17 The Coordination Chemistry of Open-Chain Polydentate Ligands By M. D.WARD School of Chemistry University of Bristol Cantock‘s Close Bristol BS8 1 TS UK 1 introduction This review is intended to give an overview of the types of ligand that are currently of interest; due to space restrictions and the ever-increasing body of literature it is quite selective. Since there is now a separate chapter dealing with bioinorganic chemistry complexes which are primarily of interest as bioinorganic models are only included if the ligands are of particular interest. Throughout the diagrams ‘pyl’ signifies 2-pyridyl. 2 Bidentate Ligands N-donor Ligands.-Biipyridines and Phenanthrolines. The crystal structures of [PdL,] [PF,] (L = bipy phen and 3,4,7,8-Me4-phen) show various ligand distortions and 71-stacking interactions.’ Perfluoroalkylated bipyridines (1) form amphiphilic com- plexes [PdLCI,] and [PtLCl,] which are potential anti-tumour agents.[Ru(bipy),L3_,J2+ [n = 0-2; L = (2)-(4)] have lower-lying .n* levels than [Ru(bipy),]’+ due to the electron-withdrawing CF substituents. [Ru(bipy),L]’’ (L = (5)-(7)) contain [Ru(bipy),]” cores with pendant pyridyl or phenol groups for attachment of peripheral metal ions;4 attachment of Mo or W complexes to the pendant phenol of [Ru(bipy),(7)I2 results in quenching of the ruthenium lumines- ~ence.~ [MLJ2+ and [Ru(bipy),L]’+ [M = Fe Ru; L = (8) (9)] undergo oxidative electropolymerization in MeCN; the resulting polymer film shows metal-centred and ligand-centred redox processes.6 Irradiation of [Ru(bipy),(10)12 + at pH 1 generates a long-lived intermediate in which (10) is monodentate (cf.reference 18).7 Derivatives of + [Ru( bipy ),I2 bearing protonatable side-chains (e.q.CH,NEt ) show pH-dependent luminescence properties.’ The effects of steric hindrance on the luminescence and electrochemical properties of [Ru(bipy),L -,I2+ (n = 0-3; L = 6,6’-diaminobipy) ’ S. Geremia L. Randaccio G. Mestroni and B. Milani J. Chem. Soc. Dalton Trans. 1992 21 17. N. Garelli and P. Vierling Inorq. Chim. Acta 1992 194 247. M. Furue K. Maruyama T. Oguni M. Naiki and M. Kamachi Inory. Chem.. 1992 31 3792. M.A. Hayes C. Meckel. E. Schatz and M. D. Ward J. Chem. Soc.. Dalton Trans. 1992 703. ’ A. Das J. A. McCleverty M. D. Ward. C.J. Jones and A.M. W. Cargill Thompson Polyhedron 1992,ll. 21 19. C. P. Horwitz and Q. Zuo Inorg. Chem. 1992. 31. 1607. ’ S. Tachiyashiki K. Nakamaru and K. Mizumachi Chem. Left. 1992 11 19. ’ R. Grigg and W. D. J. Amilaprasadh Norbert J. Chrm. So(,. Chrm. Commun.. 1992 1300. 267 268 M.D. Ward (2) X=H Y=Z=CF (3) X = CF3 Y = 2 = H (4) X = Y = 2 = CF3 (5) X = H Y = 2 = 4-pyridyl (6) X = Y = H 2 = 4-pyridyl (7) X = Y = H Z = 4-hydroxyphenyl (8) X=H Y=Me Z=CH2NHPh (9) X = H Y = 2 = CHzNHPh (10) X=Me Y=Z=H were studied.' The luminescence of [Ru(bipy),(bipy-cy~Iam)]~(bipy-cyclam com- prises a tetradentate macrocycle covalently attached to a bipy) is quenched by coordination of Cut* to the pendant macrocycle.' Attachment of Ni2+ to the pendant cyclam unit of [Ru(bipy),(ll)12+ gives a bi- nuclear complex with a photosensitizer attached to a catalytic CO reduction site.ll Dipyridophenazine (12) intercalates efficiently into DNA; [Ru*"(terpy)(O)( 12)2 + (13) R=H R=Me 2R = -CH2CH2-. 2R = -(CH2)3-N=N N-N (14) n=2,3 K. Araki M. Fuse N. Kishii. and S. Shiraishi Bull. Chem. Soc. Jpn. 1992 65 1220. lo S.C. Rawle P. Moore and N. Alcock J. Chem. Soc. Chem. Comrnun.. 1992 684. I' E. Kimura X. Bu M. Shionoya. S. Wada and S. Maruyama. Inorg. Chem. 1992. 31 4542 The Coordination Chemistry of' Open-Chain Polydentate Liyands 269 effects DNA cleavage," whereas [Ru[phen),( 12)12 * and derivatives undergo lumines- cence enhancement by factors of up to 300 on binding to DNA.' [ReBr(CO),( 13)] are capable of MLCT processes and can undergo two oxidations and two red~ctions.'~ The pendant polyoxoethylene chains of [Ru( 14)J2+ allow binding of Group 1 and Group 2 cations with high selectivity resulting in increased fluorescence quantum yields and lifetimes.' Other Bis-heterocyclic N-donor Liyands.[SnX,(pbz)] and [SnMe,Cl,(pbz)] [X = C1 Br I; pbz = 2-(2-pyridyl)benzimidazole]were evaluated for possible anti-tumour activity." [Ru(bipy),(ptz)]" [ptz = 2-(2-pyridyl)triazole] exists as two linkage isomers with the triazole ring coordinated either by N-2 or N-4. The effects of protonation on their reactivity and excited-state lifetimes were examined.' Complexes of some (2-pyridy1)triazoles and (2-pyridy1)pyrazoles with Ru(bipy)i + were prepared and the coordination mode of the triazole rings determined by NMR studies.Thermal or photochemical excitation results in [Ru(bipy),LX]"+ (X = C1 n = 1; X = MeCN n = 2) where L is now monodentate (cf. reference 7).18There is a correlation between the electrochemical and UV/VIS spectroscopic properties of [ReL,Cl,]Cl (L = one of a series of 2-arylazopyridines).' The dynamic behaviour of Pd" and Pt" complexes of the flexible ligand di(2-pyridy1)sulfide has been studied.,' Other N-donor Ligands. [NiL,X,] [L = l-(o-aminophenyl)-3,5-dimethylpyrazole] have been prepared with various anions X." In-fac-[PtMe,I( 15)] the two pyrazolyl rings are inequivalent and the eigh t-membered chelate ring is fluxional., Several homo- and heteroleptic complexes of (16) have been prepared; they tend to have agostic hydrogen interaction^.^^ The ligands (H17) have a donor group at one end and an acceptor at the other resulting in non-linear optical properties in the tetrahedral complexes [C0(17),].~~ [Mn'v(biguanide)3]+ is a rare example of Mn" in an N coordination environment outside p~rphyrins.~~ [M( 18),] (M = Fe Co)are square planar with axial interactions to cyano groups of adjacent complexes which permit antiferromagnetic exchange.Their UV/VIS spectra are similar to those of phthalocyanine complexes. Reaction with 0 affords bridged superoxide complexes of Felv and CO"'.~~ + [Rh(phen),(phi)]' and [Rh(bipy)(phi),I2+ (phi = 9,lO-phenan-N. Gupta N. Grover.G. A. Neyhart W. Liang P. Singh. and H. H. Thorp. Anqew. Chem.. Inr. Ed. Enqi.. 1992 31 1048. l3 R. M. Hartshorn and J.K. Barton. J. Am Chrm. Soc.. 1992. 114. 5919. 14 S.A. Moya. R. Pastene. R. Schmidt J. Guerro. and R. Sartori Polyhedron 1992 11 1665. lS H. Diirr R. Schwartz. I. Willner E. Joselehich and Y. Eichen. J. Chrm. Six.. Chem. Commun.. 1992. 1338. '' T.A. Kabanos. A. D. Keramidas. D. Mentzafos. U. Russo A. Terzis. and J. M. Tsangaris J. Chmi. So(,.. Dalton Truns. 1992 2729. " R. Wang J.G. Vos R. H. Schmehl and K. Hage J. Am. Chem. Soc,. 1992. 114. 1964. '" B. E. Buchanan. P. Degn. J. M. P. Velasco. H. Hughes. B. S.Creaven C. Long J.G. Vos. R. A. Hourie. R. Hage J. H. van Diemen J.G. Haasnoot. and J. Reedijk J. Chem. Soc.. Dalton Truns.. 1992 1177.1') P. Ghosh A. Pramanik. N. Bag and A. Chakravorty J. Chem. Sot. Dulron Trans. 1992. 1883. *() G. Tresoldi E. Rotondo P. Piraino. M. Lanfranchi and A. Tiripicchio. Inorq. Chim. Acru 1992,194.233. " N. Saha. A. Saha S. Chaudhuri. T. C. W. Mak. T. Banerjee. and P. Roychoudhury Polyhedron 1992. 11 2341. l2 A. J. Canty. R. T. Honeyman B. W. Skelton. and A. H. White J. Chrni. Soc.. Dulron 7iuns.. 1991 2663. l3 S. Trofimenko J.C. Calabrese and J.S. Thompson. Inorq. Chem.. 1992. 31. 974. 24 T Thami. P. Bassoul. M. A. Petit. J. Simon. A. Fort M. Barzoukas and A. Villaeys J. Am. Chrn~.Soc,.. 1992. 114. 915. 25 R. 0.C. Hart. S.G. Bott. J. L. Attwood. and S. R. Cooper. J. Chem. So(,.,Chem. Cornmun.. 1992 894. *' M. Bonamico. V. Fares A. Hamini and N. Poli.J. Chrnt. Soc.. Dulrori Trans. 1992. 3273. 270 M.D. Ward [-I CN (H17) X=OMe NM% (18) threnequinone-diimine) intercalate to DNA via the phi ligand and promote photo- chemical strand cleavage.,' 0 S and P-donor Ligands.-The crystal structures and racemization kinetics of + [Cr"'(bpdo),L] (bpdo = bipy-N,N'-dioxide; L = oxalate malonate) have been determined.28 The new bulky chelating ligands (H19)-(H22) form highly soluble and volatile lanthanide complexes [LnL3].29 2,2'-Biphosphinine (23) acts as a strong n-acceptor in [RuCl,(dmso),(24)] and [R~C1,(24),].~~ Ru" complexes with several chiral diphosphines have been ~repared.~ Pt" complexes with the chiral diphosphines (H19) R' = H R2 =But (H22) (H20) R' = R2 = Bu' (H21) R' = R2= W R2 PPh2 OPPh (24) R' = R2 = E3 (25) R' + R2 = -(CH2)3-" A.Sitlani E.C. Long A.M. Pyle and J. K. Barton J. Am. Chem. SOC. 1992 114 2303. 28 H. Kanno M. Tomita S. Utsuno and J. Fujita. Bull. Chem. SOC.Jpn.. 1992 65 1233. 29 W.A. Herrmann R. Anwander and M. Denk Chem. Ber. 1992. 125 2399. 30 D. Carmichael P. Le Floch L. Ricard and F. Mathey. Inorg. Chim. Acta 1992 198-200.437 31 H. Kawano T. Ikoriya Y. Ishii T. Kodama M. Saburi S. Yoshikawa Y. Uchida and S. Akutagawa Bull. Chem. SOC.Jpn. 1992 65 1595. The Coordination Chemistry of Open- Chain Polydentate Liyands 27 1 (24)and (25) were prepared; optically pure [PtCI2(25)] catalyses hydroformylation of styrene with 37% optical purity.32 Mixed N-0 N-S N-C N-P and N-As Donor Ligands.-The complexes [Fe2(p- S),L2I2-[L = (26k(31)] are possible models for [2Fe-2S] proteins.33 [M(31),] (M = Al Ga In) have meridional octahedral structures and were examined by variable-temperature NMR spectro~copy.~~ Electrochemical reduction of mer-[Mn"'(32),] results in mer-fac equilibration; stereoretentive reoxidation of the resultant fac-[Mn"(32),] permits preparation of fuc-[Mn1"(32),].The Mn"/Mn"' couple is isomer dependent.35 In [(Co(aet),(en)),NiI4+ (Haet = 2-+ aminoethanethiol) two cis-octahedral [Co(aet),(en)] units act as S,S-bidentate (H26) n=0 X=S (H27) n = 0 X = 0 (29) R=Me (H28) n=l X=O (30) R = W HO OH (H3 1) (H32) R = C1 Br Me But donors to the central tetrahedral Ni" ion.36 Similar behaviour occurs in [(C~(aet),),Zn,(p~-O)]~ + which undergoes four successive Co*"/Co" reduction^.^' The six-coordinate homoleptic complexes of V2 or V3+ with pyridine-2-thiol (Hpt) + quinoline-8-thiol and 2-aminothiophenol all have N3S3 coordination spheres.38 The crystal structures of [(V(O)),(pt),] I S-bridged binuclear) [Na(thf),V"'(pt),] (seven-coordinate) and [V"(pt),(tmeda)] (octahedral) were determined.39 The crystal structures of [M(33),] (M = Ni Pd Zn) reveal distorted four-coordinate geometries with a helical disposition of ligands."' Trinuclear S-bridged Cu' complexes of (H34) have unusual luminescence proper tie^.^' Square-planar [Rh(35),] + reversibly binds 0 and CO to an extent depending upon the degree of steric crowding induced by the substituent R; the crystal structure of one 32 A.L. Bandini G. Banditelli E. Cesarotti G. Minghetti and B. Bovia Inorg. Chem. 1992 31. 391. 33 P. Beardwood and J. F. Gibson J. Chem. Soc. Dalton Trans.. 1992 2457. 34 H. R. Hoveyda V. Karunaratne S.J. Retrig and C. Orvig Inorg. Chem.. 1992 31 5408. 3s P. Basu and A. Chakravorty Inorg. Chem.. 1992 31 4980. 36 T. Konno K. Okamoto and J. Hidaka Inorg. Chem. 1992. 31. 161. 37 T. Konno T. Nagashio K. Okamoto and J. Hidaka Inorg. Chem. 1992 31 1160. 38 G. Henkel B. Krebs and W. Schmidt. Angew. Chem. Int. Ed. Engl.. 1992 31 1366. 39 J.G. Reynolds S.C. Sendlinger A. M. Murray. J.C. Huffmann and G. Christou Angew. Chem.. Int. Ed. Engl. 1992 31 1253. 40 T. Kawamoto and Y. Kushi J. Chem. SoL... Dalton Trans.. 1992. 3137. 41 D.M. Knotter G. Blasse J. P. M. van Vliet and G. van Koten. Inorg. Chem. 1992 31 2196. 272 M. D. Ward (33) (Fc = ferrocenyl) (35) R = Et pr" W But X-Me Ph (37) x= P (38) X= As such oxygen adduct shows4 that the 0 is 'side-on' to the Rh'. In [Ir,(c0d),(36),]~ + and [Rh2(nbd),(36),I2' the metal atoms are bridged by the phosphinine moiety whereas the pyridyl rings are terminal.43 NMR studies of square-planar Pd" and Pt" complexes of (37) and (38) show that facile ligand redistribution occurs cia square pyramidal intermediate^.^^ The properties of Rh"' complexes containing cyclometal- lating C,N-donor ligands such as 2-phenylpyridine,45p47 2-thien~lpyridine,~~.~~ and I-phenylpyrazole and substituted derivative^,^' have been studied.Other Mixed-donor Ligands.-Ni" Pd" and Pt" complexes of the 0,P-chelating ligand 2-(diphenylphosphino)hydroquino148 and of the S,P-chelating ligand 2-(dimethypho~phino)ethanethiol~~ were prepared and structurally characterized. Elec- trochemical and UV/VIS spectroscopic studies were performed on technetium and rhenium complexes containing 2-(dipheny1phosphino)thiophenol(Hdpt); [Tc(dpt),] and [Re(dpt),] are near-~ctahedral.~' 3 Terdentate Ligands N-donor Ligands.-Tripodal Ligands. Sterically bulky tris(pyrazoly1) borates have been of particular interest. Thus Co" Ni" and Zn" complexes of (39k(46) were prepared; most are trigonally-distorted tetrahedral with the formula [MLX] = NCS NCO N3) but some are dimeric [ML(p-X),ML].*' [Cu,(42),] has an 42 C.A.Ghilardi S. Midollini. S. Moneti A. OrlandInI and G. Scapacci. J. Cfirm. Snr.,Dulron Truns. 1992 3371. 43 B. Schmid L. M. Venanzi. T. Gerfin V. Gramlich. and F. Mathey Inorg. Chrm. 1992 31. 5117. 44 G. Salem and S. B. Wild Inory. Chem.. 1992 31. 581. 45 G. Frei A. Zilian A. Raselli H. IJ. Giidel and H.-B. Riirgi. Inorg. Chrm. 1992 31 4766. 46 A. Zilian and H. U. Giidel Inorg. Chem. 1992. 31 830. 47 U. Maeder A. von Zelewsky and H. Stoeckli-Evans Hell.. Chim. Acrcc. 1992 75. 1320. 48 S. B. Sembiring. S.B. Colbran. and L. R. Hanton Inorg. Chirn. Acta. 1992 202 67. 49 M. Kita T. Yamamoto K. Kashiwabara and J. Fujita. Bull. Chrm. Sw. Jpn.. 1992 65 2272. SO J. R. Dilworth,A. J. Hutson S.Morton M. Harman M.B. Hursthouse. J. Zubieta. C. M. Archer.and J. D. Kelly Polyhedron 1992 11. 2151. 51 S. Trofimenko J.C. Calabrese J. K. Kochi. S. Wolowiek. F. B. Hulsbergen. and J. Reedijk Inory. Chrm.. 1992 31. 3943. The Coordination Chemistry of Open-Chain Polydentate Ligands H [-I R2 (39) R' = Pr' R2= Me (40) R' = neopentyl R2 = H (41) R' =But R2= Me (42) R' = Pr' R2= H (43) R' =But R2 = H (44) R'=Pr' R2=H also 4-Br on each ring (45) R' =p-tolyl R2 = H (46) R' =p-methoxyphenyl R2 = H (47) R' = R2 = Pr' unusual structure in which each Cu' is linearly coordinated by one donor atom from each (bidentate) ligand. Reaction with NO afforded [Cu(42)(NO)] the first terminal Cu-NO complex.52 [M(40),] (M = Fe Co Ni) were prepared; [Ni(40),] is octahed- ral in the crystal but five-coordinate in solution.Heteroleptic six-coordinate [M(40)(tpb)] [tpb = a tris(pyrazoly1)boratel and four-coordinate [M(40)X] are also de~cribed.'~ In [{Cu(47)),(0,)] the 0 adopts an unusual p-q :q coordination mode. The complex is spectroscopically very similar to oxyhaemocyanin and oxytyrosinase and is diamagneti~.~~ In [Mo(46)(NO)X2] (X = CO C1) the p- methoxyphenyl substituents form a bowl-like cavity and also cause a highly distorted metal coordination ge~metry.~' In the planar complexes trans-[Ni(p-C,H4X)(43)(PMe,),] (X = H Me OMe) (43) is m~nodentate.~~ [(MeGa(pz),},In] [In14] with a tris(pyrazoly1)gallate ligand has been ~repared.~ The enantiomerically pure C,-symmetric tripodal ligands (48) were prepared.58 Electrochemical and spectroscopic properties stability constants and some crystal structures of the six-coordinate complexes [M(bpma),]"+ [bpma = 1,l -bis(2-py-ridy1)methylamine; M = Fe Co Ni Cu n = 2; M = Fe n = 31 have been studied; the complexes show large degrees of steric strain.59 Mono- and binuclear Zn" complexes of tris(2-pyridy1)phosphine and tris(2-pyridy1)arsine were prepared and structurally + characterized.60 In [Pd(Htpm)Cl,'] [tpm = tris(2-pyridy1)methanel the tpm is 52 S.M. Carrier C.E. Ruggiero W. B. Tolman and G. B. Jarneson J. Am. Chem. Soc. 1992 114 4407. 53 J.C. Calabrese and S. Trofirnenko Inory. Chem. 1992 31 4810. 54 N. Kitajirna K. Fujisawa C. Fujirnoto Y.Moro-oka S. Hashirnoto T. Kitagawa K. Toriumi K. Tatsurni and A. Nakarnura J. Am. Chem. Soc. 1992 114 1277. 55 M. Cano J. V. Heras A. Monge E. Gutierrez C. J. Jones S. L. W. McWhinnine and J.A. McCleverty. J. Chem. Soc. Dalton Trans. 1992 2435. 56 E. Gutierrez S.A. Hudson A. Monge. M.C. Nicasio M. Paneque,and E.Carrnona J. Chem. Soc. Dulton Trans. 1992 2651. '' A. Frazer B. Piggott. M. Harrnan M. Mazid and M. B. Hursthouse Polyhedron 1992 11 3013. '* H. Adolfsson K. Warnrnark and C. Moberg J. Chem. Soc.. Chem. Commun. 1992 1054. " P. V. Bernhardt P. Cornba A. Mahu-Rickenbach S. Stebler S. Steiner K. Varagny and M. Zehnder Inorg. Chrm. 1992 31 4194. 6o R. Gregorzik. J. Wirbser and H. Vahrenkarnp Chem. Ber. 1992 125 1575. 274 M. L). Ward OR' (48) R' = R2 = H; R' = H R2 = Me; R' = R2= Me bidentate with a protonated pendant pyridyl group.6' Ligand (49) acts as a terminal capping ligand in the linear trinuclear complexes [Fe3(p-OH)2(p-RC02)4(49)2]3 + .62 Terpyridines and Other Triimines.Terpy can act as a fluxional bidentate ligand in fuc-[ReBr(CO),(terpy)] fuc-[PtCIMe,(terpy)] and ~is-[W(CO),(terpy)].~~ NMR and electrochemical studies on 2 1 homo- and heteroleptic Ru" complexes with terpy and 4'-substituted derivatives were performed; there is a correlation between El,2-(Ru"/Ru"') and the combined electronic properties of the two 4'-sub~tituents.~~ [RuL,]" (L = 4'-Cl-terpy and 4'-MeS0,-terpy) are the first [Ru(terpy),]'+ deriva-tives to be luminescent in fluid solution at room temperat~re.~~ Protonation or (51) X = CH~-~=&-Y=H (52) X = ferrocenyl Y = H (53) X=Y=OMe (54) X = Y = OH alkylation of the pendant 4-pyridyl groups of [Fe{ 4'-(4-pyridyl)terpy} 2]2 affects the + properties of the Fe" centre.66 The photophysical properties of [M(50)J2+ (M = Fe Ru 0s) were examined; the 0s complex has the longest-lived excited state.In [Os"(50)(5 In 1)I"+ the luminescence is quenched by the pendant viologen gro~p.~' [M(52),I2+ and [M(50)(52)I2' there is a weak electrochemical interaction between the ferrocene groups and the M(terpy)i+ cores. Again the luminescence of the 0s" 61 A.S. Canty N. J. Minchin B. W. Skelton and A. H. White Aust. J. Chem. 1992 45 423. 62 V.A. Vankai M. G. Newton and D. M. Kurtz Jr.Inorg. Chem. 1992 31 343. 63 E. W. Abel N. J. Long K. J. Orrell A. G. Osborne H. M. Pain and V. Sik. J. Chem.Soc. Chem. Commun. 1992 303. 64 E.C. Constable A. M. W. Cargill Thompson D. A. Tocher and M. A. M. Daniels New. J. Chem.. 1992 16 855. 65 E.C. Constable A. M. W. Cargill Thompson N. Armaroli V. Balzani and M. Maestri. Poljhedron. 1992 11 2707. 66 E. C. Constable and A. M. W. Cargill Thompson. J. Chem. SOL..,Dalton Trrins.. 1992 2947. 67 E. Amouyal and M. Moullem-Bahout J. Chem. Soc.. Dulton Trans.. 1992 509. The Coordination Chemistry of Open-Chain Polydentate Liyands complexes is quenched by the ferrocenyl substituent.68 Demethylation of + + [Ru(terpy)(53)I2 gives [Ru(terpy)(54)I2 with a pendant catechol binding site to which Ru(bipy)i+ and Pd(bipy) fragments were subsequently attached.69 Reaction + of ferrocenyllithium with terpy affords 3'-(ferroceny1)terpyridine.70 Terpy and 2,6-bis(1-pyrazolyl)pyridine have planar trans,trans structure^.^ The varying ligand-field strengths of (55)-(58) mean that [FeL,] + is low-spin for L = (57) or (58) high-spin for L := (56) and shows spin-crossover behaviour for L = (55); [FeLX,] and some Zn" complexes were also ~tudied.~' The electrochemical properties of Mn" complexes of (57) were investigated.[Mn(57)C12].dmf has a (55) x=s (57) R=H (56) X=O (58) R =Me (59) R = (CH&CH3 (60:)R = Ph (611) R = p-MeOC6H4 (62) R = -(CH&Ph distorted square pyramidal structure.73 Whereas [Cu,(58),I2 is helical the complex + with the analogous bidentate benzene-based (rather than pyridine-based) ligand is non-helical with two two-coordinate linear Cu' centres.The factors affecting adoption of helical as opposed to non-helical structures are discussed.74 Excitation into the ligand-centred excited states of [ML(NO,),(MeOH),] [M = lanthanide; L = (58) (59); n = 0,l) is followed by efficient energy-transfer to the metal which can then luminesce.75 [CoL,]'+ and [CoLX,] [L = (60)-(62); X = C1 Br NCS] were ~repared.'~ Electrocatalytic reduction of CO was effected with [ML,]" [M = Fe hn J.-C. Chambron. C. Coudret. and J.-P. Sauvage New. J. Chem.. 1992. 16. 361. 69 C. Howard and M. D. Ward ,4ngew. Cltem. fnt. Ed. Engl. 1992 31 1028. 70 I. R. Butler N. Burke L.J. Hobson and H. Findenegg Polyhedron 1992 11 2435. 71 C.A. Bessel R. F. See D. L. Jarneson M. R. Churchill and K.J. Takeuchi J. Chrm. Soc. Dalton Trans. 1992 3223. 72 S. Riittirnann C. M. Moreau A. F. Willidms G. Bernardinelli and A. W. Addison. Polyhedron 1992. I i 635. 73 W. Shuangxi Z. Ying Z. Fanglie W. Qiuying and W. Liufang Polyhedron 1992 11 1909. 74 S. Riittirnann C. Piguet G. Bernardinell B. Bocquet and A. F. Williams J. Am. Chrm. Soc. 1992 114 423I. 75 C. Piguet A. F. Williams. G. Bernardinelli E. Moret. and J.-C. Bunzli Nelr. Chirn. Actu. 1992.75. 1697. 16 D. A. Edwards S. D. Edwards. W. R. Martin. T.J. Pringle. and P. Thornton Polyhedron. 1992 11. 1569. 276 M. D. Ward Co Ni; L = terpy 4'-vinylterpy (60) 1,2,4,5-tetrakis(2-pyridyl)pyrazine, and 1,3,5- tris(2-pyridyl) triazine] .77 Other N-donor Ligands.Differences in the spectroscopy and electrochemistry of the homoleptic Ru" complexes of (63) are dominated by the electronic rather than steric properties of the ligands;78 [Mn(63),I2+ and [Mn(63)X2]"+ (X = C1 n = 0; X = H,O n = 2) were also ~tudied.'~ PylCH,NHCH,Pyl (Pyl = 2-pyridyl) forms fac-[ML2l2+ complexes with Mn" Zn" and Cd". The EPR properties of the Mn" complex doped into diamagnetic host lattices were measured.80 Compounds (64)and (65) act as symmetric terminal face-capping ligands in [L2Fe!1(p-O)(p-X)2]2+ (X = carboxylate diphenylphosphate); the complexes show strong antiferromagnetic R2 (63) R' and R2 = H or Me (64) R= H (65) R=Me (66) K=Et 0 PY1' (67) R = H (68) R=Me have the same core structure and under- go two well-separated Ru"'/Ru'" oxidations and a Ru"'/Ru" reduction.82 Reaction of [Mn~V(66)2(p-O),(,u-MeC02)]3+with NaClO,/MeCN affords [Mny(66)3(/i-O),(OH)]3+,a model for the oxygen-evolving site of photosystem II.83The structures and magnetic properties of [{Ni(67)x(~-X)}~] (X = N, NCS) were determined.84 [Cu(67)Br][PF6] has a chain structure with bridging bromides resulting in a triplet ground state and weak antiferromagnetic coupling.85 [Cu(68)(NCS),] is trigonal 77 C.Arana. S. Yan. M. Keshavarz-K. K.T. Potts and H. D. Abruna. Inorq. Chem. 1992 31 3680. S. Mahapatra and R. Mukherjee J. Chem. Soc. Dalton Trans. 1992 2337. 19 S.Mahapatra D. Bhuniya. and R. Mukherjee Polyhedron. 1992 11 2045. 8o J. Glerup. P. A. Goodson D. J. Hodgson. K. Michelsen K. M. Nielsen. and H. Wiehe Inorg. Chem..1992. 31 4611. '' S. Mahapatra N. Gupta and R. Mukherjee J. Chem. Soc. Dolfon Truns. 1992. 3041. '' N. Gupta S. Mukherjee S. Mahapatra M. Ray and R. Mukherjee Inorg. Chem. 1992 31 139. 83 S. Pal M. K. Chan and W. H. Armstrong J. Am. Chem. Soc. 1992 114 6398. 84 R. Cortes J. 1. R. de Larramendi L. LzTarna T. Rojo M. K. Urtiaga and M. I. Arriortua J. Chem. Soc,.. Dalton Trans.. 1992 2723. 8s T. Rojo. R. Cortes J. I. R. de Larrarnendi. and G. Madariarga. J. Chem. SOL... Dulton 7run.s.. 1992 2125. The Coordination Chemistry of Open-Chain Polydentate Ligands bipyramidal; the stereochemistries of other complexes [Cu(68)X2] are discussed.86 The stoichiometries of Co" Ni" and Cu" complexes of carcinine (H,69) were studied by potentiometric and spectroscopic methods.Several different structures from simple [M(69)] (M = Co Ni) to the cyclic tetramer [Cu4(69),] were detected.87 Other Homodentate Ligands.-The anionic cyclopentadienylcobalt species (70)-(72) act as tripodal 0,-donor ligands in various complexes with Zn Al and Tc.88389 The tri-substituted 1,4,7-triazacyclononane derivative (H,73) acts as a tripodal S donor to (70) R = Et '0-SH (71) R= OMe (72) R = OEt (H373) n = 2 or 3 (74) R=Me,Ph [4Fe-4S] cubanes as in [Fe4S,(73)(SEt)I2-,permitting site-specific reactions at the differentiated Fe site." The five-coordinate complexes [Ni(74),I2+ (in which one AsMe group is not coordinated) are members of extended electron-transfer series with oxidation states from 0 to +4 accessible electrochemically.9' Mixed N,O-donor Ligands.-Whereas [Cu,L,(p-OAc)][PF,] [L = (75) (76)] and [Ni2(76),(p-0Ac)(NCMe),][PF6] ,3-MeC02) cores all have similar M2(p-O)2(p-l [[Ni(75)(H75)),][PF6] contains two [Ni(75),] units held together by two strong hydrogen bonds between phenolate oxygen atoms.Intra-ligand n-stacking interac- tions appear to play a significant role in both types of structure.92p94The EPR and magnetic properties of the binuclear Cu" comple~es,~~ and the electrochemical Xh J. I. R. de Larramendi J. L. Mesa R. Cortes. T. Rojo M. K. Urtiaga. and M. I. Arriortua. Polyhedron 1992 11.623. 87 T. Gajda B. Henry. and J.-J. Delpuech J. Chem. Soc,. Dalton Trim.. 1992. 2313. xx A. Looney M. Cornebise D. Miller. and G. Parkin Inorg. Chem. 1992 31 989. 89 J.A. Thomas and A. Davison Inorg. Chem.. 1992 31 1976. YO D. J. Evans G. Garcia. G. J. Leigh M. S. Newton and M. D. Santana. J. Chem. Soc.. Dalton Trans. 1992 3229. 41 A. J. Downard. L. R. Hanton. and R. L. Paul. J. Chem. Soc.. Chem. Commun.. 1992 235. 92 J. C. Jeffery. E. Schatz and M. D. Ward J. Chem. Soc.. Dalton Truns. 1992. 1921. 93 J. C. Jeffery and M. D. Ward J. Chem. Soc.. Dalton Truns.. 1992 21 19. 94 B. M. Holligan J. C. Jeffery. and M. D. Ward. J. Chem. Soc.. Dalton Trans. 1992 3337. 95 J. P. Maher P. H. Rieger. P. Thornton and M. D. Ward J.Chew. Soc. Dalton Trans.. 1992 3353. 278 M.D. Ward (75) X=nothing (77) R=Me (76) X = -CH=CH-(H78) R = H (79) quinone analogue of (H80) properties of Co"' and Ru"' complexes of (75),92396were examined. Ligands (77)-(79) show N,N-bidentate N,N,O-terdentate and N,N,C-cyclometallating modes of coor- dination in Pd" complexes .9 Vanadyl complexes of (80) are the first examples of V" complexes with imidazole ligands and are models for vanadium bromoperoxida~es.~~ The crystal structure of [Vv(0)(80)(cat)] (H,cat = catechol) and 51V NMR spectra of it and related complexes are described.99 [(Mn"'(81)C1(MeOH)},] is the first Mn dimer with unsupported alkoxide bridges. loo Magnetic studies of mixed-valence trinuclear complexes [Mn"Mn~'L2(p-RCO2),X,1 [L = (82) or (83) both of which are O,N,O- terdentate ligands; X = a neutral monodentate ligand] were performed.lo' Reaction crN'R 'OH (H80) R = CH2CH2-(4-imidazolyl) (H28 1) R = CH2CH2OH (H282) R = CH2CH(OH)CH20H 0 (H283) R = CH2C(OH)(CH,OH> (H284) R = CH(CH2OH)COzH (H285) R = o-C&40H (HzS6) R = CH~(O-C~H~OH) (H87) R = CH,CH2-(2-~yridyl) (H288) R = CH2C02H (H289) R = CH2CHZC02H (H29O) R = NH-C(O)-(4-pyridyl) (H291) R = NH-C(0)-Ph of [V0l2 + salicylaldehyde and (m)-serine gives the V"/VV species [{ V0(84)},(p-O)] -.lo [V(85),] (and CH,-substituted analogues) are non-oxo V" complexes which can be reduced to the V"' and V" states.lo3 Ligands (80) and (85)-(89) were used to prepare high-spin Fe"' complexes with N204 N,O, and N40 donor sets.The effects 96 B.M. Holligan J.C. Jeffery M. K. Norgett E. Schatz and M. D. Ward,J. Chem.Soc. Dalton Trans. 1992 3345. 97 R. A. Berthon S.B. Colbran and D.C. Craig Polyhedron 1992. 11 243. 98 C. R. Cornman J. Kampf M. S. Lah and V. L. Pecoraro Inory. Chem. 1992 31 2035. 99 C. R. Cornman J. Kampf and V. L. Pecoraro Inory. Chem. 1992 31 1981. 100 E. Larson M. S. Lah X. Li J. A. Bonadies and V. L. Pecoraro Inorg. Chem.,1992 31. 373. D. P. Kessissoglou M. L. Kirk M. S. Lah X. Li. C. Raptopolou W. E. Hatfield. and V. L. Pecoraro Inorg. Chem. 1992 31 5424. 102 J. C. Pessoa. J. A. L. Silva A. L. Vieira L. Vilas-Boas P. O'Brien. and P. Thornton J. Chem. Soc.,Dalton Trans. 1992 1745. K. Ramesh T. K.Lal and R. N. Mukherjee Polyhedron. 1992. 11 3083. The Coordination Chemistry of Open-Chain Polydentate Ligands 279 of variations in donor set and stereochemistry on their spectroscopic and electrochemi- cal properties were e~amined."~ The kinetics of formation and stability constants of Fe" complexes of the salicylaldehyde hydrazones (90) and (91) and the pyridoxal hydrazones (92) and (93) were measured.lo5 Binuclear Cu" complexes of (92)-(96) were prepared and characterized; reversible oxidations to Cu"Cu"' and CU"~CU"~ states were observed.lo6 A series of bi- tri- and tetranuclear CU" complexes of the compartmental ligand Me,NCH,CH(OH)CH,NMe (HL) were prepared and structurally characterized. The tetranuclear complexes have planar cyclic structures in which each ligand is binucleating with the alkoxide bridging two metals.* 07q1 O8 The structures and R R (98) R= H (99) R=Bu" R (H2100) R = H Me C1 electrochemical properties of 0s'' 0x0 and nitrido complexes with the bulky ligand (97)were studied."' EPR studies were performed on Cu" complexes of (98) and (99).In [Cu(98)(H20),(C10,)] and related species (98) is a fac-N,N,O-donor but in + + [CuL,(X)(CIO,)] [L = (98) (99); X = azide acetate benzimidazole] boths ligands are N,N- bidentate.' lo Octahedral Fe"' and Fe" complexes of (100)were prepared and characterized.' '' Other Mixed-donor Ligands.-Mono- and binuclear Au" complexes with ( 101) were prepared and characterized and their reactions with other N-donor ligands studied.' 12,1l3 Several 1 1 complexes of Co" Ni" Cu' Cu" Zn" and Ag' with (102) were prepared.The ligand often acts as an N,S,N chelate but with Cu' and Ag' it is an Io4 K. Ramesh and R. N. Mukherjee J. Chrm. Soc.. Dalton Trans. 1992 83. 105 J.-E. Dubois H. Fakhrayan. J.-P. Doucet and J.-M. E. Chahine Inorg. Chem. 1992 31 853. 106 M. Mohan N. K. Gupta M. Kurnar N. K. Jha and W. E. Antholine Inorg. Chim. Acra. 1992. 197 39. lo' J.-C. Zheng R.R. Rousseau and S. Wang Inorg. Chrm. 1992. 31 106. 108 S. Wang S.J. Trepanier J.-C. Zheng %. Pang and M. J. Wagner Inorg. Chem. 1992. 31 21 18. Z.-Y. Li W.-Y. Yu C.-M. Che. C.-K. Poon R.-J. Wang and T. C. W. Mak J. Chem. Soc. Dalton Trans. 1992 1657. 'lo G. Batra and P. Mathur Inorg. Chem.1992 31 1575. 'I' M. Koikawa H. Okawa Y. Maeda and S. Kida Inorg. Chim. Acra 1992 194 75. 'I2 A. P. Koley L.S. Prasad P.T. Manorahan and S. Ghosh Inorg. Chim. Acta 1992 194 219. 'I3 A. P. Koley R. Nirmala L.S. Prasad S. Ghosh and P.T. Manorahan Inorg. Chrm. 1992 31 1764. 280 M.D. Ward N,N-bidentate bridge thus leading to polymeric complexes.' The preparation and crystal structure of [{C~(fpt))~(p~-P~O,)] [Hfpt is the N,N,S-donor 2-formylpyridine thiosemicarbazone] are described. The central pyrophosphate ion donates a different oxygen atom to each Cu.' Stereoregular A-helical coordination polymers of Cut and Ag' with (103) were prepared; each ligand ligates via imidazole N imine N and thiophene S atoms to three separate metal ions which have trigonal planar geometries.' l6 In [Cu\( 104)J*+ each Cut is coordinated by one N,S binding pocket from each compartmental ligand.The S atoms are bridging.' ' 6-Thienylbipy (H105) can be N,N,C-terdentate in [M( lO5)Cll uia cyclometallation of the thienyl ring or N,N-bidentate in [M(H105)C12] (M = Pd Pt). In addition [Au(H105)C13] where (H105) is monodentate converts on heating to [(Au(105)Cl2] where the ligand now acts as a bidentate bridge.' l8 Likewise reaction of (H,106) and (H2107) with ds ions results in N,C-bidentate or C,N,C-terdentate binding modes. Reaction of either ligand with Au"' results in coupling of the terminal thienyl rings to give novel hexadentate ligands."' Bipy and phen groups were directly attached to 9:TJ SH N/ N-N N-N (103) R = H Me Me3Si (104) Fc = ferrocenyl R S R aN.NAsAph H (H105) R = 2-pyridyl (H2106) R = Ph (H2107) R = 2-thienyl (H2108) R = H Me C1 Br 114 W.G. Haanstra. W. L. Driessen M. van Roon A. L. E. Stoffels. and J. Reedijk. J. Chem. Soc.. Dulron Trans. 1992. 481. 115 E. W. Ainscough A.M. Brodie. J. D. Ranford J. M. Waters and K. S. Murray Inorcq. Chirn. A<,ru. 1992. 197 107. 116 J. F. Modder K. Urieze A. L. Spek. G. Challa and G. van Koten Inory. Chem.. 1992. 31 1238. I 17 B. Delavaux-Nicot. N. Lugan and R. Mathieu Inory. Chem.. 1992 31 335. I18 E.C. Constable R. P.G. Henney. P. R. Raithby.and L. R. Sousa J. Chem. Soc.. Dulton Trans. 1992,2251. 119 E. C. Constable R. P. G. Henney and D. A. Tocher J. Chem. Soc,. Dulton Truns..1992 2467. The Coordination Chemistrji of 0pc.n-Chain Polydentate Ligands 281 phosphino-substituted ferrocenes to give potential N,N,P-terdentate ligands."' Rhenium complexes of PhN(CH,CH,PPh,) (np2) were prepared; the ligand is N,P-bidentate in [ReOCl,(np,)] but fuc-terdentate in [ReCl,(np2)].'Z1 Zn" com-plexes of pyridoxal thiosemicarbazone and methylpyruvate thiosemicarbazone which are O,N,S-donors were studied as models for Zn-S metalloproteins.'22 The elec- trochemical properties of cis-[MoV'0,(108)(S)] (S = acetone py dmf dmso) and the kinetics of its oxygen-atom transfer to PPh (affording OPPh and Mot" species) were studied.'23 4 Tetradentate Ligands N-donor Ligands.-Bridging Ligands with Two Bidentate Compartments. 2,3-Di(2-pyridy1)pyrazine (109) and the 2,5-isomer have been extensively used as bridging ligands in high-nuclearity complexes comprising multiple (up to 13) photoactive Ru" and/or 0s" polypyridyl centres; iin example is given in Figure 1.Amongst their L ,L YIP BL BL L = bipy or biq I I ,Mi. ,Mi BL = (109) L. BL BL-,BL BL. ,L ?;'. F R;lp M = central metal (RU" 0s") L BL L I M~= intermediate metal (RU") L ,BL ,Mi BL. ,L MP= peripheral metal (Ru" 0s") Yp Mp L L Figure 1 Decunuclear ruthenium (11) and osmium (11) comple-yes showing inter-component energy transfer interesting features are the different electrochemical properties of metals in different 'shells' controllable inter-component energy-transfer on photo-excitation and step- wise synthesis by protecting one binding site of the bridging ligands and then de-protecting it after complexation at the other site.' 24-1 28 The UV/VIS and electrochemical properties of [(bil~y)~Os(p-L)Ru(bipy)~]~+ [L = (109)-( 11 l)] were examined.'29 [Cu(p-L)(H,O),] [L = (109) bipym] are infinite-chain polymers.' 30 [(Re(CO),CI),L] [L = (109) (1 12) (113); n = 1,2] were prepared.All of the 120 I.R. Butler Polyhedron 1992 11 3117 121 D. Michos. X.-L. Luo and R. H. Crabtree. J. Chem. Soc. Dalton Trans.. 1992 1735. 122 M. B. Ferrari G.G. Fava C. Pelizzi and P. Tarasconi J. Chem. Soc. Dalton Trans. 1992. 2153. 123 S. Bhattacharjee and R. Bhattacharyya. J. Chem. Soc. Dalton Trans.. 1992 1357. 124 G. Denti S. Serroni. S. Campagna V. Kicevuto A. Juris M.Ciano and V. Balzani. Inorg. Chim. Acta 1992 198-200 507. 125 G. Denti. S. Campagna S. Serroni M. Ciano and V. Balzani. J. Am. Chem. Soc.. 1992 114. 2944. 126 S. Campagna G. Denti S. Serroni. M. Ciano A. Juris and V. Balzani Inorg. Chem.. 1992 31 2982. 127 S. Serroni and G. Denti Inory. Chem. 1992 31 4251. 128 S. Serroni G. Denti S. Campagna A. Juris M. Ciano. and V. Balzani. Angew. Chem.,Int. Ed. Engl.. 1992 31 1493. 129 M. M. Richter and K. J. Brewer Inorg Chem. 1992. 31 1594. 130 L. W. Morgan K.V. Goodwin W.T. I'ennington and J. D. Petersen Inorg. Chem.. 1992 31. 1103. 282 M. D.Ward (110) R=H (1 11) 2R = fused aromatic ring (112) R=Me (114) (1 15) X = (CH,) (n= 2-7.12). CH,(p-C6H,)CH2 CH2@-cyclohexyl)CH2 RmxmR (117) X = hexadentate macrocycle 4,4'-bipyridiniumdiium polyaminoethylene chain R (118) R=H (119) R=Me The Coordination Chemistry of Open-Chain Polydentate Liyands 283 mononuclear complexes and one of the binuclear complexes are luminescent.' ' A-[Ru(bipy),(ll3)]*+ promotes DNA cleavage in the presence of H,O, Cu" and 3-mercaptopropionic acid probably via formation of a {RuI1(p-1 13)Cu") binuclear complex.'32 The UV/VIS and electrochemical properties of [{ Mo(CO),),( 1 14)] (n = 1,2) indicate that the extra ligand conjugation compared to 2,5-bis-(2-py-ridy1)pyrazine results in a lowering of the LUMO and decreased basicity.' 33 [Cu,(bpp),][CF,S03] [bpp = 3,6-bis(2-pyridyl)pyridaziiie] contains four tet-rahedral Cu' ions each coordinated by bidentate cavities of two near-perpendicular ligands.It is stabilized by intra-ligand n-stacking interactions and undergoes eight ligand-based reduction^.'^^ Attachment of a Ru(bipy)i+ fragment to one bipy site of (115) and quaternization of the other to give a diquat afforded [Ru(bipy),]'+ derivatives with pendant electron-acceptors. The electron-transfer rate after photo- excitation depends on the bridge length.'35 Whereas [Cu"( 1 16)(H20)][C10,] is mononuclear [Cu\(1 16),][C104] I is a binuclear double helix with two four-coordi- nate Cu' ions. The two forms interconvert slowly. Their electrochemical and spectroscopic properties and the photophysics of the Cu' complex were inves-tigated.', The double helical complexes [Cu\( 117),12+ contain a chiral cavity delineated by the 'spacer' groups which may permit inclusion of a chiral guest.Non-helical [Cu(ll7)]+ and [Ag(ll7)]+ also form.',' [M:L,]X2 [L = (118) (119); X = BF, PF,] and [Niy(OAc),( 119),][PF,] are also double helices in which each metal is coordinated to a bipy fragment from each ligand; the octahedral Ni" ions also have bidentate acetate ligand~.'~~ Attachment of a bipy fragment to each ring of ferrocene affords a novel potentially tetradentate ligand." Magnetic studies were undertaken on polynuclear Cu" complexes of 3,5-bis(2- pyridy1)pyra~ole.'~~ [{Rh1X2},(H120)]"+[n = 1,2;X = diolefin,CO +PPh, (CO),] were prepared.I4' Homo- and hetero-binuclear complexes of (120) were prepared with Ru(bpy); +,Rh"'(ppy); or Ir"'(ppy); (Hppy = 2-phenylpyridine) fragments bound in the bidentate sites.Photo-excitation of the M(ppy)l fragment (M = Ir Rh) results in energy-transfer to the Ru(bipy); + fragment which is then luminescent. 14' Elec-trochemical spectroscopic and photophysical studies were performed on [Ru(NN),LI2+ [NN = bipy or biq; L = (121) (122)] in which only one binding site is Transient UV/VIS spectroscopy was used to study the MLCT excited states of [Ru(NN),LI2+ and [{Ru(NN),),(~-L)]~+ [NN = bipy phen dmbipy; L = (123k(125)].'43.144 Control of helix self-assembly according to metal-ion IJ1 B. J. Yoblinski M. Stathis and T. F. Guarr Inory. Chem.. 1992. 31. 5. 132 A. D. Baker R. J. Morgan and T.C. Sirekas. J. Chem. Soc.. Chem. Cornmun. 1992. 1099. R. R. Ruminski C. De Groff and S.J.Smith. fnorg. Chem. 1992 31. 3325. 134 M.-T. Youinou N. Rahmouni J. Fischer and J. A. Osborn. Aiigew. Chem. Int. Ed. Enyl.. 1992.31. 733. 135 C. K. Ryu R. Wang. R. H. Schmehl S.Ferrere M. Ludwikow J. W. Merkert. C. E. L. Headford and C. M. Elliott J. Am. Chem. Soc. 1992 114 430. 13' Y. Yao M. W. Perkovic D. P. Rillema. and C. Woods Inorg. Chern. 1992 31. 3956. 13' P. D. Beer J. W. Wheeler and C. P. Moore J. Chem. Soc. Dulton Trun.5.. 1992. 2667. 13* E. C. Constable M. J. Hannon and D. A. Tocher Anyew. Chem.. fnt. Ed. Engl. 1992. 31 230. 119 J. Pons. X. Lopez J. Casabo. F. Teixidor A. Cambet J. Rius and C. Miravitlles Inory. Chirn. Actu 1992. 195. 61. I40 M. P. Garcia M. Martin and L. A. Ora. Inorg. Chirn. Actu. 1992 191. 221. 141 J.H.van Diemen R. Hage. J.G. Haasnoot H. E. B. Lempers J. Reedijk J.G. Vos. L. De Cola. F. Barigelletti and V. Balzani Inory. Chem.. 1992. 31 3518. 142 G. Giuffrida V. Ricevuto G. Guglielmo S. Campagna and M. Ciano Inory. Chirn. Actu. 1992 194. 23. 143 T. Ohno. K. Nozaki and M. Haga. Inorg. Chem.. 1992 31. 548. I44 T. Ohno K. Nozaki and M. Haga Znory. Chem.. 1992. 31. 4256. 284 M.D. Ward (126) MePy =6-methyl-2-pyridyl stereochemistry is demonstrated by formation of a double-helix [Cu\( 126),12 + and a triple helix [Coy(126)J4+ with the same binucleating ligand. 145 Transmetallation of [Pby( 127)2(MeOH)2(C10,),]2+ with Cu" affords the corresponding bis-Cu" complex which is strongly antiferromagnetically coupled across the diazine bridge.Direct reaction of (I 27) with Cu" only gives Cu' species.'46 [(CoX,),(p-128),] contains N4X2 octahedral Co" (n = 2) or NIX2 tetrahedral Co" (n = 1). For n = 2 the complex contains a large central cavity between the parallel ligands.I4' '" C. Piguet. G. Bernardinelli. B. Bocquet. A. Quattropani and A. F. Wil1iams.J. Am. Chern. Soc.. 1992,114. 7440. 146 S.S.Tandon. L. K. Thompson. and R.C. Hynes Inorg. Chern. 1992 31 2210. 147 S.S. Tandon. L. K. Thompson. J. N. Bridson and J.C. Dewar. Can. J. Chern. 1992. 70. 2771 The Coordination Chemistrji of Open-Chair1 Poljidentate Ligands 285 Other N-donor Liyands. [M2(qtpy)J2 + (qtpy = 2,2' 6',2" 6",2"'-quaterpyridine; M = Cu Ag) have double helical structures with four-coordinate metals (a bipyridyl fragment from each ligand) possibly because the M' ions are too large to bind the ligand in a planar tetradentate array.14* In contrast qtpy is m~nonucleating'~~ in trans-octahedral [Cr(qtpy)C12]C1.4H,0 and nine-coordinate [Y (qtpy )(NO,),(H,O)] [N 0,I. H ,0.'' [ReV0(qtpy )(0hle),][C104] and [ReVN (q t py )(PPh ,)Cl][C104] both display reversible ReV/ReV1 couples and intense MLCT transitions in the visible region.' 5' [PtL][ClO,] (L = qtpy 5,5',5",5"'-Me4-qtpy) are both square planar despite steric interactions between the methyl groups in the second case. Both display long-lived luminescence in the solid state.' 52 + Cis-[Co"'LCl,] [L = the chiral tetradentate ligands (129)' 53 and (130)' s4] were prepared; the chlorides may be replaced with retention of complex stereochemistry.The kinetics of alkene oxidation by trans-[RuV'02( 131)12+ were studied.'5s Cu" complexes of (132) may be five-coordinate mononuclear or binuclear with azide or cyanate bridges. The Ni" complexes are always binuclear.lS6 Affinities for 0 of octahedral Ru"' complexes of (1 33) were measured.'" The spectroscopic and electrochemical consequences of varying the chelate ring sizes in 1 1 Cu" complexes with the ligands (134) were examined.'58 Optically pure Cu" complexes of the chiral tetraamines (135) were prepared.' 59 [Fe"( 136)CllCl is five-coordinate high-spin in the solid state but six-coordinate in solution.'" [Co( 137)LCl)' (L = a substituted pyridine) are possible vitamin B, In [C~;(138),]~' one (138)is bridging donating two N atoms to each Cu' whereas the other two ligands are terminal and bidentate.The complex has two closely-spaced Cu'/Cu" oxidations.' 62 Mixed-ligand Co"' complexes were prepared with ethylene-bis-biguanide and bidentate ligands such as acac or 8-hydroxyquinoline. '63 Square-pyramidal Fe" complexes were prepared and characterized with the bis-isothiosemicarbazones (1 39).'64p1h6 [Fe"'( 140)L2] . (L = PBu, imidazole 4-But-pyridine) have reversible Fe"'/Fe'\' and Fe"'/Fe" redox 118 E. C. Constable. M. J. Hannon. A. Martin. P. R. Raithby and D. A. Tocher. Polj.hrrlron 1992 II 7967. 149 E. C. Constable. S. M. Elder and D. A. Tocher Polj,hedroti. 1992. 11. 1337. 15'1 E. C. Constable. S. M. Elder. and D. A. Tocher Poljhedrori.1992. 11. 2599. I" C.-M. Che. Y-P. Wang. K.-S. Yeung K.-Y. Wong. and S.-M. Peng. J. Chcvi. Soc. Dnlton 7itiris.. 1997. 2675. I52 C.-W. Chan C.-M. Che. M.-C. Cheng. ,ind Y. Wang. Inory. Chtw.. 1992 31. 4874. Is3 R. R. Fenton. F.S. Stephens. R. S. Vagg and P.A. Williams. Inory. Chirn. Ac.ru. 1992. 201. 157. Is4 R. R. Fenton. F. S. Stephens R. S. Vagg and P. A. Williams. Inorcq. Chini '4c.r~. 1992 197. 237. 15' C.-M. Che C.-K. Li W.-T. Tang and W.-Y. Yu. J. Chrm. Soc.. Dulroti 7ictn.s.. 1992. 3153. 15' C. Diaz and J. Ribas Polyhedron. 1992 11. 85. Is' M.M.T. Khan S.A. Mizra Z.A. Shaikh. C. Sreelatha P. Paul. R.S. Shukla. D. Srinivas A. P. Rao. S.H. R. Abdi S. Bhatt and D. Ramachmdraiah. Polyhrtlrori. 1992. 11. 1821. I sx T. Pandiyan. M. Palanidavar. M.1.akshminarayanan. and H. Manohar. J'. C'htwi. Soc,.. Dulrori Trrms.. 1992 3377. ''' P. V. Bernhardt. P Comba. T. W. Hambley. L. L. Martin. K. Viragny. and L. Zipper. Hdr . Chir~:lc.ttr 1992 75. 145. E. Mulliez G.Guillot-Edelheit. P. Leduc. J. C.Chottard. C. Bois. A. Bousseksou. and W. Nitschke. New. J. Chmi. 1992. 16 435. "l A. Gerli and L.G. Marilli Itwry. Chiwi. 1992 31 1152. If" J.-P. Collin and M.-T. Youinou. Inory. Chim. Ac,rii 1992 201. 29. "' R. K. Ray. Polyhedron 1992 11. 469. lh4 N. V. Gerbeleu. V. B. Arion. Y.A. Simonov V. E. Zavodnik. S. S. Stavrov. K. I. Turta D. I. Gradinaru. M S. Birca. A.A. Pasynskii. and 0. Ellert. Iiiory. Chirn. .4ctu. 1992. 202. 173. I"' N. V. Gerbeleu. Y.A. Simonov. V. B. Arion. V. M. Leovac. K. I Turta. K. M. Indrichan.D. I. Gradrnaru. V. E. Zavodnik. and T. I. Malinovski. Itlory. Chm.. 1992. 31. 3265. Ihh V. M. Leovac L. S. Jovanovic V. I. Cesljevic L. J. Bjelica and N. J. Evic Polj~hrdrori,1992. 11. 1029. 286 M. D. Ward (133) X = C6H4 CH2CH2 CH2CH2NHCH2CH.; (134) R = H Me; x y = various (135) R' =Me R2 = NH,; (136) ~ 1 ~2= = H (H137) (H3139) X = NO, H; R = Me Et R Bu RR (H2140) R = H C1 The Coordination Chemistry of Open-Chain Polydentate Ligands 287 couples.'67 0s"' and 0s" complexes of (140) were prepared by reduction of trans-[Osv'O,( 140)]; the 0s"' species catalyse oxidation of alkenes by PhIO.' 68 [Cot''( 14O)X,] -(X = anionic ligand) were prepared and studied by spectroelec- trochemistry.' 69 EPR and UV/VIS spectra were recorded of Cu" complexes with the tripodal ligands N(CH,Bz) (Bz =2-benzimidazolyl or N-ethyl-2-ben~imidazolyl).~ 70 [Fey(tpm) (p-+ MeC0,),I2 [tpm = tris(2-pyridylmethyl)amine] a model for ribonucleotide reduc- tase reacts with 0 to give [Fey1(tpm),(p-O)(MeC0,),]2+ in which the acetates are now terminal.' ' [(Cr"'(tren)) ,(p-CO,)(p-OH)] is weakly antiferromagnetically + coupled. Its crystal structure and luminescence properties at 1.5 K are described.' 72 High yield routes to five-coordinate (V=O} and (Mo-N} complexes containing the triamide ligand [N(CH,CH,NMe),13 -have been developed.' 73 0,S and P-donor Ligands.-Binuclear Cu" complexes of (141) have both inter- and intramolecular antiferromagnetic interactions. '74 C,-symmetric binuclear complexes of (142) were prepared with (Ir(cod)) +,(Rh(cod))+,or (Rh(nbd))+ fragments in each bidentate cavity.'" CF,C(OH),CH,C(OH),CF (H,L) derived from hydration of hexafluoroacetylacetone acts as a bidentate ligand in [Fe(hfacac),(H,L)] -or as a bis-bidentate bridge in [(Mn"'(hfacac),),(p-L)]*-Reactions of [Ru( 143)(PPh,)] with H,S S, and CS were in~estigated.'~~ Reactions of Ni" complexes of (143) and 00 n R R C.-M.Che W.-H. Leung C.-K. Li H.-Y. Cheng and S.-M. Peng Inory. Chim. Actu. 1992 196. 43. W.-K. Cheng K.-Y. Wong. W.-F. Tong T.-F. Lai and C.-M. Che. J. Chem.Soc. Dalton Trans. 1992.91. M. Ray and R. N. Mukherjee Polyhedron 1992. 11 2929. ''() H. N. Pandley Y. S. Sharma and P. Mathur Polyhedron 1992 11 2631. 171 S. Menage Y. Zang.M. P. Hendrich and L. Que Jr. J. Am. Chem. Soc.. 1992 114 7786. 172 L. Spiccia G. D. Fallon. A. Markiewicz K. S. Murray and H. Riesen Inory. Chem. 1992 31 1066. li3 W. Plass and J. G. Verkade J. Am. Chem. Soc.. 1992 114 2215. 174 J.-P. Costes F. Dahan and J.-P. Laurent Inory. Chem.. 1992 31 284. 175 I. J. Hart Polyhedron 1992 11. 729. 176 E. Bouwman J. C. Huffman E. B. Lobkovsky G. Christou. H.-L. Tsai and D.N. Hendrickson Inory. Chem.. 1992 31 4436. 177 D. Sellmann P. Lechner F. Knoch and M. Moll. .I.Am. Chrm. Soc. 1992 114 921. 288 M. D. Ward (144) with additional monodentate ligands (phosphines pyridines) were investigated as models for Ni-S rnetall~proteins.'~~ Ph,P(CH,),PPh(CH,),PPh(CH,),PPh ('P4')acts as a binucleating ligand in bis-Pt" complexes such as [Pt2( 'P4')C13] + .'79 Binuclear complexes of (145) were prepared in which the ligand coordinates as two bidentate fragments; the crystal structures of [{MC12}2(p-145)] (M = Ni Pd) are described.'8o Mixed N,O-donor Ligands.-Bis(salicylaldimine) Complexes.Complexes of 'salen' (146) and its substituted derivatives continue to be extremely popular. Several Mn"' complexes are efficient organic oxidation catalysts using NaOCl or Ph1O.l 82 '3 [Mn"(147)] reacts with 0 to give [(Mn'V(147)(p-O)),] which can be reduced to the Mn"'/MdV state;'83 [(MnlV(L)(u-O)},] [L = (147) (148)] undergo an irreversible four-electron two 0 atom transfer to [Fe( 146)] giving [MnL] and 2[(Fe"'( 146))&1- O)].'84 Co" complexes of (146) and (149) catalyse the selective conversion of (H2146) X = H (H2147) X = 5-C1 (H2148) X = 5-OMe (H2149) X = 6-Bu' (H2150) X = 5-Br (H2151) X = 3-OMe h (h153) X = (CH& (CH,), CH2C(Me)&X2 (Hz154) R = H R = (CHz),H n = 4-14 (H2155) R = C(0)NH(C6M3-p-Me-m-NCO) arylglyoxals to z-aryl-z-hydroxyacetic esters.' 85 A spectroelectrochemical study of [(Col"( 146)(dmso)),(p-O,)] showed that a two-electron oxidation gives free 0 and [Co( 146)(dmso),] + '86 [Ru( 146)(NO)(H20)][SbF6] performs efficient Lewis-acid catalysis of Diels -Alder reactions.'" [Ti( 146)Cl,] reacts with LiMe to give 17H D.Sellmann S. Schillinger. and F. Knoch Z. Narurforsch.. 7Lil A. 1992. 47. 645. H. Goller and P. Bruggeller Incity. him. Actci. 1992. 197. 75. '"" M.R. Mason. C. M. Duff. L.L. Miller. R.A. Jacobson and J.G. Verkade Inory. Chrm.. 1992. 31. 2746. 1x1 D. R. Reddy and E. R. Thornton J. Ckc~m.Soc,.. Churn. Comtnun. 1992. 172. Ix2 D.S. Thomsen B. Schicatt and K. A. Jsrgensen. J. Chrm. Soc.. Chmi. Commun. 1992 1072. I x1 G.C. Dailey. C. P. Horwitz. and c'.A. Lisek Inorq. Chern. 1992 31 5325. '" G.C. Dailej and C. P. Horwitz Inorcq. Chum.. 1992 31 3693. K. Maruyama. Y. Murakami K. Yoda. T. Mashino. and A. Nishinaga. .I. Chem. Soc,.. Chrm. Commun.. 1992. 1617. 1Xh J. H. Cameron and S. C. Turner. .I. Chcwi. SOC...Dcrlroti /'runs.. 1992. 3285. W. Odenkirk. A. L. Rheingold. and B. Bosnich. J. Am. Chrm. Soc,.. 1992. 114 6392. The Coordination Chemistry of' 0pc.n-Chain Polydentate Liyands 289 [Ti(146)Me2] which on heating undergoes methyl migration from the metal to the electrophilic imine C-atom.Aryl groups behave similarly.'88 [CoL] [L = (146) (147) (150) (I 51)] reacts with Fe" to give binuclear 'CoLFe' species which take up O2faster than [CoL] a10ne.l~~ [Cu(146)] react with [Fe(acac),(NO,)] to give [Cu( 146)Fe(acac),] where the Fe" is coordinated by the two (bridging) phenolates.' " Similarly (M(hfacac),} fragments (M = Co" Ni" Zn") can be attached to the two phenolates of [Cr"'( 146)L,] + (L = neutral axial ligand) to give new phenolate-bridged heterobinuclear species,"' and Cu" or Ni" complexes with (146) (152) and other ligands bind Sn complexes such as [SnCl,(OEt)] at the di-phenol Elec-trochemical oxidation of Co". Ni" Cu" and Zn" complexes of salen-type ligands gives redox-active polymers some of which are conductors.' 93 Mesogenic vanadyl com- plexes of the ligands (153) form polymeric linear chains via head-to-tail V=O ...V interactions.194 [{ Mn"( 152)(p-O); '1 exhibits catalase activity. The correlation be- tween Mn .. . Mn separation and Mn-0-Mn bridge angles was discussed."' Protona-tion of [{Mn1V(152)(p-0)}2] to give [(Mn'V(152)),(p-0)(p-OH)]+increases the Mn .*. Mn separation by 0.1 A and removes the catalase activity.'95 [(Mn"'( 152)(p- OAc},].3H20 is polymeric with (Mn( 152)) + units bridged by acetates.196 Reversible binding of CO and 0 to trans-[Ru"'LCl,]- (L = salen derivatives with C1 and OMe substituents) was studied; reaction with 0 generates Rutv-superoxo species.' 97 [Zr"L,] [L = (154) or (155)] were prepared; [Zr(155),] forms a copolymer with poly(thf) containing alternating metal sites and organic blocks.' 98 Other Mixed N,O-donor Liyands.The EPR spectra of Co" complexes of (H2156) doped into isostructural Zn" complexes indicate a six-coordinate structure. '99 The crystal structure and magnetic properties of [{ Fe"'( 157)),(p-OMe),] were determined.'"" Activation of 0 by [Ni(158)] results in oxidative dehydrogenation of one CH-NH bond.,'' The magnetic properties of [Cu"( 159)M"(dmbipy),] (M = Co Mn) where Cu" is in the N,O cavity and the (M(drnbipy))'+ fragment is attached to the bridging phenolates were studied.' "' A detailed comparison between structural parameters was made for [Fe"'( 16O)Xl (X = Cl NO,) [Fe"'(l60)(CN),] - and [(Fe"'(160)),(p-0)].203 In [M'VL(Cp)2] [M = Ti Zr; L = (160k(162)] the metals lie in the ligand N,O cavity and have two lRX E.Solari C. Floriani A. Chiesi-Villa. and C. Rizzoli J. Chem. Soc.. Dulton Truns. 1992 367. 1HY Y. Abe K. Shinguhara and S. Yano Ciiem. Lett. 1992 897. Iyo D. Laroque I. Morgenstern-Badarau H. Winkler E. Bill A. X. Trautuein. and M. Julve lnory Chim. Acru 1992 192 107. C.T. Brewer and G.A. Brewer Inorg. Chim. Actu. 1992 196. 1. D. Cunningham and J. McGinley. J. Chem. Soc.. Dalton Truns. 1992. 1387. P. Audebert P. Capdevielle and M. Maumy New. J. Chrm.. 1992 16. 697. IY4 A. Serrette. P. J. Carroll and T. M. Swager J. Am. Chrm. Soc.. 1992 114 1887. 195 E. J. Larson. P. J. Riggs.J. E. Penner-Hahn and V. L. Pecoraro J. Chem.Soc.. Chem. Commun.. 1992. 102. IYb N.Aurangzelo C. E. Hulme C.A. McAuliffe. R.G. Pritchard M. Watkinson. A. Garcia-Deibe. M. K. Bermejo. and A. Sousa. J. Chem. Soc.. C'hem. Cornrnun. 1992. 1524. I 9 -M. M.T. Khan Z.A. Shaikh R. I. Kureshy and A. B. Boricha. Polyhrdror7. 1991. 11 91. IYH W. Tong and R. D. Archer. Inory. Chrni 1992. 31. 3332. 199 K. Drabent J. A. Wolny. M. F. Rudolf. and P. J. Chmielewski. Polj,hedron. 1992 11 271. 200 P. Baran A. Bottcher. H. Elias W. Haase. M.Hiiber. H. Fuess. and H. Paulus. Z. Nurur/orsc~h..7i.il B. 1992 47 1681. 20 I A. Bottcher. H. Elias L. Muller and H. Paulus. Ariyew. Chem.. Inr. Ed. Engl.. 1992. 31 623. 202 D. Liao S. Juan. Z.-H. Jiang. S.-P. Yan. P.Cheng. and G.-L. Wang. Polyhrdron. 1991. 11. 7671. 203 X. Wang W. T. Pennington D. L. Anker-s. and J. C. Fanning. Polj,hrdron. 1992 11. 2253. 290 M. D.Ward (H2156) R' =Me Et Bun R2 = H 5-C1 R3 = H 5-C1 3,5-C12 3-OMe (H2157) R=H (H2158) R = But (H2160) R' = Me R2 = H X = CH2CH2 (H2163) R = Me or Ph (H2161) R' = H R2 = C(O)Me X = 1,2-C6H4 (H2162) R' = H R2 = C(O)Me X = 1,2-(4-Me-C6H3) (H,164) R' = H. R2 = Me (H2165) R' = H R2 = CH3 (H2166) R' = Me R2 = CF3 The Coordination Chemistry of Open-Chain Polydentate Ligands 29 1 capping Cp ligand~.~'~ [Fe( 161 )(NO)] changes its spin state from S = 1/2 to S = 312 between 80 and 320 K.,05 The bis-semicarbazone of cyclohexane-l,2-dione (L)acts as a planar tetradentate N,O donor in [Co,L,(H,O),(NO,)]' where the dimer is held together by carbonylic bridges and as a tridentate ONN ligand in [NiL,]"."Oh [VO( 163)] are rare examples of oxovanadium(1v) complexes with amide ligands; they have reversible VlV/Vvand V1V/V11'couples.207 NiI'complexes of (164)-( 166) are chiral.For (1 65) and (1 66) crystallography indicates that an axial Ni . . . F interaction with the CF groups promotes slow enantiomer interconversion which was studied by NMR.~O~ The structure and EPR properties of the diradical [(VO)2(p-d~p)2]2 -(H,dcp = pyrazole-3,5-dicarboxylic acid) were determined.,09 [Co"( 167)Ll (L = py-ridine imidazole) react reversibly with 0 to give Co"'-superoxo species.2' Binding of R MeN4-Q Ho 0 "7 R \ (H,167) R = Me W But (H168) the two ligands to Ni" in trans-[Ni(l68),] brings the oxygen-donor side chains together in the right conformation to bind alkali metal cations.The stability constants of such adducts were measured. l1 The crystal structure of Ba[{ Fe'11(nta)(H,0)),(p-0)]~4H,0,where nta is face-capping was determined.,, Reduction of one carboxylate of H,nta to give N(CH,CO,H),(CH,CH,OH) (H,L) causes a remarkable change in its iron com- plexes; the crystal structures of [Fe,9(p,-O)6(p3-OH)6(p2-OH)sLlo(H20)12] + and [Fe ,(p3-O),(p3-OH),(p2-OH)loL,s(H20)l ,I3+ both have a close-packed AX,-type iron-oxo core surrounded by a shell of Fe atoms and the bridging tetradentate ligands + at the periphery.,' [Pb"(ntam),(NO,)] [ntam = nitrilotriacetamide N(CH,- CONH,),] is the first structurally characterized metal complex of ntam.It is ten-coordinate with ntam acting as an NO donor.214 Square-pyramidal [Cu"( 169)Cl) is a possible galactose oxidase [Mo,Cu,O,( 170),(p3-Me0),].2MeCN has a cubane-like core which forms an infinite chain cia Mo=O.. .Cu interactions.216 '(I4 R. Rai K. D. Mishra 0.P. Pandey. and S. J. Sengupta Polyhedron 1992 11 123. 2os E. Konig G. Ritter. J. Dengler and L. F. Larkworthy. lnorg. Chem. 1992. 31 1196. 'Oh L. P. Battaglia P. G. Berzolla A. B. Corradi C. Pelizzi G. Pelosi and C. Solinas J. Chem. SOL..,Dalton Truns. 1992 3089. "' G. R. Hanson T. A. Kabanos A. D. Keramidas. D. Mentzafos. and A. Terzis lnorg. Chern. 1992.31.2587. M. Kwiatkowski and G. Bandoli J. Chem. Soc. Dalton Trans..1992 379. 2oy C. W. Hahn P.G. Rasmussen. and J.C. Bayon lnorg. Chem.. 1992 31. 1963. 210 M. F. Rudolf J.A. Wolny. T. Lis and P. Starynowicz J. Chem. Soc. Dillton Trans. 1992 2079. "' M. W. James N. Gupta and A. Schepartz lnorg. Chem. 1992 31 1308. 'I2 S. L. Heath. A. K. Powell H. L. Uttig and M. Helliwell J. Chem. So(.. Dultun Trans.. 1992. 305. 'I3 S. L. Heath and A.K. Powell Angew Chem. Znt. Ed. Engl. 1992 31 191. 'I4 D. A. Smith S. Sucheck and A.A. Pinkerton J. Chern. Soc. Chem. Commun. 1992 367. 215 U. Rajendran R. Viswanathan M. Palaniandavar. and M. Lakshminarayanan J. Chem. Soc. Dalton Trans. 1992 3563. 216 D. P. Kessissoglou C. P. Raptopoulou EG. Bakalbassis A. Terzis and J. Mrorinski Inory. Chem. 1992. 31. 4339. 292 M.D.Ward (H169) (H3170) Mixed N,S-donor Ligands.-The interconversion of distorted tetrahedral [Cu( 17 1 )] + between diasteroisomers was studied by variable-temperature NMR spectroscopy. Oxidation gives square-pyramidal [Cu( 171)(H,O)l2+ ; the two are related by a quasi-reversible Cu'/Cu" couple.217 Reaction of [Cu( 171)] + with excess (171) gives [Cu(l71),] +,in which the Cu'is tetrahedrally coordinated by the four N atoms and the Satoms are pendant.,'* Electrochemical studies were performed on [Cu"( 172)XYl (X Y are mono anion^)^^^ and [C~"(173)(H,0)]~+ .220 Neutral lipophilic oxotech- netium(v) complexes of (H 174)-(H 176) labelled with 99mTcwere studied as possible brain perfusion agents for imaging2,' [TcV(N)L] and [TcV(0)L]+ [L = (176)-( 179)] are square pyramidal.222 A titrimetric study of complex formation of (180) with Zn" and Cd" revealed the presence of several species with different metal-to-ligand ratios.,, [Zn2(181),] contains square-pyramidal Zn" ions with a Zn,(p-S) core; [(Ni(181))3Zn2C12]2+ contains three {Ni(181)} groups bound to a Zn core by bridging sulfides.The degree of aggregation of complexes with (1 81) is solvent dependent.224 Oxidation of [Fe( 182)(CO)] causes dehydrogenation of the amines in the ligand to give an u,sc'-diimine; the resulting complex is binuclear with an Fe,(p-S) core.225 Mono- and binuclear complexes of Au"' with (183) were prepared.226 The electrochemical properties of [Sn"( 184)] and [Sn"( 184),] were examined.227 [MVOL]- [M = Tc Re; L = (185) acting as N,S2 donors] have square-pyramidal structures containing seven-membered chelate [ReV(0)( 186)] -were assessed as possible renal imaging agents.229 In [TcVNBr,(187)] (187) acts as an N face-capping ligand in the solid but in solution the pendant thioether displaces a bromide to give a 1 1 ele~trolyte.~~' The crystal structure of [Ni2(188),][C10,] 217 D.A. Nation M. R. Taylor. and K. P. Wainwright J. Chem. Soc.. Dalton Trans. 1992 1557. 2113 D. A. Nation M. R. Taylor. and K. P. Wainwright J. Chrm. Soc.. Dalton Trans. 1992 241 1. 219 M. F. Cabral. J. de 0.Cabral. E. Bouwman W. L. Driessen. J. Reedijk. U. Turpeinen. and R. Hamalainen Inorg. Chim. Acta 1992 196 137. 220 W. G. Haanstra M. F. Cabral J. de 0.Cabral W. L. Driessen. and J.Reedijk Inorg. Chrm.,1992,31.3150. 221 C. S.John L. C. Francesconi. H. F. King S. Wehrli,G. Graczyk.and P. Carroll.Po/yhrdron 1992,11,145. 222 A. Marchi L. Marvelli R. Rossi. L. Magon. V. Bertolasi V. Ferretti. and P. Gilli J. Chem. Soc. Dalton Trans.. 1992 1485. 223 A. Audeef. F. Hartenstein A. R. Chemotti. Jr. and J. A. Brown. Inorg. Chrm. 1992 31. 3701. 224 T. Tuntulani J. H. Riebenspies P. J. Farmer and M. Y. Darensbourg Inorg. Chrm. 1992 31 3497. 225 D. Sellman M. Hannakam F. Knoch and M. Moll Z. Naturfivsch. Teil B 1992 47 1545. 226 A. P. Koley S. Purohit L.S. Prasad. S. Ghosh. and P.T. Manoharan. Inorg. Chem. 1992 31 305. 227 J. E. Anderson. S.M. Sawtelle. J. S. Thompson. S.A. Kretchmar Nguyen and J. Calabrese Inorg. Chrm.. 1992. 31.2778.228 B. Chen M. J. Heeg and E. Deutsch. Inorg. Chpm.. 1992 31. 4638. 229 L. Hansen R. Chi. A. Taylor Jr. and L.G. Marzilli. Inorg. Chem.. 1992. 31 2801. 230 J.R. Dilworth D.V. Griffiths J.M. Hughes S. Morton. W. Hiller C.M. Archer J.D. Kelly and G. Walton Inorg. Chim. Actu 1992 192 59. The Coordination Chemistrj? of Open-Chain Polydentate Ligands n S N-V /N-NW 'Sw\ (173) A (yyJ SH HS RR (H4185) R = H Ph (H174) R' (H175) R' (H176) R' (H177) R' (H178) R' (H179) R' (H180) R' (H181) R' (172) R = H Me; n= 2,3 = Me R2 = H X = 2,2'-(C6H4)2 = Et R2 = H X = 2,2'-(C,H& = Et R2 = H X = CH2CH2 = Me R2 = H X = CHzCH2 = Me R2 = Et X = CH2CH2 = R2 = Me X = CH2CH2 = H R2 = Me X = CH2CH2 = H 2R2 = X = (CH2)3 bridge (187) n=1 R=CH2Ph (H188) n=2 S = H 294 M.D. Wurd reveals a Ni,(,u-S) core with one low-spin square-planar Ni" and one high-spin square pyramidal The stability constants and complexation kinetics were studied for Cu" complexes with N(CH,CH,SR) (R = Me Et).,, Although (H 189) acts as an N,N-bidentate ligand in [M(H189),] (M = Co Ni) with the nickel triad one-dimensional polymers can also result due to occupation of both N,N and S,Ssites. A trinuclear Cu" complex was also isolated.233 Other Mixed-donor Ligands.-Monocationic Tc"' and Tc" complexes of the tetrapodal ligands np and pp3 were prepared.,, [Mn"(np,)I][BPh,] has been crystallographi- cally characterized and is five-~oordinate;~~~ by contrast [Hg(np,)Me] + is four-coordinate with the bridgehead N atom not coordinated.236 In [Ni"(ps,),]' -R' [H,ps = P(o-C,H,SH),] each ligand acts as a PS donor to one Ni" and a P donor to the other.Oxidation to the delocalized Ni"/Ni"' state results in a change of geometry from near-planar to square-pyramidal with bridging thi~lates.~~' Neutral M" complexes of (190) and (191) were prepared electrochemically and their geometries discussed on the basis of magnetic and spectroscopic data.238 5 Pentadentate Ligands N-donor Ligands.-Whereas the Co" complex of qpy (qpy = 2,2' :6',2" 6",2"' :6"',2"''-quinquepyridine) is a binuclear double helix in the solid state in solution the + seven-coordinate mononuclear species [Co(qpy)(S),] (S= solvent) forms which reacts239 with Ag' or Cut to afford heterobinuclear double helices [CoM(qpy),13+.In [Cl,qpy contrast [CO(C~,~~~)(M~OH)(H,O)][PF~]~= 4',4"'-bis(4-~hlorophenyl)-231 M. Mikuriya M. Handa,S. Shigematsu S. Funaki. F. Adachi,and H. Okawa Bull. Chem. Soc.Jpn. 1992. 65 512. 232 T. H. Cooper M. J. Mayer K.-H. Leung L. A. OchryrnowycL and D. B. Rorabacher Znory. Chem. 1992. 31 3796. 233 I. Giirol V. Ahsen and 0.Bekgroglu J. Chem. Soc. Dalton Trans. 1992 2283. 234 J. R. Dilworth. D. V. Griffiths J. M. Hughes S. Morton C. M. Archer and J. D. Kelly Znory. Chim. Acta 1992 195 145. 235 F. Cecconi C. A. Ghilardi S. Midollini and A. Orlandini J. Chem. SOL..,Dalton Trans. 1992 33. 236 C. A. Ghilardi P. Innocenti S. Midollini A. Orlandini and A. Vacca,J.Chem. Soc.. Chem. Commun.. 1992. 1691. 237 J.-D. Franolic W. Y. Wang and M. Millar. J. Am. Chem. Soc. 1992 114. 6587. 238 R. Bastida A. De Blas D. E. Fenton. and T. Rodriguez. Polyhedron 1992. 11 2739. 2 39 E. C. Constable and J. V. Walker J. Chem. Snc. Chem. Commun. 1992 884. The Coordination Chemistry of Open-Chain Polpdentate Ligands (192) R' = R~= H x= CH (193) R' = C(O)NH2 R2 = H X= CH (194) R1 = H R2 =Br X=N (H3196) m=n=l R=H (H3197) m = n = 1 R = 4,6-C12 (H3198) m=2 n=2 R=H (H3199) m=n=2 R=H spy] is mononuclear and seven-coordinate in the crystal as well as in solution.24" Ligands (192)-(194) are bleomycin analogues. Whereas the mode of coordination of (192) and (193) to Fe" Cu" and Zn" is pH dependent,241 (194)is always pentadentate in its octahedral Co"' complexes for which a mechanism for light-induced damage to DNA is Mono- and binuclear complexes of Ni" Cu" and Zn" with (H2195) were prepared.243 Mixed N,O-donor Ligands.-Binuclear and tetranuclear alkoxo-bridged Mn"' com-plexes of (196) were prepared as possible models for Mn-containing photosynthetic rnetall~proteins.~~~~~~~ The variable-temperature EPR properties of the highly asymmetric complex [Mn"'Mn'V( 197),(thf)][C104] closely mimic those of the photo- synthetic 0,-evolving Bis-Ni" complexes of (196) (198) and (199) contain endogenous alkoxide and exogenous pyrazolate bridges.The effect of increasing chain length on distortions from planarity at the metal centre was in~estigated.,~~ Binuclear Fe"' and Mn"' complexes of the asymmetric ligand (200) 240 E.C. Constable J. V. Walker D A. Tocher and M. A. M. Daniels J. Chem. Soc. Chem. Comntun. 1992 768. 241 E. Kimura H. Kurosaki Y. Kurogi hl. Shionoya and M. Shiro Inorq. Chem.. 1992. 31 4314. 242 J. D. Tan S.E. Hudson S.J. Brown M. M. Olmstead and P. K. Mascharak J. Am. Chem. So(.. 1992.114 384 1. 243 G.Paohcci S.Stelluto S.Sitran. D. Ajo F. Benetollo. A. Polo. and G. Bombieri Inorq. Chim. Acru 1992 193 57. 244 M. Mikuriya Y. Yamato and T. Tokii. Bull. Chrm. Soc. Jpn 1992 65. 1466. 245 M. Mikuriya Y. Yamato and T. Tokit. Bull. Chem. Soc. Jpn. 1992 65. 2624. 246 E. Larson. A. Haddy M. L. Kirk. R. H. Sands W. E. Hatfield and V.L. Pecoraro. J. Am. Chem.Soc.. 1992 114 6263.247 M. Mikyuriya T. Sasaski. A. Anjiki S. Ikenoue and T. Tokii Bull. Chem. Soc. Jpn. 1992. 65 334. 296 M.D. Ward (H3201) R' = R2 = H R3 = Me (H3202) R' = Ph R2 = Me R3 = H (H3203) R' = H R2 = NO, R3 = Me HO R2 AO (H3204) R' = H R2 = Me (H3205) R' = R2 = Me (H3206) R' = H R2 = Ph (H2208) X = PI Y = CH R = H or OMe (H210) (H2209) X = CH Y = N R = H or OMe both have M 2(p-0)2cores with weak antiferromagnetic and ferromagnetic interac- tions respectively.248 Five-coordinate [Fe"(201 j] undergoes a redox reaction with [RuV1(tppj(Oj,] to give [(201)Fe111(,u-O)(Ru'V(tpp)}(p-O)Fe'1'(201)J.249 LFe"(202)-(3,4-Me2pyr)]+ exhibits spin-crossover beha~iour.~~' [Mn1"(OH)(203)] is the first structurally characterized mononuclear hydroxo-manganese ~omplex.~ [Cu;(204)- (p-RCO,)] in which each Cu" is nearly square-planar with endogenous alkoxide and 248 M.Mikuriya. Y. Yamato. and T. Tokii Chem. Lett.. 1992 1571. 244 L. D. Schulz G. D. Fallon B. Moubaraki K. S. Murray and B. 0.West J. Chem. Soc. Chem. Commun. 1992 971. 2so Y. Maeda Y. Noda I-I. Oshio. and Y. Takashima. Bull. Chem. Soc. Jpn.. 1992 65 1825. D. M. Eichhorn and W. H. Armstrong. J. Chem. Soc. Chem. Commun.. 1992. 85. The Coordination Chemistry of Open-Chain Polydentate Ligands 297 exogenous carboxylate bridges exhibit antiferromagnetic exchange.,' [{M1'(205)),(p-L)] [M = Ni Cu; H2L = 4,4'-di(3,5-dimethylpyrazole)]contain two { M,(205))'+ units with the bridge L donating one N atom to each metal to complete the square-planar coordination." [Mny'(206) (OMe) (MeOH)( EtOH)] [ClO,] contains an alkoxo-bridged isosceles-triangular core; its low-temperature magnetic properties were examined.254 [Cu"(207)] is a four-coordinate complex with a free external imidazole N atom which can be attached in a subsequent step to other metal complexes to give magnetically interacting polynuclear imidazolate-bridged spe- cies.2ss,2s6 Likewise [M(208)] and [M(209)] (M = Cu Ni) bind axially to iron porphyrins via the external imidazole N atom.2s7 [C~y(210)(p-EtO)(MeOH)]~ + was structurally characterized; [Cu2(210)(p-Br)Br,] was also prepared.Both exhibit moderate antiferromagnetic exchange.,'* Ligands with Other Donor Sets.-The octahedral complexes CFe"(21 l)X] [X = NH, N,H, NH,NHMe P(OR), MeOH thf py] are high-spin if X is a good a-donor and low-spin if X is a good rr-a~ceptor.~'~ Ni" complexes of (211t(214) undergo ligand-transfer reactions with other metals which provides a convenient route to new complexes; [Mo'"(O)L] [L = (21l) (212)] were crystallographically character- ized.260 The reactivity of the nitrosyl ligand of [Ru(214)(NO)]Br was examined.261 [Fe(215)L] (L = CO NO PMe, N,H,) were prepared.262 Cu" complexes of open-chain N,S-containing ligands such as (216),263 (21 7),263.264 (218)-(220),264 and (221)_(222)26s are of interest as possible type I cuproprotein models.In this regard their electrochemical EPR and UV/VIS properties are of interest. [Cuy(223)(p- Cl),Cl] contains endogenous phenolate and exogenous chloride bridges; two of these binuclear units are linked by long Cu-Cl bonds and NH 3..C1 hydrogen bonds to give a tetranuclear dimer in the crystal.2h6 6 Hexadentate Ligands N-donor and 0-donor Ligands.-A new preparation of sexipy (2,2' 6',2" 6",2"' 6"',2"" :6"",2""'-sexipyridine) by coupling 2-bromo-terpy using Ni' was developed; the reaction product is the double-helical [Ni~(sexipy),][PF,] which is demetallated with cyanide to give the free ligand.267 [Eu(sexipy)(NO,),][No,l 252 T. Kawata M. Yarnanaka S. Ohba Y. Nishida M. Nagarnatsu T. Tokii. M. Kato. and 0.W. Steward. Bull. Chem. SOC.Jpn. 1992 65 2739. 253 P. E. Kruger G.D. Fallon B. Moubaraki. and K.S. Murray J. Chum. Soc.. Chem. Cornmun. 1992 1726. 251 M. Mikuriya K. Majirna and Y.Yarnato Chem. Lett. 1992 1929. 2s5 S.Ohkubo K. Inoue H. Tarnaki M. Ohha N. Matsumot0.H. Okawa and S. Kida Bull. Chem.Sot,. Jpn. 1992 65 1603. 256 N. Matsurnoto K. Inoue M. Ohba. H. Okawa and S. Kida Bull. Chem. Soc. Jpn.. 1992. 65. 2283. 25' C.T. Brewer and G. Brewer J. Chem. Soc. Dalton Trans. 1992. 1669. 2sx Y. Shiping. C. Peng L. Daizheng J. Zonghui W. Genglin W. Honggen and Y. Xinkan. Polyhedron 1992. 11 879. "'D. Sellrnann W. Soglowek F. Knoch G. Ritter and J. Dengler Inorq. Chem. 1992 31 371 1. 260 D. Sellrnann S. Fiinfgelder and F. Knoch Z. Nuturforsch. Teil B 1992 47 51. 26' D. Sellrnann. M. Geck and M. Moll Z. Naturforsc,h. Tuil B 1992 47. 74. 262 D. Sellrnann W. Soglawek and M. Moll Z. Naturjorsch.. Teil B 1992 47 1105. 263 S. Liu C.R. Lucas R.C. Hynes and J.-P. Charland Cun. J. Chem. 1992. 70 1773. 264 R. P. F. Kanters R. Yu. and A. W. Addison Inory. Chim. Actu. 1992 196 97. 265 H. Masuda T. Sugimori. T. Kohzurna A. Odani and 0.Yamauchi Bull. Chem. SOC.Jpn.. 1992.65 786. '" J.C. Wilson P. D. Verweiji. W. L. Driessen. and J. Reedijk Inory. Chim. Actu 1992 192 219. '" E. C. Constable and R. Chotalia. J. Chern. Soc.. Chem. Commun.. 1992. 64. 298 M.D. Ward R R (H2211) X=NH R=H (H2212) X = 0 R = H (H2213) X = CH2 R = H (H2214) X = S R= H (H2215) X=NH R=Bu' R R (216) X = S Y = 0,R = H (217) X=Y =S R=H (218) X=Y=S R=Me (221) X=NH Y=S R=H (219) n= 1 (220) n= 2 (222) (H223) is ten-coordinate with the sexipy twisted into a shallow mono-helical geometry.The complex is intensely luminescent.268 Ligands (224) and (225) react with Cu' to give trinuclear double helices [Cu\L2l3' in which each Cu' is tetrahedrally coordinated by two bipy fragments. Assembly of the helices involves positive ~o-operativity.~~~ The bis(terpyridy1) ligand (226) forms binuclear double helices [MY(226),l4+ (M = Fe Ru) with octahedral metal centres.270 By using a lanthanide (capable of nine-fold "* E. C. Constable R. Chotaiia and D.A. Tocher J. Chern. Soc.. Chem. Commun. 1992 771. 269 A. Pfeil and J.-M. Lehn J. Chem. Soc. Chem. Commun.. 1992. 838. 2'o J. D. Crane and J.-P. Sauvage New. J. Chem.. 1992 16 649. The Coordination Chemistry of Open-Chain Polydentate Ligands 299 X pq/o~op-q (224) X=H (225) X = CO2Et R coordination) as template the triple helical [Eu2(227)J6+ can be assembled.27 ' In [Mn2(228)(p-O),(p-MeC02)]"+ (n = 2 Mn"'/Mnlv; n = 3; Mn;") the ligand spans the {Mn,(p-O),} core leaving two syn-oriented sites perpendicular to the Mn202 plane.[{ Mn:V(,u-O)4(OH)(228)} 2(p-228)]6 + comprises two linked {Mn304)4+ (incomplete cubane) cores. The electrochemical magnetic and spectro- scopic properties of these complexes were in~estigated.~~~,~~~ Irradiation of [FeLI2 + [L = (228) (229)] to give the initial 'MLCT excited state is followed by rapid ( <1 ps) inter-system crossing to a long-lived 5T2state.274 [M(228)I2+ (M = Fe Co Ni) can mediate electrocatalytic reduction of C02.77 (228) X = (CH& (229) X = (CH2)3 (230) n= 3 (232) X = 1,3-C6H (231) n=5 27' G.Bernardinelli C. Piguet and A. F. Williams. Angew. Chrm. Int. Ed. Enyl. 1992 31 1622. 272 S. Pal J. W. Gohdes W.C.A. Wilisch and W. H. Armstrong. Inory. Chem. 1992 31 713. 273 S. Pal and W. H. Armstrong Inorg. Chrm. 1992 31 5417. 274 J. K. McKusker. K.N. Walda R. C. Dunn. J. D. Simon D. Magde. and D. N. Hendrickson. J. Am. Chrm. Soc. 1992 114 6919. 300 M. D. Ward Bis-Cu’ complexes of (230) and (23 1) are haemocyanin models. Their binding of and reactivity with CO and 0 was studied in Similarly binuclear Cu’ and Cu” complexes of (232) were prepared and some crystal structures determined. They undergo reversible interconversion between Cuy Cu’Cu” and Cu; at potentials that are strongly solvent-dependent. The binding constant of CO in [Cu;(232)(CO)J2 + was measured.276 Electrochemical measurements showed that two molecules of the bis-Cu’ complexes of the ligand series (233) react with one molecule of 0,.277 bim7 N-X-N bimJ @im = 2-benzimidazolyl) (233) X = (CHZ),, n = 3,4,6 (234) X = nothing 1,4-CH2C,H&H, CH2CH(OH)CH2 (235) x = 1,4-c6H4 OH OH OH (239) m=n=2,3; n=3,m=4 The ‘back-to-back’ bis-terpyridines (234) and (235) can form one-dimensional polymers with Ru”.Binuclear complexes [(4’-X-terpy)Ru(pL)Ru(4’-X-terpy)l4+were also prepared and characterized with a variety of electron-donating or withdrawing groups X on the terminal terpy ligand~~~~ (cf. reference 313). Mono- bi- and K. D. Karlin Z. Tyelkar A. Farcqq M. S. Haka P. Ghosh R. W.Cruse. Y. Gultneh. J.C. Hayes. P.J. Toscano and J. Zubieta Inorg. Chem. 1992 31 1436. *” S. Schindler D. J. Szalda and C. Creutz Inorg. Chem. 1992 31 2255. ’” Y. Nishida I. Watanabe and K. Unoura Z. Naturforsch. Trrl B. 1992 47. 109. ”’ E.C. Constable and A. M. W. Cargill Thompson. J. Chrrn. Soc. Dulton Trans. 1992 3467. The Coordination Chemistry of Open-Chain Polydentate Ligands 301 tri-metallic complexes of hexaazatriphenylene (236) were prepared by attaching {Ru(NN),),' and (Rh(NN),)3+ (NN =bidentate chelating ligand) moieties to its binding sites. Their fast atom bombardment mass spectra were studied in Pd" and Pt" complexes of the achirally and chirally-substituted hexadentate ligands (237) and their mononucleating terdentate 'dien' analogues bind to nucleic acids and may be used as structural probes.280 [M(238)] (M = Cu Ni) where the metal is in the planar N cavity act as bidentate ligands to additional metal ions uia the external pyridazine N atoms.This enables preparation of binuclear complexes such as [Ni(238)Ni(hfacac),] and trinuclear complexes such as [{M(238)),CuX,,] (X =halide) which can show strong antifer- romagnetic couplings.'8 1.282 Vv complexes of the tris-catechol ligands (239) are possible enterobactin models.283 Mixed N,O-donorLigands.-[V"'(240)] is oxidized by 0 to [V'"(240)] which has a ~ cis-N,O donor set with no 0x0-ligands. Reversible V'"/VV and V'"/V"' couples were observed.284 [Mn"'L][PF,] [L = (241) (242)] have Jahn-Teller distorted octahedral structures; spectroelectrochemical EPR studies on [Mn"LI2 indicate rhombically + distorted structures.28s [Mn1"(243)] are also octahedral and undergo quasi-reversible reductions to Mn11'.2X6 contains a linear array [Mn~'(244),(MeO),(MeOH)8][C104]2 of four Mn"' ions with each ligand (244) bridging three of them.In DMF solution it dissociates to a binuclear species that exhibits catalase Spectroscopic and electrochemical studies were performed on [R~"'(245)].~~~ Heterobinuclear complexes of (246) were prepared containing a first-row ion [V(O) + Cu" Ni"] in the internal N,02 cavity and a lanthanide in the external cavity; the fluorescence of Eu"' in such complexes was partially q~enched.~~~,~~' Binuclear complexes of (247) and homo- and heterobinuclear complexes of (248) with first-row transition metal dications are weakly antiferromagnetically coupled ziia the bridging phenolates.291*292 Schiff bases (249) were prepared with different substituents on the aromatic rings and also form phenolate-bridged binuclear complexes.Their magnetic properties and the effects of the ring substituents on their electrochemical behaviour were e~amined.~~~.~~~ 27y P. Didier L. Jacquet A. Kirsch-De Mesrnaeker. R. Huber and A. van Dorsselaer Inorg. Chem. 1992.31 4803. 2x0 R. Alul. M. B. Cleaver and J. S. Taylor. Inorg. Chem. 1992 31. 3636. 2x1 M. Abed Ali Miah. D. J. Phillips and A. I). Rae. Inorg. Chim. Acta 1992 201 191. 2R2 G.C.Chiumia M. Abed Ali Miah and D.J. Phillips Inory. Chim. Actu 1992. 191 19. 283 A.Butler R. de la Rosa. Q. Zhou. A. Jhanji and C. J. Carrano. Inorg. Chem.. 1992. 31 5072. 2"4 A. Neves. A.S. Ceccato I. Vencato Y.P. Mascarenhas. and C. Erasrnus-Buhr. J. Chem. Soc. Chrm. Commun.. 1992 6.52. 2K5 A. Neves. S. M. D. Erthal. I. Vencato. A.S Ceccato Y. P. Mascarenhas. 0.R. Nascirnento M. Horner and A.A. Batista Inorg. Chern. 1992 31 1749. *" S.K. Chandra. and A. Chakravorty. Inorg. Chrm. 1992 31. 760. 2R7 K. Shindo. Y. Mori K. Motoda. H. Sakiyarna. N. Matsurnoto. and H. Okawa Inorg. Chem. 1992 31 4987. 2XH Z. Shirin and R. N. Mukherjee. Polyhrdrori. 1992 11. 262.5. 2H9 M. Sakamoto M. Ohsaki. K. Yamarnoto. 1'.Nakayama A. Matsurnoto and H. Okawa. Bull. Chem.Soc. Jpn. 1992 65,2514. 290 M. Sakamoto. M. Hashimura. Y.Nakayama. A. Matsurnoto and H.Okawa. Bull. Chem. Soc. Jpn.. 1992. 65. 1162. ")' X.Y. Zhou Z. W. Wu R. J. Tao. H.X. Han. D. M. Jin. and D.Z. Liao Polyhedron. 1992. 11. 3041. 2y2 B. Srinivas. N. Arulsamy and P. S. Zacharias Polyhedron 1992 1I 21 1 2Y3 B. Srinivas and P. S. Zacharias Can. J. Chem. 1992 70 2906. 2Y4 B. Srinivas and P. S. Zacharias. Polyhedron. 1992. 11. 1949. 302 M.D. Ward 0 0 H OH HO (H2244) (H3245) R = H 3-Me 4-Me 5-Me (H2248) Z=O (H2249) Z = N-C6H3XY; X,Y = H Me OMe SMe Br in various positions Substituted oxamide ligands such as (250)-(255) can act as binucleating ligands in two ways (cis,with N and 0 compartments or trans with two N20compartments see Figure 2). A potentiometric study of the formation of homo- and heterometallic complexes of (H2250) was performed.[Cu','(250)(NCO),] has a one-dimensional chain structure in which square-pyramidal Cu" are bridged alternately by trans-(250) and cyanato Reaction of (H,250) or (H2251) with Cu(NO,) gives two complexes one where two planar (Cu(cis-L)) units bind to a central Cu" with their 295 F. Lloret M. Julve J. Faus R. Ruiz I. Castro M. Mollar and M. Philoche-Levisalles Inory.Chern.,l992 31 784. The Coordination Chemistry of Open-Chain Polydentate Liyands Cis Trans Figure 2 'cis' and 'trans' hinucieating modes for dioxnmide ligunds pendant 0,O sites giving a {(CuN,)( CUO,)(CUN,)}~ arrangement and a tetranuc- + lear complex in which both bridging modes occur.296 [Cu"(cis-L)Ni"(mac)] + [L =(250)-(252); mac =N or N macrocycle] contain a Ni" centre attached to the external 0,O site of a (CuL) fragment.297 Whereas (253) is structurally versatile and forms polynuclear complexes in which both cis and trans binding modes occur the steric hindrance caused by an additional N-methyl group means that (254) always adopts a trans binding mode.298 In [{Ni"(H20),},(255)] the bridging ligand is trans with two terdentate binding pockets but in the infinite chain [Cu"(H2255)(H,0),] the bridging ligand is bis-monodentate uia the carboxylate groups at each end.299 Variable-temperature magnetic studies were performed on binuclear Cu"/Ni" com-plexes of (256)-(258).300 See also references 334-337.R' R2 OvNH KNR3R4 OANH NR3R4 I I R R w\ (H2250) R' =R2 =R3 =R4=H (H4255) R =C02H (H3257) R =OH (H2251) R' =R2 =Me R3 =R4 =H (H2256) R =2-pyridyl (H3258) R =NHMe (H2252) R' =R3 =R4 =H R2 =OH (H2253) R1 =R2=R3 =H R4 =Me (H22%) R' =R2=H R3 =R4 =Me Cu,[M"(cdta)],(N03),~1 5H,O (M =Cu Ni; H,cdta =cyclohexane-l,2-diamine-tetraacetic acid) are isostructural containing infinite chains in which (M(cdta)) units alternate with hydrated Cu" centres.They have novel magnetic proper tie^.^" The 296 V.G. Albano C. Castellari A.C. Fabretti and A. Giusti Inorg. Chrm. Actu. 1992 191 213. 297 A. Escuer R. Vicente J. Ribas R. Costa and X. Solans Inorg. Chem. 1992 31 2627. 298 F. Lloret M. Julve J.A. Real J. Faus R. Ruiz M. Mollar I. Castro and C. Bois Inorg. Chem. 1992.31 2956. 299 F. Lloret. J. Sletten R. Ruiz. M. Julve J. Faus and M.Verdaguer Inory. Chem. 1992 31 778. 300 M. Ohba M. Shiozuka N. Matsumoto and H. Okawa Bull. Chem. SOC.Jpn. 1992 65 1988. 301 F. Sapifia E. Escriva J. V. Folgado A. Beltran D. Beltran A. Fuertes,and M. Drillon. Inorg. Chem.. 1992. 31,3851. 304 M. D. Ward stability constants of Fe"' complexes with ligands such as (259)302 and (260)303 were found to be higher than those of some natural catechol-based siderophores; stability constants for a series of other metal complexes with (260) were measured.303 (H4259) R = CH2-(3-hydroxy-6-methyl)-2-pyridy1 (261) X = CH2CH2 (H4260) R = 2-hydroxyphenyl (262) X = 1,2-C& Ligands with Other Donor Sets.-Although CNi(261 )][ClO,] contains N3S3-coor- dinated Ni" in [Ni(262)(ClO4)][ClO,] the ligand is N3S2 pentadentate with only two 'arms' and the bridgehead N atom binding.304 Cu" complexes of (263) (264) and their reduced (imine to amine) analogues are six-coordinate with N2S donor sets.All undergo metal-centred reductions and give tetragonal EPR ~pectra.~" In contrast [Cu"L] [L = (265) (266)] can be oxidized to CU"'.~~~ Bis-Cu' complexes of (267)-(269) undergo two one-electron oxidations. K values for the mixed-valence states were mea~ured.~" Ligands (270)-(273) react with [RhCl(PPh,),] to afford a (263) n=2 (H2265) n= 1 (264) n = 3 (H2266) n=2 nrX7n m R2P PR2 Ph2E EPh2 (" I) EPh2 PhzE (270) R = 2-C&SMe (267) E= P X=nothmg (271) R = 2-C&Sh1 (268) E = As X = nothing (272) R = 2-benzimidazolyl (269) E = P x = 1,3-C& (273) R = 2-benzthiazolyl 302 R.J. Motekaitis Y. Sun and A. E. Martell Imry. Chirn. Actu. 1992 198-200. 421. 303 J. F. Gibson and 0.J. Vaughan J. Chem. Soc. Dulton Trans.. 1992 1375. 304 K.G. Ragunathan and P. K. Bharadwaj J. Chem. Soc.. Dalton Trans.. 1Y92. 2417. 305 S. Mandal and P.K. Bharadwaj. Polyhedron. 1992. 11. 1037. S. Mandal R. Shukla. and P.K. Bharadwaj Polyhedron 1992 11. 1855. 30' M. M. T. Khan and P. Paul Polyhedron. 1992. 11. 805. The Coordination Chemistry qf Open-Chain Polydentate Ligands 9-OH HO-Q N*N (274) n=2,3; X=O,S variety of products in which the ligand binding modes vary from P,P-bidentate up to bridging he~adentate.~" [Ni"(274)] have distorted N,O,X,-octahedral structures (X =0 or S)and for X =S may be oxidized to the Ni"' state which was examined by EPR spectroscopy .309 7 Ligands of Higher Denticity N-donor and 0-donor Ligands.-The octadentate ligands (275) bind four Cu" ions in a rectangular structure with the terminal pairs each sharing a hydroxide bridge.There are antiferromagnetic couplings within and between these pain3lo [Cu~(276)(H,O),]-l0H2O contains two square-pyramidal Cu" centres with the molecules linked by a hydrogen-bonding net~ork.~' Molecular mechanics and solution EPR studies on the binuclear Cu" complexes of (276) and (277) indicate that the solution structures are similar to the crystal structure^.^^ 1,3,5-Tris(4 -ter- pyridy1)benzene (ttbz) contains three terpy fragments linked to a central phenyl ring; trinuclear complexes [{Ru(4'-X-terpy)),(p-ttbz)l6+ represent the first steps in the preparation of new cascade polymers with three chains linked at the central ligand.3'3*278 Binding of Cu" or Zn" in the bis-acac sites of (278) brings the polyether xx A H2NqNq YNH NH2 (H4276) X=O (275) R =2-pyridyl or 3- 4- or (277) X =2H 5-methyl-2-pyridyl 30H M.F. M. Al-Dulaymmi A. Hills P. B. Hitchcock D. L. Hughes. and R. L. Richards J. Chem. Soc,.,Dalton Truns. 1992 241. 3"y S.B. Choudhury D. Ray and A. Chakravorty J. Chem. Soc. Dalton Trans.. 1992 107. 310 S.S. Tandon S.K. Mandal L.K. Thompson and R.C. Hynes Inory. Chrm. 1992 31. 2215. 311 Z. Shourong L. Qinhui S. Mengchang D. Anbang and H. Liangren Polyhedron 1992. 11 941. 312 P. V. Bernhardt P. Comba T. W. Hambley S.S.Massous and S. Steber Inorg. Chrm. 1992 31 2644. 313 E. C. Constable and A.M. W. Cargill Thompson J. Chrm. Soc. Chem. Commun.. 1992. 617. 306 M.D.Ward (H2278) n = 1 ,2 chain into the correct conformation for size-selective binding of alkali metal cations. These complexes therefore display positive co-operativity. l4 Mixed Donor Ligands.-Compartmental ligands such as (279)-(290) form binuclear complexes with an endogenous alkoxide or phenoxide bridge and are extensively used to prepare models of polynuclear metalloprotein active sites. Examples include manganese complexes as models for the oxygen-evolving centre of photosystem I1 [ligands (281),' and (285)-(288)3'6]; iron complexes as models for iron-oxo proteins such as catalase haemerythrin and purple acid phosphatase [ligands (281),31 7,3l8 (282),,19 (283),318 (284),320 and (287)321]; and copper complexes as models for type 111 cuproproteins [ligands (279k(280),275 (289),322 and (290)"'l.[VF(H284)2]2-contains a V,(p-O) core with pentagonal-bipyramidal metal centres. Each ligand is + hexadentate with a non-coordinated acid [Ni;(286)(p-RCO2),] may be oxidized to the Ni"/Ni"' and Niy' states which were characterized by EPR spectros-copy.32 The tripodal ligand (245) (with X = H) acts as a heptadentate ligand in [Mn~'02(245)2]2+, with the bridgehead N atom coordinated (cJ reference 288).326 [Ln(H3291)(N0,),] (Ln = a lanthanide ion) dimerize in base to give [(Ln(291)},] in which the bicapped-octahedral metals are linked by bridging phenolates resulting in weak antiferr~magnetism.,~~ Ligand (291 ) can be either N,O,-hexadentate N402-hexadentate or N40,-heptadentate in complexes with Al" Ga"' and In"'.328 Lu"' and Gd"' complexes of (292) are potential magnetic resonance imaging agents.329 314 Y.Kobuke and Y. Satoh J. Am. Chem. Soc. 1992 114 789. 315 M. L. Kirk M. K. Chan W. H. Armstrong. and E. I. Solomon J. Am. Chem. Soc. 1992 114 10432. 316 Y. Gultneh A. Farooq S. Liu K. D. Karlin and J. Zubieta Inorg. Chem. 1992 31 3607. 317 Y. Nishida M. Nasu and T. Akamatsu 2.Naturforsch. Teil B 1992 47 115. 318 Y. Nishida T. Akamatsu T. Ishii and Y. Oda J. Chem. Soc. Chem. Commun. 1992 496. 319 Y. Hayashi M. Suzuki A. Uehra Y. Mizutani and T. Kitagawa Chem. Lett. 1992 91. 320 S.Kawata M.Nakamura Y. Yamashita. K. Asai K. Kikuchi I. Ikemoto M. Katada.and H. Sano Chem. Lett. 1992 135. 321 M. S. Mashuta R. J. Webb J. K. McKusker E.A. Schmitt K. J. Oberhausen J.F. Richardson R. M. Buchanan and D. N. Hendrickson J. Am. Chem. Soc. 1992 114 381 5. 322 M. R. Malachowski. M.G. Davidson and J.D. Davis Inorg. Chim. Acta 1992. 192. 157. 323 M. Mahroof-Tahir N. N. Murthy. K. D. Karlin N. J. Blackburn S.N.Shaikh and J. Zubieta Inorg. Chem. 1992 31 3001. 324 J. C. Robles. M. Shimoi and H. Ogino Chem. Lett. 1992 309. 325 T. R. Holman M. P. Hendrich. and L. Que. Jr. Inorg. Chem. 1992. 31 937. 326 C. Gedye C. Harding V.McKee J. Nelson and J. Patterson J. Chem. Soc.. Chem. Commun. 1992 392. 327 S. Liu L. Gelmini S.J. Rettig R.C. Thompson and C.Orvig J. Am. Chem. Soc. 1992 114 6081. 328 S. Liu S.J. Rettig and C. Orvig Inorg. Chem. 1992 31 5400. 329 P. P. K. Claire C. J. Jones K. W. Chiu J. R. Thornback. and M. McPartlin. Polyhedron. 1992 11,499. The Coordination Chemistry of Open-Chain Polydentate Ligands 307 (H279) X = H R = 2-pyridy1 n = 2 R = (280) X = C(O)C~H~C~HS 2-pyridy1 n = 2 (H281) X = H R = 2-pyridy1 n = 1 (H282) X = H R = 6-methyl-2-pyridy1 n = 1 (H283) X = H R = 2-benzimidazoly1 n = 1 (H5284) X = H R = CO,H R I (H285) R = H n = 2 D = 2-pyridyl (H286) R = Me n = 1 D = 2-pyridyl (H287) R = Me n = 1 D = 1-methyl-2-imidazolyl (H288) R = Me n = 1 D = 1,4,7-triazacyclononyl (H289) R = H n = 1 D = 3,5-dimethyl-l-pyrazolyl (H290) (H3291) R = H C1 Br Eight-coordinate Zr’” and Hf’” complexes of (H02CCH2)2NCH2(CH,0CH2)2- CH,N(CH,CO,H) are i~ostructural.~~~ Stability constants of several complexes of the N,O,-donor N[CH2CH2N(Me)CH2C02H]3were measured and the solution 330 D.F. Evans.G. W. Griffiths C. O’Mahoney D. J. Williams. C.Y. Wang,and J. D. Woo1ins.J. Chern. Soc. Dalton Trans. 1992 2415. 308 M.D. Ward NMR behaviour of the Zn" and La"' complexes studied.331 Luminescence properties of Eu"' and Tb"' complexes with the ligands in Figure 3 were examined to determine the suitability of the complexes for luminescence-based bioaffinity assays.332,333 bridge bridge = 2,6-pyridyl 6,6'-bipyri dyl 6,6"-terpyridyl H 1,lO-phenanthrolinyl 1,8-naphthyridinyl f "'1 f "1 H02C CO,H H02C CO2H Figure 3 Series of' ligands used to prepare luminescent Eu"' and Tb"' complexes [Cu"L]'-[L = (293) (294)] contain a planar Cu" in the central N cavity of the bis-dioxamide ligand.Binding of Ni" at the external 0,O-chelating sites affords trinuclear Ni-Cu-Ni complexes.334 Likewise binding of lanthanides at the external 0,O-chelating sites of [Cu"(295)I2 -permits synthesis of a wide variety of one-dimensional and two-dimensional Such complexes are of interest both for their unusual structures and their magnetic properties (cf references 295-300). OAXH HXAO (b293) X = N R' = OH R2 = H (b294) X = N R' = R2= Me (H4295) X = 0 R' = R2 = H f:JG3N-x-Ny 331 C. F.G. C. Geraldes E. Rrucher S. Cortes S.H. Koenig and A. D. Sherry .I. Chem. Soc..Dalron Truns. 1992 2517. 332 V.-M. Mukkala and J. Kankare Helu. Chim. Acra 1992 75 1578. 333 V.-M. Mukkala. C. Sund M. Kwiatkowski. P. Pasanen. M. Hogberg. J. Kankare and H. Takalo Helu. Chim. Acta 1992 75 1621. 334 R. Vicente A. Escuer. and J. Ribas Polyhedron 1992 11. 857. 335 0.Guillou P. Bergerat 0.Kahn E. Bakalbassis. K. Boubekeur P. Batail and M. Guillot Inorg. Chem. 1992. 31 110. 336 0.Guillou R. L. Oushoorn 0.Kahn K. Boubekeur and P. Ratail .4nyerc. Chem.,Int. Ed. Engl. 1992,31 626. 337 0.Guillou 0.Kahn. R. L. Oushoorn. K. Boubekeur and P. Batail Inory. Chim. Acra 1992,198-200.1 19. The Coordination Chemistry of Open-Chain Polydentate Ligands 309 NH HN (H3298) Ligands (296) and (297) are new tetrahydroxamic acid chelating agents for Fe"' Th" and Nd'1'.338 Electrochemical and spectroscopic studies were performed on mono- and bridged binuclear complexes of (298) with first-row metal di~ations.~~~ Binding of the terminal phosphine groups of Ph,PCH,(CH,OCH,),CH,PPh (n = 3-5) to a (PtCI,) group folds the polyoxoethylene chain into a 'crown-ether-like' confirmation which can bind alkali metal cations.340 A.S. Gopalan V. J. Huber 0.Zincircioglu and P. H. Smith J. Chem. Soc. Chem. Commun. 1992. 1266. 33y B. Adhikary. K. K. Nanda R. Das S. K. Mandal and K. Nag. Polyhedron 1992 11 347. A. Varshney M. L. Webster and G. M. Gray Inoryl. Chrrn. 1992. 31 2580.