9 Zinc Cadmium and Mercury By I. B. GORRELL School of Chemistry and Molecular Sciences University of Sussex Falmer Brighton BNl SQJ UK 1 Introduction This chapter is mainly concerned with the organometallic and coordination chemistry of the title elements. However compounds containing macrocyclic ligands (excluding porphyrins) or open-chain polydentate ligands are not covered here unless there is a description of reactivity at the metal centre. Compounds consisting of extended frameworks are also excluded and the role of these elements in organic synthesis and in biological chemistry receives no mention although some models for biological systems are included. Papers on more than one element are cited under the lighter element unless the emphasis is on the heavier element.2 Zinc The stereodynamics and ligand exchange in solutions of tetrahedral chelate complexes of zinc cadmium and mercury have been reviewed.' Carbondonor Ligands.-Solid state 13C NMR studies have suggested a y3-allyl structure for 2-methylpropene when adsorbed on ZnO. Zincates of the type [Li(tmta),] [ZnRtR2] containing trigonal planar zinc have been prepared from ZnRi and LiR2 (R' = CH,SiMe, CH(SiMe,), CH(SiMe,CH,),SiMe,; R2 = Me Ph) in the presence of tmta. The amides [Li(trnta)(p-N(SiMe3),)Zn(CH,SiMe3),] and [ZnN(SiMe,),CH(Me,Si),] were also rep~rted.~ Reaction of (Me3Si),CLi.2THF with ZnCl in THF/Et20 gave Li[Zn,C13{C(SiMe3)3}2].2THF.Et,0. This reacted with RLi (R = Me Bun CH(SiMe,), C(SiMe,), Ph mes N(SiMe,), NHPh) to give (Me3Si)3CZnR.4 The compounds (1) have been prepared by reaction of the corresponding dilithium derivatives with ZnCl (R' = R2 = R3 = R4 = H; R' = Me R2 = R3 = R4 = H; R2 = Me R' = R3 = R4 = H; R' = R4 = Me R2 = R3 = H; R1 = R4 = H R2 = R3 = Me; L = Et,O tmeda dme).' Nitrogen-donor Ligands.-Porphyrins and Phthalocyanines.The crystal structure of the ' V. I. Minkin L. E. Nivorozhkin and M. S. Korobov Russ. Chem. Rev. 1994 63 289. A. A. Kheir T. Howard and J. F. Haw J. Am. Chem. SOC. 1994 116 10839. ' M. Westerhausen B. Rademacher W. Schwarz and S. Henkel Z. Naturforsch. Teil B 1994,49 199. M. Westerhausen B. Rademacher W. Schwarz J. Weidlein and S. Henkel J.Organomet. Chem. 1994,469 135. H.-0. Frohlich B. Kosan B. Undeutsch and H. Gorls J. Organomet.Chem. 1994 472 1. 115 116 I.B. Gorrell pyridine adduct of a zinc porphyrin trimer in which the porphyrin rings are linked by diphenyldiacetylene units has been reported revealing a system of interlocked dimers of trimers. The quinuclidine adduct formed a discrete trimer ;the different structure of the pyridine adduct was ascribed to pyridine n interactions with the pyrrole rings.6 Unsymmetrical porphyrin dimers and trimers have been prepared by intramolecular coupling of alkyne ~ubstituents.~ Such compounds are of interest as models for zinc enzymes. A phthalocyanine-pyrazinoporphyrazinederivative of zinc has been syn- thesized and found to be similar to homonuclear analogues but did not exhibit fluorescence.8 Dendritic zinc porphyrins have been prepared as models for electron- transfer proteinsg and a zinc porphyrin linked through a tetramethylene chain to a redox active crown ether has been prepared as a biomimetic model for a photosynthetic reaction centre.' * Redox potentials and fluorescence spectra have been determined for a series of zinc porphyrin-quinone cyclophanes in order to investigate the driving force for photo- induced electron-transfer reactions.X-Ray diffraction data indicated that an interac- tion between the quinone carbonyl group and the zinc centre could be considered as an alternative to through space electron-transfer in very fast solvent independent electron-transfer.' ' A time-resolved EPR study of the intermolecular interactions in the triplet dimers of zinc complexes of crown ether-substituted porphyrins and phthalocyanines showed that the metal played an important role in the former but not in the latter.I2 It was found that 2,3-dichloro-5,6-dicyano-p-benzoquinone oxidized zinc tetraneopentoxyphthalocyanineby one electron to the radical cation which was stable only in the solid state.A redox series of species were proposed on the basis of spectroscopic e~idence.'~ Photochemical formation and optical studies of the ring reduced anions [Zn(pc(-3))] -have been described and the electronic configuration of the anion radical defined using optical data and MCD. The first complete assignment of the optical spectrum for a porphyrin or phthalocyanine radical anion has been proposed.l4 H. L. Anderson A.Bashall K. Henrick M. McPartlin and J. K. M. Sanders Angew. Chem. Int. Ed. Engl. 1994 33 429. ' A. Vidal-Ferran C. M. Muller and J. K. M. Sanders J. Chem. SOC.,Chem. Commun. 1994 2657. ' N. Kobayashi Y. Higashi and T. Osa J. Chem. Soc. Chem. Commun. 1994 1785. P. J. Dandliker,F. Diederich M. Gross C. B. Knobler A. Louati and E. M. Sanford,Angew. Chem. Int. Ed. Engl. 1994 33 1739. lo L. Sun J. von Gersdorff D. Niethammer P. Tian and H. Kurreck Angew. Chem. Int. Ed. Engl. 1994,33 2318. H. A. Staab T. Carell and A. Dohling Chem. Ber. 1994,127,223;H. A. Staab C. Krieger C. Anders and A. Ruckemann Chem. Ber. 1994 127 231. l2 R. Miyamoto S. Yamauchi N. Kobayashi T. Osa Y. Ohba and M. Iwaizumi Coord. Chem. Rev. 1994 132 57. l3 Y. Fu G. Fu and A.B.P.Lever Inorg. Chem. 1994 33 1038. l4 J. Mack and M. J. Stillman J. Am. Chem. SOC.,1994 116 1292. Zinc Cadmium and Mercury 117 A new time-resolved Raman spectroscopic technique has allowed observation of the excited electronic states of Zn(oep) and confirmed theoretical predictions that Jahn-Teller distortion is much more pronounced in the triplet state than in the singlet state.lS Long-lived triplet excited states have been achieved by compartmentalizing Zn(tpp) in either an amphiphilic copolymer' or a liquid crystalline polymethacrylate bearing a cholesterol ~ide-chain.'~ Spectroscopic and theoretical studies on zinc(I1) octa-p-halotetrakis(pentafluoropheny1)porphyrins have pointed to substituent-in-duced saddling of the porphyrin. The observed stabilization of the HOMO was thought to be important in the design of porphyrin catalysts resistant to oxidative degradation." Electrochemical spectroscopic and MO investigations of zinc complexes of a tetraazaporphyrin containing two naphthalene molecules at opposite pyrrole rings have been reported and comparisons made with analogous phthalocyanines.A diporphyrin complex of zinc with N and N,S cores has been synthesized with the metal in the N ring. Only weak interaction was observed between the sub-units but with copper in the N,S ring there was strong interaction.20 Zinc porphyrin polymers in which rings are linked by acetylene units have been prepared as potential third-order non-linear optical materiak2' A tetra(3,5-di-t-butyl-pheny1)porphyrin zinc complex with 3',5'-di-t-butyl-2-stilbazole was found to be re-versibly photoswitchable by UV and visible light via trans-cis isomerization of the stilbazole.22 The use of Zn(tpp) in a photovoltaic cell has been reported.23 Zinc phthalocyanine complexes with three crown ethers and one hexanoyloxy acid side- chain have been prepared for the functionalization of polymeric chains or metal oxide surfaces.The new materials have potential for the determination of alkali and alkaline earth metals.24 A zinc porphyrin which formed a discotic mesophase has been extended via substitution of the porphyrin at the 5 and 15 positions to give calmitic nematic and smectic A phases at high temperatures2 A novel chiral metalloporphyrin complex which enantioselectively recognizes amino acids in the carboxylate forms has been synthesized.26A new synthesis of dinuclear porphyrin complexes with H-Zn Zn-Zn and Zn-Co centres which are of interest as electrocatalysts has been rep~rted.'~ A study of the solution conformation of Zn(hexaethyltetramethy1)porphyrinsugges-ted that the two species observed at low temperature by NMR correspond to cis- and trans-methyl groups of the meso ethyl groups rather than the syn- and anti-structures proposed earlier.28 A series of zinc derivatives of 2-nitro-substituted 5,10,15,20- tetraaryl porphyrins have been synthesized and investigated by spectroscopic and electrochemical technique^.^^ The polymeric structure of the sterically strained Is D.H.Kreszowski G. Deinum and G.T. Babcock J.Am. Chem. Soc. 1994 116 7463. Y. Morishima K. Saegusa and M. Kamachi Chem. Lett. 1994 583. " Y. Morishima S. Yusa K. Saegusa K. Tashiro and M. Kamachi Chem. Lett. 1994 631. T. Takeuchi H. B. Gray and W. A. Goddard 111 J. Am. Chem. Soc. 1994 116 9730. N. Kobayashi T. Ashida T. Osa and H. Konami Inorg. Chem. 1994 33 1735. R. P. Pandian and T. K. Chandrashekar Inorg. Chem. 1994 33 3317. '' H. L. Anderson S.J. Martin and D. D. C. Bradley Angew. Chem. Int. Ed. Enyl. 1994 33 655. 22 Y. Iseki and S. Inoue J. Chem. Soc. Chem. Commun. 1994 2577. 23 K. Takahashi K. Hashimoto T. Komura and K. Murata Chem. Lett. 1994 269. 24 J. Vacus G. Memetzidis P. Doppelt and J. Simon J. Chem. Soc. Chem. Commun. 1994 697. 25 D.W. Bruce M.A. Wali and Q.M. Wang J. Chem. Soc. Chem.Commun. 1994 2089. L6 K. Konishi K. Yahara H. Toshishige T. Aida and S. Inoue J. Am. Chem. Soc. 1994 116 1337. 27 X. Zhou and K. S. Chan J. Chem. Soc. Chem. Commun. 1994 2493. '' C.J. Medforth M. 0.Senge T. P. Forsyth J. D. Hobbs J. A. Shelnutt and K. M. Smith Inorg. Chem. 1994 33 3865. 29 T.A. Rao and B.G. Maiya Polyhedron 1994 13 1863. 118 I. B. Gorrell non-planar zinc octaethyltetranitroporphyrin has been shown to be achieved by utilization of the nitro groups for axial ligation to the zinc centre.,' A zinc phthalocyanine containing dienophile substituents has been rep~rted.~' The elec- trochemical properties of zinc phlorin anions have been found to depend on the nature of the axial ligand., Other Nitrogen-donor Ligands. The pyrimidine rings were found to bind in a monodentate fashion in the bis adduct formed in the reaction of ZnC1 with 5,7-dimethyl[ 1,2,4]triazolo[ 1,5-a]~yrimidine.~ The synthesis and structure of the racemic compound [Zn(tren)C1]C1.3H20 containing trigonal bipyramidal zinc has been reported.34 The reaction of [Zn(tppyz)(H,O),](C10,) with ZnC1 in EtOH/H,O gave [Zn5C1,,(tppyz)(H,0),], the structure of which showed two twisted dinuclear units connected by three Cl-Zn-Cl bridges.35 The complexes [(Fe,(CO),Cp,),(CN(CH,),NC)] (n = 2,3) have been shown to act as bidentate chelating ligands through nitrogen towards ZnX (X = C1 I OAc) CdX (X = C1 I) and HgC1,.36 N-R-substituted (R = H Me Bz) tris(benzimidazolylmethy1)amine (L) ligands have been used in the preparation of trigonal bipyramidal zinc complexes with various co-ligands (OH, C1 Br I ONO,) in the open axial position.In the aquo complexes OH could be replaced by F C1 Br CN N, OAc and tosylate. The crystal structures of [L.ZnCI][py.ZnCl,] and [L.ZnONO,][NO,] have revealed a coordina- tion geometry intermediate between tetrahedral and trigonal bipyramidal. The above ligands also formed complexes with biologically active ligands and the aquo complexes formed hydrogen bonds to nitriles and aldehyde^.,^ The reaction of ZnS0,.7H20 with 2,2' bipyrimidine gave [Zn,(p-C,H,N,)(H,O),] [S04],.2H,0. The structure of the cation is shown in (2)., 1+ The complexes [zn,(bipy)6(Co,)(H,o)2][C10,],(bipy).2H,0 in which the p3 carbonate bridged all three zinc atoms,,' [Zn(Him),(0A~),],~' and 30 M.O.Senge and K. M. Smith J. Chem. Soc. Chem. Commun. 1994,923. 31 C. Feucht T. Linssen and M. Hanack Chem. Ber. 1994 127 113. 32 G. Balducci G. Chottard C. Gueutin D. Lexa and J.-M. Saveant Inory. Chem. 1994 33 1972. 33 J. M. Salas M.A. Romero A. Rahmani and R. Faure Acta Crystallogr. Sect. C 1994 50 510. 34 A. Marzotto D.A. Clemente and G. Valle Acta Crystallogr. Sect. C 1994 50 1451. 35 M. Graf and H. Stoeckli-Evans Acta Crystallogr. Sect. C 1994 50 1461. 36 S. Schrolkamp W. Sperber D. Lentz and W. P. Fehlhammer Chem. Ber. 1994 127 621. 37 R. Gregorzik U. Hartmann and H. Vahrenkamp Chem. Ber. 1994,127,2117; U. Hartmann R. Gregorzik and H. Vahrenkamp Chem. Ber. 1994,127 2123. 38 G. de Munno and M. Julve Acta Crystallogr. Sect.C 1994 50 1034. 39 X.-M. Chen Q.-Y. Deng G. Wang and Y.-J. Xu Polyhedron 1994 13 3085. 40 X.-M. Chen Z.-T. Xu and X.-C. Huang J. Chem. Soc. Dalton Trans. 1994 2331. Zinc Cadmium and Mercury [Zn,(bipy),(OA~),][ClO~],~~ the first dinuclear zinc complex containing a monoden- tate carboxylate bridge have been prepared as models for the carboxylate-his- tidine-zinc interactions observed in zinc enzymes such as carbonic anhydrase. The structures of [Zn(phen),(OAc),][ClO,] and [Zn(bipy)(C5H5NCH,C0,][C10,] showed zinc to adopt a distorted octahedral geometry in the former and a distorted trigonal bipyramidal geometry in the latter.42 The structure of [Zn(bipy),(OAc)] [C1O,].2H2O was similar to the phen derivative., A mixture of zinc and sulfur boiled under reflux in pyridine gave py,Zn(S,) which contains a seven-membered ring with the zinc atom in a distorted tetra- hedral en~ironrnent.,~ The crystal structures of Zn(SCN),(hmta) and [Zn(SCN),.hmta.2H20] have been determined.In the former compound the zinc atom was tetrahedral and the hmta mondentate in the latter the zinc was octahedral and the ligand bridging bidentate. The polymer formed zigzag chains.45 A series of diorganozinc compounds R,Zn have been reacted with (2,6-Pr\C6H,),dab to give thermally unstable 1 1 complexes which subsequently under- went a regioselective alkyl or aryl group transfer from Zn to an imine nitrogen (R = Ph) or carbon atom (saturated R = But; unsaturated R Me Pr" Bun Bus CH,Bu' Bz) of the ligand (see Scheme 1).The alkylation was regioselectively directed by the introduction of bulky ortho aryl substituents on the nitrogen atoms. These results together with those obtained earlier for alkyl substituents were interpreted using both steric and electronic argument^.,^ Ar I RZn RZn c' - / .. Lr .. Ar Ar Ar Scheme 1 The mechanism of these reactions has been suggested to involve prior formation of R,Zn(R;dab) (R' = alkyl or aryl) followed by intramolecular ligand to ligand electron transfer (SET) generating via homolytic C-Zn bond cleavage a [RZn(R;dab)] '/R * radical pair. Collapse of this pair would give the observed products. An alternative 41 X.-M. Chen Y.-X. Tong and T.C. W. Mak Inorg. Chem. 1994 33 4586. 42 X.-M. Chen Z.-T. Xu X.-L. Yu and T.C.W. Mak Polyhedron 1994 13 2079. 43 X.-M. Chen Z.-T. Xu and T.C. W. Mak Polyhedron 1994 13 3329. 44 H. Li S. Du and X. Wu Acta Crystallogr. Sect. C 1994 50 498. 45 J. Pickardt G.-T. Gong S. Wischnack and C. Steinkopff 2. Naturforsch. Teil B 1994 49 325. 46 E. Wising K. van Gorp J. Boersma and G. van Koten Inorg. Chim. Acta 1994 220 55. 120 I. B. Gorrell mechanism involving cationic species has been discussed and the model species [RZn(Bu:dab)]OTf (R = Me 2,6 xylyl) and [Me,Zn(bipy)] were prepared. The radicals [RZn(Buidab)] have been prepared by independent routes and found to be in equilibrium with the C-C coupled species in which form they crystallized. Their reactivity with alkyl halides was described. The products of the thermal and photochemical decomposition of [R,Zn(Bu\dab)] have been in~estigated.~~ Triplet ligand-centred biradicals [Zn(Bu:dab),] could be prepared from activated zinc ZnH, Zn/ZnH, or ZnCI at -100“C.Room temperature EPR spectra revealed an equilibrium with the radical salt [Zn(Bu\dab),][Zn(Bu\dab),] .48 The thermal- and light-induced spin transition in [Fe,Zn -,(mtz),][ClO,] has been studied by Mossbauer spectroscopy and magnetic susceptibility measurements. The presence of zinc shifted the transition to lower temperature^.,^ A series of polymetallic complexes shown in (3) (X = C I) and (4) (for M =Zn X = C1 L =4-Mepy Bu‘NC; base-free Zn X = Et W(CO),Cp Mn(NC)(CO),Cp‘; for M = Cd X = Mo(CO),Cp W(CO),Cp Mn(NC)(CO),Cp’; for M = Hg W(CO),Cp) have been ~repared.~’ PhZY (CO),Fe-kL I ‘x Si(OMe) (3) (4) Reaction of PrlZn with pyz tetramethylpyrazine or 4,4’-bipy gave bis adducts characterized by intense ligand-ligand charge-transfer transition^.^ An X-ray analy- sis of the structure of [Zn(NSF,),][AsF,] has been reported.52 Oxygen-donor Ligands.-The crystal structure of zinc(1r) bis(phosphog1ycolate) dihyd- rate has been shown to consist of a linear polymer containing octahedral zinc atoms.’ Hydrogen bonding gave rise to a distorted tetrahedral environment around zinc in [Zn(C,C1,0,),(CH4N,S),].H,0,54[Zn(C,H502)2(CH,N,S)2],55 and [Zn(4-ClC7H402)2(tn)2].s6 EXAFS and vibrational spectra of acetone solutions of zinc ethylxanthate showed monodentate coordination for the latter with two acetone 47 E.Wissing M.Kaupp J.Boersma A. L. Spek and G. van Koten Organometallics 1994 13 2349; E. Wissing S. van der Linden E. Rijnberg J. Boersma W. J. J. Smeets A. L. Spek and G. van Koten Organometallics,1994,13,2602;E. Wissing E. Rijnberg P. A. van der Schaaf K. van Gorp J. Boersma and G. van Koten Organometallics 1994 13 2609. 4x M.G. Gardiner G. R. Hanson M. J. Henderson F.C. Lee and C. L. Raston Inorg. Chem. 1994,33,2456. 49 T. Buchen P. Poganiuch and P. Giitlich J. Chem. Soc. Dalton Trans. 1994 2285. 5o P. Braunstein M. Knorr M. Strampfer A. DeCian and J. Fischer J. Chem. Soc.,Dalton Trans. 1994,117. ” S. Hasenzahl W. Kaim and T. Stahl Inorg. Chim. Acta 1994 225. 23. 52 U. Rehrens R. Hoppenheit W. Isenberg E. Lork J. Petersen and R. Mews 2.Naturforsch. Teil B 1994 49 238.” T. Lis Acta Crystallogr. Sect. C 1994 50 181. 54 I. Potocnak M. Dunaj-Jurco U. Petricek and J. Cerniik Acta Crystullogr. Sect. C 1994 SO 1902. s5 K. Smolander M. Ahlgren M. Melnik J. Skorsepa and K. Gyoryova Acta Crystallogr. Sect. C 1994,SO 1900. 56 M.R. Sundberg Acta Cheni. Scand. 1994 48 195. Zinc Cadmium and Mercury 121 molecules weakly bound to zinc.57 The compound R'C(CH20R2),0H (R' = Bu' R2 = Pr'; R' = Bu' R2 = Et; R' = CF, R2 = Pr') reacted with Zn[N(SiMe,),] to give the monomeric dialkoxides which sublimed at low temperatures5 The first zinc-semiquinone structure has been determined for (tmeda)Zn(3,6-dbsq) . The compound has a diamagnetic singlet ground state and gives an EPR spectrum arising from an S = 1 excited state.59 The reaction of dmao with zinc halides gave ZnX,(dmao) in a 1:1 ratio or (ZnCl,),(damao) and ZnX,(dmao) (X = Br I) at higher ligand :zinc ratios.X-Ray structural analyses of ZnBr,(dmao) and ZnI,(dmao) and the solution behaviour of the compounds were reported.60 The zincates M,[Zn(OCMe,),] (M = Na K) have been prepared from MOCMe and ZnCl,. Both compounds sublimed at low temperature and are hydrocarbon soluble.61 Molecular solid solutions of the CrfZn Tutton salts (NH,)2[Cro~,Zno~,(H2~)6](so4)2 and (NH,)2[Cro~22Zno~7,(H20)4](S0,)2 have been studied using single crystal X-ray analysis and neutron diffraction. The results show6 that the aqua ligands in the latter compound are disordered. The compound Zn( 1 ,2-C2BlOH ,C02),.2THF has been synthesized from the carboxylic acid and Et,Zn.63 Incorporation of divalent zinc into the structure of AlPO,-18 yields solid acid catalysts that generate 65-70% ethene and propene with 100°/~ conversion of methanol in the range 35M00"C.64 Sulfur-and Selenium-donor Ligands.-Solid state NMR spectra of [M(Se,),I2 -(M = Zn Cd Hg) have been reported as well as the crystal structure of [(Me,N),]- [Hg(Se,),].O.SDMF and the FT Raman spectrum of [(Me,N),][Cd(Se,),].65 The reaction of Zn[N(SiMe,),] with 2,6-di-mes-C,H,SH has been shown to give a monomeric two-coordinate zinc complex with a low S-Zn-S angle of 151.7"C probably as a result of metal-ring interactions.66 Insertion of sulfur into half the metal-carbon bonds of Et,Zn yielded [Zn(SEt)Et] which exhibited a new molecular structure based on edge-shared MS tetrahedra.67 Compounds of general formula M'M2(EPh),L [M' = Zn Cd Hg; M2 = divalent (x = 4)or trivalent (x = 5) rare earth; E = S Se Te; L = thf py] have been prepared as potential precursors to ternary chalcogenides.Crystal structures of a europium(I1) and a samarium(rI1) complex were reported.68 Octanuclear sulfur bridged complexes [{Ir(aet),),M,O]Br, M = Zn or Zn,.,Co,., with a tetrahedral M core have been synthe~ized.~~ Monomeric five- coordinate bis(diethyldithiocarbamato)M(trialkylphosphine)complexes (M = Zn Cd; alkyl = Me Et) have been synthesized by addition of trialkylphosphines to toluene solutions of bis(diethy1dithiocarbamato)M.The compounds are monomeric in the solid state and the phosphines are labile in solution.The depe bridged dinuclear 57 M. Valli P. Persson and I. Persson Acta Chem. Scand. 1994 48 810. 58 W.A. Herrmann and N. W. Huber Chem. Ber. 1994 127 821. 59 C. W. Lange B.J. Conklin and C.G. Pierpont Inorg. Chem. 1994 33 1276. 6o G. Borisov S. G. Varbanov L. M. Venanzi A. Albinati and F. Demartin Inorg. Chem. 1994 33 5430. 61 A. P. Purdy and C. F. George Polyhedron 1994 13 709. 62 F.A. Cotton L. M. Daniels L. R. Falvello C.A. Murillo and A. J. Schult Inorg. Chem. 1994 33 5396. 0.Kriz A. L. Rheingold M. Shang and T. P. Fehlner Inorg. Chem. 1994 33 3777. 64 J. Chen and J.M. Thomas J. Chem. Soc. Chem. Commun. 1994 603. 65 P. J. Barrie R. J. H. Clark R. Withnall D.-Y. Chung K.-W. Kim and M.G. Kanatzidis Inorg. Chem. 1994,33 1212. 6b J.J.Ellison and P. P. Power Inorg. Chem. 1994 33 4231. '' D. Zeng M. J. Hampden-Smith and E.N. Duesler Inorg. Chem. 1994 33 5376. M. Berardini T. Emge and J.G. Brennan J. Am. Chem. Soc. 1994 116 6941. 69 K.-I. Okamoto T. Konno and J. Hidaka J. Chem. SOC.,Dalton Trans. 1994 533. 122 I. B. Gorrell complexes [(Et,NCS),M1(depe)M2(SCNEt,),] (MI = M2 = Zn; M' = Zn; M2 = Cd) were also prepared. These compounds decomposed to give metal sulfides.70 A distorted trigonal bipyramidal environment was found for zinc in the structure of (Et,NCS,),Zn(depe)Zn(S2CNEt2)2.71 Reactions of [Zn(EAr),] (E = S Se; Ar = 2,4,6-BU\C6H2) with N S or P donor ligands gave monomeric three-coordinate complexes Zn(EAr),(L) (L = 2,6-lutidine tht PMe, PMePh,). With excess N-methylimidazole tetracoordinate complexes were obtained which lost one imidazole on recrystallization from toluene.The results illustrated that Zn-L bond lengths even with a high degree of steric hindrance are determined by electronic factors.72 Halogen-donor Ligands.-The complexes formed between ZnC1 and aromatic al- dehydes were found to exhibit three different structural types.73 Solution equilibria between zinc@) and halide ions have been studied in DMA. Formation-constants -enthalpies and -entropies of these tetrahedral binary and ternary species have been determined.74 The reaction of the clusters Mo,S,L (L = R,P(S)S; R = Et Pr) with MI (M = Zn Cd Hg) in the presence of pyridine gave [Mo,S,L,py,][MI,py] (M = Zn Cd) and [MO,S,L~~~,][H~I~].~~ The preparation of the zinc chloride complex with the new sterically-hindered thiourea (5) has been reported.76 S Me,NAN,CH2CH =CH2 @NCHjMe2 L/ A series of complexes of dmpo (6) ZnX,(dmpo) (X = C1 Br I NO,) has been synthe~ized.~~ The complex ZnCl,(Me,SiNPMe,) has been prepared as a monomer with a distorted tetrahedral zinc centre.78 Complexes of 4-nitrosodimethylaniline with ZnC1 (1:2) CdC1 (1 l),CdI,(1 :2) and HgI (1 :2) have been prepared and studied using solid state NMR.79 The structures and binding energies of (MX,) (M = Zn Cd; X = F C1 H) have been computed at the ab initio level.All except Cd,H, show symmetrically bridged D, structures in contrast to those expected on the basis of quasi-relativistic calculations for (HgHal,) . Relativistic effects were found to change trends in dimerization energy from Hg > Cd > Zn to Cd > Zn >> Hg and the trends in Group 12 chemistry involving electronegative ligands could be understood in terms of electrostatic bonding and its relativistic reduction for mercury.80 Reaction of MCGaH,] (M = Li Na) with ZnCl,(pmdeta) gave the heterobimetallic species 70 D.Zeng M. J. Hampden-Smith T. M. Alam and A. L. Rheingold Polyhedron 1994 13 2715. 71 D. Zeng M. J. Hampden-Smith and E. M. Larson Acta Crystallogr. Sect. C 1994 50 1OOO. 72 M. Bochmann G.C. Bwembya R. Grinter A. K. Powell K. J. Webb M. B. Hursthouse K. M. A. Malik and M. A. Mazid Inorg. Chem. 1994 33 2290. 73 B. Muller M. Ruf and H. Vahrenkamp Angew. Chem. Int. Ed. Engl. 1994 33 2089. 74 H.Suzuki M. Koide and S. Ishiguro Bull. Chem. Soc. Jpn. 1994,67 1320. 75 H. Diller H. Keck W. Kuchen and H. Wunderlich Inorg. Chim. Acta 1994 216 177. 76 D.J. Williams T. A. Ly J. W. Mudge D. VanDerveer and R. L. Jones Inorg. Chim. Acta 1994,218 133. 77 S. Varbanov E. Russeva and A. Ganchev Z. Naturforsch. Teil €3 1994 49 258. 78 R. M. zu Kocker G. Frenzen B. Neumuller K. Dehnicke and J. Magull 2.Anorg. Allg. Chem. 1994,620 431. 79 M. Cameron B. G. Gowenlock and G. Vasapollo Polyhedron 1994 13 1371. 8o M. Kaupp and H.G. von Schnering Inorg. Chem. 1994 33,4718. Zinc Cadmium and Mercury 123 Zn(q’-GaH,)Cl(pmdeta) whereas reaction of MCGaH,] with ZnCl,(tmeda) gave Zn(q2-GaH,)Cl(tmeda); MCBH,] gave the analogous borohydride.81 3 Cadmium Carbon-donor Ligands.-The multidimensional structures associated with poly-cyanocadmium compounds continue to excite interest showing similarity to silica frameworks and often forming clathrates.The structure of [Cd(CN),.2/3hmta] has been reported.82 The compounds Cd(CN),.pyz and Cd(CN),.{ 1,4-bis(4-pyridyl)butadiyne}have been shown to contain square-grid [Cd(CN),] sheets linked by pyz or bis(pyridy1butadiyne) bridges. The latter initially colourless complex acquired a deep blue colour on exposure to light indicating diacetylene polymerization in the crystal.83 The reaction of CdC1 with K[Ag(CN),] and 4,4‘-bipy gave [Cd(4,4’-bipy),fAg(CN),},]and the reaction of K,[Cd(CN),] AgNO, and pyrazine gave [Cd(pyz)(Ag,(CN),}(Ag(CN),}]. The former complex consisted of two- and the latter of three-separate interpenetrating frameworks built up of 2D networks supported by 4,4’-bipy or NC-Ag-CN pillars re~pectively.~, Enantiomorphic crystals of Rb[Cd(Ag(CN),),] have also been found to contain three identical independent interpenetrating framework^.^^ The cadmium atom in [Cd(bipy)][Ni(CN),] was found in a highly distorted octahedral environment with the [Ni(CN),] units bridging four cadmium atoms to form an infinite 2D network.The bipy units chelated cadmium alternately above and below the chains.86 An aqueous solution of CdCl, K[Ag(CN),] and 4-Mepy gave the clathrate [Cd(4-Mepy),{Ag(CN),},](4-Mepy),a double interwoven network and CCd(4-Mepy),(Ag (CN),}][Ag(CN),] made up of infinite linear chains8 Absorption of acetonitrile vapour by an aqueous solution containing CuCN and K,[Cd(CN),] gave [Cd(H,O),Cu(CN),].MeCN a layered clathrate structure consisting of [Cu,(CN),] 4-units with each nitrogen linked to a cadmium.88 Two new [Cd(CN),] frameworks with linear channels of hexagonal cross-section have been found in Cd(CN),-G (G = DMF or DMSO) clathrate~.~~ The cadmium cyanide host clathrates Cd8(CN),,(H,0),.6G (G = Et,O PrlO) and Cd,(CN),(H2O),.2Pr~O have been prepared and structurally characterized.” A series of 17 inclusion compounds of composition [am.xG][Cd,(CN),] (am = organo-nitrogen or -sulfur cation; x = 1-2) including six structural types have been obtained from the 3D anionic [Cd,(CN),]- salt of a cation am and a neutral guest molecule G.9’ Three series of clathrate compounds Cd(CN),.G [CdM(CN),].2G (M = Zn Hg) and [NMe,.G] [CuM(CN),] (M = Zn Cd) have been ~ynthesized.~ 81 G.A.Koutsantonis F.C. Lee and C. L. Raston J. Chem. Soc. Chem. Commun. 1994 1975. J. Pickardt and G.-T. Gong Z. Anorg. Allg. Chem. 1994,620 183. 83 B.F. Abrahams M. J. Hardie B. F. Hoskins R. Robson and E. E. Sunderland J. Chem. SOC. Chem. Commun. 1994 1049. 84 T. Soma H. Yuge and T. Iwamoto Angew. Chem. Int. Ed. Engl. 1994,33 1665. 85 B.F. Hoskins R. Robson and N.V.Y. Scarlett J. Chem. SOC. Chem. Commun. 1994 2025. 86 M. Hashimoto and T. Iwamoto Acta Crystallogr. Sect. C 1994 50 496. ” T. Soma and T. Iwamoto Chem. Lett. 1994 821. 88 S.-I. Nishikiori and T. Iwamoto Chem. Lett. 1994 1199. H9 J. Kim D. Whang Y.-S. Koh and K. Kim J.Chem. Soc. Chem. Commun. 1994,637. 90 T. Kitazawa T. Kikuyama M. Takahashi and M. Takeda J. Chem. Soc. Dalton Trans. 1994 2933. 91 T. Kitazawa S.-I. Nishikiori and T. Iwamoto J. Chem. Soc. Dalton Trans. 1994 3695. 92 T. Kitazawa S.-I. Nishikiori R. Kuroda and T. Iwamoto J. Chem. SOC.,Dalton Trans. 1994 1029. 124 I. B. Gorrell Nitrogen- and Phosphorus-donor Ligands.-A halide free route has been used to synthesize the new complexes [Cd (PhC-C) (tmeda)] and [Li (thf),] [Cd(C ,H8N),] from Cd[N(SiMe,),],.93 { [Cd(4,4'-bipy),]N03],) has been found to consist of 2D networks made up of layers of edge-sharing planar squares with a cadmium at each corner and a 4,4'-bipy at each side. The compound formed a 1:2 clathrate with o-dibromobenzene and catalysed the cyanosilylation of aldehyde^.^ The preparation and structure of a 1Dpolymer {[Cd,(p-bpe),](NO,),), containing seven-coordinate cadmium has been reported.95 The disilylphosphido complexes M[P(SiPh,),] (M = Zn Cd Hg) have been prepared and found to be monmeric in solution.A crystal structure determination of the cadmium complex revealed a two-coordinate linear geometry and the compound formed unstable adducts with pyridine and PMe,.96 Oxygen-donor Ligands.-Infrared studies have shown that dimethyl and diethyl cadmium react with both hydroxyl and siloxane groups on a silica surface to form -=Si-0-Cd-CE and GS1-H fragments. At 200 "C p-elimination yielded GSi-0-Cd-H and at 600 "Cmetallic cadmium and regeneration of Depending on the amount of Hmoe used the partial alcoholysis of [cd(C6F5),] gave the complexes [Cd4(C6F5)4(moe)41 [Cd7(C6F5)fj(moe)81 and [Cdf5(C6F5)4(moe)fj] which have (C~&L~-OR)~)~+, (Cd7(p3-OR)8)6+ and (Cd6(p3-OR)8)4+ cores re~pectively.~~ The synthesis and X-ray structural analysis of polymeric [Cd(OH)(H,L)(H,O),],.nH,O (H,L = piperazine-1,4-diylbis(methylene)bis(phosphonic acid) have been re- ported.99 The volatile alkoxide Cd[OC(OCH,Pr'),Bu'] made from Cd[N(SiMe,),] and the alcohol has been found to be dimeric in the solid state but monomeric in the gas-phase.' O0 The preparation and spectroscopic characterization of [MeO(CH,),] Cd has been reported.'" Sulfur- and Selenium-donor Ligands.-The compound obtained by boiling CdBr, CS, NaOEt and 4-methoxyaniline under reflux in ethanol was found to be a dimer of distorted octahedral cadmium atoms each coordinated to six sulfur atoms from one bidentate xanthato group two bridging bidentate xanthato groups and one monodentate N N'-bis(4-methoxyphenyl)thiourea.' O2 The crystal structure of [Cd(S,PPh,),] shows a dimer containing an eight-membered ring each cadmium atom also being bonded in a bidentate fashion to an external S,PPh ring.lo3 A number of cadmium thiocyanate complexes have been investigated using '',Cd NMR to characterize the various modes of linkage isomerism exhibited by the SCN y3 D.Barr A.J. Edwards P. R. Raithby M.-A. Rennie K. Verhorevoort and D. S. Wright J. Chem. Soc. Chem. Commun. 1994 1627. y4 M. Fujita Y.J. Kwon S. Washizu and K. Ogura J. Am. Chem. Soc.1994 116 1151. 95 M. Fujita Y. J. Kwon M. Miyazawa and K. Ogura J. Chem. Soc. Chem. Commun. 1994 1977. 96 M.A. Matchett M.Y. Chiang and W. E. Buhro Inorg. Chem. 1994 33 1109. 97 V. A. Dodonov A. A. OIeynik M. 3.Molotovshchikova G. N. Lysenko. and 0.N. Druzhov Russ. Chem. BuEl. 1993 42 1639. 98 1. Biisching and H. Strasdeit .I. Chem. Soc. Chem. Commun. 1994 2789. 99 N. Choi I. Khan R.W. Matthews M. McPartlin and B. P. Murphy Polyhedron 1994 13 847. lo" W.A. Herrmann N. W. Huber and T. Priermeier Angew. Chem. Int. Ed. EngI. 1994 33 105. lo' M. J. Almond M. P. Beer P. Heath C. A. Heyburn D. A. Rice and L. A. Sheridan J. Organomet. Chem. 1994 469 11. lo2 Z.-F. Sun C.-Y. Duan X.-Z. You and X.-Y. Huang Acta Crystallogr. Sect. C 1994 50 1012. J. S. Casas M.S. Garcia-Tasende A. Sanchez J. Sordo E. M. Vazquez-Lopez E. E. Castellano and J. Zukerman-Schpector Inorg. Chim. Acta 1994 219 115. Zinc Cadmium and Mercury groups.' O4 Plasma desorption time-of-flight mass spectrometry has been used to investigate cadmium arenethiolates. Gas-phase clustering has been observed and a structural model involving Cd,(SR) rhombuses sharing trans edges was presented to account for the compositions and transformations of the ions."' A series of pentafluorophenyl cadmium thiolates [{Cd(C,F,)(SR)},] (n = 4 co;R = Bu' 2,4,6- Pr\C,H, 2,4,6-Bu\C6H,) have been prepared.lo6 The compound [HNEt,],[Cd,(p- SC6H,Bu'-4),(SC,H,Bu'-4)~~~] consisted of a Cd,(p-S) adamantane-like cage.lo7 Cadmium chalcogenide complexes attract attention as potential CVD precursors to the Group 2-6 semiconductors CdS quantum dots and photocatalysts.Thus the synthesis and characterization of NpCdE,CNEt (E = S Se) and NpZno,,Cdo~,- Se,CNEt have been reported and have included the X-ray structural analysis of dimeric NpCdSe,CNEt,. All compounds decomposed on heating to give the binary or ternary chalcogenide. lo* The thermal decomposition of CdX2.2SC(NH,) (X = C1 Br Illo9 or Cd(RCO,),.nSC(NH,) (R = H n = 2; R = Me II = 1-2)'1° has been shown to give CdS. Pyridine selenolate complexes of cadmium(i1) and mercury(I1) have been prepared and characterized. The cadmium compound was polymeric but the mercury compound was square planar with only weak intermolecular interactions. Both sublimed without decomposition and decompose at higher temperatures to yield MSe.Negatively charged stabilizers such as polyacrylic acid formed microcrystal- line CdS photocatalysts which on photoreduction of CO gave only formate whereas positively charged stabilizers such as polyethyleneimine gave only CO.' l2 CdS microcrystals covalently bound with viologen groups have been prepared and found to mediate electron-transfer to methylene blue in solution. Monodisperse colloidal silica-CdS nanocomposites have been prepared using water-in-oil microemulsions to produce colloidal silica which was then exposed to Cd(NO,) and (NH,),S."4 Halogen-donor Ligands.-The cadmium atoms in [Et,N],[CdBr,] have been shown to be tetrahedral.' lS The reaction of CdBr with 3-methyl-4-nitropyridine-N-oxide gave [Cd(C,H,N,O,),Br,] the structure of which showed octahedrally coordinated cadmium (20,4Br) with 1D chains formed by edge-sharing through bromine.' l6 The structure of cadmium tetrahydroborate in thf was found to be fluxional and best described as Cd[(p-H),BH,],.nthf.Reaction with Li[BH,] gave Li[Cd(BH,),] while Li [Cd(BH,),] .4 diglyme precipitated from diglyme solutions. Equilibria involving ICd(BH,) CdI, CdI; [Cd(BH,),] -,and/or [ICd(BH,),] -resulted from Cd(BH,) and LiI in thf or diglyme.' l7 '" K. Eichele and R. E. Wasylishen lnory. Chem. 1994 33 2766. lo' A.G. Craig K. J. Fisher R. Garbutt I.G. Dance and P.J. Derrick lnorg. Chem. 1994 33 2890. lo6 A,-K. Duhme and H. Strasdeit Z. Naturforsch. Teil B,1994 49 119. lo' K. Tang T. Xia X.Jin and Y. Tang Polyhedron 1994 13 3023. I. Abrahams A. Malik M. Motevalli and P. O'Brien J. Organomet. Chem. 1994 465 73. '09 M. Stoev and S. Ruseva Monatsh. Chem. 1994 125 599. M. Stoev S. Ruseva and B. Keremidchieva Monatsh. Chem. 1994 125 1215. Y. Cheng T. J. Emge and J. G. Brennan lnorg. Chem. 1994,33 3711. H. Inoue R. Nakamura and H. Yoneyama Chem. Lett. 1994 1227. T. Torimoto K. Maeda T. Sakata H. Mori and H. Yoneyama Chcm. Lett. 1994 977. S.-Y. Chang L. Liu and S.A. Asher J. Am. Chem. Soc. 1994 116 6739. M. Geselle and H. Fuess Acta Crystullogr. Sect. C 1994 50 1582. 'I6 H. Sheng-Zhi S. Da-Shuang H. You-Qing L. Song-Xian and Y. Yan-Chao Acta Crystallogr. Sect. C 1994 50 893. H. Noth and M. Thomann Z. Naturforsch. Teil B 1994 49 9. 126 I.B.Gorrell 4 Mercury Carbon-donor Ligands.-The synthesis and spectroscopic characterization of [Hg(CO),][Sb,F J2 and [Hg,(CO),][Sb,F 'I2 the first thermally stable carbonyl derivatives of a post-transition element have been reported.' l8 The organomercuric hydrides and deuterides RHgH and RHgD have been characterized in solution by low temperature multinuclear NMR (R = alkyl cycloalkyl Ph)' ' and mass spectro- scopic and NMR (R = Me Et Ph C6F5) techniques.12' Electrospray mass spectra have been used to investigate ligand exchange reactions in solution for [MeHgL] + (L = nitrogen base). Reaction with other nitrogen bases phosphines phosphine sulfides and selenides were reported.',' A 2 1 adduct [Cr(NH,),NC],Hg6+ containing the Cr-NC-Hg link has been formed in aqueous solution by reaction of + Cr(NH,),CN2 with Hg2 + .Evidence was also obtained for 4:1and 2 1adducts in the solid state.', A series of bis(fluoropheny1)mercury compounds have been prepared by decar- boxylation of the corresponding fluorobenzoates in boiling pyridine.' 23 Secondary interactions cause angles at mercury to deviate from linearity in the structures of and (C1Hg),C(COMe),.MeCN.'25 (C1Hg),C(COMe)C0,Et.1/2MeCN124 (2-pyr-roly1)mercuric chloride has been prepared and used as a ligand transfer agent in the preparation of osmium and ruthenium derivatives.126 The compounds Hg(CHCl,) and RHgCHCl (R = Me Et) have been synthesized and ~haracterized.'~~ The reactions of [Bu,N],[cis-Pt(C,F,),(C=CR),] (R = But SiMe,) with HgX (X = C1 Br I) have given the monomeric bis y2-alkyne mercury(I1) compounds [Bu,N],[(~~s-P~(C~F,),O,)H~~~].Also [Bu4N],[PtCrCR),].2H2O have been shown to react with HgX in a 1:2 ratio to give the corresponding trinuclear products.12* Treatment of CpM(CO) (M = Mn Re) with 5 equivalents of Hg(OAc) gave the pentakis(acetoxy)mercuric derivatives in high yields. The manganese compound has been converted into pentahalogeno compounds by CuCl, CuBr, or K13.'29 The preparation of 1,2-bis(chloromercuri)alkenes,1-trimethylsilyl-2-chloro-mercurialkenes and 1-trimethylsil yl-2-organomercurialkenes by transmetallation of the corresponding trimethylstannyl compounds with HgC1 and RHgCl (R = Me Ph) have been reported.' 30 Kinetics of the acetoxymercuration of 1-arylpropynes have been investigated.' The mercuration of a series of aryliminomethylferrocenes occurred predominantly in an ortho position of the substituent ferrocenyl ring suggesting initial coordination of mercury to the imino nitrogen with subsequent electrophilic attack.An X-ray structural analysis revealed the Hg-N intramolecular 118 H. Willner M. Bodenbinder C. Wang and F. Aubke J. Chem. SOC. Chem. Commun. 1994 1189. 11' K. Kwetkat and W. Kitching J. Chem. SOC. Chem. Commun. 1994 345. ''* P. J. Craig H. Garraud S.H. Laurie D. Mennie and G. H. Stojak J. Organomet. Chem. 1994,468 7. ''' A. J. Canty and R. Colton Inorg. Chim. Acta 1994 215 179. ''' M. Rievaj D. Bustin J. Mocak P. Riccieri and E. Zinato Inorg. Chim. Acta 1994 216 113. N. J. Barassi G. B.Deacon and J.A. Weigold Z. Anorg. Allg. Chem. 1994 620 993. lZ4 P. Toledano C. Bonhomme M. Henry and J. Livage Acta Crystallogr. Sect. C 1994 50 365. lZ5 C. Bonhomme P. Toledano and J. Livage Acta Crystallogr. Sect. C 1994 50 1590. M. M. P. Ng W.R. Roper and L. J. Wright Organometallics 1994 13 2563. R. Imdahl H.-D. Hausen and J. Weidlein 2. Anorg. Allg. Chem. 1994 620 625. lZ8 J. R. Berenguer,J. Fornies E. Lalinde A. Martin and M.T. Moreno J. Chem. SOC.,Dalton Trans. 1994 3343. lZ9 S.A. Kur M.J. Heeg and C. H. Winter Organometallics 1994 13 1865. 130 T.N. Mitchell and B. Kowall J. Organomet. Chem. 1994,471 39. 13' B. Floris and E. Tassoni Organometallics 1994 13 4746. Zinc Cadmium and Mercury 127 intera~ti0n.l~~ A study of the mercuration of benzylideneanilines showed that the mercury was directed to the para position of the N-phenyl ring.', Mercuration of the liquid crystalline dialkylazobenzenes gave RHgCl (R = C6H,(N=NC,H,X-4')-2; X = C,H, C10H2' OC,H, OC8H17).However none of the compounds showed mesomorphic behaviour. '34 Mercurated phosphorus ylides Ph,P=CR[HgN(SiMe,),] (R = Me Et Pri Ph) have been prepared. Reaction with PhCHO gave the vinylmercury amides PhHC=CR[HgN(SiMe,),] which were cleaved by aqueous NaOH to give divinylmercury compounds (PhHC=CR),Hg. Stereochemistry and a salt effect were disc~ssed.'~ The first example of a dithiadiazolium ring bound to a metal centre via the carbon was reported with the preparation of [Hg(CNSNS),][AsF,],. Reaction with X (X = Br I) gave [XCNSNS][ASF,].'~~ Nitrogen-donor Ligands.-A study of the substitution of a homodinuclear mercury(I1) porphyrin with copper(1r) in aqueous solution using a new stopped-flow EXAFS technique has been reported and the reaction mechanism discussed.' 37 Crystals of Hg(SCN),.2HgC12.2hmta were obtained from aqueous solution.The structure consisted of a network of chains with hmta lying in channels between the chains as bridging ligands.' 38 Sulfur-donor Ligands.-The mercury atom in PhHg(S,OCEt) has been shown to be linear.', The compounds [RHg(S,PR;)] (R = Me Ph; R' = Et Cy) have been synthesized and characterized including an X-ray structural analysis of [HgPh(S,PEt,)] which showed the angle at mercury to be 177".140 A series of salts [A],[(p-SR),-,(p-X),(HgX),] (A = R,N Ph,P; R = Et Pr' Bun; X = C1 Br I; m = &2) have been prepared as models for the mercury binding site in metallo- thioneins and investigated using 19,Hg NMR and X-ray diffra~ti0n.l~~ The reaction of (Ph,P),PtSCH,COCH with HgX (X = C1 Br I) gave 1:1 dimeric adducts with distorted tetrahedral mercury centres.142 Halogen-donor Ligands.-A review of chloromercury(I1) anions has appeared.143 The kinetics of formation and photoredox chemistry of iodomercurate(I1) complexes in MeCN have been inve~tigated.',~ The structure and bonding in solvated (with H,O MeCN dmso py) mercury-dihalide and -dicyanide complexes have been studied using EXAFS and theoretical ~alculations.'~~ The adducts of an olefinic double betaine with 132 S.Q. Huo Y.J. Wu Y. Zhu and L. Yang J. Organornet. Chem. 1994 470 17. 133 P. Chattopadhyay and C. Sinha Polyhedron 1994 13 2689. 134 J. Vicente M. D. Bermudez F. J. Carrion and G. Martinez-Nicolas J. Organomet. Chem. 1994,480 103. 13' M. Steiner H. Pritzkow and H. Grutzmacher Chem. Ber. 1994 127 1177. A. J. Banister I. Lavender S. E. Lawrence J. M. Rawson and W. Clegg J. Chem. Sou.,Chem. Cornrnun. 1994 29. H. Ohtaki Y. Inada S. Funahashi M. Tabata K. Ozutsumi and K. Nakajima J. Chem. Sou. Chem. Commun. 1994 1023; M. Tabata and K. Ozutsumi Bull. Chem. Sou. Jpn. 1994,67 1608. 138 J. Pickardt G.-T. Gong and D. Roleke Z. Naturforsch. Teil B 1994 49 321. 139 E. R.T. Tiekink Acta Crystallogr. Sect. C 1994 50 861. I4O J. S. Casas A. Castiiieiras A. Sanchez J. Sordo and E.M. Vazquez-Lopez J. Organomet. Chem. 1994 468,1. i41 P.A. W. Dean J. J. Vittal and Y. Wu lnorg. Chem. 1994 33 2180. 142 W. Henderson B. K. Nicholson and R. D.W. Kemmitt J. Chem. SOC.,Dalton Trans. 1994 2489. 143 D.A. House W.T. Robinson and V. McKee Coord. Chem. Rev. 1994 135/136 533. 0.Horvath and A. Vogler Inorg. Chim. Acta 1994 221 79. 14' R. Akesson I. Persson M. Sandtrom and U. Wahlgren Inory. Chem. 1994 33 3715. 128 I. B. Gorrell HgX (X = C1 Br) have been prepared and structurally characterized as [{Hg,L2X,.6HgX,},] (L = (Me,NC,H,N),C,(CO,),). The structure contained a centrosymmetric 14-membered ring with nearly linear HgX units that were further interlinked by weak intermolecular contacts to form a polymeric network. A relativistic ab initio pseudopotential study of (HgX,) (X = F C1 Br 1 H) showed that the preference of many solid mercury compounds for molecular structures with low coordination number and lower boiling points (as compared with the correspond- ing zinc and cadmium compounds) is due to relativistic effects.In particular the relativistic increase of the Hg(6s) ionization energy reduced the charge separation in and intermolecular interactions between HgX molecules with electronegative sub~tituents.'~' Such calculations also showed that HgF should exist as a free molecule whereas CdF and ZnF would eliminate fluorine exothermically. A large relativistic destabilization of HgF was considered responsible. Possible preparative routes to HgF were disc~ssed.'~~ The stability of Hgf+ was found to be due to differential aggregation/solvation effects in the solid state modified by relativistic effects.The zinc and cadmium analogues as opposed to Hgf +,were considered most likely to be found in the gas-~hase.'~~ Mercury-Transition-metal Complexes.-The Cr-Hg-Cr unit in Hg[Cr(CO) C,H,(CO,Et)] was shown to be 1ir1ear.l~' The syntheses of [E(CO),($-RC,H,)] ,Hg (E = Cr Mo W; R = Me Et Bun) from PhHgCl and the corresponding lithium derivative have been described.' 51 The reaction of HgC1 with [Mo(CO),(dmp)] gave [Mo(CO),(dmp)(HgCl)Cl] a capped trigonal prism. The reaction of this and related derivatives with tin dihalides was studied.' 52 The preparation and structural characterization of the pentanuclear clusters [PPh,][Mn,(CO) ,(p3-H)(p-HgE)] (E = Mo(CO),Cp W(CO),Cp Mn(CO), Co(CO), Fe(CO),Cp C,Cl, 2,3,4,6-Cl,C& 2,4,6-C1,C6H,) from [PPh,][Mn,(CO),,(p-H)] and EHgCl have been reported.' 53 The compounds Re,(p-PR,)(CO),(HgE) and ReMo(pPR,)Cp(CO),(HgE) (R = Ph Cy; E = C1 W(CO),Cp) have been prepared and structurally characterized.' 54 The preparation of [M{SeFe3(C0)9),]2- (M = Cd Hg) has been reported.The mercury was tetrahedral and bridged the Fe-Fe bond in both iron units.', The reaction of [PPh,][Fe,(CO) with EHgCl (E = Mo(CO),Cp W(CO),Cp Mn(CO), Co(CO), Fe(CO),Cp) gave the pentametallic compounds [PPh,]- [Fe,(CO),,(p-CO)(p-HgE)] which showed a spiked butterfly geometry; electrochemi- cal oxidation gave [Fe,(CO) ,(p-HgE)] '.156 Mercury was inserted into the Fe-I bonds in [FeI,(CNR),] (R = But Ph 4-MeC,H4)in the presence of phosphines L to 146 D.-D.Wu and T.C. W. Mak Polyhedron 1994 13 3333. M. Kaupp and H. G. von Schnering Inorg. Chem. 1994 33 2555. 14* M. Kaupp M. Dolg H. Stoll and H.G. von Schnering Inorg. Chem. 1994 33 2122. 149 M. Kaupp and H.G. von Schnering Inorg. Chem. 1994 33,4179. L.-C. Song Q.-M. Hu R.-J. Wang and H.-G. Wang Acta Crystallogr. Sect. C 1994 50 1592. L.-C. Song Z.-F. Tao Q.-M. Hu R.-J. Wang and H.-G. Wang Polyhedron 1994 13 2179. lS2 M. Cano M. Panizo J. A. Campo E. Guitierrez-Puebla M. A. Monge and C. Ruiz-Valero Polyhedron. 1994 13 1669. 153 0.Rossell M. Seco G. SegalCs S. Alvarez M. A. Pellinghelli and A. Tiripicchio Organometallics 1994. 13 2205. 154 H.-J. Haupt A. Merla and U.Florke Z. Anorg. Allg. Chem. 1994 620 999. M. Shieh and Y.-C. Tsai Inorg. Chem. 1994 33 2303. R. Reina 0.Rossell M. Seco D. de Montauzon and R. Zquiak Organometallics 1994 13 4300. Zinc Cadmium and Mercury 129 give [Fe(HgI,)L(CNR),] (n = 4 L = PPh, dppm; n = 3 L = d~pe).'~~ The reaction of Hg(OAc) with Fe(CO) in ROH (R = Me Et) gave Hg[Fe(CO,R)(CO),] with linear (R = Me) or nearly linear coordination (R = Et) at mercury.158 Compound (7) reacted with Pt(C,H,)(PPh,) to give cis-and trans-[Fe(CO),{p-Si(OMe),(OMe))(p-dppm)(p-H g)(Pt(c,Cl,)PPh,)]. The reactivity of these species was investigated.' 59 Ph2PAPPh2 II (C0)3Fe-Hg-C6C15 I (MeO),Si The compounds [Rh(CECR)(HgPh)Cl(PPr\)2] have been prepared from trans-[RhCl(=C=C(SnPh,)R(PPr',),] and PhHgCl (R = Me Ph CH20H CH,OMe CMe,OH CH(Me)OH CH(Ph)OH SiMe, SnPh,).'60 A mercury atom has been shown to occupy the centre of a trigonal prism of platinum atoms in the 96 electron cluster [HgPt,(2,6-Me,C,H,NC)lz].XPS data and Hiickel calculations were also carried out."' A series of platinum-gold clusters [(Ph,P)Pt(AuPPh,),(HgX)] + (X = NO, C1 Br I Co(CO),) have been prepared and structurally characterized. Mercury was found to exchange reversibly with C0.'62 15' S. COCOand F. Mayor J. Organomet. Chem. 1994 464 215. 15' A. E. Mauro V. A. de Lucca Neto J. R.Zamian R. H. de Almeida Santos M. T. do Prado Gambardella J.R. Lechat and H. R. Rechenberg J. Organomet. Chem. 1994 484 13. 159 P. Braunstein M. Knorr M. Strampfer A. Tiripicchio and F.Ugozzoli Organometallics 1994,13,3038. I6O M. Baum N. Mahr and H. Werner Chem. Ber. 1994 127 1877. 16' Y. Yamamoto and H. Yamazaki Inorg. Chim. Acta 1994 217 121. R.A.T. Gould and L.H. Pignolet Inorg. Chem 1994 33 40.