ph Ph 25 [BF4] Fe OC X C(OMe) [OTf] 26 [RuMC–– – CC(R@)Ph(CH 2 COR)N(PPh 3 ) 2 (g5-C 9 H 7 )].These complexes can be easily protonated to give the stable cationic vinylidene complexes [RuM––C––C(H)C(R@)Ph(CH 2 COR)N(PPh 3 ) 2 (g5-C 9 H 7 )][BF 4 ].138 The chiral ligand complexes (R,R)-25 (L\acetonitrile, acrolein, benzaldehyde), are catalysts in the asymmetric Diels–Alder reactions between a,b-enals and dienes.139 The cationic iron–carbene chelate complexes 26 (X\Cl or OMe) react with alkoxides,RO~ to give either the neutral chelate complex [FeMC 6 H 4 o-C(OR)(OMe)(OR)N(CO)Cp*] (for X\Cl; R\Me or Et) or the crystallographically characterised carbene complex [FeM––C(OEt) 2N(C 6 H 4 OMe-2)Cp*] (X\OMe).140 Treatment of [OsCl(PPr* 3 ) 2 Cp] with thallium acetate a§ords [OsMjO1-OC(O)CH 3N(PPr* 3 ) 2 Cp], which reacts with 1,1-diphenylprop-2-yn-1-ol to give the p-alkyne complex [OsMjO1- OC(O)CH 3N(PPr* 3 ) 2Mg2-HC 2 C(OH)Ph 2NCp].The last is unstable above[40 °C, and rapidly rearranges to the structurally characterised complex 27.141 The complex [RuCl(PPh 3 ) 2 (g5-C 7 H 9 )] reacts withH 2 initially to a§ord [RuCl(PPh 3 ) 2 (g3-C 7 H 11 )], and finally [RuH(Cl)(PPh 3 ) 3 ], [Ru 2 H 4 Cl 2 (PPh 3 ) 4 ], and unidentified products; this is Os Pri 3P H H O H O Ph Me O 27 R2P MeO Ru O B O R2P F F H F BF3 O Me 28 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 364a rare example of the hydrogenation of a co-ordinated ligand which remains bonded to the metal.142 Reaction of [Ru(OAc) 2 (MeOBiphep)] with two equivalents of HBF 4 yields 28 [R\3,5-di-tert-butylphenyl, Ph (crystallographically characterised) or C 6 H 4 Me-4], which have the rare co-ordinated phosphinite chelate ligand, (aryl) 2 POB(OH)F 2 and a (aryl) 2 P(g6-arene), eight-electron donor chelate.143 The demethylation of co-ordinated C 6 Me 6 in [Ru(OTf)(g3-C 3 H 3 )(g6-C 6 Me 6 )] is integrated into [3]2] allyl/alkyne coupling; these reactions proceed in high yield at room temperature or below to give [Ru(g5-1,2-R)(g6-C 6 Me 5 H)][OTf] (R\dialkylcyclopentadienyl) and methane.144 The first 19-, 18- and 17-electron triads of stable isostructural complexes of the type [M(g5-C 5 R 5 )(g6-arene)]z [z\0, 1 or 2; M\Fe, R\H or Me; arene\C 6 H 6~n (n\0-6), C 6 H 5 NMe 2 or C 6 Me 5 NH 2 ; M\Ru, R\Me, arene\C 6 Me 6 ] have been prepared, and their redox properties investigated; the 17-electron complexes [Fe(g5-C 5 R 5 )(g6-arene)]2` (R\H or Me) are a new family of strong oxidants.145 Certain types of carbon and sulfur nucleophiles add to the b-terminus of the styrene unit in the a,b-unsaturated arene Ru(II) complexes, [RuCp(g6-C 10 H 6 R,R@-4,7)][PF 6 ], to give products where, in some cases, unexpected endo-addition has occurred.146 Three Ru complexes with p-bonded nitrogen heterocycles have been prepared, including (])-29, which has been crystallographically Me Me Me Me Me N NMe2 29 Ru S* M* O Me H O (L) Cl O 30 * characterised; they are all e§ective catalysts for the addition of alcohols to ketenes, the acylation of alcohols with diketene and the ring-opening of azlactones.147 New chiral-at-metal complexes, 30 [L\Cp*, M\Rh(III), Ir(III); L\p-cymene, M\Ru(II), Os(II); L\C 6 Me 6 , M\Ru(II)] with excellent stereospecificity at the metal, have been prepared and structurally characterised.148 The complexes [M(allyl)(TpP3*)] (M\Fe, Co or Ni) and [Fe(R)(TpP3*)] (R\p-methylbenzyl) have been prepared and crystallographically characterised.The allyl ligand is g1-bound to a highly co-ordinatively unsaturated, 14-electron iron centre; g3-co-ordination is observed in the Co and Ni complexes.149 7 Cobalt, rhodium and iridium The spectroscopic identification and reactivity of [Ir(Me)I 2 (CO) 3 ], a key reactive intermediate in iridium-catalysed methanol carbonylation, have been described.150 The azido complexes [Rh(N 3 )(––C––C–– CRR@)(PPr* 3 ) 2 ] [R\R@\Ph; R\Ph, R@\Bu5 (crystallographically characterised); R\R@\C 6 H 4 OMe-4] react with CO (R\R@\aryl), with spontaneous loss of N 2 , to give r-bonded [RhMC(CN)––CRR@N(CO)(PPr* 3 ) 2 ] (crystallographically characterised for Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 365R\R@\C 6 H 4 OMe-4). Unprecedented C–N coupling follows the migration of an azido ligand to a C––C––CRR@ group.151 The electronic and EPR spectra and electron transfer properties of the 17-electron cation [RhH(CO)(PPh 3 ) 3 ]` have been reported. 152 Protonation of the iridapyrrole complex [IrMC(Me)––C(Me)C(Me)––NHN(H)Tp@] gives two possible stereoisomers of the chelating Ir(III) alkylidene, [IrM––C(Me)CH(Me)C(Me)––NHNH(Tp@)][BMC 6 H 3 (CF 3 ) 2 -3,5N4 ] which have been isolated and spectroscopically characterised; the kinetically preferred isomer has been structurally characterised.153 Treatment of [MRhClL 2N2 ] (L\C 2 H 4 or cyclooctene) with two equivalents of C 6 H 3 (CF 3 )-1-(CH 2 PBu5 2 ) 2 -2,6 gives 31, via an unprecedented oxidative-addition of a strong, unstrained Ar–CF 3 bond to a metal.154 Reaction of C 6 H 4 (CH 2 PBu5 2 ) 2 -1,3 with one equivalent of [Rh(CO)(solv)n(g2-C 2 H 4 )]- [OTf] (n\1 or 2) in thf a§ords the crystallographically characterised complex 32 (two But 2 P P But 2 Rh CF3 Cl 31 PBut 2 PBut 2 Rh H CO + PBut 2 PBut 2 Rh H CO + [OTf] 32 contributing resonance forms shown), which has an g2-C–H agostic bond.155 Treatment of LiL [L\ArNC(Me)CHC(Me)NAr, Ar\C 6 H 3 Me 2 -2,6] with [MRhCl(g2- coe) 2N2 ] gives the crystallographically characterised three-co-ordinate complex [RhL(g2-coe)]; at room temperature the RhL unit moves rapidly over one face of the coe ligand via reversible allyl hydride formation.156 Both rhodium(0)157 and iridium- (0) and -([I)158 complexes of (5H-dibenzo[a,d]cyclohepten-5-yl)diphenylphosphine have been prepared, including 33,157 which has been crystallographically character- Ph2 P Ph2 P Rh 33 ised.Treatment of 2-phenyl-1-methylenecyclopropane with [RhCl(PPh 3 ) 3 ] for 16 h at 50 and 0 °C a§ords the crystallographically characterised complexes, [RhCl(PPh 3 ) 2 (g4-CH 2 ––CPhCH–– CH 2 )] and [RhCl(PPh 3 ) 2 (g2-CH 2 –– CCH 2 CHPh)] respectively; warming [RhCl(PPh 3 ) 2 (g2-CH 2 –– CCH 2 CHPh)] in benzene at 50 °C gives [RhCl(PPh 3 ) 2 (g4-CH 2 ––CPhCH–– CH 2 )] in low yield.Reaction of 2-phenyl-1- methylenecyclopropane with [RhCl(PPh 3 ) 3 ], and with [RhCl(PPh 3 ) 2 (g2- CH 2 ––CCH 2 CHPh)] at 50 °C, furnishes [RhCl(PPh 3 ) 2 (g4-CH 2 ––CPhCH–– CH 2 )] and 2-phenylbuta-1,3-diene.159 A sub-picosecond infrared spectroscopic study has identified the cyclohexane solvate [Rh(CO)(C 6 H 12 )Cp], the reactive intermediate in cyclohexane C–H bond activation by [Rh(CO) 2 Cp].160 The preparation, crystal structure and chemistry of the Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 366iridium carbyne complex [Ir(–– – CPh)(PMe 3 )(g5-C 5 Me 4 Et)][BMC 6 H 3 (CF 3 -3,5) 2N4 ] have been described.161 A planar chiral ligand induces C–H activation with asymmetric induction at an iridium centre; one complex, 34, has been crystallographically Ir P Me2 Me I 34 characterised as its (RR),(SS) configuration.162 Treatment of [Rh(––CPh 2 )(PPr* 3 )Cp] with either two equivalents of HCl or one equivalent of PF 3 gives [RhCl 2 (PPr* 3 )(g5- C 5 H 4 CHPh 2 )] or [Rh(PF 3 )(PPr* 3 )(g5-C 5 H 4 CHPh 2 )] via migratory insertion of the carbene ligand into one of the C–H bonds of the cyclopentadienyl ring; the complex [Rh(PF 3 )(PPr* 3 )(g5-C 5 H 4 CHPh 2 )] is the first Rh–PF 3 half-sandwich complex to be crystallographically characterised.163 The oxidative-addition of alkyl halides, R@X, with [Rh(CO)Mg5:g1-(L)nN] [Ln \C 9 H 6 (CH 2 )nPR 2 ; n\2-4; C 9 H 6 \g5-1-indenyl; R\Ph, c-C 6 H 11 ] gives the complexes [RhX(COR@)Mg5:g1-LnN] with high diastereoselectivity; the crystal structure of one of the major isomers, (R*,S*)- [RhI(COMe)Mg5:g1-C 9 H 6 (CH 2 ) 3 PPh 2N] is also described.164 The synthesis, molecular structure and electrochemical properties of 35, which has a novel planar ligand, S Co S S C S C CN CN 35 Co Ph3P H CO2Et SO2Ph H 36 P But 2 Co 37 have been reported.165 Reaction of the metallocyclobutene complex [CoMC(SO 2 Ph)––C(SiMe 3 )CH(CO 2 Et)N(PPh 3 )Cp] with [NBu/4 ]F and MeOH in acetone at 70 °C gives three crystallographically characterised isomeric allene complexes, including (E)-36.166 The first transition-metal complexes of bicyclopropylidene, including 37 which has been crystallographically characterised, have been prepared. 167 The synthesis, molecular structure (R\Me, R@\Pr*) and reactivity of the o-benzoquinone methide complexes [IrMg4-C 6 H 3 R@(––O)(––CR 2 )NCp*] (R\R@\H; R\H, R@\CH 3 ; R\CH 3 , R@\H; R\CH 3 ; R@\Pr*) have been reported.168 The first metallacyclopentadiene(alkyne) complexes, 38 (R\H, L\C 5 H 5 , C 5 Me 5 , C 5 H 4 Me, C 9 H 7 ; R\Pr*, L\C 5 H 5 ), and their isomerisation to g4-bonded arenes have been described; complexes 38 provide the missing link in the prevalent mechanism of transition-metal catalysed alkyne cyclotrimerisation.169 Allyl/alkyne [3]2] cycloaddition reactions of the p-allyls [Co(OTf)(g3-C 3 H 3 RR@-2,3)Cp*] with alkynes give functionalised seven-membered ring complexes [CoCp*(g5-C 7 H 7 RR@)][OTf], useful for the synthesis of functionalised cycloheptadienes.170 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 367R Co R L 38 8 Nickel, palladium and platinum The highly electrophilic cationic complexes, [PtMeLM(C 2 F 5 ) 2 P(CH 2 ) 2 P(C 2 F 5 ) 2N]` (L\CO, NC 5 F 5 ), [Pt(SO 3 F)(CO)M(C 2 F 5 ) 2 P(CH 2 ) 2 P(C 2 F 5 ) 2N]`, and [Pt(CO) 2M(C 2 F 5 ) 2 P(CH 2 ) 2 P(C 2 F 5 ) 2N]2` have been prepared in superacid media.171 Complex 39 is the first crystallographically characterised nickel complex which does not polymerise ethene, but rather catalyses a mixture of carbon monoxide and ethene under mild conditions to a§ord a perfectly alternating polyketone.172 Treatment of [Pt(PPh 3 ) 2 (g2-C 2 H 4 )] with Ph 2 P(CH 2 ) 2 SiPh 3~nMen (n\0 or 1) at elevated temperatures gives [Pt(PPh 2 CH 2 CH 2 SiPh 2~nMen)Ph(MenPh 3~nSiCH 2 CH 2 PPh 2 )] via oxidative-addition of the Si–C1)%/:- group.173 The structurally characterised iminoacyl [PdMC(Me)–– N(C 6 H 4 C–– – CSiMe 3 -2)NCl(PEt 3 ) 2 ] undergoes intramolecular insertion of alkyne at 45 °C, to a§ord the crystallographically characterised complex 40, in quantitative yield.174 The Pt(II) complexes [PtMe 2 (L–L)] (L–L\bipy, phen, tmen) are oxidised by dioxygen in methanol to give the corresponding alkoxo Pt(IV) complexes [PtMe 2 (OH)(OMe)(L–L)].175 N N N N B H Ni P N N 39 N Pd Me3Si Cl PEt3 Et3P Me 40 The first Pt(IV) complexes containing glucopyranose ligands have been described, including 41 which has been structurally characterised.176 The solution decomposition of [PtF(PPh 3 ) 3 ]` in the presence of trace amounts of water gives the crystallographically characterised orthometallated complex 42, as its [SbF 6 ]~ salt.177 The Pd complex [PdMe(NCMe)(bipy)][OTf] undergoes sequential insertion of carbon monoxide and imine into theM–C bond in a manner analogous to that seen in alkene and carbon monoxide alternating copolymerisations; one of the crystallographically characterised insertion products, 43, is very similar to that of alkene/carbon monoxide Annu.Rep.Prog. Chem., Sect. A, 1999, 95, 353–374 368O O OH OH Pt Me Me Me OH [BF4] 41 Pt Ph2P PPh3 PPh3 42 + H Tol N CH3 O CH2Ph (bipy)Pd [OTf] 43 insertion intermediates, and is a novel example of imine insertion into a late M–C bond.178 The quantitative formation of the intermediate of alkene insertion in the copolymerisation of carbon monoxide and p-methylstyrene catalysed by [PdMe(NCMe)(Pr*dab)][BMC 6 H 3 (CF 3 ) 2 -3,5N4 ] has been described.179 Treatment of [PdCl 2 (dmpp)] with 1-vinylimidazole in ClCH 2 CH 2 Cl a§ords the structurally characterised product 44, via a Diels–Alder promoted reaction between 1-phenyl-3,4- dimethylphosphole and 1-vinylimidazole.180 Hydrogenation of the crystallographically characterised thiaplatinacycle [Pt(C,S-CH––CHC 6 H 4 S)(dppe)] derived from benzothiophene gives [Pt(C,S-CHMeC 6 H 4 S)(dppe)] in which two hydrogen atoms have added, and a hydrogen shift has occurred.181 The asymmetric synthesis of a series of palladacycles such as the norbornadiene derivative 45 [E\CO 2 -(S)- CH(Me)CO 2 Me], by the oxidative-cyclisation of C 2 -symmetrical, chiral cyclopropenes having lactate esters at the 1- and 2-positions, has been reported.182 The consecutive reactions of [PtI 2MCNC 6 H 3 (OMe) 2 -3,5N2 ] withNH 2 Pr and CHCl 3 a§ord the novel dicyclometallated bis(carbene) Pt(IV) complex, 46.183 N N ClCH2CH2 Me Me P Ph Cl Pd Cl 44 E E E E 45 Pd OMe OMe HN Pt I C C NHPr PrHN NH OMe I MeO 46 Treatment of equimolar amounts of [PdMe 2 (Me 2 NCH 2 CH 2 NMe 2 )] and B(C 6 F 5 ) 3 in the presence of C 2 H 4 gives [PdMe(Me 2 NCH 2 CH 2 NMe 2 )(g2-C 2 H 4 )]- [BMe(C 6 F 5 ) 3 ], which catalyses the oligomerisation of ethene to highly branched products.These products are apparently formed via both reversible b-eliminationreinsertion processes and incorporation of short chain oligomeric products.184 The first square-planar complexes, [PtMe(N,N-chelate)(g2-CH 2 ––CHCOR)][BF 4 ] (R\H, NMe 2 ,Me or OMe), containing electron-poor alkenes, include the crystallographically characterised salt [PtMe(L)(g2-CH 2 ––CHCO 2 Me)][BF 4 ] (L\diacetylbis( diethylphenylimine)].185 Very high ([95%) stereoselectivity of a-alkene co-ordination has been seen in new chiral Pt(II) complexes of types [PtMcis-1-(N––CHC 6 H 4 )- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 369HNHPtHNPh47+RS RN NNRPd48¡E ¡E2-(N¡V¡VCHPh)C6H10N(g2-CH2¡V¡VCHR)][BF4] and [PtMtrans-1-(N¡V¡VCHC6H4)-2-(N¡V¡VCHPh)C6H10N(g2-CH2¡V¡VCHR)][BF4] (R\H, Me, Ph, C6H4Me-4); the firststructurally characterised chiral model complex, 47, for the stereoselectivecopolymerisation of a prochiral alkene by a late transition-metal complex is alsodescribed.186 Reaction of the cationic allenylpropargyl complex [Pt(PPh3)2(g3-C3H3)][BF4] with PhNMe2gives the arylallyl complex [Pt(PPh3)2Mg3-CH2C(C6H4NMe2-4)][BF4], via the unprecedented selective addition of the para-arylC¡VH bond of the PhNMe2fragment.187 The preparation and reactivity of the neutralp-allyl complexes 48 (R\Me, Bu5), and their catalytic activity for the cyclopropanationof ketene silyl acetal with allylic acetates, have been described.188References1 M.I. Bruce, Chem. Rev., 1998, 98, 2797.2 W.M. Jones and J. Klosin, Adv. Organomet. Chem., 1998, 42, 147.3 H. Fischer, R. Stumpf and G. Roth, Adv. Organomet. Chem., 1998, 43, 125.4 S. Sabo-Etienne and B. Chaudret, Chem. Rev., 1998, 98, 2077.5 M. Fourmigue , Coord. Chem. Rev., 1998, 178¡V180, 823.6 I.R. Whittall, A. M. McDonagh, M.G.Humphrey and M. Samoc, Adv. Organomet. Chem.,1998, 42, 291.7 I.R. Whittall, A. M. McDonagh, M.G. Humphrey and M. Samoc, Adv. Organomet. Chem.,1998, 43, 349.8 J.-P. Majoral, P. Meunier, A. Igau, N. Pirio, M. Zablocka, A. Skowronska and S.Bredeau, Coord. Chem.Rev., 1998, 178¡V180, 145.9 R. Poli and L.-S. Wang, Coord. Chem. Rev., 1998, 178¡V180, 169.10 P. K. Baker, Chem. Soc.Rev., 1998, 27, 125.11 F. R.-Munch, V. Gagliardini, C. Renard and E. Rose, Coord. Chem. Rev., 1998, 178¡V180, 249.12 J.-J. Brunet, R. Chauvin, O. Diallo, F. Kindela, P. Leglaye and D. Neibecker, Coord.Chem. Rev., 1998,178¡V180, 331.13 J.-Y. SalauÆØ n, P. Laurent and H. des Abbayes, Coord. Chem. Rev., 1998, 178¡V180, 353.14 D. Touchard and P. H. Dixneuf, Coord. Chem. Rev., 1998, 178¡V180, 409.15 J.C. Green, Chem. Soc. Rev., 1998, 27, 263.16 L. Weber, Angew. Chem., Int. Ed., 1998, 37, 1515.17 Le Floch and F. Mathey, Coord. Chem. Rev., 1998, 179¡V180, 771.18 M.R. DuBois, Coord. Chem. Rev., 1998, 174, 191.19 N. J. Coville and L. Cheng, J. Organomet. Chem., 1998, 571, 149.20 A. J. Lees, Coord. Chem. Rev., 1998, 177, 3.21 A. Vogler and H. Kunkely, Coord. Chem.Rev., 1998, 177, 81.22 E. J. Baerends and A. Rosa, Coord. Chem. Rev., 1998, 177, 97.23 D. J. Stufkens and A. Vlc£¾ek, Jr., Coord. Chem. Rev., 1998, 177, 127.24 A. Vlc£¾ek, Jr., Coord. Chem. Rev., 1998, 177, 219.25 I. S. Zavarine and C. P. Kubiak, Coord. Chem. Rev., 1998, 171, 419.26 D. Guillaumont, K. Finger, M. R. Hachey and C. Daniel, Coord. Chem. Rev., 1998, 171, 439.27 A. L.McKnight and R. M. Waymouth, Chem. Rev., 1998, 98, 2587.28 W. Kaminsky, J. Chem. Soc., Dalton Trans., 1998, 1413.29 H. G. Alt and E. Samuel, Chem. Soc. Rev., 1998, 27, 323.30 R. Pre toÆÙ t, G.C. Lloyd-Jones and A. Pfaltz, Pure Appl. Chem., 1998, 70, 1035.Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 353¡V374 37031 P. H. Dixneuf, C. Bruneau and S. De� rien, Pure Appl. Chem., 1998, 70, 1065. 32 S. S. Stahl, J. A. Labinger and J. E. Bercaw, Angew. Chem., Int. Ed., 1998, 37, 2180. 33 R. A. Gossage, L. A. van de Kuil and G. van Koten, Acc. Chem. Res., 1998, 31, 423. 34 P. Wipf, H. Takahashi and N. Zhuang, Pure Appl. Chem., 1998, 70, 1077. 35 W.D. Wul§, Organometallics, 1998, 17, 3116. 36 S.-J. Shieh, K.-W. Liang, W.-T. Li, L.-H. Shu, M. Chandrasekharam and R.-S. Liu, Pure Appl.Chem., 1998, 70, 1111. 37 L. R. Cox and S. V. Ley, Chem. Soc. Rev., 1998, 27, 301. 38 J. F. Hartwig, Acc. Chem. Res., 1998, 31, 852. 39 M.E. Kra§t, Z. Fu, M. J. Procter, A. M. Wilson, O. A. Dasse and C. Hirosawa, Pure Appl. Chem., 1998, 70, 1083. 40 W. Scherer, W. Hieringer, M. Spiegler, P. Sirsch, G. S. McGrady, A. J. Downs, A. Haaland and B. Pedersen, Chem. Commun., 1998, 2471. 41 A. Bashall, P. E. Collier, L. H. Gade, M. McPartlin, P. Mountford and D. J. M. Tro� sch, Chem. Commun., 1998, 2555. 42 P. J. Fischer, K. A. Ahrendt, V. G. Young, Jr. and J. E. Ellis, Organometallics, 1998, 17, 13. 43 M.G. Thorn, J. S. Vilardo, P. E. Fanwick and I. P. Rothwell, Chem. Commun., 1998, 2427. 44 L. R. Sita and J. R. Babcock, Organometallics, 1998, 17, 5228. 45 S.Doherty, R. J. Errington, A. P. Jarvis, S. Collins, W. Clegg and M.R. J. Elsegood, Organometallics, 1998, 17, 3408. 46 S. J. Brown, X. Gao, D. G. Harrison, L. Koch, R. E. v. H. Spence and G. P. A. Yap, Organometallics, 1998, 17, 5445. 47 E. E. C. G. Gielens, J. Y. Tiesnitsch, B. Hessen and J. H. Teuben, Organometallics, 1998, 17, 1652. 48 H. van der Heijden, B. Hessen and A. G.Orpen, J. Am. Chem. Soc., 1998, 120, 1112. 49 Y. Sun, W. E. Piers and S. J. Rettig, Chem. Commun., 1998, 127. 50 Y. Miquel, A. Igau, B. Donnadieu, J.-P. Majoral, N. Pirio and P. Meunier, J. Am. Chem. Soc., 1998, 120, 3504. 51 M.V. Galakhov, G. Heinz and P. Royo, Chem. Commun., 1998, 17. 52 L. Hao, H.-G. Woo, A.-M. Lebuis, E. Samuel and J. F. Harrod, Chem. Commun., 1998, 2013. 53 J.M. Dysard and T. D. Tilley, J. Am. Chem. Soc., 1998, 120, 8245. 54 C. J. Schaverien, R. Ernst, P. Schut, W. M. Ski§, L. Resconi, E. Barbassa, D. Balboni, Y. A.Dubitsky, A. G. Orpen, P. Mercandelli, M. Moret and A. Sironi, J. Am. Chem. Soc., 1998, 120, 9945. 55 J. Scholz, S. Kahlert and H. Go� rls, Organometallics, 1998, 17, 2876. 56 J. L. Polse, A. W. Kaplan, R. A. Andersen and R.G. Bergman, J. Am. Chem. Soc., 1998, 120, 6316. 57 J. L. Polse, R. A. Andersen and R. G. Bergman, J. Am. Chem. Soc., 1998, 120, 13 405. 58 Z. K. Sweeney, J. L. Polse, R. A. Andersen and R. G. Bergman, J. Am. Chem. Soc., 1998, 120, 7825. 59 J. R. Hagadorn and J. Arnold, Angew. Chem., Int. Ed., 1998, 37, 1729. 60 J. K. Seaburg, P. J. Fischer, V. G. Young, Jr. and J. E. Ellis, Angew.Chem., Int. Ed., 1998, 37, 155. 61 A. J. Blake, S. C. Dunn, J. C. Green, N. M. Jones, A. G. Moody and P. Mountford, Chem. Commun., 1998, 1235. 62 M.V. Barybin, V. G. Young, Jr. and J. E. Ellis, J. Am. Chem. Soc., 1998, 120, 429. 63 P. J. Da§, P. Legzdins and S. J. Rettig, J. Am. Chem. Soc., 1998, 120, 2688. 64 F. Gue� rin, D. H. McConville, J. J. Vittal and G. P. A. Yap, Organometallics, 1998, 17, 1290. 65 J. Ja§art, R. Mathieu, M. Etienne, J. E. McGrady, O. Eisenstein and F. Maseras, Chem. Commun., 1998, 2011. 66 G. Rodriguez, J. P. Graham, W. D. Cotter, C. K. Sperry, G. C. Bazan and B. E. Bursten, J. Am. Chem. Soc., 1998, 120, 12 512. 67 J. C. Linehan, C. R. Yonker, J. T. Bays, S. T. Autrey, T. E. Bitterwolf and S. Gallagher, J. Am. Chem. Soc., 1998, 120, 5826. 68 K. Mashima, M. Kaidzu, Y. Tanaka, Y. Nakayama, A. Nakamura, J. G. Hamilton and J. J.Rooney, Organometallics, 1998, 17, 4183. 69 A. Antin8 olo, F. Carrillo-Hermosilla, A. Castel, M. Fajardo, J. Ferna� ndez-Baeza, M. Lanfranchi, A. Otero, M.A. Pellinghelli, G. Rima, J. Satge� and E. Villasen8 or, Organometallics, 1998, 17, 1523. 70 P. J. Alonso, L. R. Falvello, J. Fornie� s, M.A.Garcý� a-Monforte, A. Martý� n, B. Menjo� n and G. Rodgrý� guez, Chem. Commun., 1998, 1721. 71 P. A. Cameron, G. J. P. Britovsek, V. C. Gibson, D. J. Williams and A. J. P. White, Chem. Commun., 1998, 737. 72 J. M. Cole, V. C. Gibson, J. A. K. Howard, G. J. McIntyre and G. L. P. Walker, Chem. Commun., 1998, 1829. 73 G. E. Greco, A. I. Popa and R. R. Schrock, Organometallics, 1998, 17, 5591. 74 D. F. Schafer II and P. T. Wolczanski, J. Am. Chem. Soc., 1998, 120, 4881. 75 T. Chen, Z. Wu, L. Li, K. R. Sorasaenee, J. B. Diminnie, H. Pan, I. A. Guzei, A. L. Rheingold and Z. Xue, J. Am. Chem. Soc., 1998, 120, 13 519. 76 C. F. Bernasconi, F. X. Flores and K. W. Kittredge, J. Am. Chem. Soc., 1998, 120, 7983. 77 E. Licandro, S. Maiorana, R. Manzotti, A. Papagni, D. Perdicchia, M.Pryce, A. Tiripicchio and M. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 371Lanfranchi, Chem. Commun., 1998, 383. 78 R. Polo, J. M. Moreto¢¥ , U. Schick and S. Ricart, Organometallics, 1998, 17, 2135. 79 M. J. van Eis, C. M. D. Komen, F. J. J. de Kanter, W. H. de Wolf, K. Lammertsma, F. Bickelhaupt, M. Lutz and A. L. Spek, Angew. Chem., Int. Ed., 1998, 37, 1547. 80 J. L. Bookham, Inorg. Chem. Commun., 1998, 1, 309. 81 H. Kelm and H.-J. Kru¡§ ger, Eur. J. Inorg. Chem., 1998, 1381. 82 S. Thomas, P. J. Lim, R. W. Gable and C. G. Young, Inorg. Chem., 1998, 37, 590. 83 G. Nakamura, Y. Harada, C. Arita, H. Seino, Y. Mizobe and M. Hidai, Organometallics, 1998, 17, 1010. 84 D. S. Frohnapfel, S. Reinartz, P. S. White and J. L. Templeton, Organometallics, 1998, 17, 3759. 85 T. B. Gunnoe, J. L. Caldarelli, P. S. White and J. L. Templeton, Angew. Chem., Int. Ed., 1998, 37, 2093. 86 G. Barrado, M. M. Hricko, D. Miguel, V. Riera, H. Wally and S. Garc©¥¢¥ a-Granda, Organometallics, 1998, 17, 820. 87 A. F. Hill, J. M. Malget, A. J. P. White and D. J. Williams, Inorg. Chem., 1998, 37, 598. 88 K. E. Torraca, K.A. Abboud and L. McElwee-White, Organometallics, 1998, 17, 4413. 89 K. Ueno, M. Sakai and H. Ogino, Organometallics, 1998, 17, 2138. 90 J. Ipaktschi, F. Mirzaei, K. Reimann, J. Beck and M. Serafin, Organometallics, 1998, 17, 5086. 91 K.M. Smith, R. Poli and P. Legzdins, Chem. Commun., 1998, 1903. 92 B. Pleune, R. Poli and J. C. Fettinger, J. Am. Chem. Soc., 1998, 120, 3257. 93 C. A. Bayse, M.B. Hall, B. Pleune and R. Poli, Organometallics, 1998, 17, 4309. 94 R. Poli and L.-S. Wang, J. Am. Chem. Soc., 1998, 120, 2831. 95 L.-S. Wang, J. C. Fettinger, R. Poli and R. Meunier-Prest, Organometallics, 1998, 17, 2692. 96 C. J. Beddows, M. R. Box, C. Butters, N. Carr, M. Green, M. Kursawe and M.F. Mahon, J. Organomet. Chem., 1998, 550, 267. 97 B.-C. Huang, Y.-C. Lin, Y.-H. Liu and Y. Wang, Chem. Commun., 1998, 2027. 98 J.-S. Fan and R.-S. Liu, Organometallics, 1998, 17, 1002. 99 E. P. Ku¡§ ndig, M. Kondratenko and P. Romanens, Angew. Chem., Int. Ed., 1998, 37, 3146. 100 D. Albanese, S. E. Gibson (ne¢¥ e Thomas) and E. Rahimian, Chem. Commun., 1998, 2571. 101 W. E. Buschmann, A. M. Arif and J. S. Miller, Angew. Chem., Int. Ed., 1998, 37, 781. 102 J. Huhmann-Vincent, B. L. Scott and G. J. Kubas, J.Am. Chem. Soc., 1998, 120, 6808. 103 C. J. Kleverlaan, D. J. Stufkens, I. P. Clark, W. R. George, J. J. Turner, D. M. Martino, H. van Willigen and A. Vlc¢§ek, Jr., J. Am. Chem. Soc., 1998, 120, 10 871. 104 V. W.-W. Yam, S. H.-F. Chong and K.-K.Cheung, Chem. Commun., 1998, 2121. 105 D. H. Gibson, B. A. Sleadd, X. Yin and A. Vij, Organometallics, 1998, 17, 2689. 106 J. Ruiz, V.Riera, M. Vivanco, M. Lanfranchi and A. Tiripichio, Organometallics, 1998, 17, 3835. 107 B. C. Brooks, R. M. Chin and W.D. Harman, Organometallics, 1998, 17, 4716. 108 F. Minutolo and J. A. Katzenellenbogen, J. Am. Chem. Soc., 1998, 120, 13 264. 109 S. Geftakis and G. E. Ball, J. Am. Chem. Soc. C. P. Casey, J. T. Brady, T. M. Boller, F. Weinhold and R. K. Hayashi, J.Am. Chem. Soc., 1998, 120, 12 500. 111 H. Tobita, K. Hashidzume, K. Endo and H. Ogino, Organometallics, 1998, 17, 3405. 112 D.M. Heinekey and C. E. Radzewich, Organometallics, 1998, 17, 51. 113 J. M. Je¡×eris and G. S. Girolami, Organometallics, 1998, 17, 3630. 114 J. L. Kisko, T. Hascall and G. Parkin, J. Am. Chem. Soc., 1998, 120, 10 561. 115 T. P. Fong, A. J. Lough, R.H. Morris, A. Mezzetti, E. Rocchini and P. Rigo, J. Chem. Soc., Dalton Trans., 1998, 2111. 116 C. Wieser-Jeunesse, D. Matt and A. De Cian, Angew. Chem., Int. Ed., 1998, 37, 2861. 117 D. Luart, N. le Gall, J.-Y. Salau¡§ n, L. Toupet and H. des Abbayes, Organometallics, 1998, 17, 2680. 118 A.M. Clark, C. E. F. Rickard, W.R. Roper and L. J. Wright, Organometallics, 1998, 17, 4535. 119 M.Shivakumar, K. Pramanik, P. Ghosh and A. Chakravorty, Chem. Commun., 1998, 2103. 120 V. W.-W. Yam, B. W.-K. Chu and K.-K. Cheung, Chem. Commun., 1998, 2261. 121 R. Salzmann, C. J. Ziegler, N. Godbout, M.T. McMahon, K. S. Suslick and E. Oldfield, J. Am. Chem. Soc., 1998, 120, 11 323. 122 M. Arroyo, S. Berne` s, J.L. Brianzo, E. Mayoral, R. L. Richards, J. Rius and H. Torrens, Inorg.Chem. Commun., 1998, 1, 273. 123 T. Weskamp, W.C. Schattenmann, M. Spiegler and W.A. Herrmann, Angew. Chem., Int. Ed., 1998, 37, 2490. 124 G. J. Spivak, J. N. Coalter, M. Oliva¢¥ n, O. Eisenstein and K. G. Caulton, Organometallics, 1998, 17, 999. 125 J. Wolf, W. Stu¡§ er, C. Gru¡§ nwald, H. Werner, P. Schwab and M. Schulz, Angew. Chem., Int. Ed., 1998, 37, 1124. 126 A. Klose, E.Solari, C. Floriani, S. Geremia and L. Randaccio, Angew. Chem., Int. Ed., 1998, 37, 148. 127 K. J. Harlow, A. F. Hill, T. Welton, A. J. P. White and D. J. Williams, Organometallics, 1998, 17, 1916. 128 A. F. Hill, C. Jones, A. J. P. White, D. J. Williams and J. D. E. T. Wilton-Ely, Chem. Commun., 1998, 367. 129 F. Delpech, S. Sabo-Etienne, B. Donnadieu and B. Chaudret, Organometallics, 1998, 17, 4926. 130 Y. Motoyama, K. Murata, O. Kurihara, T. Naitoh, K. Aoki and H. Nishiyama, Organometallics, 1998, 17, 1251. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 353.374 372131 S. V. Ley and L. R. Cox, Chem. Commun., 1998, 227. 132 S. V. Ley, L. R. Cox, B. Middleton and J. M. Worrall, Chem. Commun., 1998, 1339. 133 S. V. Ley and B. Middleton, Chem. Commun., 1998, 1995. 134 Y. Takemoto, Y. Baba, N. Yoshikawa, C. Iwata, T. Tanaka and T. Ibuka, Chem. Commun., 1998, 1911. 135 W. Simanko, V. N. Sapunov, R. Schmid, K. Kirchner and S. Wherland, Organometallics, 1998, 17, 2391. 136 C. L. Gross and G. S. Girolami, J. Am. Chem. Soc., 1998, 120, 6605. 137 K. Kubo, H. Nakazawa, K. Kawamura, T. Mizuta and K. Miyoshi, J. Am. Chem. Soc., 1998, 120, 6715. 138 V.Cadierno, M.P. Gamasa, J. Gimeno, E. Pe� rez- Carren8 o and A. Ienco, Organometallics, 1998, 17, 5216. 139 M. E. Bruin and E. P. Ku� ndig, Chem. Commun., 1998, 2635. 140 G. Poignant, S. Sinbandhit, L. Toupet and V. Guerchais, Angew. Chem., Int. Ed., 1998, 37, 963. 141 P. Crochet, M.A. Esteruelas and E. Gutie� rrez-Puebla, Organometallics, 1998, 17, 3141. 142 B. E. Mann and G.A. Sun, J. Organomet. Chem., 1998, 551, 21. 143 C. J. den Reijer, H. Ru� egger and P. S. Pregosin, Organometallics, 1998, 17, 5213. 144 C.M. Older and J. M. Stryker, Organometallics, 1998, 17, 5596. 145 J. Ruiz, F. Olgiaro, J.-Y. Saillard, J.-F. Halet, F. Varret and D. Astruc, J. Am. Chem. Soc., 1998, 120, 11 693. 146 R.M. Moriarty, L. A. Enache, R. Gilardi, G. L. Gould and D. J.Wink, Chem. Commun., 1998, 1155. 147 C. E. Garrett and G. C. Fu, J. Am. Chem. Soc., 1998, 120, 7479. 148 M. Otto, J. Parr and A. M. Z. Slawin, Organometallics, 1998, 17, 4527. 149 M. Akita, N. Shirasawa, S. Hikichi and Y. Moro-oka, Chem. Commun., 1998, 973. 150 T. Gha§ar, H. Adams, P. M. Maitlis, G. J. Sunley, M.J. Baker and A. Haynes, Chem. Commun., 1998, 1023. 151 M. Laubender and H.Werner, Angew. Chem., Int. Ed., 1998, 37, 150. 152 D. Menglet, A.M. Bond, K. Coutinho, R. S. Dickson, G. G. Lazarev, S. A. Olsen and J. R. Pilbrow, J. Am. Chem. Soc., 1998, 120, 2086. 153 F. M. Alý� as, M.L. Poveda, M. Sellin, E. Carmona, E. Gutie� rrez-Puebla and A. Monge, Organometallics, 1998, 17, 4124. 154 M. E. van der Boom, Y. Ben-David and D. Milstein, Chem. Commun., 1998, 917. 155 A. Vigalok, O. Uzan, L. J. W. Shimon, Y. Ben-David, J. M.L. Martin and D. Milstein, J. Am. Chem. Soc., 1998, 120, 12 539. 156 P. H. M. Budzelaar, R. de Gelder and A. W. Gal, Organometallics, 1998, 17, 4121. 157 H. Scho� nberg, S. Boulmaa� z, M.Wo� rle, L. Liesum, A. Schweiger and H. Gru� tzmacher, Angew. Chem., Int. Ed., 1998, 37, 1423. 158 S. Boulmaa� z, M. Mlakar, S. Loss, H. Scho� nberg, S.Deblom, M. Wo� rle, R. Nesper and H.Gru� tzmacher, Chem. Commun., 1998, 2623. 159 K. Osakada, H. Takimoto and T. Yamamoto, Organometallics, 1998, 17, 4532. 160 J. B. Asbury, H. N. Ghosh, J. S. Yeston, R. G. Bergman and T. Lian, Organometallics, 1998, 17, 3417. 161 H. F. Luecke and R. G. Bergman, J. Am. Chem. Soc., 1998, 120, 11 008. 162 T. A. Mobley and R. G. Bergman, J. Am. Chem. Soc., 1998, 120, 3253. 163 U. Herber, E. Bleuel, O. Gevert, M. Laubender and H. Werner, Organometallics, 1998, 17, 10. 164 Y. Kataoka, A. Shibahara, Y. Saito, T. Yamagata and K. Tani, Organometallics, 1998, 17, 4338. 165 C. Takayama, E. Suzuki, M. Kajitani, T. Sugiyama and A. Sugimori, Organometallics, 1998, 17, 4341. 166 J. M. O’Connor, M.-C. Chen, B. S. Fong, A. Wenzel, P. Gantzel, A. L. Rheingold and I. A. Guzei, J. Am. Chem. Soc., 1998, 120, 1100. 167 J. Foerstner, S. Kozhushkov, P. Binger, P. Wedemann, M. Noltemeyer, A. de Meijere and H. Butenscho� n, Chem. Commun., 1998, 239. 168 H. Amouri, Y. Besace, J. Le Bras and J. Vaissermann, J. Am. Chem. Soc., 1998, 120, 6171. 169 R. Diercks, B. E. Eaton, S. Gu� rtzgen, S. Jalisatgi, A. J. Matzger, R. H. Radde and K. P. C. Vollhardt, J. Am. Chem. Soc., 1998, 120, 8247. 170 N. Etkin, T. L. Dzwiniel, K. E. Schweibert and J. M. Stryker, J. Am. Chem. Soc., 1998, 120, 9702. 171 J. F. Houlis and D. M. Roddick, J. Am. Chem. Soc., 1998, 120, 11 020. 172 B. Domho� ver, W. Kla� ui, A. Kremer-Aach, R. Bell and D. Mootz, Angew. Chem., Int. Ed., 1998, 37, 3050. 173 H. Gilges and U. Schubert, Organometallics, 1998, 17, 4760. 174 K. Onitsuka, M. Segawa and S. Takahashi, Organometallics, 1998, 17, 4335. 175 V. V. Rostovtsev, J. A. Labinger, J. E. Bercaw, T. L. Lasseter and K. I. Goldberg, Organometallics, 1998, 17, 4530. 176 H. Junicke, C. Bruhn, D. Stro� hl, R. Kluge and D. Steinborn, Inorg. Chem., 1998, 37, 4603. 177 H. C. S. Clark, J. Fawcett, J. H. Holloway, E. G. Hope, L. A. Peck and D. R. Russell, J. Chem. Soc., Dalton Trans., 1998, 1249. 178 R. D. Dghaym, K. J. Yaccato and B. A. Arndtsen, Organometallics, 1998, 17, 4. 179 C. Carfagna, M. Formica, G. Gatti, A. Musco and A. Pierleoni, Chem. Commun., 1998, 1113. 180 H. Lang, J. J. Vittal and P.-H. Leung, J. Chem. Soc., Dalton Trans., 1998, 2109. 181 A. Iretskii, H. Adams, J. J. Garcia, G. Picazo and P. M. Maitlis, Chem. Commun., 1998, 61. 182 A. S. K. Hashmi, F. Naumann and M. Bolte, Organometallics, 1998, 17, 2385. 183 S.-W. Zhang and S. Takahashi, Organometallics, 1998, 17, 4757. 184 S. Y. Desjardins, A. A. Way, M.C. Murray, D. Adirim and M.C. Baird, Organometallics, 1998, 17, 2382. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 353–374 373185 P. Ganis, I. Orabona, F. Ru§o and A. Vitagliano, Organometallics, 1998, 17, 2646. 186 C. R. Baar, H. A. Jenkins, G. P. A. Yap and R. J. Puddephatt, Organometallics, 1998, 17, 4329. 187 J.-T. Chen, R.-H. Hsu and A.-J. Chen, J. Am. Chem. Soc., 1998, 120, 3243. 188 A. Satake and T. Nakata, J. Am. Chem. Soc., 1998, 120, 10 391. Annu. Rep. Prog. Chem.

ISSN:0260-1818    

DOI:10.1039/a805977b

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

20 Organometallic chemistry of bi- and poly-nuclear complexes S. Doherty Department of Chemistry, Bedson Building, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, UK NE1 7RU 1 Introduction This review covers developments in the organometallic chemistry of bi- and polynuclear complexes published in 1998. A number of issues of J. Chem. Soc., Dalton Trans. contain perspectives either dedicated to polynuclear organometallic chemistry or that incorporate some aspect of this field and include: a review of recent studies on the synthesis, structure and reactivity of triosmium alkylidyne clusters, ruthenium clusters containing a l4 -nitrene ligand and mixed metal clusters of osmium and palladium1a and a perspective exploring the interactions of d-block elements with boron; a case for electronically unsaturated metalloborane clusters.1b Other articles relevant to this contribution to Annual Reports A include: a feature article covering reductive cleavage and related reactions leading to Mo–element multiple bonds: new pathways o§ered by three-co-ordinate Mo(III), which describes recent developments in the chemistry of monomeric molybdenum(III) complexes supported by sterically demanding n-tetralkylanilide ligands1c and reviews entitled hydrogenation, hydrogenolysis and desulfurisation of thiophenes by soluble metal complexes: recent achievements and future progress,1d the chemistry of ruthenium carbide clusters [Ru 5 C(CO) 15 ] and [Ru 6 C(CO) 17 ],1e main-group transition-metal compounds of Group 15 elements,1f bridged silylene and germylene complexes,1g the chemistry of [MRu(l-OMe)Cp*N2 ],1h crystal engineering and organometallic architecture,1i ruthenium catalysed reactions in organic synthesis1j and a comprehensive coverage of transition-metal complexes containing allenylidene, cumulenylidene and related ligands.1k 2 Titanium, zirconium and hafnium Reaction of [TiCl 3 Cp*] with the chiral substituted diphenylbutanediol (2S,3S)- ArCH 2 CH(OH)CH(OH)CH 2 Ar (Ar\2-CF 3 C 6 H 4 ), in the presence of NEt 3 , gives the dimer [MTiClCp*[l-g1:g1-ArCH 2 CH(OH)CH(OH)CH 2 Ar]N2 ]. In contrast, Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 375[ZrCl 3 Cp*] reacts with 3,5-Me 2 C 6 H 3 CH 2 CH(OH)CH(OH)CH 2 Me 2 C 6 H 3 -3,5 to give [NEt 3 H][Zr 2 Cl 2 Cp* 2 (l-Cl)Ml-g1:g2-3,5-Me 2 C 6 H 3 CH 2 CH(OH)CH(OH)CH 2 - Me 2 C 6 H 3 -3,5N].2 Reaction of the azine Ph 2 C––C–N––CMe 2 with [TiCp 2 ], generated from [Ti(g2-Me 3 SiC–– – CSiMe 3 )Cp 2 ], involves C–H activation to give [TiMCH 2 C(Me)––N–NCHMe 2NCp 2 ].3 In contrast, the azine PhHC––N–N––CHPh reacts with [Ti(g2-Me 3 SiC–– – CSiMe 3 )Cp 2 ] via substitution of the alkyne and reductive coupling of two azine molecules to give the Ti(III) dimer [(TiCp 2 ) 2 (l-g4-2: 3,6: 7- PhHC––NNCHPhCHPhNN––CHPh)] 1 which reacts with [Co(C 2 H 4 ) 2 Cp] via cleavage of the central C–C bond and the azine N–N bond to give the bis(alkylidenamido) [Cp 2 Ti(l-N––CHPh) 2 CoCp] 2 [eqn. (1)].4 Reduction of [Ti(OC 6 H 2 Bu5 2 -2,4-Np- Cp2Ti N CHPh CoCp N CHPh Cp2Ti N N CHPh CHPh PhHC N N TiCp2 PhHC [Co(C2H4)2Cp] (1) 2 1 6)Cl 2 Cp] with sodium amalgam gave [MTi(OC 6 H 2 Bu5 2 -2,4-Np-6)(l-Cl)CpN2 ], a Ti(III)–Ti(III) dimer with bridging chlorides and terminal aryloxide and Cp ligands.Interestingly, the Ti–Ti distance is exactly intermediate between that found in paramagnetic [MTi(l-Cl) 2 CpN2 ] and diamagnetic [MTi(OAr) 2 (l-Cl)N2 ].5 Thermal and/or photochemical reaction of ketones with [MTi(l-O)Cp*N3 (l3 -CMe)] a§ords the alkoxide [MTi(l-O)Cp*N3 (l3 -C––CH 2 )(OCHRR1)] via insertion of the ketone into the Ti–H bond of an intermediate hydride–vinylidene [MTi(l-O)Cp*N3 H(l3 -C––CH 2 )].6 The chemistry of Ti–S complexes containing one Cp ligand and one aryloxide fragment has been investigated.Reduction of [Ti(OC 6 H 3 Pr* 2 -2,6)Cl 2 Cp@] (Cp@\Cp, Cp*) with BuLi a§ords the Ti(III) dimer [MTi(OC 6 H 3 Pr* 2 -2,6)(l-Cl)Cp@N2 ].Reaction of [Ti(OC 6 H 3 Pr* 2 -2,6)Cl 2 Cp@] with two equivalents of BuLi followed by elemental sulfur gave [Ti(OC 6 H 3 Pr* 2 -2,6)S 5 Cp@]. Oxidation of [MTi(OC 6 H 3 Pr* 2 -2,6)(l-Cl)Cp@N2 ] with S 8 gives [MTi(OC 6 H 3 Pr* 2 -2,6)CpN2 (l-S)(l-S 2 )], which can also be prepared by reversible addition of sulfur to [MTi(OC 6 H 3 Pr* 2 -2,6)(l-S)CpN2 ].Addition of PPh 3 to [MTi(OC 6 H 3 Pr* 2 -2,6)CpN2 (l-S)(l-S 2 )] regenerates [MTi(OC 6 H 3 Pr* 2 -2,6)(l-S)CpN2 ].7 The titanium thiolate complex [Ti(OC 6 H 3 Pr* 2 -2,6)(SBu) 2 Cp] undergoes C–S cleavage and dimerisation to a§ord the sulfide [MTi(OC 6 H 3 Pr* 2 -2,6)(l-S)CpN2 ], possibly via a terminal sulfido intermediate. In contrast, [Ti(OC 6 H 3 Pr* 2 -2,6)(SBu)ClCp], [Ti(OC 6 H 3 Pr* 2 -2,6)(SMe) 2 Cp] and [Ti(OC 6 H 3 Pr* 2 -2,6)(SPh) 2 Cp] are thermally stable, although the last two undergo a thermally induced ligand redistribution via a dimeric thiolate bridged intermediate.The Li adduct of the terminal sulfido [Li(thf)] [Ti(OC 6 H 3 Pr* 2 -2,6)(l-Cl)(l-S)Cp*] isolated from the reaction between [Ti(OC 6 H 3 Pr* 2 -2,6)Cl 2 Cp*] and Li 2 S reacts with PMe 3 to a§ord [Ti(OC 6 H 3 Pr* 2 - 2,6)Cp*], which is unstable with respect to [MTi(OC 6 H 3 Pr* 2 -2,6)(l-S)Cp*N2 ].8 The C 2 -bridged titanocene complex [Ti(C–– – Cfc) 2 (g5-C 5 H 4 SiMe 3 ) 2 ] isolated from Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 376the reaction between [TiCl 2 (g5-C 5 H 4 SiMe 3 ) 2 ] and fcC–– – CLi reacts with [Ni(CO) 4 ] to give [MTi(C–– – Cfc) 2 (g5-C 4 H 4 SiMe 3 ) 2NNi(CO)] and with NiCl 2 to give [fcC–– – C–C–– – Cfc], [TiCl 2 (g5-C 5 H 4 SiMe 3 ) 2 ] and Ni(0) in a redox reaction.The C 4 -bridged derivative has also been prepared via a chemical oxidation of [Ti(C–– – Cfc) 2 (g5-C 5 H 4 SiMe 3 ) 2 ].9 Fluorination of [Ti 4 O 5 Cl 2 Cp* 4 ] a§ords the titanoxane fluoride [Ti 4 O 5 F 2 Cp* 4 ].Reaction of [Ti 4 O 5 Cl 2 Cp* 4 ] and [Ti 4 O 5 F 2 Cp* 4 ] with AlR 3 (R\Me, Et, CH 2 Ph) results in alkylation to give the eight-membered alkylated rings [MTi(l-O)RCp*N4 ]. The reaction of [Ti 4 O 5 F 2 Cp* 4 ] and [MTi(l-O)FCp*N4 ] with stoichiometric amounts of SiMe 3 Cl results in F/Cl exchange while treatment with excess SiMe 3 Cl results in O/Cl exchange to give [TiCl 3 Cp*].10 The reaction of [TiF 2 Cp 2 ] with one equivalent of AlEt 3 results in reduction to give the Ti(III) dimer [MTi(l-F) 2 Cp 2 AlEt 2N2 ] while reaction with an excess of AlEt 3 occurs with Ti–F and C–H activation to give [MTi(l-H)Cp(g5:g1- C 5 H 4 )AlEt 2N2 ].11 Lithium fluoride prepared in situ from lithium chloride and trimethyl tin fluoride has been trapped by [MTiF 3 Cp*N2 ] to give [MTiF 3 Cp*N4 (LiF)] which consists of two [Ti 2 F 6 Cp* 2 ] units connected by a lithium atom and a bridging fluoride atom; each titanium is co-ordinated by five fluoride ions and a Cp* ligand and the lithium is co-ordinated to four fluorides arranged in a distorted tetrahedron.Variable temperature 19F NMR studies reveal an entropy driven equilibrium involving [Ti 2 F 7 Cp* 2 ]~ and [MTiF 3 Cp*N2 ] (*Gt\75^3 kJ mol~1, *St\19^7 J mol~1K~1).12 The zirconium borato–cyclopentadienyl half-sandwich complex [NEt 4 ]- [Zr(NMe 2 ) 3MC 5 H 4 B(C 6 F 5 ) 3N] reacts with excess SiMe 3 Cl to give the chloro-bridged dimer [NEt 4 ] 2 [MZrCl 2 (l-Cl)[g5-C 5 H 4 B(C 6 F 5 ) 3 ]N2 ].13 Alkylation of the diamido [ZrCl 2 (Bu5NSiMe 2 NCH 2 CH 2 NMe 2 )] with diisobutylmagnesium chloride gave [Zr(CH 2 CHMe 2 ) 2 (Bu5NSiMe 2 NCH 2 CH 2 NMe 2 )] together with low yields of the diimine magnesium chloride adduct [MZr(CH 2 CHMe 2 ) 2 (Bu5NSiMe 2 NCH 2 - CH 2 NMe 2 )MgCl 2N2 ].14 Treatment of [ZrCl 2 (g5-C 5 H 4 SiMe 3 ) 2 ] with excess LiAlH 4 a§ords the zirconocene dihydride–alane adducts [ZrH(l-H) 2 (g5-C 5 H 4 SiMe 3 ) 2 ] 3 Al and [ZrH(l-H) 2 (g5-C 5 H 4 SiMe 3 ) 2 ] 2 AlH.In the former, the three zirconocene fragments form two hydrogen atom bridges, each to a central aluminium atom forming an octahedral environment about each Al centre; the two zirconium atoms in the latter bridge the central aluminium atom to form a distorted square-based pyramidal geometry.15 The potential of [Zr(thf)(NR)Cp 2 ] as an imido transfer reagent has been investigated.Treatment of the pinacolate complex [Ir(OCMe 2 CMe 2 O)Cp*] with [Zr(thf)(NBu5)Cp 2 ] gave the bis(imido) bridged [Cp*Ir(l-NBu5) 2 ZrCp 2 ] whereas reaction of [Ir(thf) 3 Cp*][OTf] 2 with [Zr(thf)(NBu5)Cp 2 ] resulted in cyclopentadienyl transfer. Mechanistic possibilities have been discussed.16 Improved syntheses of [TiCl(CH 2 EMe 3 ) 3 ] (E\C, Si) and [ZrCl(CH 2 CMe 3 ) 3 ] have been reported.Crystallization of [ZrCl(CH 2 CMe 3 ) 3 ] from hexane a§ords the linear polymeric chains –Cl–Zr(CH 2 CMe 3 ) 3 –Cl–Zr(CH 2 CMe 3 )– with linear symmetric chloride bridges (Cl–Zr–Cl\180°, Zr–Cl\2.547Å).17 3 Vanadium, niobium and tantulum Protonation of the bis(alkylidyne) complex [Ta 2 (l-CR) 2 (CH 2 R) 4 ] 3 (R\SiMe 3 ) occurs at the alkylidyne carbon to give [Ta 2 Cl 2 (l-CHR) 2 (CH 2 R) 4 ] 4 which subse- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 377Scheme 1 quently decomposes via SiMe 4 elimination to form [Ta 2 Cl 2 (l-CHR)(l-CR)(CH 2 R) 3 ] 5. Substitution of the chlorides in [Ta 2 Cl 2 (l-CHR) 2 (CH 2 R) 4 ] 4 with SiR 3 (R\SiMe 3 ) gave the first silyl bis(alkylidyne) [Ta 2 (CH 2 R) 3 (SiR 3 )(l-CR) 2 ] 6 via elimination of SiR 3 H, and addition of PMe 3 to [Ta 2 Cl 2 (l-CHR) 2 (CH 2 R) 4 ] 4 gave the 1,2-dimetallacyclobutadiene derivative [Ta 2 Cl 2 (l-CR) 2 (CH 2 R) 2 (PMe 3 ) 2 ] 7, containing an unsymmetrical bridging alkylidyne ligand (Scheme 1).18 The isocyanate ligands in [MNbCl(g5-C 5 H 4 SiMe 3 )N2Mj2-N1,C1-l-1,3-(OCN) 2 C 6 H 4N] and [MNbCl(g5- C 5 H 4 SiMe 3 )N2Mj2-N1,C1-l-1,4-(OCN) 2 C 6 H 4N] are co-ordinated in a j2-C,N mode.Reduction of these complexes (Na–Hg) followed by protonation a§ords the corresponding NHCO complexes [MNb(g5-C 5 H 4 SiMe 3 )N2Ml-1,3-(OCHN) 2 C 6 H 4N] and [MNb(g5-C 5 H 4 SiMe 3 )N2Ml-1,4-(OCHN) 2 C 6 H 4N], whereas thermolysis leads to loss of CO to give the imido derivatives [MNbCl(g5-C 5 H 4 SiMe 3 )N2 (1,3-N 2 C 6 H 4 )] and [MNbCl(g5-C 5 H 4 SiMe 3 )N2 (1,4-N 2 C 6 H 4 )].Alternatively, these imido derivatives can be prepared from [MNbCl(g5-C 5 H 4 SiMe 3 )N2 ] and 1,3- or 1,4-phenyldiamine. Alkylation of [MNbCl(g5-C 5 H 4 SiMe 3 )N2 (1,3-N 2 C 6 H 4 )] and [MNbCl(g5-C 5 H 4 SiMe 3 )N2 (1,4- N 2 C 6 H 4 )] with RMgX (R\Et, Me, Pr*) gives the corresponding substitution products [MNbR(g5-C 5 H 4 SiMe 3 )N2 (1,3-N 2 C 6 H 4 )] and [MNbR(g5-C 5 H 4 SiMe 3 )N2 (1,4- N 2 C 6 H 4 )] respectively.19 The binuclear Nb(II) complex [Li(tmen) 3 ][Nb 2 Cl 5 ] reacts with KNPh 2 to give mixed-valence [Nb 2 Cl 2 (l-Cl) 3 (tmen) 2 ], trivalent [Li(tmen) 2 ][MNb(Ph 2 N) 2N2Ml- NPh(l-g1: g2-C 6 H 4 )N(l-H)]·C 6 H 5 Me, which contains a hydride and cyclometallated phenyl ring, and the neutral mixed-valence dimer [Nb 2 (NPh 2 ) 2Ml-NPh(g6-C 6 H 5 )N2 ] which can be generated by thermolysis of a toluene solution of the cyclometallated derivative and involves C–H reductive elimination and amide migration.20 In contrast, the divalent niobium complex [Li(tmen)][Nb 2 Cl 5 (tmen) 2 ] reacts with lithium or potassium dipyridyl amide to give [Nb 2MN(C 5 H 4 N-2) 2N(l-C 5 H 4 N)Ml- N(C 5 H 4 N-2)N][Li 2 Cl 2 (thf) 4 ], via oxidative cleavage of a C–N bond.21 Controlled hydrolysis of [NbCl(OR)(O)Tp*] (R\Me, Et) gave the oxo-bridged complex [MNbCl(O)Tp*N2 (l-O)].22 Reduction of [TaCl 4 Cp@] (Cp@\C 5 Me 4 R, R\H, Me) with Bu 3 SnH results in reduction and hydride transfer to give the ditantalum(IV) hydrides [Ta 2 (l-H) 2 Cl 4 Cp@2 ]; several possible radical and non-radical Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 378pathways were discussed.23 Density functional theory has determined that [Ta(CO) 6 ] can exist as a C 2 -symmetric dimer, containing two linear semi-bridging carbonyls. Three possible structures have been considered for the chelated dimer [MTa 2 (CO) 4 (dppe)N2 ] all of closely similar stability; in each case linear semi-bridging carbonyls support a weak delocalised Ta–Ta interaction.24 4 Chromium, molybdenum and tungsten The chromium chloride complex [M(C 6 H 3 R 2 )NC(Me)CHC(Me)N(C 6 H 3 R 2 )N- MCrCl(l-Cl)N2 ] reacts with trimethylaluminium to a§ord [M(C 6 H 3 R 2 )NC- (Me)CHC(Me)N(C 6 H 3 R 2 )NMCrMe(l-Cl)N2 ].The olefin polymerization activity of both complexes depends on the nature of the activator, alkyl aluminium chloride being more compatible with these precatalysts than MAO.25 The homoleptic (dimethylamino)methylchromate(II) complex [Li(thf) 3 ][Cr 2 (CH 2 NMe 2 ) 6 ] has been prepared from [CrCl 2 (thf) 2 ] and LiCH 2 NMe 2 . The structure reveals an unsupported Cr–Cr quadruple bond [2.884(1)Å] with each metal co-ordinated to two g1- CH 2 NMe 2 ligands and one co-ordinated in an g2 manner.The magnetic moment (k%&& 0.67 kB per Cr) is consistent with a dinuclear d4 Cr(II) core.26 The 24-electron triple decker sandwich [Cr 2 Cp 2Ml-g6:g6-(l-1,2-C 3 H 6 -1,2-C 2 B 4 H 4 )N] has been isolated in low yield. An X-ray structure determination revealed a planar C 2 B 4 tetraborabenzene ring sandwiched between two CpCr fragments.27 The reaction between [Mo 2 (l-O 2 CMe) 4 ] and KCp* in the presence of PMe 3 results in facile P–CH 3 bond cleavage to give the dimethylphosphido methyl complex [MCp*Mo(l-O 2 CMe)N2 (l-PMe 2 )(l-Me)].28 Thermolysis of PhNHNH 2 with [Mo 2 (l-Cl)(l-SMe) 3 Cp 2 ] in thf gave the diazenido co-ordination isomers [Mo 2 (l- N 2 Ph)(l-SMe) 3 Cp 2 ] and [Mo 2 (l-g1:g1-N––NPh)(l-SMe) 3 Cp 2 ].Protonation of these two complexes gave the g1-hydrazido complex [Mo 2 (l-g1-NNHPh)(l-SMe) 3 Cp 2 ] [BF 4 ] and its g2-diazene isomer [Mo 2 (l-g2-NHNPh)(l-SMe) 3 Cp 2 ][BF 4 ] respectively. 29 Reaction of two equivalents of K 2 [C 8 H 4 (SiPr* 3 ) 2 -1,4] with [Mo 2 (OAc) 4 ] gave the bimetallic bis(pentalene) sandwich complex [Mo 2MC 8 H 4 (SiPr* 3 ) 2 -1,4N2 ].The pentalene ligands are e§ectively planar, parallel and only slightly twisted from an eclipsed conformation.30 Reduction of [Mo(CO) 4 (tmen)] (M\Mo, W) with stoichiometric [NEt 4 ][BH 4 ] gave [NEt 4 ] 2 [Mo 2 (CO) 8 (l-H) 2 ].31 Deoxygenation of [M(CO) 2 Cp(l-PPh 2 )Mo(CO) 5 ] (M\Mo, W) with phosphinimide Ph 3 P––NR (R\Ph, CH 2 Ph, Pr*) occurs regiospecifically to give [M(CO) 2 Cp(l- PPh 2 )Mo(CO) 4 (CNR)] with the isocyanide co-ordinated to the Mo atom.32 Desulfurisation of dialkyl trithiocarbamate (RS) 2 C––S with the dimolybdenum alkyne complex [Mo 2 (l-CO 2 MeC–– – CCO 2 Me)(CO) 4 Cp 2 ] a§ords [Mo 2 Cp 2 (l-SR)(l-S)Ml- C(CO 2 Me)C(SR)C(CO 2 Me)N] via fragmentation of the trithiocarbamate into sulfide, thiolate and CSR; the last inserts into the C–– – C triple bond to give a dimetallaallyl ligand.33 Two routes to the dithiolene complexes [Mo 2 S(l-S) 2 (SCR1––CR2S)Cp 2 ] (R1\R2\H; R1\H, R2\Me; R1\R2\Et; R1\R2\CO 2 Me) starting from [Mo 2 (l-alkyne)(CO) 4 Cp 2 ] have been described.In one, [Mo 2 (l-alkyne)(CO) 4 Cp 2 ] is heated with elemental sulfur. In the second, reaction of 1,3-dithiole-2-thione with [Mo 2 (l-CO 2 MeC–– – CCO 2 Me)(CO) 4 Cp 2 ] results in cleavage of the C––S bond to give [Mo 2 (l-S)Ml-C(CO 2 Me)C(CO 2 Me)C(S)CSCRCRSNCp 2 ] (R\CO 2 Me, SMe, Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 379SCOPh), which reacts with elemental sulfur to give [Mo 2 S(l- S) 2MS(CO 2 Me)C––C(CO 2 Me)SNCp 2 ] together with a five-membered sulfur heterocycle. 34 Oxidation of [Mo 2 (CO)(l-C 4 Ph 4 )Cp 2 ] causes partial migration of the metallacyclopentadiene ligand to one molybdenum atom to give [Mo 2 (O)(l-O)(l- C 4 Ph 4 )Cp 2 ].Thermolysis of [Mo 2 (O)(l-O)(l-C 4 Ph 4 )Cp 2 ] with PhNCO results in oxo–imido exchange to give [Mo 2 (O)(l-NPh)(l-C 4 Ph 4 )Cp 2 ]. In both compounds the bridging C 4 Ph 4 ligand adopts an unusual bonding mode in which one terminus bridges the two metal atoms while the other is bonded to only one Mo, as a terminal alkylidene.Further oxidation with elemental sulfur causes cyclisation of the organic ligand to give the cyclobutadiene derivative [Mo 2 (O)(l-O)(l-S)(g-C 4 Ph 4 )Cp 2 ].35 Treatment of a solution of [Mo(g3-C 3 H 4 Me)(bipy)(CO) 2 (OCMe 2 )][BF 4 ] with a solution of Na 2 MoO 4 in water gave a crystalline precipitate of [MMo(g3- C 3 H 4 Me)(bipy)(CO) 2N2 (l-MoO 4 )].A single crystal X-ray analysis revealed weak intermolecular contacts between the bipy protons and theMo–– Ogroup.36 Hydrocarbon solutions of [W 2 (OPr*) 4 (l-H) 2 (g2-dmpe)] react with CO and CO 2 to give [W 2 (OPr*) 4 (g2-dmpe)(CO)] and the formate complex [W 2 (OPr*) 4 H(g2-dmpe)(g1- O 2 CH)], respectively. Hydrolysis of [W 2 (OPr*) 4 (l-H) 2 (g2-dmpe)] and [W 2 (OPr*) 4 (g2-dmpe)(CO)] gives [W 2 O 4 (l-O)H(g2-dmpe) 2 ] and [W 2 O 4 (l- O)MW(g2-dmpe) 2 CON2 ] respectively.In each case unsupportedW–Wbonds are found between metal atoms in vastly di§erent oxidation states.37 The bonding in the ethyne complex [W 2 (l-C 2 H 2 )(l-ONp) 2 (ONp) 6 ] has been examined by various computational methods.The non-parallel/non-perpendicular M–C 2 H 2 geometry has been rationalized on electronic grounds and results from a Jahn–Teller distortional stabilization. 38 The Lewis acid adduct [WMN(CH 2 CH 2 NSiMe 3 ) 3N–– – P–GaCl 3 ] decomposes in dichloromethane to give a tetrahedral W 2 P 2 cluster, via elimination of SiMe 3 Cl and dimerisation.39 The sterically protected diphosphinidenecyclobutene [M(Tip)PNCM(Tip)PNCC(Ph)C(Ph)] reacts with [W(CO) 5 (thf)] to give [W(CO) 4M(Tip)PNMC(Ph)C(Ph)NCMP(Tip)NW(CO) 3 ], with one chelate interaction to W(CO) 4 and two exocyclic P–– C and one endocyclic C––C interaction to the W(CO) 3 fragment.40 5 Manganese, technetium and rhenium Cobaltocene reduction of the g6-benzothiophene complex [Mn(CO) 3 (g6- C 8 H 4 SRR@)]` 8 under CO results in insertion of a [Mn(CO) 4 ] fragment into a C(aryl)–S bond to give the neutral dimanganese metallacycle [Mn 2 (CO) 7 (C 8 H 4 SRR@)] 9 (R\R@\H, Me).Treatment of 9 with dihydrogen results in hydrogenolysis of a Mn–Cr-bond to give [Mn 2 (CO) 8 (H)(l-SCR–– CR1Ph)] 10 (R\R1\H), containing a bridging thiolate ligand (Scheme 2).Reduction of [Ru(g6-btp)(g6-C 6 Me 6 )]` in the presence of CO and [Mn(CO) 3 (g6-menp)]` a§ords the cationic heterometallic complex [Ru(g6-C 6 Me 6 )Mg6-C 6 H 4 CHCHSMn(CO) 4N]` 11 which reacts with H~ to give the neutral cyclohexadienyl complex [Ru(g6-C 6 Me 6 )Mg5-C 6 H 5 CHCHSMn(CO) 4N] 12 [eqn. (2)].41 Reduction of [Mn(CO) 3 (g6-dbt)][BF 4 ] 13 with cobaltocene or Na–Hg gave an isomeric mixture of the bis(cyclohexadienyl) complex [MMn(CO) 3N2 (g5:g5- bdbt)] 14 via coupling of the dienyl rings.A minor amount of [(Mg6- Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 380Scheme 2 Scheme 3 Ru Mn S Mn S Ru (C6Me6) (CO)4 (CO)4 11 12 H – + (C6Me6) (2) C 6 H 4 –Mn(CO) 4 –S–C 6 H 4N)Mn(CO) 3MMn 2 (CO) 8N] 15 results from insertion of [Mn(CO) 4 ] into the adjacent C–S bond and co-ordination of [Mn 2 (CO) 8 ] to the sulfur atom of the metallathiacyclic ring (Scheme 3).Hydrogenation of 15 at 500 psi and 97 °C results in hydrogenolysis of the Mn–C r-bond to a§ord the biphenyl thiolate-bridged [Mn 2 (CO) 8 (l-H)(l-SC 6 H 4 C 6 H 5 )] 16.42 Reduction of [Mn 2 (CO) 6 (l- S 2 CPR 3 )] (R\Pr*) with Na–Hg amalgam gave the anion [Mn 2 (CO) 6 (l-S 2 CPR 3 )]2~.Protonation of [Mn 2 (CO) 6 (l-S 2 CPR 3 )]2~ with NH 4 PF 6 a§ords [Mn 2 (CO) 6 (l- SH)Ml-SC(H)PR 3N(NH 3 )] which readily substitutes the co-ordinated NH 3 with PEt 3 to give [Mn 2 (CO) 6 (l-SH)Ml-SC(H)PR 3N(PEt 3 )] as a stable crystalline solid. Overall the reduction-protonation sequence amounts to hydrogenolysis of the S–C bond of the Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 381bridging ligand to give thiolate and the novel five-membered donor l-g1(S):g2(C,S)- MR 3 P(H)SN~.43 Multipole analysis of X-ray data collected on a crystal of [Mn 2 (CO) 10 ] showed a significant total electron density o(r) in the metal–metal region. The Bader analysis revealed the electron density to be contracted towards each metal nucleus, behaviour not typical of a covalent interaction.44 Mixtures of [M(dag) 2 ] (M\Mn, Fe) and [Mn 3 Mes 6 ] and [Fe 2 Mes 4 ] undergo ligand redistribution to a§ord the mixed alkoxo cluster [M 2 (Mes) 2 (l-dag)M(l-Mes) 2 ] (M\Mn, Fe), both with linear trinuclear skeletons and bridging mesityl and alkoxo groups.45 Low temperature addition of LiR to a solution of [Re 2 (CO) 8 (l-PPh 2 ) 2 ] (R\Me, Bu, Ph, Bu5) a§ords the acylate Li[Re 2 (CO) 7Max-C(R)ON(l-PPh 2 ) 2 ] which reacts with a second equivalent of LiR1 (R1\Me, Ph, Bu) at 20 °C to give the diacylate Li 2 - [Re 2 (CO) 6Max-C(R)ONMax-C(R1)ON(l-PPh 2 ) 2 ] as either trans or cis isomers, depending on the substituents R and R1.Subsequent O-alkylation a§ords the mono- and di-carbene derivatives Li[Re 2 (CO) 7Max-C(R)OR2N(l-PPh 2 ) 2 ] and [Re 2 (CO) 6Max- C(R1)OR2N2 (l-PPh 2 ) 2 ] respectively (R2\Me, Et).46 The heterocubane cluster anion [MRe 3 S(CO) 9 (l3 -S) 4 ]~ (M\Mo, W), prepared from [Re(CO) 5 (CF 3 SO 3 )], Li 2 S and [NEt 4 ] 2 [MS 4 ], contains a tetrathiometallate corner and three six-co-ordinate lowvalent metal centres. The e§ect of tetrathiometallate co-ordination by [MRe(CO) 3N3 (l3 -S)]` is to lower the first one-electron reduction potential to [1.20V (Mo) and [1.61V (W) from [2.94V (Mo) and [3.16V (W) in [NEt 4 ] 2 [MS 4 ].47 Addition of BH 3 ·thf to [ReCl 4 Cp*] a§ords [MReCp*N2 B 7 H 7 ].Its isostructural and isoelectronic tungsten counterpart [MWCp*N2 B 7 H 7 ] is formed as a minor product during the pyrolysis of a toluene solution of [WH 3 (B 4 H 8 )Cp*].Geometric and molecular orbital calculations suggest that both compounds can be described as molecular metallaborane counterparts of anionic hypoelectronic main-group cluster Zintl phases.48 Electrospray mass spectrometric studies of rhenium hydroxy and methoxy carbonyl complexes [Re 3 (l-OR) 3 (CO) 6 ]~ (R\Me, H) have shown that these complexes exchange with alcohols.At high temperatures and voltages dehydration of [Re 2 (l-OH) 3 (CO) 6 ]~ (20 V) and b-hydrogen elimination of [Re 2 (l- OMe) 3 (CO) 6 ]~ (50 V) have also been observed.49 The nitrile complex [Re 3 (l-H) 3 (CO) 11 (NCMe)] reacts with Hampy or Hmerpy in refluxing toluene to give [Re 2 (CO) 6 (l-ampy) 2 ] and [Re 2 (CO) 6 (l-merpy) 2 ] respectively. The unsaturated cluster [Re 4 (l-H) 4 (CO) 12 ] reacts with Hampy and Hmerpy in 1,2-dichloroethane to give the anions [Re 3 (l-H) 3 (l3 -ampy)(CO) 9 ]~ and [Re 3 (l- H) 3 (l3 -merpy)(CO) 9 ]~ respectively.The solid state structure of the former reveals H-bonding interactions between carbonyl oxygen atoms and N–H of the ampy ligand.50 Protonation of [Re 2 (CO) 6 (l-OR) 3 ]~ (R\H, Me, Et) with p-toluenesulfonic acid and 1,1-bis(diphenylphosphino)ferrocene results in the replacement of one bridging OR~ to give [Re 2 (CO) 6 (l-OR) 2 (l-dppf)].In the case of R\Et, 1H NMR spectroscopy has shown that twisting of the dppf bridge interchanges enantiomers. Treatment of [Re 2 (CO) 6 (l-OMe) 3 ]~ with an atmosphere of CO gave [Re 3 (CO) 9 (l- OMe) 3 (l3 -OMe)]~.51 The silyl esters [Re(NO)(PPh 3 )(CO 2 SiR 3 )Cp] (R 3 Si\ PhMe 2 Si, Et 3 Si) readily convert into the bimetallocarboxylates [Re(NO)(PPh 3 )Cp(CO 2 )Re(CO)(NO)(PPh 3 )(OSiR 3 )], a rearrangement initiated by the presence of extraneous water and involving an g5:g1-Cp ring shift commensurate with O,O-chelation of a rhenium carboxylate.52 Two structural isomers of [Re 2 (l- Annu.Rep.Prog. Chem., Sect. A, 1999, 95, 375–408 382Br) 2 (l-dppm) 2 Br(CO)(xyl) 2 ]` di§ering only in the conformation of the [Re 2 (l- dppm) 2 ] unit (chair versus boat) have been separated and structurally characterized. Solutions of the boat conformer slowly convert into the thermodynamically more stable chair isomer.53 Reaction of [MRe 2 (CO) 2 Cp*N2 ] with diethylfumurate results in fragmentation to give [Re(CO) 3 Cp*] and [Re(CO)Mg2-(E)- EtO 2 CCH––CHCO 2 EtN(thf)Cp*].54 The mixed imido–oxo rhenium(VII) complexes [Re(Me)O 3~x(NR)x] (x\1, 2) exist as equilibrium mixtures of monomers and oxo-bridged dimers in solution and as dimers in the solid state.Reaction of [Re(O)(NR) 2 Me] with [Re(O) 3 (g5-C 5 H 4 Me)] gave the mixed dimer [Re 2 Me(l-O) 2 (O) 2 (NR) 2 (g5-C 5 H 4 Me)], involving intramolecular exchange of oxo and imido groups in a dimeric intermediate.55 The epoxide deoxygenation catalyst [MReOCp*N2 (l-O) 2 ] is deactivated via comproportionation between Re(V) and Re(VII) to form clusters [Re 3 (l-O) 6 Cp 3 ][ReO 4 ] 2 and [Re 4 (O) 3 (l- O) 3 (l3 -O) 3 Cp* 3 ][ReO 4 ].56 6 Iron, ruthenium and osmium At 110 °C a-substituted [Fe 2 (CO) 6 (l-PPh 2 )(l-PhC–– CH 2 )] 17 is cleanly converted into the b-isomer [Fe 2 (CO) 6 (l-PPh 2 )(l-HC––CHPh)] 18 [(eqn.(3)], a process which is (CO)3Fe Fe(CO)3 P Ph2 C C H H Ph (CO)3Fe Fe(CO)3 P Ph2 C C H Ph H heat (3) 18 17 accelerated in the presence of arylphosphines. Thermolysis of [Fe 2 (CO) 6 (l-PPh 2 )(l- PhC––CH 2 )] with trimethylphosphite at 70 °C a§ords the mono- and di-substituted complexes which cleanly isomerise at higher temperatures.57 Primary amines react with the diiron allenyl complex [Fe 2 (CO) 6 (l-PPh 2 )(l-g1:g2-HC––C––CH 2 )] 19 via addition to Cb to give the zwitterionic dimetallacyclopentane derivatives [Fe 2 (CO) 6 (l- PPh 2 )Ml-g1: g1-H 2 CC(NHR)CH 2N] 20 (R\Pr*, CH 2 Ph, C 6 H 11 , Pr/).In refluxing toluene these metallacyclopentane complexes readily lose CO to give the nitrogen-coordinated organodiiron a,b-unsaturated amines [Fe 2 (CO) 5 (l-PPh 2 )Ml- g1(C): g2(C):g1(N)-HC––C(CH 3 )(NHR)N] 21.Addition of trimethyl phosphite to 21 a§ords the stable alkylidene valence isomer [Fe 2 (CO) 5MP(OMe) 3N(l-PPh 2 )Ml- CHC(CH 3 )(NHR)N] 22 (R\Pr*, C 6 H 11 ). In contrast, in refluxing toluene, 20 reacts with trimethyl phosphite to give the a,b-unsaturated bridging acyl complex [Fe 2 (CO) 5MP(OMe) 3N(l-PPh 2 )Ml-O––CCH––C(CH 3 )(NHR)N] 23 (R\Pr*, CH 2 Ph), as a mixture of isomers which di§er in the location of the phosphite, either trans to the Fe–Fe bond or trans to the phosphido bridge (Scheme 4).58 Addition of Li 2 Cu(CN)R@2 (R@\Me, Bu/, Ph) to [Ru 2Ml-CN(Me)RN(l- CO)(CO) 2 Cp 2 ][SO 3 CF 3 ] (R\Me, CH 2 Ph) gave the acyl complex [Ru 2Ml- CN(Me)RN(l-CO)(COR@)(CO)Cp 2 ].In comparison, reaction of [Ru 2Ml-CN(Me)RN(l- CO)(CO) 2 Cp 2 ][SO 3 CF 3 ] 24 with ClMgCH 2 Ph gave the corresponding acyl complex Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 383Scheme 4 N Me R Ru Ru C O C CO Cp CO Cp N Me R Ru Ru C O C C Cp CO Cp O R N Me R Ru Ru C O C CO CO Cp R H (4) + ClMgR 26 + 25 24 [Ru 2Ml-CN(Me)RN(l-CO)(COCH 2 Ph)(CO)Cp 2 ] 25 together with the g4-pentadiene derivative [Ru 2Ml-CN(Me)RN(l-CO)(CO) 2 (g4-C 5 H 5 CH 2 Ph)Cp] 26 [eqn.� (4)].59 The labile l-methylene complex [Ru 2 (CO) 2 (NCMe)(l-CH 2 )Cp 2 ] reacts with monosubstituted diazoalkenes N 2 ––CHR (R\H, Me, SiMe 3 , CO2 Et) to give the alkenyl –hydride [Ru 2 (CO) 2 (l-H)(l-CH––CHR)Cp 2 ], and with disubstituted aryldiazoalkanes, N 2 ––CR1R2 (R1\R2\Ph; R1\Ph, R2\CO 2 Ph), to give the corresponding olefin CH 2 –– CR1R2.Labeling experiments show that the l-CH 2 fragment generates the l-H and a-CH of the alkenyl–hydride derivative while the diazoalkane CHR fragment forms Cb.60 Successive treatment of [Fe(CO) 5 ] with LiR (R\Me, Bu/, Bu5, C 6 H 4 OMe-4), trifluoroacetic anhydride and PPh 3 gave [Fe(CO) 3 (PPh 3 ) 2 ], whereas the sterically more demanding LiC 6 H 3 Me 2 -2,6 gave the bis(carbamoyl) complex [Fe 2 (CO) 5 (PPh 3 )(l-r,r@-OCC 6 H 3 Me 2 -2,6) 2 ], in addition to [Fe(CO) 3 (PPh 3 ) 2 ].61 Dehydrohalogenation of sulfido-bridged [MRuCl(l-SH)Cp*N2 ] with triethylamine gives the cubane cluster [MRu(l3 -S)Cp*N4 ].In the presence of alkyne dehydrohalogenation a§ords the dithiolene-bridged complex [MRu(l-g2:g4- S 2 C 2 R1R2)Cp*N2 ], which readily adds CO with Ru–Ru bond cleavage to give [Cp*Ru(CO)(l-g2:g4-S 2 C 2 R1R2)RuCp*]. Condensation of [MRuCl(l-SH)Cp*N2 ] with [RuH 2 (PPh 3 ) 4 ] gives [MCp*Ru(l3 -S)N2 (l-H)RuCl(PPh 3 ) 2 ] which reacts with NaBH 4 followed by COto give [MCp*Ru(l3 -S)N2 (l-H)RuH(PPh 3 ) 2 ] and [MCp*Ru(l3 - S)N2 Ru(CO) 2 (PPh 3 ) 2 ] respectively.62 Annu. Rep.Prog. Chem., Sect. A, 1999, 95, 375–408 384Irradiation of [MFe(CO)CpN2 (l-CO) 2 ] in a hydrocarbon matrix leads to the double- CO-loss product [MFe(CO)CpN2 ] with an unsupported Fe–Fe triple bond. The double- CO-loss product is generated in an excited triplet form, with terminal COs, which undergoes thermal relaxation to the bridgingCOsinglet ground state before slow back reaction with CO to give [Fe 2 (l-CO) 3 Cp 2 ].63 White phosphorus reacts with [MFe(CO) 2 Cp@N2 ] (Cp@\C 5 H 2 Bu5 3 -1,2,4) to give the butterfly complex [MFe(CO) 2 Cp@N2 (l-g1:g1-P 4 )] with the iron atoms co-ordinated to the wing-tip phosphorus- atoms.Thermolysis of a decalin solution of [MFe(CO) 2 Cp@N2 (l-g1:g1-P 4 )] a§ords the sandwich complex [FeCp@(g5-P 5 )] and the bridged dimer [(FeCp@) 2 (l- g4:g4-P 4 )].64 Oxidation of [Cp*(dippe)Fe(l-C 4 )Fe(dippe)Cp*] with two aliquots of ferrocenium hexafluorophosphate followed by silver hexafluorophosphate gave the deep blue cation [Cp*(dippe)Fe(l-C 4 )Fe(dippe)Cp*][PF 6 ] 3 which has been characterised by single-crystal X-ray crystallography, 57Fe Mo� ssbauer spectroscopy and low temperature EPR spectroscopy.65 The spirocyclic 1,7-ferrocenophanes [MFe(g5- C 5 H 4 ) 2N2 E] (E\Si, Ge) and [MFe(g5-C 5 H 4 ) 2NSi(CH 2 ) 3 ] have been prepared by treating [Fe(g5-C 5 H 4 Li) 2 ·tmen] with SiCl 4 , GeCl 4 and Cl 2 Si(CH 2 ) 3 respectively.The cyclic voltammograms of the first two compounds show two oxidation waves with a large separation (*E09 \0.37 V), suggesting significant interaction between the two ferrocenophane units.66 Thermal rearrangement of [MFe(CO)(l-CO)N2 (g5:g5- C 5 R 4 GeMe 2 Me 2 GeC 5 R 4N] a§ords [MFe(CO)(l-CO)(g5:g1-C 5 R 4 GeMe 2 )N2 ] via metathesis of Ge–Ge and Fe–Fe bonds.Reduction of [MFe(CO)(l-CO)N2 (g5:g5- C 5 R 4 GeMe 2 Me 2 GeC 5 R 4 )] with I 2 or Na–Hg amalgam results in Fe–Fe bond cleavage. 67 Addition of RSH to [Ru 2 (CO) 4 (NCMe) 4 (PR 3 ) 2 ][BF 4 ] 2 (R\Ph, Me) in the presence of NEt 3 gave [Ru 2 (CO) 4 (l-SR1) 2 (PR 3 ) 2 ] (R1\Bu5, Pr*, Ph), either exclusively in the syn or anti form or as an equilibrium mixture of both, depending upon the nature of the thiolate bridge.Oxidation of [Ru 2 (CO) 4 (l-SR1) 2 (PR 3 ) 2 ] with I 2 results in Ru–Ru bond cleavage to give [Ru 2 (CO) 4 I 2 (l-SR1) 2 (PR 3 ) 2 ].68 1H NMR spectroscopic studies have shown that protonation of [Ru 2 (CO)(PR 3 )(l-CO) 2 Cp 2 ] also occurs at the Ru–Ru bond rather than at the more basic Ru atom.Enthalpies of protonation suggest that the Ru–Ru bond in [Ru 2 (CO)(PR 3 )(l-CO) 2 Cp 2 ] is 11.6 kcal mol~1 more basic than that in [Ru 2 (CO) 4 Cp 2 ], as expected for replacement of CO by PMe 3 .The enthalpies for protonation of the Mo–Mo bond in [MMo(CO)(PR 3 )CpN2 ] show that the PMe 3 derivative [[27.4(2) kcal mol~1] is considerably more basic than its PMe 2 Ph analogue [[18.9(5) kcal mol~1].69 Protonation of the dithiolate-bridged complex[M 2 (CO) 6 (l-bdt)] (M\Ru, Os) gave the cationic hydride-bridged derivative [M 2 (l-H)(CO) 6 (l-bdt)][BF 4 ], whereas [Fe 2 (CO) 6 (l-bdt)] was unreactive with respect to protonation.Molecular orbital calculations at the extended Huckel level indicate that protonation occurs under orbital as well as charge control.70 The enthalpies ofction of [MRuCl 2 (p-cym)N2 ] withN-pyrrolyl-substituted tertiary phosphines have been measured by solution calorimetry.The enthalpy trend was shown to be P(NC 4 H 4 ) 3\P(NC 4 H 4 ) 2 (C 6 H 5 )\P(NC 4 H 4 )(C 6 H 5 ) 2\P(NC 4 H 8 ) 3 and structural studies have shown an increase in Ru–P bond length in the order P(CH 2 C 6 H 5 ) 3[P(NC 4 H 4 ) 2 (C 6 H 5 )[P(NC 4 H 4 ) 3 . This trend in reaction enthalpies has been accounted for by considering the relative r-donor and p-acceptor character of the phosphines.71 The trend in the enthalpies of reaction of [MOsCl 2 (p-cym)N2 ] with monodentate tertiary phosphines can be explained in terms of electronic and steric Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 385contributions, both factors playing an important role. A qualitative relationship has been established between electronic and thermodynamic parameters.72 The thiolate-bridged complex [MRuH(triphos)[l-S(C 6 H 4 )CH 2 CH 3 ]N2 ], isolated from the reaction between [RuH(BH 4 )(triphos)] and benzo[b]thiophene, reacts with dihydrogen and HBF 4 to give ethylbenzene and 2-ethylthiophenol respectively.Other products isolated include [RuH(triphos)MBH 3 [o-S(C 6 H 4 )CH 2 CH 3 ]N], [Ru(triphos)Mg4-S(C 6 H 4 )CH(CH 3 )N] and [MRuH(triphos)N2 (l-BH 4 )]`.73 1H NMR spectroscopic studies of the ethylene complex [Os 2 (CO) 8 (l-g1:g1- C 2 H 4 )] in liquid crystal solvents have been used to examine their solution and solid state structures.74 Electrospray mass spectrometry has been used to characterise a variety of neutral metal carbonyl compounds. The ionisation reagent of choice is NaOMe in methanol which gives [M]OMe]~ ions for compounds in which the ligand sphere is predominantly carbonyls, [M]Na]` ions for higher substituted electron rich species and [M[H]~ ions for compounds containing acidic hydrogen atoms.75 Treatment of Na 2 SO 3 with basic [Fe(CO) 5 ] in refluxing methanol gave the tetranuclear cluster anion [Fe 3 (CO) 9 S]2~, which reacts with H` and Me` to give [Fe 3 (CO) 9 (l3 -S)(l-H)n]2~n (n\1, 2) and [Fe 3 (CO) 9 (l-SMe)]~ respectively.76 Alkylation of [N(PPh 3 ) 2 ][Fe 3 (CO) 9 S] with methyl triflate or methyl iodide occurs at the sulfur atom to give [N(PPh 3 ) 2 ]Fe 3 (CO) 9 (l-SMe)] whereas alkylation of [N(PPh 3 ) 2 ]- [Fe 3 (CO) 9 E] (E\Te, Se) occurs at the metal atom framework to give [N(PPh 3 ) 2 ]- [Fe 3 (CO) 9 (Me)E], a rare example of a terminal bonded methyl group on a metal cluster.77 Ru(CO2) Ru(CO)3 C C C C But P Ph2 Ru (CO)3Ru Ru Ru(CO)2 C C P Ph C C But CO CO (CO)3Ru (CO)3Ru C C C Ph C But CO (CO)2 (CO)2 (CO)2 Ph2P 29 28 27 C But 2 Ru(CO)2 P Ph2 Ru CO Ru (CO)2Ru C Ph Thermolysis of [Ru 3 (CO) 11 (PPh 2 C–– – CC–– – CBu5)] in thf a§ords [Ru 4 (CO) 9 (l- PPh 2 ) 2Ml4 -g1: g2:g1:g2-C–– – CC–– – C(Bu5)C–– – CC–– – CBu5N] 27 via head to tail coupling of two diynyl units, [Ru 4 (CO) 9 (l-CO) 2 (l4 -PPh)(l4 -g1: g1:g2:g2-Bu5C–– – CC–– – CPh)] 28 and [Ru 4 (CO) 10 (l4 -PPh)(l4 -g1:g1:g2: g3-PhC–– – CC–– – CBu5)] 29 via phenyl migration from PPh 2 to a terminal carbon of the diynyl fragment, and [Ru 5 (CO) 11 (l-CO)(l- PPh 2 ) 2 (l3 -g1:g1:g1-C–– – CC–– – CBu5)(l4 -C)(l-g1: g1-CC–– – CBu5)] and [Ru 6 (CO) 13 (l- CO) 2 (l-PPh 2 )(l5 -C)(l3 -g1: g1:g1-CC–– – CBu5)] via cleavage of the terminal car- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 386(CO)3Ru Ru(CO)3 Ru H Ph2P (CO)3Ru Ru(CO)3 Ru H Ph2P (CO)2Ru (CO)3Ru Ru(CO)2 Ru(CO)3 N P OC (CO)3Ru (CO)2Ru Ru(CO)2 Ru(CO)2 P NH CO C O (CO)3Ru Ru(CO)3 Ru H Ph2P (CO)3 (CO)3 (CO)3 31b – + 31a Ph Ph 30c 30b 30a NH HN N Scheme 5 bon–carbon bond of the diynyl fragment.78 The three isomeric tertiary phosphines diphenyl(n-pyrrolyl)phosphine (n\1, 2, 3) react with [Ru 3 (CO) 12 ] firstly to give the simple substitution products [Ru 3 (CO) 11 L], co-ordinated through phosphorus, before undergoing metallation of the pyrollyl ring to give three isomers of [Ru 3 (l- H)(CO) 9 (l-PPh 2 C 4 H 3 N)] 30a–30c.Subsequent reaction with [Ru 3 (CO) 12 ] gives isomers of [Ru 4 (CO) 11 (l-C 4 H 3 N)(l4 -PPh)] 31a, 31b, which contain the diagonal C,Cbonded and parallel C,N-bonded pyrrolyne ligands (Scheme 5).79 Protonation of the phosphine substituted g1-1-azavinylidene derivatives [Ru 3 (l- H)(CO) 8 (l-dppm)(l-N–– CPh 2 )], [Ru 3 (l-H)(CO) 9 (PPh 3 )(l-N––CPh 2 )] and [Ru 3 (l- H)(CO) 8 (PPh 3 ) 2 (l-N––CPh 2 )] gave the corresponding cationic dihydrides [Ru 3 (l- H) 2 (CO) 8 (l-dppm)(l-N––CPh 2 )][BF 4 ], [Ru 3 (l-H) 2 (CO) 9 (PPh 3 )(l-N––CPh 2 )][BF 4 ] and [Ru 3 (l-H) 2 (CO) 8 (PPh 3 ) 2 (l-N––CPh 2 )][BF 4 ].EHMO calculations on the model compound [Ru 3 (l-H)(CO) 8 (PH 3 ) 2 (l-N––CPh 2 )] have shown that the ten highest occupied molecular orbitals are primarily metal-based and that the ruthenium atoms are more electron rich than those of [Ru 3 (l-H)(CO) 10 (l-N––CPh 2 )].80 Hydrogenation of [Ru 3 (l-H)(CO) 10 (l-N–– CPh 2 )] results in loss of H 2 NCHPh 2 to give [Ru 4 (l- H) 4 (CO) 12 ] via the imido and amido intermediates [Ru 3 (l-H) 2 (CO) 9 (l-NCHPh 2 )] and [Ru 3 (l-H)(CO) 10 (l-HNCHPh 2 )] respectively.81 The cluster [Ru 3 (l-H)(CO) 10 (l- N––CPh 2 )] reacts with phenyl-1-propyne and diphenylacetylene in refluxing dichloroethane to give [Ru 2 (CO) 4 (l-CO)Ml-PhC––C(R)C(Ph)––CRN––CPh(C 6 H 4 )N] (R\Me, Ph) via double alkyne insertion and orthometallation of a phenyl ring of the 1-azavinylidene.At lower temperatures cluster fragmentation and insertion of alkyne into a Ru–Hbond to give the binuclear alkenyl derivative [Ru 2 (CO) 6 (l-R1CCHR 2 )(l- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 387N––CPh 2 )] is the dominant reaction. In selected cases these alkenyl derivatives react with additional alkyne to give the corresponding metallacyclic complex [Ru 2 (CO) 4 (l- CO)Ml-PhC––C(R)C(Ph)––CRN–– CPh(C 6 H 4 )N] while others are unreactive at higher temperatures.82 The l3 -benzyne complex [Ru 3 (CO) 7 (l-PPh 2 ) 2 (l3 -C 6 H 4 )] 32 reacts with L, to give [Ru 3 (CO) 6 L 2 (l-PPh 2 ) 2 (l3 -C 6 H 4 CO)] 33 (L\CO, PMe 3 , Bu5NC) [eqn. (5)] which contains an orthometallated l3 -benzoyl ligand derived from migratory insertion of CO into a benzyne–Ru r-bond.The phosphine-substituted benzyne derivative [Ru 3 (CO) 6 (PR 3 )(l-PPh 2 ) 2 (l3 -C 6 H 4 )] (R\Ph, Pr*) also reacts with CO to give the corresponding l3 -benzoyl [Ru 3 (CO) 7 (PR 3 )(l-PPh 2 ) 2 (l3 -C 6 H 4 CO)].83 The reaction between [Ru 3 (CO) 9Ml3 -PPhCH 2 PPh(C 6 H 4 )N] and HC–– – CPh involves insertion of a diene, formed by coupling of the alkynes, into the Ru–P(phosphido) bond to give PPh(C 6 H 4 )CH 2 PPh(C 4 H 2 Ph 2 ), which undergoes P–C cleavage upon thermolysis to regenerate the original phosphido phosphine ligand and the alkyne dimer, which co-ordinates in the usual g1:g4-manner.Similar metallacyclopentadiene complexes have been prepared from [Ru 3 (CO) 9Ml3 -PPh 2 CH 2 PPh(C 6 H 4 )N] and HC–– – CCO 2 Me, [Ru 3 (CO) 7 (l-CO)(l-dppm)(l3 -RC–– – CCO 2 Me)] and PhC–– – CPh (R\CO 2 Me, H) and [Ru 3 (CO) 9 (l3 -PPhCH 2 PPh 2 )]~ and PhC–– – CPh followed by protonation.84 The reaction of P–– – CBu5 with [Os 3 (CO) 10 (l3 -g1:g2: g1-MeC–– – CMe)] gives [Os 3 (CO) 8 (l- P–– – CBu5)Ml3 -PC(Me)C(Me)C(Bu5)N] which contains a 1-osma-2-phosphacyclopentadiene ring that results from insertion of an osmium atom into a intermediate phosphacyclobutadiene ligand formed in a [2]2] cycloaddition between but-2-yne and P–– – CBu5.85 Thermolysis of [M 3 (CO) 12 ] (M\Fe, Ru, Os) with biphenylene, (C 6 H 4 ) 2 , results in carbon–carbon cleavage to give [M 2 (CO) 6Ml-g2: g4-(C 6 H 4 ) 2N] and in the case of Ru and Os, [Ru 6 (CO) 17 (l6 -C)] and the butterfly cluster [Os 4 (CO) 12Ml4 -g2-(C 6 H 3 )PhN] respectively.In contrast, [Os 3 (CO) 10 (NCMe) 2 ] reacts with biphenylene via C–H activation to a§ord [Os 3 (CO) 9 (l-H) 2Ml3 -g2-C 6 H 2 (C 6 H 4 )N].86 The rutheniumcatalysed cross carbonylation of alkynes and 2-norbornene a§ords unsymmetrical substituted hydroquinones via a maleoylruthenium intermediate [eqn.(6)].87 OH OH 60 atm, 140 °C 3 % [Ru3(CO)12] + 2CO (6) Hydrogenation of the lightly stabilized clusters [Ru 3 (CO) 11 (NCMe)] a§ords [Ru 3 H 2 (CO) 11 ]. 1H and 13C NMR spectroscopic studies have shown that the structure is di§erent to that originally suggested by Keister,88a and contains a bridging Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 388N (CO)3Os Os(CO)3 Os R R1 H N (CO)3Os Os(CO)3 Os R R1 H H H H N (CO)3Os Os(CO)3 Os R R1 H H H H H H H (CO)3 (CO)3 (CO)3 36 35 H –/H+ 34 H –/H+ Scheme 6 carbonyl and hydride across the same Ru–Ru bond.Low temperature addition of CF 3 CO 2 H to a solution of [Ru 3 H 2 (CO) 11 ] results in reversible protonation at the Lewis basic oxygen atom of the bridging carbonyl before transformation into [Ru 3 (l- H)(CO) 10 (l3 -CF 3 CO 2 )].88b The molecular structure of [Ru 3 (l-H)(l3 -g1: g1:g3- C 12 H 7 )(CO) 9 ] has been shown to contain a l3 -C 12 H 17 ligand by a combination of X-ray data, electrospray mass spectrometry Mm/z\867, Ru 3 H(CO) 9 (C 12 H 17 )]Ag]MeCN]`N and 1H and 13C NMR spectroscopy.89 The radical cations [Ru 3 H 3 (l-CX)(CO) 6 L 3 ]` [X\OMe; L\(PPh 3 ) 2 L1; L1\CO, PPh 3 , CNCH 2 Ph] have been prepared by chemical and electrochemical oxidation of [Ru 3 H 3 (l3 -CX)(CO) 6 (PPh 3 ) 2 ] (X\OMe, Ph, SEt, NMePh).These clusters are coordinatively less reactive than monometallic 17-electron complexes.For instance, chemically generated [Ru 3 H 3 (l-CX)(CO) 6 (PPh 3 )]` does not react with halogen atom donors such as CCl 4 while hard Lewis acids induce disproportionation to regenerate the 48-electron precursor in high yield.90 The thiazolide clusters [Os 3 (l-H)(CO) 10 (l-2,3-g2-C––NCH––CHS)] and [Os 3 (l- H)(CO) 10 (l-3,4-g2-HC––NC––CHS)], isolated from the reaction between [Os 3 (CO) 10 (NCMe) 2 ] and thiazole, react with PPh 3 to give [Os 3 (l-H)(CO) 9 (PPh 3 )(l- 2,3-g2-C–– NCH––CHS)] and [Os 3 (l-H)(CO) 9 (PPh 3 )(l-3,4-g2-HC––NC––CHS)] respectively, both of which exist as a mixture of two isomers which di§er in the position of substitution of PPh 3 .91 Deuterium labeling experiments have shown that reaction of the electron deficient cluster [Os 3 (l-H)(CO) 9 (l3 -g3-C 9 H 4 NRR1)] 34 (R\R1\H; R\4-Me, R1\H; R\H, R1\3-Me) with H~ occurs at the 5-position of the quinoline ring.Subsequent protonation gives [Os 3 (l-H)(CO) 9 (l3 -g3-C 9 H 6 RR1N)] 35 which reacts with a further equivalent of H~/H` to give [Os 3 (l-H) 2 (CO) 9 (l3 -g3- C 9 H 7 RR1N)] 36 (Scheme 6).Similar studies have shown that [Os 3 (l-H)(CO) 9 (l3 -g2- C 9 H 8 N)], which contains a C–– N bond in a partially reduced heterocyclic ring, reacts with H~ at the N-imine carbon and subsequently with H` at the metal centre.92 The molecular structure of [Os 3 (CO) 11 (g2-C 60 )] is derived from [Os 3 (CO) 12 ] by substitution of an equatorial carbonyl ligand. Various other triosmium clusters of C 60 have been isolated including [Os 3 (CO) 10 (NCMe)(g2-C 60 )], [Os 3 (CO) 10 (PPh 3 )(g2- C 60 )], [Os 3 (CO) 9 (PR 3 ) 2 (g2-C 60 )] (R\Me, Ph), [Os 3 (CO) 9 (PPh 3 )(l-g2:g2:g2-C 60 )] and [Os 3 (CO) 8 (PMe 3 )(l-g2: g2:g2-C 60 )].Variable temperature 13C NMR spectroscopic studies have shown that the equatorial carbonyl ligands of [Os 3 (CO) 10 (NCMe)(g2-C 60 )] and [Os 3 (CO) 9 (PPh 3 ) 2 (g2-C 60 )] equilibrate via a triply bridging intermediate (*Gt\12.7^0.1 kcal mol~1).93 The 48-electron cluster [Ru 3 (CO) 9 (PCy 3 ) 3 ] and highly electron deficient 44-electron derivative [Ru 3 H 2 (CO) 6 (PCy 3 ) 3 ] have been isolated from the reaction between Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 389Na[Ru 3 H(CO) 11 ] and PCy 3 .94 The influence of phosphine size on the formation, equilibration and reactivity of isomeric vinyl clusters [Os 3 (l-H)(CO) 9 (PR 3 )(l- CH–– CH 2 )] (R\Et, CH 3 OC 6 H 4 , CH 3 C 6 H 4 , C 6 H 11 ) has been investigated.Equilibration between the two structural isomers of [Os 3 (CO) 9 L(l-H)(l-CH––CH 2 )] shows an increasing preference for positioning the vinyl group remote from the phosphine ligand.TrimethylamineN-oxide promoted removal of CO occurs selectively from one isomer to give the corresponding vinylidene hydride [Os 3 (CO) 9 (PR 3 )(l-H) 2 (l- C––CH 2 )].95 The osmium clusters [Os 3 (CO) 11M(R)-binapN], [Os 3 (CO) 10M(R)-binapN], and [Os 3 (l-H)(CO) 8Ml3 -(R)-binap[HN], contain monodentate, chelating and orthometallated 2,2@-bis(diphenylphosphino)-1-1@-binaphthyl ligands respectively.The former two clusters are fluxional, the first existing as a mixture of two interconverting isomers, which have di§erent conformations within the monodentate binap ligand. The decacarbonyl cluster undergoes a dynamic merry-go-round motion about the two Os(CO) 4 units.96 The cluster [Os 3 (CO) 11MP(C 6 H 4 F-p) 3N] exists in two forms, one in which all the axial carbonyl groups are perpendicular to the Os 3 triangle while in the other neighboring Os(CO) 3 L (L\CO, PR 3 ) units are mutually twisted.In contrast, [Os 3 (CO) 11 (PBu5 3 )] adopts a staggered structure, possibly as a result of the strong r-donor properties and large size of PBu5 3 which destabilises the peripheral Os–Os bonding in the Os 3 skeleton such that the sterically preferred staggered conformer is favoured.97 Decarbonylation of [Os 3 (CO) 9 (l3 -g2:g2: g2-C 60 )] with Me 3 NO–MeCN in the presence of various phosphines a§ords [Os 3 (CO) 8 (PPh 3 )(l3 -g2:g2:g2-C 60 )] and [Os 3 (CO) 7 (PMe 3 ) 2 (l3 -g2: g2:g2-C 60 )].The former is derived from [Os 3 (CO) 11 (PPh 3 )] by substitution of three axial carbonyl ligands with a face capping C 6 ring of the C 60 .The electronic properties of these compounds are characterised by a number of reversible redox couples with C 60 mediated electron transfer to the metal cluster.98 The mixed phosphido bridged clusters [Ru 3 (l-H)(CO) 7 (l-PBu5)(PCy 2 ) 2 ], [Ru 3 (l-H) 2 (CO) 8 (l-PBu5)(PCy 2 )] and the 46-electron [Ru 3 (l-H) 2 (CO) 5 (l-CO)(l- PBu5) 2 (PBu5 2 H)], have been isolated from the reaction between [Ru 3 (l-H) 2 (CO) 8 (l- PBu5) 2 ] and PCy 2 H.The last cluster can be isolated in near quantitative yields from the reaction between PBu5 2 H and [Ru 3 (l-H)(CO) 8 (l-PBu5 2 ) 2 ].99 Thermolysis of [Os 3 (CO) 10 (l-dppm)] with PPh 2 H gave [Os 3 (CO) 9 (l-dppm)(PPh 2 H)] and an isomeric mixture of [Os 3 H(l-H)(CO) 7 (l-dppm)(l-PPh 2 ) 2 ].The 46-electron cluster [Os 3 (l-H)(CO) 8Ml-Ph 2 PCH 2 PPh(C 6 H 4 )N] reacts with PPh 2 H to give [Os 3 (l- H)(CO) 8Ml-PPh 2 CH 2 PPh(C 6 H 4 )N(PPh 2 H)] and [Os 3 (CO) 8 (l-dppm)(PPh 2 H) 2 ] which undergoes thermal decarbonylation to give [Os 3 H(l-H)(CO) 7 (l-dppm)(l- PPh 2 ) 2 ] and two isomers of [Os 3 (l-H) 2 (CO) 6 (l-dppm)(l-PPh 2 )].100 Addition of NH 3 to [Ru 3 H(l-H)(l-CO)(CO) 10 ] and [Os 3 H(l-H)(CO) 11 ] a§ords [NEt 4 ][M 3 (l-H)(l-CO)(CO) 10 ] via nucleophilic addition to a carbonyl to give a zwitterionic amino-carbonyl, NH 3 –CO (M\Ru), or carbamoyl, NH 2 –COH (M\Os), intermediate before loss of H`.101 Spectroscopic studies of the reaction between [Os 3 (CO) 11 (NCMe)] and para-thiocresol to form [Os 3 (l-H)(CO) 10 (l- SC 6 H 4 Me)] indicate that the reaction involves a two-step consecutive process.Reversible dissociation of MeCN, to give the labile co-ordinatively unsaturated intermediate [Os 3 (CO) 11 ] which adds thiol to give [Os 3 (CO) 11 (RSH)] in which there is an agostic Os · · · H–S interaction, is followed by slow cleavage of the S–H bond and concomitant dissociation of CO.102 The photochemistry of the diimine substituted clusters [Os 3 (CO) 10 (a-diimine)] has been examined.Upon irradiation in a co-ordinating Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 390Scheme 7 solvent the zwitterion [~Os(CO) 4 Os(CO) 4 Os`(solv)(CO) 2 (a-dimine)] is formed while in non-co-ordinating solvents the biradical [·Os(CO) 4 Os(CO) 4 Os`(CO) 2 (a- diimine·~)] is formed; lifetimes are from 5 ns to 1 ls. The biradicals undergo an intramolecular photodisproportionation to give zwitterionic derivatives [~Os(CO) 4 Os(CO) 4 Os`(CO)L(a-dimine)] in the presence of Lewis bases.103 Bromination of [Os 3 (CO) 11 (EPh 3 )] (E\P, Sb) results in Os–Os bond cleavage to give two regioisomers of Br 2 addition, [Os 3 (CO) 11 (EPh 3 )Br 2 ], one of which contains tandem donor–acceptor metal–metal bonds.104 Pyridyl functionalised metalloporphyrins react with [Os 3 (CO) 11 (NCMe)] to give products in which the pyridyl ring of the porphyrin is orthometallated and bridging one edge of the Os 3 triangle, similar to the structure of [Os 3 (l-H)(CO) 10 (l-NC 5 H 4 )].The absorption spectra of these clustersubstituted porphyrins are similar to their unsubstituted counterparts.105 Refluxing a toluene solution of [Ru 2 (CO) 6 (l-PPh 2 )(l-g1:g2-C–– – CPh)] 37 gave two electronically unsaturated tetraruthenium clusters, the spiked triangular [Ru 4 (CO) 9 (l-PPh 2 )Ml4 -Ph 2 PCC(Ph)CC(Ph)N] 38 and open chain [Ru 4 (CO) 10 (l- PPh 2 )Ml4 -Ph 2 PC(Ph)CCC(Ph)N] 39, which involve head to tail and head to head coupling of the two acetylides respectively.The former cluster is co-ordinatively unsaturated and undergoes a fully reversible triple addition of CO to give [Ru 4 (CO) 11 (l-PPh 2 )Ml4 -Ph 2 PC(CO)C(Ph)N] 40 (Scheme 7).106 Condensation of [Ru 4 (CO) 13 (l3 -PNCy 2 )] with [Ru(CO) 5 ] in refluxing hexane gives [Ru 5 (CO) 15 (l4 - PNCy 2 )], which reacts with HBF 4 to give [Ru 5 (CO) 15 (l4 -PF)], the first cluster complex containing a l4 -fluorophosphinidene, and with HBF 4 ·H 2 Oto give low yields of the fluorophosphinidene cluster together with [NH 2 Cy 2 ][Ru 5 (CO) 15 (l4 -P–– O)], which contains a quadruply bridging phosphorus monoxide.107 The amino–phosphinidene clusters [Ru 4 (CO) 10 (l-CO)(l4 -PPh)(l4 -PNPr* 2 )] and [Ru 4 (CO) 12 (l4 - PNPr* 2 ) 2 ] have been isolated from the reaction between [PCl 2 NPr* 2 ] and Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 391[Ru 4 (CO) 12 (l3 -PPh)]2~ and [Ru 4 (CO) 12 ]4~ respectively. The four ruthenium atoms of [Ru 4 (CO) 10 (l-CO)(l4 -PPh)(l-PNPr* 2 )] form a square planar arrangement with the phosphinidene ligands capping both sides of the Ru 4 square plane while the four ruthenium atoms in [Ru 4 (CO) 12 (l4 -PNPr* 2 ) 2 ] form a puckered square.108 1,6- Bis(trimethylsilyl)hexa-1,3,5-triyne reacts with [Ru 3 (CO) 12 ] in refluxing hexane to give the butterfly cluster [Ru 4 (CO) 12 (l4 -g1:g1: g2:g2-Me 3 SiC–– – CC 2 C–– – CSiMe 3 )] and the binuclear derivative [Ru 2 (CO) 6Ml-g2:g4- C(C–– – CSiMe 3 )––C(C–– – CSiMe 3 )–– C(C–– – CSiMe 3 )C(C–– – CSiMe 3 )N] and with [Ru 4 (CO) 13 (l3 -PPh)] to give [Ru 4 (CO) 8 (l3 -PPh)Ml4 -g2:g4: g2:g4- (Me 3 SiC–– – C)CC(C–– – CSiMe 3 )C(C–– – CSiMe 3 )CCC(SiMe 3 )C(C–– – CSiMe 3 )C(C–– – CSiMe 3 )N] via coupling of three equivalents of triyne.109 Thermolysis of an octane solution of [Ru 3 (CO) 9 (l3 -CO)(l3 -NOMe)] and tolylacetylene a§ords the nitrene-bridged tetraruthenium clusters [Ru 4 (CO) 9 (l-CO) 2 (l-NH)(l-g2-HC–– – Ctol)] and [Ru 4 (CO) 9 (l- CO)Ml-N(CO)OMeN(l-g2-HC–– – Ctol)] which co-crystallise in an asymmetric unit containing two identical molecules of the former cluster and two isomers of the latter.110 The trinuclear ruthenaborane [Ru 3 B 3 H 8 Cp* 3 ] has been isolated from the reaction of [MRuCl 2 Cp*N2 ] with [BH 4 ]~.Rather than adopt the closo-octahedral geometry expected for a seven-skeletal electron-pair cluster with six vertices, the cluster is based on a square pyramid with the Ru 3 face capped by the third BH 3 fragment.111 Reaction of the monoanion [Os 3 H(CO) 11 ]~ with [Ru(NCMe) 3 Cp]` gave the tetrahedral cluster [Os 3 RuH(CO) 11 Cp] which could be deprotonated with dbu to give [Os 3 Ru(CO) 11 Cp]~ and reacted with a second equivalent of [Ru(NCMe) 3 Cp]` to give the capped tetrahedral cluster [Os 3 Ru 2 (CO) 9 (l3 -CO) 2 Cp 2 ].112 Hydrogenation of [Ru 2 (CO) 4 (O 2 CH) 2 (PCy 2 H) 2 ] a§ords the tetranuclear cluster [Ru 4 H 4 (CO) 8 (PCy 2 ) 4 ] and [Ru 5 H 5 (CO) 8 (PCy 2 ) 3 ], the former containing a 64-electron square planar core and the latter an electron deficient 62-electron metal atom framework with a Ru––Ru double bond.113 The face co-ordinated C 60 carbido clusters [Ru 5 (CO) 11 (PPh 3 )(l-C)(l-g2:g2: g2-C 60 )], [Ru 5 (CO) 10 (dppe)(l-C)(l-g2: g2:g2- C 60 )] and [Ru 5 (CO) 10 (dppf)(l-C)(l-g2:g2: g2-C 60 )] have been isolated from refluxing chlorobenzene solutions of [Ru 5 (CO) 15 (l-C)] and C 60 with PPh 3 , dppe and dppf respectively.114 The ruthenium arene clusters [Ru 6 (CO) 14 (l-C)(g6-PhCHMePh)], [Ru 6 (CO) 14 (l-C)(g6-PhC––CH 2 Ph)] and [Ru 6 (CO) 14 (l-C)(l3 -j: g6:g6- C 6 H 4 CH 2 C 6 H 4 )] have been isolated from refluxing octane solutions of [Ru 3 (CO) 12 ] and 1,1-diphenylethene.In the first of these the organic group is hydrogenated at the C––C centre and co-ordinates in a g6-manner whereas in the second the ligand remains unsaturated and co-ordinates in a similar manner. In the last of these the 1,1- diphenylethene has undergone C––C cleavage, hydrogenation of the carbene and orthometallation of both aromatic rings.115 Substitution of CO in [Ru 10 (CO) 22 (l- C 2 )]2~ for allene gives [Ru 10 (CO) 20 (l-C 2 )(l-g2:g2-C 3 H 4 )]2~ and [Ru 10 (CO) 22 (l- C 2 )(l-g2: g2:g1-C 3 H 4 )]2~, both of which have framework structures based on edgeshared bioctahedra with the allene ligand bridging apical positions.In both cases, variable temperature 13C NMR studies have revealed a carbonyl scrambling process which involves the localised three fold rotation of a set of carbonyls, each set composed of one bridging and two terminal carbonyls attached to an equatorial ruthenium atom.116 Substitution of carbonyl ligands in the edge shared bioctahedral cluster [N(PPh 3 ) 2 ][Ru 10 (CO) 24 (l-C 2 )] by norbornadiene gives [N(PPh 3 ) 2 ][Ru 10 (CO) 22 (l- C 2 )(nbd)], which is readily oxidised to [Ru 10 (CO) 22 (l-C 2 )(nbd)] in the presence of Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 392Scheme 8 [FeCp 2 ]`. Spectroscopic and crystallographic studies show that the norbornadiene co-ordinates as a bidentate chelating ligand on one of the outer ruthenium atoms in the bifurcated Ru 10 C 2 framework.117 Oxidative substitution of [Ru 10 (CO) 22 (l- C 2 )(nbd)]2~ with diazomethane a§ords [Ru 10 (CO) 22 (l-C 2 )(l-CH 2 )], the methylene bridging adjacent apical ruthenium centres of the bioctahedral Ru 10 C 2 framework.Thermolysis of [Ru 10 (CO) 22 (l-C 2 )(l-CH 2 )] in toluene generates the methylidyne tautomer [Ru 10 (CO) 22 (l-C 2 )(nbd)(l-CH)(H)].118 7 Cobalt, rhodium and iridium The Bu 2 BOTf mediated condensation of stannylsilanes CH 2 –– CHCH(SiMe 3 )SnBu 3 with c-methoxy-alkynoate and -alkynone hexacarbonyldicobalt complexes [Co 2 (CO) 6Mg2-MeOCH 2 C–– – CC(O)RN] 41 gave the alkyl and vinylsilanes [Co 2 (CO) 6Mg2-CH 2 ––CHCH(SiMe 3 )CH 2 C–– –CC(O)RN] 42 and [Co 2 (CO) 6Mg2- SiMe 3 C(H)––C(H)CH 2 CH 2 C–– – CC(O)RN] 43 respectively.Conversion of the carbonyl group in 42 into a leaving group by low temperature reduction with dibal and acetic anhydride followed by a BF 3 ·OEt 2 mediated intramolecular reaction a§ords the cycloheptenyne hexacarbonyldicobalt complexes [Co 2 (CO) 6MC–– – CCHRCH 2 CH 2 ––CHCH 2N] 44 (Scheme 8).119 In the presence of triethylamine, (but-2-yne-1,4-diol)hexacarbonyldicobalt reacts with dichlorodialkylsilanes R 2 SiCl 2 (R\Me, Et, CH––CH 2 , Ph) to a§ord the 1,3-dioxa-2-silacycloheptyne derivatives as the major product, together with small quantities of nine-membered ring siloxanes that most likely arise from competitive hydrolysis.120 Reaction of Ic@ with [Co(C 2 H 4 ) 2 Cp] gave [MCoCpN2 Ic@] as a mixture of cis and trans isomers, which interconvert rapidly on the NMR time scale.The cyclic voltammetric response of [MCoCpN2 Ic@] revealed four stepwise redox processes, which indicates a significant intramolecular interaction between the cobalt centres. Reaction of Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 393Scheme 9 [MCoCpN2 Ic@] with [NH 4 ][BF 4 ] gave [MCoCpN2 (Ic@H 2 )][BF 4 ] 2 via attack at the central carbon atom of the indacene rings; the dication [MCoCpN2 (Ic@)][OTf] 2 was successfully generated by oxidation with silver triflate.121 Ring opening of hexaphenylcyclohexaarsine (PhAs) 6 with [Co 2 (CO) 8 ] at room temperature gives [Co 4 (CO) 10 (l4 - AsPh) 2 ] and [Co 4 (CO) 10 (l3 -AsPh)(l4 -g2:g2: g1-As 4 Ph 4 )].In contrast, reaction of cyclo-(AsPh) 6 with [Co 2 (CO) 6 (l-R1C–– – CR2)] a§ords [Co 2 (CO) 4 (R1C–– – CR2)Ml-cyclo- (AsPh) 6N] (R1\R2\H or Ph) in which the As 6 ring remains intact and acts as a bidentate ligand.122 The bis(dihydrosilyl)hydrocarbon X(SiH 2 R) 2 (X\CH 2 CH 2 , C 6 H 4 , CH2 CH 2 CH 2 ) reacts with [Co 2 (CO) 8 ] to give the silylene bridged [Co 2 (CO) 6 (l-RSiXSiR)], which contains a Si 2 Co 2 butterfly core with a short Si · · · Si interaction.123 Starburst molecules with rigid [Co 2 (CO) 6 ] containing arms have been isolated from the reaction between CM(p-C 6 H 4 -C–– – C)nHN4 (n\1, 2, 3) and [Co 2 (CO) 8 ].124 Reaction of methylene-bridged [Rh 2 (l-CH 2 ) 2 (l-SH)Cp* 2 ][BPh 4 ] with [Rh 2 (l- OH) 3 Cp* 2 ][BPh 4 ] gave the l3 -g2- E -acetylene derivative [Rh 3 (l3 -g2- E - HC–– – CH)(l3 -S)Cp* 3 ], via deprotonation and carbon–carbon coupling of two l-CH 2 groups.125 The terminal thiol complex [Rh 2 (SH) 2 (l-CH 2 ) 2 Cp* 2 ] and cationic thiolate bridged [Rh 2 (l-CH 2 ) 2 (l-SH)Cp* 2 ]` 45 react with dialkylacetylenedicarboxylate to give [Rh 2 (l-CH 2 ) 2 (SCR1––CHR 2 ) 2 Cp* 2 ] (R1\R2\CO 2 Me, CO 2 Et), a terminal bis(ethenethiolate), and [Rh 2 (l-CH 2 ) 2 (l-SCR1––CHR 2 )Cp* 2 ]` 46 in Michael-type addition reactions.Addition of excess alkylacetylene dicarboxylate (R3C–– – CR4) to 46 a§ords butadiene-bridged [Rh 2 (l-CH 2 –– CR3CR4–– CH 2 )(l-SCR1–– CHR2)Cp* 2 ]` 47 (R3\R4\CO 2 Me, CO 2 Et, CO 2 Ph), via coupling of two l-CH 2 groups and the alkyne (Scheme 9).126 The bridging methylene ligand in [MRh(NCMe)(l-CH 2 )Cp*N2 ]- [BF 4 ] 2 undergoes a regiocontrolled coupling of two phenylacetylene molecules to give [(RhCp*) 2Ml-g1:g4-g2-CHC(Ph)CHC(Ph)CHCH 2N][BF 4 ].On the basis of 1H NMR studies [(RhCp*) 2Ml-g1: g4-g2-CHC(Ph)CHC(Ph)CHCH 2N][BF 4 ] was suggested to form via g2-alkyne co-ordination and C–C coupling to give an intermediate vinylcarbene followed by further C–C coupling with another molecule of alkyne and deprotonation.127 The triphenylsilyl ligands in [MRh(H)L(SiPh 3 )N2 (l-H)(l-Cl)] (L\PPr* 3 ) exchange with HSiPh 3~n(C 6 H 4 F-p)n (n\3, 2, 1) at room temperature to a§ord [MRh(H)L[SiPh 3~n(C 6 H 4 F-p)n]N2 (l-H)(l-Cl)].Thermolysis of [MRh(H)L(SiPh 3 )N2 (l- H)(l-Cl)] in toluene results in facile Si–C bond cleavage and elimination of benzene to give the diarylsilylene–diarylsilyl bridged [MRh(H)LN2 (l-SiPh 3 )(l-SiPh 2 )(l-Cl)].128 Primary and secondary amines react with [MRh(l-Cl)(CO)(PPh 3 )]N2 ] to a§ord [Rh(CO)Cl(PPh 3 )(NRR@RA)], which is an e¶cient catalyst for the hydrosilation of Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 394hexene and the polymerisation of styrene and methylmethacrylate, in the presence of halogenoalkenes such as CCl 4 .129 Addition of H 2 to [Rh(g4-C 8 H 12 )(j2-As,PCy 2 AsCH 2 PCy 2 )][PF 6 ] in the presence of CF 3 CO 2 H gave the binuclear hydridobridged complex [MRhH(j2-As,P-Cy 2 AsCH 2 PCy 2 )N2 (l-H)(l-O 2 CCF 3 ) 2 ][PF 6 ].130 The rhodium dithiocarbamate complexes [Rh(S 2 CNMePh)L 2 ] [L\cod, (CO) 2 ] react with [Rh(cod)(OCMe 2 )n][BF 4 ] as metalloligands to give the binuclear complexes [Rh 2 (l-S 2 CNMePh)(cod)L 2 ][BF 4 ] in which the dithiolate is l-g2: g2-(S,S) bridging. 131 The solid state structures of bis(para-substituted)aryl isocyanide adducts [Rh 2 (OAc) 4MCN(C 6 H 4 X-p)N2 ] (X\NMe 2 , H, CF 3 ) have several features in common; short Ru–C bonds, an inversion centre between the two rhodium atoms, coplanar aryl rings and non-linear Rh–C–N bonds.These characteristics are consistent with p- backbonding from the Rh–Rh p* molecular orbital to the p-acceptor orbital of the isocyanide.132 High pressure NMR and IR spectroscopic studies have shown that hydrogenation of styrene using [MRh(l-OMe)(CO)(cod)N2 ] with bdpp involves an equilibrium mixture of [RhH(bdpp)(CO) 2 ] and [MRh(bdpp)(CO) 2N2 ], the monomer being the catalytically active species for hydrogenation.Under high pressures of CO the dithiolate-bridged rhodium complex [MRh(l-bcos)(cod)N2 ] gave [Rh 2 (l-bcos)(l-bdpp)(CO) 2 ] which reacts with H 2 to a§ord a similar equilibrium mixture.133 The thiolate-bridged dimer [MRh(l-SC 6 H 4 NHMe-o)(cod)N2 ] has been isolated from the thermolysis of [Rh(NHC 6 H 4 SMe-o)(cod)] and via transmetallation of [Zr(NHC 6 H 4 SMe-o) 2 Cp 2 ] with [MRh(l-Cl)(cod)N2 ].134 The pyrazolyl-bridged diiridium(I) complex [MIr(g2-C 2 H 4 ) 2 (l-pz)N2 ] is stable only under an atmosphere of ethylene as is its MeI addition product, the diiridium(II) complex [IrMe(g2-C 2 H 4 ) 2 (l-pz) 2 IrI(g2-C 2 H 4 ) 2 ], which contrast with their thermally stable chelating diolefin counterparts [MIr(cod)(l-pz)N2 ] and [IrMe(cod)(l- pz) 2 IrI(cod)].Although the tetrafluoroethylene pyrazolyl-bridged complex [MIr(g2- C 2 F 4 )(g2-C 2 H 4 )(l-pz)N2 ] could not be prepared, its precursor [MIr(g2-C 2 F 4 )(g2- C 2 H 4 )(l-Cl)N2 ] was unexpectedly stable and has been characterised by multinuclear and variable temperature NMR spectroscopy; it exists in equilibrium with two isomeric solvent stabilised mononuclear complexes cis- and trans-[Ir(g2-C 2 H 4 )(g2- C 2 F 4 )Cl(solv)].135 Oxidative addition of PhCH 2 Cl to [MIr(l-pz)(CNBu5) 2N2 ] gave [MIr(CNBu5) 2 (l-pz)N2 Cl(CH 2 Ph)] as an equilibrium mixture of dinuclear valence tautomers. Oxidative addition of another equivalent of PhCH 2 Cl gave the iridium(III) dimer [MIr(l-pz)(CH 2 Ph)(CNBu5) 2N2 (l-Cl)]Cl.136 The pyrazolyl-bridged complex [Ir 2 (l-H)H 3 (Hpz)(PPr* 3 ) 2 (l-pz) 2 ] readily and reversibly adds ethylene to give the ethyl derivative [Ir 2 (l-H)H 2 (Et)(l-pz) 2 (Hpz)(PPr* 3 ) 2 ].137 The iodide-bridged dimer [MIr(CO) 2 I(l-I)MeN] 2 ], obtained by InI 3 promoted removal of I~ from [NBu 4 ]- [Ir(CO) 2 I 3 Me], reacts with CO to give [Ir(CO) 3 I 2 Me], a possible key intermediate in iridium-catalysed methanol carbonylation.138 The new fluorine-containing phosphine [(2,6-F 2 H 3 C 6 ) 2 PCH 2 CH 2 P(C 6 H 3 F 2 -2,6) 2 ] reacts with [MIrCl(l-Cl)Cp*N2 ] to give [MIrCl 2 Cp*N2M(C 6 H 3 F 2 -2,6) 2 PCH 2 CH 2 P(C 6 H 3 F 2 -2,6) 2N].139 Oxidative addition of water to the dinuclear Ir(I) complex cis-trans-[Ir 2 (l-Cl) 2M(R),(S)-ppfpPh 2N2 ] a§ords [MIrHCl(l-OH)M(R),(S)-ppfpPh 2N2 ] as a mixture of cis and trans hydroxy-bridged isomers.Lewis base pre-co-ordination was thought to be necessary to trigger oxidative addition.140 Controlled potential electrolysis of a solution of [Ir 3 (CH 2 CN)(g4-C 5 Me 5 )Cp* 2 (l3 - Annu. Rep. Prog. Chem., Sect.A, 1999, 95, 375–408 395S) 2 ]` in CD 3 CN at[1.55V resulted in catalytic generation of oxalate via coupling of two molecules of CO 2 .141 The product of the reaction between [Co 2 (CO) 8 ] and REER, newly formulated as [Co 3 (l3 -E)R(CO) 9 ] (E\S, R\Ph, Et), reacts with PhC–– – CH to give [Co 3 (l3 -E)MPhC–– CHC(O)RN(CO) 7 ] via insertion of phenylacetylene into an acyl intermediate followed by co-ordination of the acyl oxygen to give a five-membered metallacyclic ring.142 The [Rh 4 (CO) 12 ] catalysed hydroformylation of vinylpyridine has been studied.While 3-vinylpyridine is transformed into a mixture of linear and branched aldehydes, 4-vinylpyridine undergoes hydrogenation exclusively to a§ord 2-ethylpyridine, and 2-vinylpyridine shows intermediate behaviour, undergoing hydrogenation and hydroformylation.143 Diphenylditelluride reacts with [Ir 6 (CO) 15 ]2~ and [Ir 6 (CO) 16 ] to give [Ir 6 (CO) 14 (l-TePh)]~ and [Ir 6 (CO) 13 (l-TePh) 2 ] respectively, containing one and two edge bridged phenyltellurate ligands.Electrochemical experiments suggest that addition of PhTeTePh occurs upon oxidation of the dianion.144 Pyrolysis of [NMe 4 ]- [Co 9 (l-C)(CO) 14 ] in Me(OCH 2 CH 2 ) 2 OMe at 130 °C gave the paramagnetic dianion [NMe 4 ] 2 [Co 9 (C 2 )(CO) 19 ], described as a tricapped trigonal prism of Co atoms with an interstitial acetylide.145 8 Nickel, palladium and platinum The dinuclear l-alkylidene-l-hydride cation [Pd 2 (dppf) 2 (l-H)(l-CHCH 2 Ar)]Br (Ar\p-MeOC 6 H 4 ) has been isolated from the reaction between [PtCl 2 (dppf)] and NaBH 4 and norbornene.Alternatively, treatment of [PtCl 2 (dppf)] with LiBEt 3 Hgave an insoluble precipitate formulated as [MPtH(dppf)Nn] which also reacts with pmethoxybromostyrene to give [Pd 2 (dppf) 2 (l-H)(l-CHCH 2 Ar)]Br.146 Binuclear palladium, nickel and rhodium salts of the type [M 2 L1(OAc) 2 ][BF 4 ] (M\Pd, Ni) [Pd 2 L1Me 2 ][BF 4 ] and [Rh 2 L1(CO) 2 ][BF 4 ] have been prepared from the corresponding metal precursors and L1H, (L1H\1,3-bis[M2-(diphenylphosphino)benzylidene Namino]propan-2-ol).The rhodium derivative is an active catalyst for the hydrosilation of acetophenone.147 Oxidative addition of the Si–Si bond in 1,1,6,6- tetramethyl-1,5,6-trisilaspiro[4.4]nonane to [Pd(CNBu5) 2 ] gave the silylene-bridged dimer [Pd 2 (CNBu5) 2 (l-CNBu5)Ml-SiMe 2 (CH 2 ) 3 Si(CH 2 ) 3 SiMe 2N].Reaction of 1,1,6,6- tetramethyl-1,5,6-trisilaspiro[4.4]nonane with [Pd(g3-C 3 H 5 )Cp] also results in oxidative addition to a§ord the stable Pd(IV) derivative [PdMSiMe 2 (CH 2 ) 3N2 SiCH 2 CH––CH 2 ].148 The binuclear palladium complexes [Pd 2 (l- SiHPh 2 ) 2 (PMe 3 ) 2 ] and [Pd 2 (l-SiHPh 2 ) 2 (PMe 3 ) 3 ], isolated by fractional crystallisation from a reaction mixture of [PdEt 2 (PMe 3 ) 2 ] and SiH 2 Ph 2 , contain bridging silyl ligands with an agostic interaction between the H of l-SiHPh 2 and palladium.149 Catalysis of the Baeyer–Villiger oxidation of ketones by the diphosphine complexes [MPd(P–P)(l-OH)N2 ] (P–P\dppm, dppe, dppp, dppb) has been studied.The catalyst activity depends largely on chelate ring size and bite angle, larger ring sizes giving more e¶cient catalysts.Catalysis appears to involve cleavage of the hydoxy-bridged dimer and the formation of a peroxymetallacyclic intermediate via intramolecular nucleophilic attack of a co-ordinated hydroperoxy ligand at the carbonyl carbon of a coordinated ketone.150 The alkynyl-bridged dimer trans-[MPt(PPh 3 )(C 6 F 5 )(l-g1:g2-C–– – CR)N2 ] (R\OEt, Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 396OMe) reacts with PhSH to give the thiolate cyclobutene-diylidene bridged cis- [MPt(PPh 3 )(C 6 F 5 )N2Ml-CCEtMeOH)C(C––CEtMe)N(l-SPh)], via [2]2] cycloaddition of two alkynyl fragments and elimination of water.151 Hydrolysis of the g3- allenyl/propargyl platinum complex [Pt(PPh 3 ) 2 (g3-C 3 H 3 )][BF 3 ] gave the diplatina –g6-diallylether derivative [MPt(PPh 3 ) 2N2Ml-O(C 3 H 4 ) 2N].152 The isomeric diplatinum complexes syn-[Pt 2 (l-dpmp) 2 (CNR) 2 ][[PF 6 ] 2 and anti-[Pt 2 (l- dpmp) 2 (CNR) 2 ][[PF 6 ] 2 have been isolated from the reaction between [Pt 2 (CNR) 6 ]- [PF 6 ] 2 and dpmp.Addition of [M 3 (CNxyl) 6 ] to syn-[Pt 2 (l-dpmp) 2 (CNR) 2 ][PF 6 ] 2 gave the linear d9–d10–d9 trinuclear cluster [Pt 2 M(l-dpmp) 2 (CNxyl) 2 ][PF 6 ] 2 via a one-electron transfer while the anti-isomer reacts with [M 3 (CNR) 6 ] to give the Aframe trinuclear cluster [Pt 2 M(l-dpmp) 2 (CNR) 2 ][PF 6 ] 2 via insertion of the d10 [M(CNR) 2 ] fragment into the Pt–Pt r-bond.153 The activated alkyne dmad reacts with [Pt 3 (l-CO) 3 L 3 ] (L\PCy 3 ) and [Pt 6 (l-CO) 6 (l-dppm) 3 ] at low temperature to give [Pt 3 (l-CO) 3 L 3 (l-dmad)] and [Pt 6 (l-CO) 6 (l-dppm) 3 (l-dmad)] which undergo fragmentation upon warming to give [Pt 2 (CO) 2 L 2 (l-dmad)] and [Pt 2 (CO) 2 (l- dppm)(l-dmad)] respectively.154 Oxidative addition of Ni(0) to the phosphavinyl phosphonium complex [NiCl(PPh 3 )Mg2-CCl(PPh 3 )––PN(SiMe 3 ) 2 ] gave the phosphavinylidene- phosphorane [Ni 2 Cl 2 (PPh 3 ) 2Ml-g2:g2-C(PPh 3 )––PN(SiMe 3 ) 2N] in which the bridging P-containing ligand acts as a six-electron donor to the two nickel atoms.155 The second harmonic generation of the cyclometallated imine complexes [M 2 (l-X)(l-SCnH 2n`1 )(RC 6 H 3 CH––NC 6 H 4 R@)] (M\Pd, Pt; X\Cl, CH 3 CO 2 ; R, R@\NO 2 , OC 8 H 17 , NBu 2 , n\4 or 8) has been measured and their b-values compared with those of the free imine.156 9 Heterometallics The bimetallic ruthenium olefin metathesis catalysts [(g6-p-cym)RuCl(l- Cl) 2 RuCl(PCy 3 )M––C(CHCPh 2 )HN], [(g6-p-cym)OsCl(l-Cl) 2 RuCl(PCy 3 )M––C- (CHCPh 2 )HN] and [(g6-p-cym)RhCl(l-Cl) 2 RuCl(PCy 3 )M––C(CHCPh 2 )HN] have been prepared and their catalytic activity towards the ring opening metathesis polymerisation of cycloocta-1,5-diene shown to increase in the order Ru\Os\Rh, all with higher activities than the monomer [RuCl 2 (PCy 3 ) 2 (––CHR)] (R\CHCPh 2 , Ph).157 The cationic carbene complex [M(CO) 2 (–– – CPh)Cp][BBr 4 ] (M\Mn, Re) reacts with [NMe 4 ][FeH(CO) 4 ] to give the carbene bridged [MFe(CO)xMl-C(H)PhNCp] (x\5, Mn, x\6, Re) and [M(CO) 3 Cp]. The former reacts with CO to give the benzene-co-ordinated acyl complex [Fe(CO) 3 (PhCHCO)] via cleavage of the l-C–Mn and Mn–Fe bonds while the latter undergoes CO substitution with PPh 3 to give [ReFe(CO) 5 (PPh 3 )Ml-C(H)PhNCp].158 The complex [M(CO) 2 (–– – CPh)Cp][BBr 4 ] (M\Mn, Re) reacts with [N(PPh 3 ) 2 ][FeCo(CO) 8 ] to give carbyne-bridged [MCo(CO) 5 (l-CC 6 H 5 )Cp] and carbene-bridged [MCo(CO) 5Ml-C(CO)C 6 H 5NCp]; the latter reacts with [Fe 2 (CO) 9 ] to give [MFeCo(CO) 8 (l3 -CC 6 H 5 )Cp].159 Similarly, [M(CO) 2 (–– – CC 6 H 5 )Cp][BBr 4 ] (M\Mn, Re) reacts with [NEt 4 ][Fe 2 (CO) 7 (l-SR)] to give the binuclear carbene-bridged [MFe(CO) 5Ml-(C 6 H 5 )(SR)NCp] (R\C 4 H 9 , C 6 H 5 , p-CH 3 C 6 H 4 ).160 The A-frame acetylide [RhIr(CO) 2 (l-g1: g2-C–– – CPh)(l-dppm) 2 ][SO 3 CF 3 ] reacts with CO and SO 2 to give [RhIr(CO) 2 (l-CO)(l-g1:g2-C–– – CPh)(l-dppm) 2 ][SO 3 CF 3 ] Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 397and [RhIr(CO) 2 (l-SO 2 )(l-g1: g2-C–– – CPh)(l-dppm) 2 ][SO 3 CF 3 ] respectively. Addition of H~ occurs exclusively at iridium to give [RhIrH(CO) 2 (l-g1:g2-C–– – CPh)(l- dppm) 2 ] which subsequently rearranges into its phenyl vinylidene isomer [RhIr(CO) 2 (l-g1:g2-C––CHPh)(l-dppm) 2 ].Neutral donor ligands such as phosphines, olefins and alkynes all bind as two-electron donors to iridium. In the case of terminal alkynes, [RhIr(CO) 2 (PhC–– – CH)(l-g1:g2-C–– – CPh)(l-dppm) 2 ][SO 3 CF 3 ] undergoes oxidative addition to a§ord the bis(acetylide) [RhIrH(CO) 2 (l-g1:g2- C–– – CPh) 2 (l-dppm) 2 ][SO 3 CF 3 ].161 The heterometallic complexes [Fe(CO) 3 (SiR 3 )(l- dppm)Pd(g3-allyl)] and [Fe(CO) 3Ml-Si(OR) 2 ORN(l-dppm)PdCl] are e§ective catalysts for the dehydrogenative coupling of triorganotin hydrides.The catalyst properties and life-times depend largely on the substituents at silicon; a possible reaction mechanism has been discussed.The results of these catalytic studies have been compared with those of several mononuclear Pd(II) complexes. In general, mononuclear Pd(II) complexes are less e¶cient catalysts than their heterobinuclear counterparts.162 The bis(alkynyl)-bridged [M(PEt 3 )Cp*(l-C–– – CR) 2 M@(C 6 F 5 ) 2 ] (M\Rh,M@\Pt, Pd, M\Ir, M@\Pt, Pd) and alkynylhalide-bridged [M(PEt 3 )Cp*(l-C–– – CR)(l- X)M@(C 6 F 5 ) 2 ] (X\Cl, I) complexes have been isolated from the reaction between [M@(C 6 F 5 ) 2 (thf) 2 ] and the corresponding bis(alkynyl) and monoalkynyl derivatives [M(C–– – CR) 2 (PEt 3 ) 2 Cp*] and [M(C–– – CR)X(PEt 3 ) 2 Cp*] respectively.In the majority of cases the alkynyl ligand is r-bonded to the Group 9 metal and g2-bonded to Pd or Pt. In the case of [Rh(PEt 3 )Cp*(l-r: g2-C–– – CSiMe 3 )(l-g2: r-C–– – CSiMe 3 )Pt(C 6 F 5 ) 2 ] the structure is zwitterionic, and comprised of the alkynyl fragments [Rh`(C–– – CSiMe 3 )(PEt 3 )Cp*] and cis-[Pt~(C–– – CR)(C 6 F 5 ) 2 ] held together by g2-bonding of the alkynyl groups.163 Square planar trans-[Ir(CO)ClMPh 2 P(C 5 H 4 N-2)N] reacts with SO 2 , halogens, HCl and CH 3 I in a manner reminiscent of Vaska’s compound, and with [PdCl 2 (NCPh) 2 ] to give the Ir(II)–Pd(I) complex [IrPd(CO)Cl 3Ml- Ph 2 P(C 5 H 4 N-2)N2 ].The hydroformylation of styrene using trans- [Ir(CO)ClMPh 2 P(C 5 H 4 N-2)N] as a catalyst precursor is considerably faster than that with Vaska’s compound, albeit with lower chemoselectivity.A modified catalytic cycle has been presented.164 Aryllithium reagents react with the l-(1-3-g: 4-7-cycloheptatrienyl) complex [Mn(CO) 3 Fe(CO) 3 (C 7 H 7 )] 48, via addition to CO to give an intermediate acylate, 49, which reacts with Et 3 OBF 4 to give [Mn(CO) 3 Fe(CO) 3MC 8 H 7 (OEt)ArN] 50, via ring opening coupling of the polyene and alkoxycarbene (Scheme 10).165 The Pd(0) mediated coupling of transition-metal iodides and trialkyltin acetylide has been investigated.Oxidative addition of [g5-1-(diphenylphosphino)-2,4-diphenylcyclopentadienyl] tricarbonylmetal iodide 51 (M\Mo, W) to Pd(0) gives [M(CO) 3 Pd(PPh 3 )I(g5-1-Ph 2 P-2,4-Ph 2 C 5 H 2 )] 52, which readily undergoes transmetallation with trialkyltin acetylide to a§ord trans-[M(CO) 3 Pd(PPh 3 )(C–– – CPh)(g5-1- Ph 2 P-2,4-Ph 2 C 5 H 2 )] 53. At 353 K, cis–trans isomerisation to give 54 followed by reductive elimination a§ords the expected acetylide [M(CO) 3 (C–– – CPh)(g5-1-Ph 2 P-2,4- Ph 2 C 5 H 2 )] 55 (Scheme 11).166 The heterometallic acetylide-bridged [WRe(CO) 5 (l-X)(l-C–– – CPh)Cp*] (X\I, Br) has been prepared from the reaction between [ReX(CO) 5 ] and [W(CO) 3 (C–– – CPh)Cp*], and converted into the thiolate- and acetate-bridged derivatives [WRe(CO) 5 (l-SPh)(l-C–– – CPh)Cp*] and [WRe(CO) 5 (l-O 2 CMe)(l-C–– – CPh)Cp*] respectively. Oxidation of [WRe(CO) 5 (l-SPh)(l-C–– – CPh)Cp*] gave two linkage isomers Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 398(CO)3Mn Fe(CO)3 (CO)3Mn Fe C O Ar CO CO Fe EtO Ar Mn(CO)3 (CO)3 50 2 LiAr – 49 48 Scheme 10 Scheme 11 of the sulfinate-bridged complexes [WRe(CO) 5 (l-SO 2 Ph)(l-C–– – CPh)Cp*], one with oxygen co-ordinated to Re the other to tungsten.167 Treatment of the iron acetylide [Fe(C–– – CH)(dppe)Cp*] with Schwartz’s reagent [MZrHClCp 2Nn] results in hydrogen elimination to give [Fe(dppe)Cp*(C–– – C)ZrClCp 2 ], not the expected product [Fe(dppe)Cp*MC(H)––C(H)NZrClCp 2 ], possibly because steric protection of the a-carbon of the iron acetylide prevents close approach of the electrophilic hydride.168 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 399Qualitative and semi-qualitative arguments suggest that Robinson’s proposal of a Ga–– – Fe triple bond in [Ar*GaFe(CO) 4 ] [Ar*\2,6-(2,4,6-triisopropylphenyl)phenyl] is unfounded. Moreover, experimental data and theory support a single Ga–Fe dative bond which apparently ‘‘comes no closer to a triple bond than does the Fe–P bond in [Fe(CO) 4 (PPh 3 )]’’.169 O O R R N3Zr Fe CO CO O O Fe CO CO ZrN3 R R N3 = HC{SiMe2N(2-FC6H3)}3 (56, R = Me; 57, R = OMe) + (7) Ring opening addition of the lactones 1,3-dimethyl-6H-benzo[b]naphtho[1,2-d]- pyranone and 1,3-dimethoxy-6H-benzo[b]naphtho[1,2-d]pyranone with [ZrMHC[SiMe 2 N(2-FC 6 H 3 )] 3NFe(CO) 2 Cp] gave the aryloxozirconium acyl iron derivatives 56 and 57 respectively [eqn.(7)]; the latter readily decarbonylates to generate the corresponding heterobimetallic in which the iron atom is r-bonded directly to the naphthalene ring.170 The vinylmethyltitanium complex [Ti(CH––CH 2 )(Me)Cp* 2 ] reacts with the Group 12 derivatives MLX, [MCuCl(PMe 3 )N4 ], [MCuCl(PPh 3 )N4 ], [MCu(C–– – CPh)(PMe 3 )N4 ] and [MAuCl(PPh 3 )N4 ] to give [TiCp* 2 X(l-C––CH 2 )ML], via liberation of methane.171 The carbonylation of anti-[Cr(CO) 3 (l-g1:g1-ind)Ir(cod)] gives first [g1-Mg6- Cr(CO) 3 (ind)NIr(cod)(CO) 2 ] at 273K and then [g1-Mg6-Cr(CO) 3 (ind)NIr(CO) 4 ] at 313 K, both of which contain an g1-co-ordinate iridium.In contrast, anti-[Cr(CO) 3 (l- g1:g1-ind)Ir(C 8 H 14 ) 2 ] reacts with CO to give [g1-Mg6-Cr(CO) 3 (ind)NIr(CO) 4 ] in a single step.172 Reaction of [(CrCp*) 2 (B 4 H 8 )] with BHCl 2 ·SMe 2 results in cluster expansion to give [(CrCp*) 2 (B 5 H 9 )], a six-skeletal electron-pair cluster based on a trigonal bipyramidal Cr 2 B 3 unit.Reaction of [(CrCp*) 2 (B 4 H 8 )] with [Fe 2 (CO) 9 ] and [Co 2 (CO) 8 ] gave the mixed-metal metallaboranes [(CrCp*) 2 (B 4 H 8 )Fe(CO) 3 ], and [(CrCp*) 2 (B 4 H 7 )Co(CO) 3 ] respectively.In contrast, the molybdaborane [(MoCp*) 2 (B 5 H 9 )], reacts with [Fe 2 (CO) 9 ] to give [(MoCp*) 2 (B 5 H 9 )Fe(CO) 3 ] with a bicapped octahedral geometry.173 The molybdenum dimer [Mo 2 (CO) 4 Cp 2 ] reacts with [Ru(CO) 2 (C–– – CR)Cp] (R\Me, Ph) to give the metalloalkyne bridged [Cp 2 Mo 2 (CO) 4 (l-g2- MeC–– – C)Ru(CO) 2 Cp] and with [Fe(CO) 2 (C–– – CR)Cp] to give [Mo 2 (CO) 4 (l-g2- HC–– – CR)Cp 2 ], via alkyne group transfer.174 Treatment of [Co 2 (CO) 6 (l-PhC–– – CH)] in refluxing thf with [Mo 2 (CO) 4 Cp 2 ] gave the l-alkylidyne clusters [Co 2 Mo(CO) 8 (l3 - CCH 2 Ph)Cp], as the major product together with minor amounts of [CoMo 2 (CO) 7 (l3 -CCH 2 Ph)Cp 2 ] and [Co 2 Mo 2 (CO) 4 (l-CO) 4 (l4 -PhC–– – CH)Cp 2 ].In contrast, the reaction between [Co 2 (CO) 6 (l-CF 3 C–– – CR)] (R\H, CF 3 ) and [Mo 2 (CO) 4 Cp 2 ] results in metal atom exchange to give [CoMo(CO) 5 (l- Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 400CF 3 C–– – CR)Cp].175 Co-ordination of the terminal alkyne groups of [Ru(C 9 H 7 )(PPh 3 ) 2MC–– – CCPh 2 (C–– – CH)N] and [Ru(PPh 3 ) 2 (g5-C 9 H 7 )MC–– – CCH–– CH(C–– – CPh)N] to [Co 2 (CO) 8 ] a§ords [RuCo 2 (CO) 6 (PPh 3 ) 2 (C 9 H 7 )MC–– – CCPh 2 (l-g2- C–– – CH)N] and [RuCo 2 (CO) 6 (PPh 3 ) 2 (C 9 H 7 )MC–– – CCH––CH(l-g2-C–– – CPh)N] both of which undergo Pauson–Khand cyclisation with strained cyclic alkenes such as norbornene to generate the corresponding cyclopentenone derivatives.176 Pentamethylcyclopentadienyl gallium reacts with [Fe(CO) 3 (cht)], [Co 2 (CO) 8 ] and [Ni(CO) 4 ] to give [Fe 2 (CO) 6 (l-GaCp*) 3 ], [Co 2 (CO) 6 (l-GaCp*) 2 ] and [Ni 4 (CO) 6 (GaCp*) 4 ] respectively.In each case GaCp* acts as a ligand by virtue of the gallium centred lone pair; the p-bonding between the Cp* unit and the gallium is preserved.GaCp* is similar in its electronic properties to triorganophosphines i.e. a good r-donor but a poor p-acceptor.177 The 46-electron heteronuclear clusters [PtM(l3 -g1: g1:g2-PhC––CC––CPh)(CO) 5 (PPh 3 ) 2 ] are formed by treating [Pt(g2- PhC–– – CC–– – CPh)(PPh 3 ) 2 ] with [Fe(CO) 5 ] or [Ru 3 (CO) 12 ] in refluxing toluene.178 The oxo-capped trinuclear clusters [MFe 2 (CO) 6 (l-SR)(l3 -O)(g5-C 5 H 4 R1)] have been prepared by reacting [NEt 3 H][Fe 2 (CO) 7 (l-SR)] with the triply bonded dimer [MM(CO) 2 (g5-C 5 H 4 R1)N2 ] (M\Mo, W; R1\H, MeCO, MeO 2 C, EtO 2 C) followed by air oxidation.179 Thermolysis of the thiocarbonyl-capped cluster [(CoCp) 2MFe(CO) 2 (PPh 3 )N(l3 -S)(l3 -CS)] in CS 2 a§ords [(CoCp) 2MFe(CO)(PPh 3 )N(l3 - S)Ml3 -CSC(S)SN], via coupling of the nucleophilic thiocarbonyl with CS 2 .180 Reaction of the phosphinidene cluster [Ru 4 (CO) 13 (l3 -PPh)] with [W(CO) 3 (C–– – CPh)L] (L\Cp, Cp*) gave interconvertible isomers of [WRu 4 (CO) 11 (l3 -PPh)(l-C–– – CPh)L], based on a WRu 4 P octahedral core with the acetylide co-ordinated to a WRu 2 triangle and its C–C vector perpendicular to the Ru–Ru edge.The two isomers di§er in the location of the phosphinidene, either trans or cis to theWatom.181 Condensation of the imido cluster [Ru 3 (CO) 10 (l3 -NPh)] with [WO 2 (C–– – CR)Cp*] gives [WRu 3 (CO) 8 O(l-O)(C–– – CR)(l-NPh)Cp*] (R\Ph, CMe––CH 2 ).Thermolysis of [WRu 3 (CO) 8 (C–– – CPh)O(l-O)(l-NPh)Cp*] with additional [Ru 3 (CO) 12 ] in refluxing toluene gave [WRu 4 (CO) 10 (C–– – CPh)O(l-O)(l3 - NPh)Cp*].Loss of CO from [WRu 3 (CO) 8 (C–– – CCMe––CH 2 )O(l-O)(l3 -NPh)Cp*] gave [WRu 3 (CO) 6 (C–– – CCMe––CH 2 )(l-O) 2 (l3 -NPh)Cp*]. Addition of CO to [WRu 3 (CO) 6 (C–– – CCMe––CH 2 )(l-O) 2 (l3 -NPh)Cp*] a§ords first [WRu 3 (CO) 7 - (C–– – CCMe––CH 2 )O(l-O)(l3 -NPh)Cp*] and then [WRu 3 (CO) 8 (C–– – CCMe––CH 2 )O 2 (l3 - NPh)Cp*], transformations involving dissociation of the g2-co-ordinated vinyl and WO 2 fragments respectively.182 Thermolysis of the acetylide-bridged [WOs 3 (CO) 9 (l- C–– – CPh)(l-O) 2 Cp*] with diphenylacetylene at 100 °C gave [WOs 3 (CO) 8 (l- C–– – CPh)(PhC–– – CPh)O(l-O)Cp*] and [WOs 3 (CO) 8 (l-CCPhCPhCPh)(O)(l-O)Cp*] via alkyne co-ordination and acetylide–alkyne coupling respectively.Under similar conditions phenylacetylene reacts with [WOs 3 (CO) 9 (l-C–– – CPh)(l-O) 2 Cp*] to give the analogous coupled product [WOs 3 (CO) 8 (l-CCPhCHCPh)O(l-O)Cp*] together with [WOs 3 (CO) 8 (l-CCPhCCHPh)O(l-O)Cp*], via an alkyne to vinylidene rearrangement. 183 Carbonylation of the carbido–benzofuryl cluster [WOs 3 (l-H) 2 (CO) 9 (l4 - C)Cp*(l-C 8 H 6 O)] a§ords [WOs 3 (l-H)(CO) 11 (l4 -C)Cp*], which decarbonylates in the presence of trimethylamineN-oxide and diisopropylacetylenedicarboxylate to give the allyl cluster [WOs 3 (CO) 10MC 3 H(CO 2 Pr*) 2NCp*], via C–C bond formation and hydrogen migration.Thermolysis of [WOs 3 (CO) 10MC 3 H(CO 2 Pr*) 2NCp*] a§ords two clusters, the g6-tetramethylfulvene cluster [WOs 3 (l-H)(CO) 9 - Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 401MC 3 H(CO 2 Pr*) 2NMC 5 Me 4 (CH 2 )N], and the trialkylidyne cluster [WOs 3 (CO) 9 (l-CH)(l- CCO 2 Pr*) 2 Cp*], via cleavage of the two allyl C–C bonds.184 Terminal alkynes HC–– – CR (R\Bu5, Ph) react with [W 2 Ir 2 (CO) 10 Cp 2 ] to give [W 2 Ir 2 (CO) 4 (l-CO) 4 (l4 - g2-HC–– – CR)Cp 2 ] via insertion of the alkyne into the W–W bond.Similarly, [W 2 Ir 2 (CO) 10 Cp 2 ] reacts with the buta-1,3-diynyl derivatives [W(CO) 3 (C–– – CC–– – CH)Cp] to give [W 2 Ir 2 (CO) 4 (l-CO) 4Ml4 -g2- HC 2 C–– – CW(CO) 3 CpNCp 2 ], via regiospecific insertion of the C–– – C–H fragment into the W–W bond.In contrast, while terminal alkynes are unreactive towards [WIr 2 (CO) 11 Cp], the tungsten acetylide [W(CO) 3 (C–– – CR)Cp] (R\Ph, C 6 H 4 Me-4, C 6 H 4 NO 2 -4, C–– – CPh) reacts via insertion into the Ir–Ir bond to give [W 2 Ir 3 (CO) 9 (l- CO)(l4 -g2-C–– – CR)Cp 2 ].185 Reaction of the metallaalkyne [MRu 2 (CO) 2 CpN2 (l-C–– – C)] with [Mo 2 (CO) 4 Cp 2 ] gave [MoRu 2 (l-CO) 3 (l3 -C–– – C)MRu(CO) 2 CpNCp 3 ], a 45-electron cluster with the metallacetylide [C–– – CRu(CO) 2 Cp] triply bridging the MoRu 2 triangle.186 Variable temperature 13C NMR spectroscopic studies have shown that intramolecular scrambling of carbonyl ligands in [Rh 4 (CO) 12 ] and [IrRh 3 (CO) 12 ] occurs via a merry-go-round process about the triangular faces of the metal tetrahedron.Variable pressure 13C spectra of [Rh 4 (CO) 12 ] gave an activation volume of [6^1 cm3 mol~1 indicating that the transition state has a smaller molar volume than the ground sate, consistent with a substantial shortening of the unbridgedM–M bonds relative to the bridged bonds. The free enthalpy of activation for the merry-goround process (42.8^0.4 kJ mol~1 at 298 K) in [Rh 4 (CO) 12 ] is substantially lower than that in [IrRh 3 (CO) 12 ].187 A series of dicationic pentanuclear bow-tie clusters [M(IrCp*) 4 (l3 -S) 4 ]2` (M\Fe, Co, Ni), with 78-, 79- and 80-electrons, have been prepared and their electrochemical properties investigated.In each case the cluster is prepared from the reaction between [MIrCl(l-SH)Cp*N2 ] and the corresponding metal dihalide. The 78-electron cluster [Fe(IrCp*) 4 (l3 -S) 4 ]2` has been prepared by treating the binuclear cluster [MIrCl(l-SH)Cp*N2 ] with FeCl 2 followed by Na[BPh 4 ], while the 79- and 80-electron Co and Ni analogues have been isolated from reaction of [MIrCl(l- SH)Cp*N2 ] with CoCl 2 and NiCl 2 ·6H 2 O respectively.One-electron reduction of each cluster with [CoCp 2 ] gave the corresponding 79- to 81-electron bow-tie clusters [M(IrCp*) 4 (l3 -S) 4 ]` (M\Fe, Co, Ni). X-Ray structural studies have revealed dramatic changes in the bow-tie cluster core as the electron count increases from 78 to 81, which have been explained in terms of valence electron counts and molecular orbital analysis.188 The mixed-metal cluster [IrRu 3 H(CO) 13 ] reacts with one and two equivalents of RC–– – CR (R\Ph, Me) to give [IrRu 3 H(CO) 11 (l3 -g2-RC–– – CR)] and [IrRu 3 (CO) 10 (l4 -g2-RC–– – CR)(l-RC––CHR)].The hydrido cluster [IrRu 3 H(CO) 13 ] is active for the catalytic hydrogenation of diphenylacetylene to give stilbene.189 The 50-electron nido-cluster [Ru 3 (CO) 7 (PPh 3 ) 2 (l3 -Se) 2 ] reacts with [M(CO) 3 (NCMe) 3 ] (M\Mo, W) to give the 60-electron bicapped square planar clusters [M 2 Ru 2 (CO) 6 (l-CO) 4 (PPh 3 ) 2 (l3 -Se) 2 ].190 Thermolysis of [Re 5 Ir(CO) 17 (l6 - C)Ml3 -Re(CO) 3N2 ]2~ in refluxing MeCN results in loss of a [Re(CO) 3 ]` capping unit to give [Re 5 Ir(CO) 17 (l6 -C)Ml-Re(CO) 3N]3~.Addition of one or two equivalents of [AuCl(PPh 3 )] to [Re 5 Ir(CO) 17 (l6 -C)Ml-Re(CO) 3N]3~ gives [Re 6 Ir(CO) 20 (l-C)Ml- Au(PPh 3 )N]2~ and [Re 6 Ir(CO) 20 (Ml-C)Ml-Au(PPh 3 )N2 ]~ respectively. The 13C NMR spectrum of the mono gold derivative has been interpreted in terms of several isomers that di§er in the location of the l3 -Au(PPh 3 ) ligand.191 The mixed ruthenium–rho- Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 402dium carbonyl anions [Ru 3 Rh(CO) 13 ]~ and [RuRh 3 (CO) 12 ]~ have been prepared and crystallographically characterised as their [N(PPh 3 ) 2 ]` salts. Both anions have a tetrahedral core the former with idealised C 3 -symmetry the latter with C4 symmetry; both contain terminal and bridging carbonyl ligands.192 Reaction of [Ir 4 H(CO) 14 (l-PPh 2 )] with [Pt(dppe)(g2-P–– – CBu5) gave four Ir 4 Pt clusters [Ir 4 Pt(dppe)(CO)nMl-PC(H)Bu5N(l-PPh 2 )] (n\9, 10), [Ir 4 PtH(dppe)(CO) 7 (l- CO)(l-PCH 2 Bu5)(l-PPh 2 )] and [Ir 4 Pt(dppe)(CO) 8 (l-CO)(l5 -P)(l-PPh 2 )]; the first three involve hydrometallation of the P–C triple bond of the phosphaalkyne, while the last involves cleavage of the P–– – C triple bond.193 Electrophilic addition of ClHgM to [NEt 4 ] 2 [Fe 5 (C)(CO) 14 ] a§ords the tetranuclear clusters [NEt 4 ][Fe 5 (C)(CO) 14 (l- HgM)] [M\Mo(CO) 3 Cp, W(CO) 3 Cp, Mn(CO) 5 , Co(CO) 4 , Fe(CO) 2 Cp].In each case cyclic voltammetry revealed three main electrode processes, one irreversible oxidation and two reductions.194 Addition of [Ir(CO) 4 ]~ to [Pt 3 (l3 -CO)(l-dppm)]2` results in metal atom substitution of Pt by [Ir(CO)]~ to give [Pt 2 Ir(l3 -CO)(CO)(l- dppm) 3 ]` via the isomeric butterfly clusters [Pt 3MIr(CO)(l-CO) 2N(l-CO)(l-dppm) 3 ]` and [Pt 2 IrMPt(CO)(l-CO) 2N(CO)(l-dppm) 3 ]`, in which the iridium atom occupies wingtip and hinge positions respectively.195 Irradiation of a thf solution of [RhH 2 (SiEt 3 ) 2 Cp*] containing [MNi(CO)CpN2 ], [MCo(NO)CpN2 ] and [M(CO) 2 Cp] (M\Fe, Ru) with a high pressure mercury lamp gave [Rh 2 Ni 2 (CO) 2 Cp 2 Cp* 2 ], [RhCo 2 (NO) 2 Cp 2 Cp*] and [RhM 2 (CO) 4 Cp 2 Cp*] respectively.The ruthenium tetrahydride [(RuCp*) 2 (l-H) 4 ] also reacts with [MNi(CO)CpN2 ], [Co(CO) 2 Cp] and [MFe(CO) 2 CpN2 ] via condensation to give [Ru 2 Ni 2 (CO) 2 Cp 2 Cp* 2 ], [Ru 2 Co(CO) 4 CpCp* 2 ] and [Ru 2 Fe 2 (CO) 4 Cp 2 Cp* 2 ] respectively.196 The 84-electron hexaplatinum clusters [Pt 6 (l-CO) 6 (l-dppm) 3 ] reacts in a 1: 2 mol ratio with either zero-electron ligands [ML]` (L\PPh 3 , M\Cu, Ag, Au) or InX 3 (X\Cl, Br) or the two-electron ligands Tl` and Hg to give the 84-electron clusters [Pt 6 (l-ML) 2 (l- CO) 6 (l-dppm) 3 ]2` or [Pt 6 (l-InX 3 ) 2 (l-CO) 6 (l-dppm) 3 ]2` or 88-electron cluster [Pt 6 (l3 -M) 2 (l-CO) 6 (l-dppm) 3 ]n` (M\Tl, n\2; M\Hg, n\0).Addition of [Ir(CO) 4 ]~ to [Pt 6 (l-CO) 6 (l-dppm) 3 ] a§ords the 98-electron anion [Pt 6Ml3 - Ir(CO) 2N(l-CO) 6 (l-dppm) 3 ]~, which adds [Au(PPh 3 )]` to give [Pt 6Ml-Ir(CO) 2NMl- Au(PPh 3 )N(l-CO) 6 (l-dppm) 3 ], and is expected to have a significant intertriangular Pt · · · Pt separation.197 The layered platinum ruthenium cluster [Pt 3 Ru 6 (CO) 19 (SMe 2 )(l3 -H)(l-H)(l3 -PhC 2 Ph)] catalyses the hydrogenation of PhC–– – CPh to (Z)-stilbene with higher turnover numbers than [Pt 3 Ru 6 (CO) 20 (l3 -H)(l- H)(l3 -PhC 2 Ph)].The higher catalytic activity is thought to arise from the lability of the SMe 2 ligand co-ordinated to the PhC–– – CPh bridged Ru 3 triangle, the most likely site for catalytic activity.198 Hydosilation of diphenylacetylene with triethylsilane catalysed by [Ru 6 Pt 3 (CO) 20 (l-H)(l3 -H)(l3 -PhC 2 Ph)] a§ords (E)-[(1,2- diphenyl)ethenyl]triethylsilane. A mechanism involving CO dissociation, oxidative addition of R 3 SiH, alkyne co-ordination and migratory insertion to form a r-g2-vinyl fragment, followed by Si–C reductive elimination to liberate the silylolefin is suggested to occur at a single Ru 3 triangle.199 Annu.Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 403References 1 (a)W. T. Wang, J. Chem. Soc., Dalton Trans., 1998, 1253; (b) T.P. Fehlner, J. Chem. Soc., Dalton Trans., 1998, 1525; (c) C.C.Cummins, Chem. Commun., 1998, 1777; (d) C. Bianchini and A. Meli, Acc. Chem. Res., 1998, 109; (e) P. J. Dyson, Adv. Organomet. Chem., 1998, 44, 43; ( f ) K.H. Whitmire, Adv. Organomet. Chem., 1998, 42, 1; (g) H. Ognio and H. Tobita, Adv. Organomet. Chem., 1998, 42, 223; (h) U. Koelle, Chem. Rev., 1998, 98, 1313; (i) D. Braga, F. Grepioni and G. R. Desiraju, Chem. Rev., 1998, 98, 1375; (j) T.Naota, H. Takaya and S. I. Murahashi, Chem. Rev., 1998, 98, 2599; (k)M. I. Bruce, Chem. Rev., 1998, 98, 2797. 2 D.L. Clark, D. R. Click, S. K. Grumbine, B. L. Scott and J. G. Watkin, Inorg. Chem., 1998, 37, 6237. 3 A. Oh§, T. Zippel, P. Arndt, A. Spannenberg, R. Kempe and U. Rosenthal, Organometallics, 1998, 17, 1649. 4 T. Zippel, P. Arndt, A. Oh§, A. Spannenberg, R.Kempe and U. Rosenthal, Organometallics, 1998, 17, 4429. 5 J. S. Vilardo, M. G. Thorn, P. E. Fanwick and I. P. Rothwell, Chem. Commun., 1998, 2425. 6 M. Galakhov, M. Mena and C. Santamaria, Chem. Commun., 1998, 691. 7 A.V. Firth and D. W. Stephan, Inorg. Chem., 1998, 37, 4726. 8 A.V. Firth, E. Witt and D.W. Stephan, Organometallics, 1998, 17, 3716. 9 S. Back, H. Pritzkow and H.Lang, Organometallics, 1998, 17, 41. 10 P. Yu, T. Pape, I. Uson, M. A. Said, H. W. Roesky, M.L. Montero, H. G. Schmidt and A. Demsar, Inorg. Chem., 1998, 37, 5117. 11 P. Yu, M. L. Montero, C. E. Barnes, H. W. Roesky and I. Uson, Inorg. Chem., 1998, 37, 2595. 12 A. Demsar, A. Pevec, L. Golic, S. Petricok, A. Petric and H. W. Roesky, Chem. Commun., 1998, 1029. 13 S. J. Lancaster, M.T. Thornton-Pett, D.M. Dawson and M. Bochmann, Organometallics, 1998, 17, 3829. 14 F. J. Schattenmann, R. R. Schrock and W.M. Davis, Organometallics, 1998, 17, 989. 15 N. Etkin and D.W. Stephan, Organometallics, 1998, 17, 763. 16 P. L. Holland, R. A. Andersen and R. G. Bergman, Organometallics, 1998, 17, 433. 17 L. H. McAlexander, L. Li, Y. Yang, J. L. Pollitte and Z. Xue, Inorg.Chem., 1998, 37, 1423. 18 X. Liu, L. Li, J. B. Diminnie, G. P. A. Yap, A. L. Rheingold and Z. Xue, Organometallics, 1998, 17, 4597. 19 A. Antinolo, F. Carrillo-Hermosilla, A. Otero, M. Fajardo, A. Garces, P. Gomez-Sal, G. Lopez-Mardomingo, A. Martin and C. Miranda, J. Chem. Soc., Dalton Trans., 1998, 59. 20 M. Tayebani, K. Feghali, S. Gambarotta and G. Yap, Organometallics, 1998, 17, 4282. 21 M. Tayebani, S. Gambarotta and G. Yap, Organometallics, 1998, 17, 3639. 22 A. Antinolo, F. Carillo-Hermosilla, J. Fernandez-Baeza, M. Lanfranchi, A. Lara-Sanchez, A. Otero, E. Palomarres, M. A. Pellinghelli and A.M. Rodriguez, Organometallics, 1998, 17, 3015. 23 T. Y. Lee and L. Hesserle, J. Organomet. Chem., 1998, 553, 397. 24 T. F. Miller, D. L. Strout and M.B. Hall, Organometallics, 1998, 17, 4164. 25 V. Gibson, P. J. Maddox, C. Newton, C. Redshaw, G. A. Solan, A. J. P. White and D. J. Williams, Chem. Commun., 1998, 1651. 26 F. Becke, P. Wiegeleben, T. Ru§er, C. Wagner, R. Boese, D. Blaser and S. Steinborn, Organometallics, 1998, 17, 475. 27 K. Kawamura, M. Shang, O. Wiest and T. P. Fehlner, Inorg. Chem., 1998, 37, 608. 28 J. H. Shin and G. Parkin, Chem.Commun., 1998, 1273. 29 P. Schollhammer, E. Guenin, F. Y. Petillon, J. Talarmin, K. W. Muir and D. S. Yufit, Organometallics, 1998, 17, 1922. 30 M.C. Kuchta, F. G. N. Cloke and P. B. Hitchcock, Organometallics, 1998, 17, 1934. 31 J.-T. Lin and P.-H. Huang, Organometallics, 1998, 17, 3619. 32 S.-G. Shyu, R. Singh and K.-J. Lin, Organometallics, 1998, 17, 4739. 33 H. Adams, C. Allott, M.N. Bancroft and M. J. Morris, J. Chem. Soc., Dalton Trans., 1998, 2607. 34 A. Abbot, M. N. Bancroft, M. J. Morris, G. Hogarth and S. P. Redmond, Chem. Commun., 1998, 389. 35 H. Adams, L. J. Gill and M. J. Morris, J. Chem. Soc., Dalton Trans., 1998, 2451. 36 C. Borgmann, C. Limberg and L. Zsolnai, Chem. Commun., 1998, 2729. 37 M.H. Chisholm, K. Folting, K. S. Kramer and W.E. Streib, Inorg. Chem., 1998, 37, 1549. 38 M.H. Chisholm and M. A. Lynn, J. Organomet. Chem., 1998, 550, 141. 39 M. Scheer, J. Muller, G. Baum and M. Haser, Chem. Commun., 1998, 1051. 40 M. Yoshifuji, Y. Ichikawa, N. Yamada and K. Toyota, Chem. Commun., 1998, 27. 41 X. Zhang, C. A. Dallaghan, E. J. Watson, G. B. Carpenter and D. A. Sweigart, Organometallics, 1998, 17, 2067. 42 X.Zhang, C. A. Dullaghan, G. B. Carpenter, D. A. Sweigart and Q. Meng, Chem. Commun., 1998, 93. 43 J. Li, D. Miguel, M. D. Morales, V. Riera and S. Garcia-Granada, Organometallics, 1998, 17, 3448. 44 B. Bianchi, G. Gervasio and D. Marabello, Chem. Commun., 1998, 1535. 45 U. Piarulli, C. Floriani, N. Re, G. Gervasio and D. Viterbo, Inorg. Chem., 1998, 37, 5142. 46 H. J. Haupt, D. Petters and U.Florker, J. Organomet Chem., 1998, 558, 81. 47 F.M. Hornung, K. W. Klinkhammer and W. Kaim, Chem. Commun., 1998, 2055. 48 A. S. Weller, M. Shang and T. P. Fehlner, Chem. Commun., 1998, 1787. 49 C. Jiang, W. Henderson, T. S. A. Hor, L. J. McCa§rey and Y. K. Yan, Chem. Commun., 1998, 2029. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 40450 J. A. Cabeza, A. Llamazares, V.Riera, R. Trivedi and F. Grepioni, Organometallics, 1998, 17, 5580. 51 C. Jiang, Y. S. Wen, L. K. Liu, T. S. A. Hor and Y. K. Yan, Organometallics, 1998, 17, 173. 52 S. M. Tetrick, M. DiBiase Cavanaugh, F. S. Tham and A. R. Cutler, Organometallics, 1998, 17, 1925. 53 W. Wu, P. E. Fanwick and R. A. Walton, Inorg. Chem., 1998, 37, 3122. 54 C. P. Casey, R. S. Carino, J.T. Brady and R. K. Hayashi, J. Organomet. Chem., 1998, 569, 55. 55 W. A. Hermnann, H. Ding, F. E. Kuhn and W. Scherer, Organometallics, 1998, 17, 2751. 56 K. P. Gable, F. A. Zhuravlev and A. F. T. Yokochi, Chem. Commun., 1998, 799. 57 S. Doherty and G. Hogarth, Chem. Commun., 1998, 1815. 58 S. Doherty, G. Hogarth, M. R. J. Elsgood, W. Clegg, N. H. Rees and M. Waugh, Organometallics, 1998, 17, 3331. 59 V. G. Albano, L. Busetto, C. Camiletti, M. Monari and V. Zanotti, J. Organomet. Chem., 1998, 563, 153. 60 M. Akita, R. Hua, S. A. R. Knox, Y. Moro-Oka, S. Nakanishi and M.I. Yates, J. Organomet. Chem., 1998, 569, 71. 61 S. Anderson, A. F. Hill, A. M.Z. Slawin, A. J. P. White and D. J. Williams, Inorg. Chem., 1998, 37, 594. 62 S. Kuwata, M. Andou, K. Hashizume, Y. Mizobe and M.Hidai, Organometallics, 1998, 17, 3429. 63 M. Vitale, M.E. Archer and B. E. Bursten, Chem. Commun., 1998, 179. 64 O. J. Scherer, T. Hilt and G. Wolmershauser, Organometallics, 1998, 17, 4110. 65 M. Guillemot, L. Toupet and C. Lapinte, Organometallics, 1998, 17, 1928. 66 M. J. MacLachlan, A. J. Lough, W. E. Geiger and I. Manners, Organometallics, 1998, 17, 1873. 67 W. Xue, B.Wang, X. Dai, S. Xu and X. Zhou, Organometallics, 1998, 17, 5406. 68 K.-B. Shiu, S.-L. Wang, F. L. Liao, M.-Y. Chiang, S.-M. Peng, G.-H. Lee, J.-C. Wang and L.-S. Liou, Organometallics, 1998, 17, 1790. 69 C. Natoro and R. J. Angelici, Inorg. Chem., 1998, 37, 2975. 70 J. A. Cabeza, M. A. Martinez-Garcia, V. Riera, D. Ardura and S. Garcia-Granda, Organometallics, 1998, 17, 1471. 71 S. Serron, S. P. Nolan, Y. A. Abramov, L. Brammer and J. E. Petersen, Organometallics, 1998, 17, 104. 72 J. Huang, S. Serron and S. P. Nolan, Organometallics, 1998, 17, 4004. 73 C. Bianchini, D. Masi, A. Meli, M. Peruzzini, F. Vizza and F. Zanobini, Organometallics, 1998, 17, 2495. 74 B. R. Bender, R. T. Hembre, J. R. Norton and E. E. Burnel, Inorg. Chem., 1998, 37, 1720. 75 W. Henderson, J.S. McIndoe, B. K. Nicholson and P. J. Dyson, J. Chem. Soc., Dalton Trans., 1998, 519. 76 J.-J. Cherng, Y.-C. Tsai, C.-H. Ueng, G.-H. Lee, S.-M. Peng and M. Shieh, Organometallics, 1998, 17, 255. 77 J. Willem van Hal and K. H. Whitmire, Organometallics, 1998, 17, 5197. 78 P. Blenkiron, G. D. Enright, P. J. Low, J. F. Corrigan, N. J. Taylor, Y. Chi, J.-Y. Saillard and A.J. Carty, Organometallics, 1998, 17, 2447. 79 A. J. Arce, A. J. Deeming, Y. De Sanctis, S. K. Johal, C. M. Martin, M. Shinhmar, D. M. Speel and A. Vassos, Chem. Commun., 1998, 233. 80 J. A. Cabeza, I. del Rio, V. Riera and D. Ardura, J. Organomet. Chem., 1998, 554, 117. 81 C. Bois, J. A. Cabeza, R. J. Franco, V. Riera and E. Saborit, J. Organomet. Chem., 1998, 564, 201. 82 J. A. Cabeza, I.del Rio, M. Moreno, V. Riera and F. Grepioni, Organometallics, 1998, 17, 3027. 83 J. P. H. Charmant, H. A. A. Dickson, N. J. Grist, S. A. R. Knox, A. G. Orpen, K. Saynor and J. M. Vinas, J. Organomet. Chem., 1998, 565, 141. 84 M. I. Bruce, J. R. Hinchli§e, P. A. Humphrey, P. J. Surynt, B. W. Skelton and A. H. White, J. Organomet. Chem., 1998, 552, 109. 85 M. Nowotny, B.F. G. Johnson, J. F. Nixon and S. Parsons, Chem. Commun., 1998, 2223. 86 W.-Y. Yeh, S. C.-N. Hsu, S.-M. Peng and G.-H. Lee, Organometallics, 1998, 17, 2477. 87 N. Suzuki, T. Kondo and T. Mitsudo, Organometallics, 1998, 17, 766. 88 (a) J.B. Keisler, J. Organomet. Chem., 1980, 190, C36; (b) S. Aime, W. Dastru, R. Gobetto and A. Viale, Organometallics, 1998, 17, 3182. 89 M. I. Bruce, H.-K.Fun, B. K. Nicholson, O. bin Shawkataly and R. A. Thomson, J. Chem. Soc., Dalton Trans., 1998, 751. 90 W. G. Feighery, H. Yao, A. F. Hollenkamp, R. D. Allendoerfer, J. B. Keister, Organometallics, 1998, 17, 872. 91 K. A. Azam, M.B. Hursthouse, S. A. Hussain, S. E. Kabir, K. M.A. Malik, M. Mukhlesur Rahman, E. Rosenberg, J. Organomet. Chem., 1998, 559, 81. 92 E. Arcia, D. S.Kolwaite, E. Rosenberg, K. Hardcastle, J. Ciurash, R. Duque, R. Gobetto, L. Milone, D. Osella, M. Botta, W. Dastru, A. Viale and I. Feidler, Organometallics, 1998, 17, 415. 93 J.-T. Park, H. Song, J.-J. Cho, M.-K. Chung, J.-H. Lee and I.-H. Suh, Organometallics, 1998, 17, 227. 94 G. Suss-Fink, T. Godefroy, V. Ferrand, A. Neels and H. Stoeckli-Evans, J. Chem. Soc., Dalton Trans., 1998, 515. 95 D. H. Hamilton and J. R. Shapley, Organometallics, 1998, 17, 3087. 96 A. J. Deeming and M. Stchedro§, J. Chem. Soc., Dalton Trans., 1998, 3819. 97 V. H. Hansen, A. K. Ma, K. Biradha, R. K. Pomeroy and M. J. Zaworotko, Organometallics, 1998, 17, 5267. 98 H. Song, K. Lee, J.-T. Park and M.-G. Choi, Organometallics, 1998, 17, 4477. 99 M. Graf, K. Merzweiler, G. Bruhn and H.-C.Bottcher, J. Organomet. Chem., 1998, 553, 371. 100 K. A. Azam, M. B. Hursthouse, M.R. Islam, S. E. Kabir, K.M. A. Malik, R. Miah, C. Sudbrake and H. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 405Vahrenkamp, J. Chem. Soc., Dalton Trans., 1998, 1097. 101 S. Aime, W. Dastru, R. Gobetto and A. Viale, Organometallics, 1998, 17, 5353. 102 K. Kiriakidou, M.R. Plutino, F. Prestopino, M.Monari, M. Johansson, L. T. Elding, E. Valls, R. Gobetto, S. Aime and E. Nordlander, Chem. Commun., 1998, 2721. 103 J. Nijho§, M.J. Bakker, F. Hartl, D. J. Stufkens, W. F. Fu and R. van Eldik, Inorg. Chem., 1998, 37, 661. 104 Y. Lui, W.-K. Leong and R. K. Pomeroy, Organometallics, 1998, 17, 3387. 105 S. L. Darling, P. K. Y. Goh, N. Bampos, N. Freeder, M. Montalti, L.Prodi, B. F. G. Johnson and J. K.M. Sanders, Chem. Commun., 1998, 2031. 106 E. Delgado, Y. Chi, W. Wang, G. Hogarth, P. J. Low, G.DEnright, S.-M. Peng, G.-H. Lee and A. J. Carty, Organometallics, 1998, 17, 2936. 107 J. H. Yamamoto, K. A. Udachin, G. D. Enright and A. J. Carty, Chem. Commun., 1998, 2259. 108 W. Wang, J. F. Corrigan, G. D. Enright, N. J. Taylor and A. J. Carty, Organometallics, 1998, 17, 427. 109 P. J. Low, G. D. Enright and A. J. Carty, J. Organomet. Chem., 1998, 565, 279. 110 E. N.-M. Ho and W.-T. Wang, J. Chem. Soc., Dalton Trans., 1998, 513. 111 X. Lei, M. Shang and T. P. Fehlner, Inorg. Chem., 1998, 37, 3900. 112 R. Buntem, J. Lewis, C. A. Morewood, P. R. Raithby, H. Raminez de Arellano and G. P. Shields, J. Chem. Soc., Dalton Trans., 1998, 1091. 113 G. Suss-Fink, I. Godefroy, A. Beguin, G. Rheinwald, A. Neeels and H. Stoeckli-Evans, J. Chem. Soc., Dalton Trans., 1998, 2211. 114 K. Lee and J. R. Shapley, Organometallics, 1998, 17, 3020. 115 B. F. G. Johnson, D. S. Shephard, D. Braga, F. Grepioni and S. Parsons, J. Chem. Soc., Dalton Trans., 1998, 311. 116 K. Lee and J. R. Shapley, Organometallics, 1998, 17, 4030. 117 K. Lee and J.R. Shapley, Organometallics, 1998, 17, 4368. 118 K. Lee, S. R. Wilson and J. R. Shapley, Organometallics, 1998, 17, 4113. 119 J. Green, Chem. Commun., 1998, 1751. 120 M. A. Brook, J. Urschey and M. Stradiotto, Organometallics, 1998, 17, 5342. 121 P. Roussel, M. J. Drewitt, D. R. Cary, C. G. Webster and D. O’Hare, Chem. Commun., 1998, 2205. 122 R.M. De Silva, M.J. Mays, J. E.Davis, P. R. Raithby, M.A. Rennie and G. P. Shields, J. Chem. Soc., Dalton Trans., 1998, 439. 123 S. Bourg, B. Bourg, F. H. Carre and R. J. P. Corriu, Organometallics, 1998, 17, 167. 124 E. C. Constable, O. Eich, C. E. Housecroft and L. A. Johnston, Chem. Commun., 1998, 2661. 125 T. Nishioka, K. Isobe, I. Kinoshita, Y. Ozawa, A. Vazquez de Miguel, T. Nakai and S. Miyajima, Organometallics, 1998, 17, 1637. 126 Y. Kaneko, N. Suzuki, A. Nishiyama, T. Suzuki and K. Isobe, Organometallics, 1998, 17, 4875. 127 Y. Kaneko, T. Suzuki, K. Isobe and P. M. Maitlis, J. Organomet. Chem., 1998, 554, 155. 128 T. Koizumi, K. Osakada and T. Yamamoto, Organometallics, 1998, 17, 5721. 129 M. G. L. Petrucci, A. M. Lebuis and A. K. Kakkar, Organometallics, 1998, 17, 4966. 130 H. Werner, M.Manger, U. Schmidt, M. Laubender and B. Weberndorfer, Organometallics, 1998, 17, 2619. 131 A. Elduque, C. Finestra, J. A. Lopez, F. J. Lahez, F. Merchan, L. A. Oro and M.T. Pinillos, Inorg. Chem., 1998, 37, 824. 132 G. T. Eagle, D. G. Farrer, C. U. Pfa§, J. A. Davies, C. Kluwe and L. Miller, Organometallics, 1998, 17, 4523. 133 A. Castellanos-Paez, S. Castillon, C. Claver, P.W.N. M. van Leeuwen and W.G. J. de Lange, Organometallics, 1998, 17, 2543. 134 R. Fandos, M. Martinez-Ripoll, A. Otero, M. J. Ruiz, A. Rodriguez and P. Terreros, Organometallics, 1998, 17, 1465. 135 M. A. Arthurs, J. Bickerton, S. R. Stobart and J. Wang, Organometallics, 1998, 17, 2743. 136 C. Tejel, M. A. Ciriano, J. A. Lopez, F. J. Lahoz and L. A. Oro, Organometallics, 1998, 17, 1449. 137 E. Sola, V. I. Bakhmutov, F. Torres, A. Elduque, J. A. Lopoz, F. J. Lohez, H. Werner and L. A. Oro, Organometallics, 1998, 17, 683. 138 T. Gha§ar, H. Adams, P. M. Maitlis, G. J. Sunley, M.J. Baker and A. Haynes, Chem. Commun., 1998, 1023. 139 J. Fawcett, S. Friedrichs, J. H. Holloway, E. G. Hope, V. McKee, M. Nieuwenhuyzen, D. R. Russell and G. C. Saunders, J. Chem. Soc., Dalton Trans., 1998, 1477. 140 R. Dorta and A. Togni, Organometallics, 1998, 17, 3423. 141 K. Tanaka, Y. Kushi, K. Tsuge, K. Toyohara, T. Nishioka and K. Isobe, Inorg. Chem., 1998, 37, 120. 142 J. E. Davis, M. J. Mays, P. R. Raithby, V. Sarveswaran and G. P. Shields, J. Chem. Soc., DaltonTrans., 1998, 775. 143 R. Settambolo, S. Scamuzzi, A. Caiazzo and R. Lazzaroni, Organometallics, 1998, 17, 2127. 144 R. D. Pergola, A. Ceriotti, A. Cinquantini, F. F. de Biani, L. Garlaschelli, M. Manassero, R. Piacentini, M. Sansoni and P. Zanello, Organometallics, 1998, 17, 802. 145 S. Martinengo, L. Noziglia, A. Fumagalli, V. G. Albano, D. Braga and F. Grepioni, J. Chem. Soc., Dalton Trans., 1998, 2493. 146 M. A. Zhuravel, D. S. Glueck, L. M. Liable-Sands and A. L. Rheingold, Organometallics, 1998, 17, 574. 147 E. K. van der Beuken, N. Veldman, W.J. J. Smeets, A. L. Spek and B. L. Feringa, Organometallics, 1998, 17, Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 406636. 148 M. Suginome, Y. Kato, N. Takeda, H. Oike and Y. Ito, Organometallics, 1998, 17, 495. 149 Y. J. Kim, S. C. Lee, J. I. Park, K. Osakada, J. C. Choi and T. Yamamoto, Organometallics, 1998, 17, 4929. 150 R. Gavagnin, M. Cataldo, F. Pinna and G. Strukul, Organometallics, 1998, 17, 661. 151 J. R. Berenguer, J. Fornies, E. Lalinde, F. Martinez, L. Sanchez and B. Serrano, Organometallics, 1998, 17, 1640. 152 Y.-C. Cheng, Y.-K. Chen, T.-M. Huang, C.-I. Yu, G.-H. Lee, Y. Wang and J.-T. Chen, Organometallics, 1998, 17, 2953. 153 T. Tanase, H. Ukaji, H. Takahata, H. Toda, T. Igoshi and Y. Yamamoto, Organometallics, 1998, 17, 196. 154 G. J. Spivak and R. J. Puddephatt, J. Organomet. Chem., 1998, 551, 383. 155 W. V. Konze, V. G. Young, Jr. and R. J. Angelici, Organometallics, 1998, 17, 1569. 156 J. Buey, S. Coco, L. Diez, P. Espinet, J. M. Martin-Alverez, J. A. Miguel, S. Garcia-Granda, A. Tesouro, I. Ledoux and J. Zyss, Organometallics, 1998, 17, 1750. 157 E. L. Dias and R. H. Grubbs, Organometallics, 1998, 17, 2758. 158 Y. Tang, J. Sun and J. Chen, J. Chem. Soc., Dalton Trans., 1998, 931. 159 Y. Tang, J. Sun and J. Chen, Organometallics, 1998, 17, 2945. 160 Z. Qui, J. Sen and J. Chen, Organometallics, 1998, 17, 600. 161 D. S. A. George, R. McDonald and M. Cowie, Organometallics, 1998, 17, 2553. 162 P. Braunstein and X. Morise, Organometallics, 1998, 17, 540. 163 I. Ara, J. R. Berenguer, E. Eguizabal, J. Fornies, E. Lalinde, A. Martin and F. Martinez, Organometallics, 1998, 17, 4578. 164 G. Francio, R. Scopelliti, C. Grazia-Arena, G. Bruno, D. Drommi and F. Faraone, Organometallics, 1998, 17, 338. 165 B. Wang, R. Li, J. Sun and J. Chen, Chem. Commun., 1998, 631. 166 S. Tollis, V. Narducci, P. Cianfriglia, C. L. Sterzo and E. Viola, Organometallics, 1998, 17, 2388. 167 C.-W. Pin, J.-J. Peng, C.-W. Shiu, Y. Chi, S.-M. Peng and G.-H. Lee, Organometallics, 1998, 17, 438. 168 X. Gu and M.B. Sponsler, Organometallics, 1998, 17, 5920. 169 F. A. Cotton and X. Feng, Organometallics, 1998, 17, 128. 170 A. Schneider, L. H. Gade, M. Breuning, G. Bringmann, I. J. Scowan and M. McPartlin, Organometallics, 1998, 17, 1643. 171 R. Beckhaus, J. Oster, R. Wang and U. Bohme, Organometallics, 1998, 17, 2215. 172 P. Cecchetto, A. Ceccon, A. Gambaro, S. Santi, P. Ganis, R. Gobetto, G. Valle and A. Venzo, Organometallics, 1998, 17, 752. 173 S. Aldridge, H. Hashimoto, K. Kawamura, M. Shang and T. P. Fehlner, Inorg. Chem., 1998, 37, 928. 174 L. T. Byrne, C. S. Gri¶th, G. A. Koutsantonis, B. W. Skelton and A. H. White, J. Chem. Soc., Dalton Trans., 1998, 1575. 175 R. Rumin, P. Abiven, F. Y. Petillon and K. W. Muir, J. Organomet. Chem., 1998, 554, 89. 176 V. Cadierno, M. P. Gamasa, J. Gimeno, J. M. Moreto, S. Ricart, A. Roig and E. Molins, Organometallics, 1998, 17, 697. 177 P. Jutzi, B. Neumann, G. Reumann and H. G. Stammler, Organometallics, 1998, 17, 1305. 178 S. Yamazaki, A. J. Deeming and D.M. Speel, Organometallics, 1998, 17, 775. 179 L.-C. Song, H.-T. Fan, Q.-M. Hu, X.-D. Quin, W.-F. Zhu, Y. Chen and J. Sun, Organometallics, 1998, 17, 3454. 180 A. R. Manning, A. J. Palmer, J. McAdam, B. H. Robinson and J. Simpson, Chem. Commun., 1998, 1577. 181 W.-C. Tseng, Y. Chi, C.-J. Su, A. J. Carty, S.-M. Peng and G.-H. Lee, J. Chem. Soc., Dalton Trans., 1998, 1053. 182 C.W. Pin, Y. Chi, C. Chung, A. J. Carty, S.-M. Peng and G.-H. Lee, Organometallics, 1998, 17, 4146. 183 C.-W. Shiu, Y. Chi, C. Chung, S.-M. Peng and G.-H. Lee, Organometallics, 1998, 17, 2970. 184 C. Chung, W.-C. Tseng, Y. Chi, S.-M. Peng and G.-H. Lee, Organometallics, 1998, 17, 2207. 185 S. M. Waterman, M. G. Humphrey, V. A. Tolhurst, M.I. Bruce, P. J. Low and D. C. Hockless, Organometallics, 1998, 17, 5789. 186 C. S. Gri¶th, G. A. Koutsantonis, B. W. Skelton and A. H. White, Chem. Commun., 1998, 1805. 187 K. Besancon, G. Laurenczy, T. Lumini, R. Roulet, R. Bruyndonckx and C. Daul, Inorg. Chem., 1998, 37, 5634. 188 L. Tang, Y. Nomura, S. Kuwata, Y. Ishii, Y. Mizobe and M. Hidai, Inorg. Chem., 1998, 37, 4909. 189 V. Ferrand, G. Suss-Fink, A. Neels and H. Stoeckli-Evans, J. Chem. Soc., Dalton Trans., 1998, 3825. 190 D. Cauzzi, C. Grai§, C. Massera, G. Mori, G. Predieri and A. Tiripicchio, J. Chem. Soc., Dalton Trans., 1998, 321. 191 L. Ma, U. Brand and J. R. Shapley, Inorg. Chem., 1998, 37, 3060. 192 A. Fumagalli, M. Bianchi, M. Malatesta, G. Ciani, M. Moret and A. Sironi, Inorg. Chem., 1998, 37, 1324. 193 M. H. Araujo, A. G. Avent, P. B. Hitchcock, J. F. Nixon and M.D. Vargas, Organometallics, 1998, 17, 5460. 194 R. Reina, O. Riba, O. Rossell, M. Seco, P. Gomez-Sal, A. Martin, D. de Montauzon and A. Mari, Organometallics, 1998, 17, 4127. 195 B. T. Sterenberg, G. J. Spivak, G. P. A. Yap and R. J. Puddephatt, Organometallics, 1998, 17, 2433. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 407196 T. Nakajima, I. Shimizu, K. Kobayashi and Y. Wakatsuki, Organometallics, 1998, 17, 262. 197 G. J. Spivak, J. J. Vittal and R. J. Puddephatt, Inorg. Chem., 1998, 37, 5474. 198 R. D. Adams and T. S. Barnard, Organometallics, 1998, 17, 2885. 199 R. D. Adams and T. S. Barnard, Organometallics, 1998, 17, 2567. Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 375–408 408

ISSN:0260-1818    

DOI:10.1039/a804899a

出版商:RSC    

年代:1999

数据来源: RSC