9 The Transition Elements By W. E. SMITH Department of Pure and Applied Chemistry, The University of Strathclyde Glasgow and J. M. WINFIELD Department of Chemistry The University of Glasgow 1 Introduction The scope and format of this report are similar to previous years and papers dealing with organometallic compounds and kinetics and mechanisms are largely excluded. Coverage is not comprehensive and for this the reader is directed to the appropriate Specialist Periodical Report.* Topics that have been reviewed this year include the magnetic properties of polynuclear compounds,' the use of magnetic resonance techniques for studying electronic structures,2 ligand field spectra and bonding in solid^,^ spin-forbidden electronic bands,4 transition-metal cations in synthetic zeolites,' and photo-chemistry of transition-metal compounds in the solid state and in solution.6 Nomenclature.-Metals are denoted by M cations by A anions by X or Y, organic radicals by R and ligands by L using Latin numerical prefixes to indicate denticity e.g.biL for a neutral bidentate ligand. When possible the first co-ordination sphere is indicated by square brackets and the structures of poly-nuclear compounds are denoted following current usage e.g. anhydrous Mo" chloride is [(Mo6Cl,)C1,C14,,] . Commonly used solvents and ligands are abbreviated as follows dimethyl sulphoxide (DMSO) tetrahydrofuran (THF) dimethylformamide (DMF), ethylenediamine (en) pyridine (py) 2,2'-bipyridyl (bipy) terpyridyl (terpy), ' J. S. Griffith Structure and Bonding 1972 10 87; A.P. Ginsberg Inorg. Chim. Acta Rev. 1971 5 45. D. R. Eaton and K. Zaw Co-ordination Chem. Rev. 1971,7 197. D. Reinen Angew. Chem. Inrernar. Edn. 1971 10 901. L. L. Lohr jun. Co-ordination Chem. Rev. 1972,8 241. I. D. Mikheikin G. M. Zhidomirov and V. B. Kazanskii Russ. Chem. Rev 1972, 41 468. E. L. Simmons and W. W. Wendlandt Co-ordination Chem. Rev. 1971 7 11; W. L. Waltz and R. G. Sutherland Chem. SOC. Rev. 1972 1 241. * 'Inorganic Chemistry of the Transition Elements' ed. B. F. G. Johnson (Specialist Periodical Reports) The Chemical Society London Vol. 1 1972 Vol. 2 1973. 27 278 W. E. Smith and J. M . WinJield 1,lO-phenanthroline (phen) 8-quinolinolate (oxine) 1,2-bis(diphenylphosphino)-ethane (diphos) o-phenylenebis(dimethy1arsine) (diars) acetylacetonate (acac), acetate (OAc) oxalate (ox) and ethylenediaminetetra-acetate (edta).2 The Rare Earths Scandium.-Recent work reported on t h s element again illustrates its similarity to 3d elements and to the lanthanides. The preparation of Sc[N(SiMe,),] from ScCI and LiN(SiMe,) has been described.' The compound forms part of the series M[N(SiMe,),] (M = Sc-Cr and Fe; see also lanthanides) containing trigonally co-ordinated M but from its i.r. spectrum Sc-N n-bonding appears not to be important. X-Ray work has shown that Sc is approximately dodecahed-rally co-ordinated in Sc,(ox) ,6H,O by six carboxylate and two water 0 atoms. The structure is similar to that found for other aquo-oxalato-complexes with each ox group forming two chelate rings (Sc-0 = 218-226pm).8 The com-pounds A,Sc(NO,) (A = K Rb or Cs) are formulated as nitrato-scandates rather than double salts from their i.r.spectra. They are stable in solution only in the presence of concentrated HNO .' Adduct formation between Sc(biX), (biX = thenoyltrifluoroacetonate) and tributyl phosphate (L) has been studied in various solvents. Unlike related systems there was no evidence for adducts other than Sc(biX),L." A procedure for obtaining anhydrous ScX (X = C1 or Br) from aqueous solution has been described" in which hydrolysis of Sc"' is prevented during the preparation by the formation of ScX,,-. The procedure is similar to that used previously to prepare anhydrous LnX (X = Cl-I inclusive), but attempts to prepare ScI were unsuccessful possibly because the formation of SCI,~ - is unfavourable for steric reasons.Yttrium and the Lanthanides.-The behaviour of high-temperature (1 273-1473K) molecular beams of LnF in inhomogeneous electric fields has been examined to obtain information on the vapour-phase structures of these com-pounds. Significant distortions from D, symmetry either of a pyramidal or of an in-plane C, type are indicated for La Gd Lu Sc and Y trifluorides whereas those of Pr Nd Tb Dy and Ho appear to have D, symmetry. Small distortions are indicated where Ln = Ce Er and Tm and are probably absent where Ln = Sm Eu and Yb. It is noteworthy that the significant distortions correspond to fo f' or f " configurations. This study conflicts with some of the structural conclusions drawn previously from the vibrational spectra of matrix-isolated LnF, but the spectrum of PrF has been re-interpreted in D, symmetry.14 The co-ordination chemistry of Sc has been reviewed.', ' E.C. Alyea D. C. Bradley and R. G. Copperthwaite J.C.S. Dalton 1972 1580. * E. Hansson Acfa Chem. Scand. 1972 26 1337. L. N. Komissarova G. Ya. Pushkina and V. I. Spitsyn Russ. J . Inorg. Chem. 1971, 16 1262. l o K. Akiba T. Ishikawa and N. Suzuki J . Inorg. Nuclear Chem. 1971 33 4161. ' * R. W. Stotz and G. A. Melson Inorg. Chem. 1972 11 1720. l 2 G. A. Melson and R. W. Stotz Co-ordination Chem. Rev. 1971,7 133. l 3 E. W. Kaiser W. E. Falconer and W. Klemperer J . Chem. Phys. 1972 56 5392. l 4 M. Lesiecki J. W. Nibler and C. W. DeKock J . Chem. Phys. 1972.57 1352 The Transition Elements 279 Co-ordination numbers greater than six are characteristic of lanthanide compounds in condensed phases but one of the most notable advances this year is the characterization of volatile monomeric Ln[N(SiMe,),] (Ln = La Pr Sm, Eu Gd or Lu) compound^.'^ The Eu"' compound appears to have a structure similar to the Fe"' analogue (see also Scandium) and the compounds thus contain three-co-ordinated Ln"'.The ability of bulky ligands to produce low co-ordina-tion numbers in Ln"' chemistry is illustrated also by [Li(THF),] [LuAr,] (Ar = 2,6-dimethylphenyl) which X-ray work has shown to contain an approximately tetrahedrally co-ordinated Lu atom.' A suggestion that cubic stereochemistry may be as common for LnL groups as it is for the actinides comes from X-ray work on the [La(py0),l3' cation.17 The polyhedron approximates to D symmetry with a large deviation from a square antiprism towards a cube.Bidentate ligands figure largely in this year's work either in new complexes designed to produce high co-ordination numbers, or in physical studies on known complexes. The ligand characteristics of 1,s-naphthyridine (1) towards 3d metals are similar to NO - and high co-ordination numbers can be obtained (see previous reports). Its behaviour to Ln"' has been examined and typical of the products formed are Ln(biL),(NO,) (Ln = La-Nd), Ln(biL),(NO,) Ln = (Y Sm-Yb) [Ln(biL),](ClO,) (Ln = La-Pr) and [Ln(biL),](ClO,) (Ln = Nd-Eu). Co-ordination numbers of 12 or 10 are suggested from spectral and conductance work. Structures for the complexes of Ln"' with the nicotinate anion (2) had previously been formulated assuming the presence of terdentate ligands but X-ray work has shown that they are [(H,O),(biX)Ln(biX),Ln(biX)(H,O),] each Ln having a highly distorted antiprismatic environment with bidentate (2 x 0) nicotinate ligands.While the Gd compound has a normal magnetic moment those of the Pr"' and Nd"' analogues are low." Often a small change in the ligand can produce a change in molecular geometry which may be reflected in the elec-tronic spectrum. Eu"' complexes are particularly favourable for such work (cf: previous reports) and a fluorescence spectral study of antiprismatic [Eu(biX),] -anions indicates that when biX = di-p-bromodibenzoylmethide the anion's structure is (3) compared with the previously determined structure (4) where I s D.C. Bradley J. S . Ghotra and F. A. Hart J.C.S.Chem. Comm. 1972 349. l 6 S . A. Cotton F. A. Hart M. B. Hursthouse and A. J. Welch J.C.S. Chem. Comm., 1972 1225. A. R. Al-Karaghouli and J. S. Wood J.C.S. Chem. Comm. 1972 516. R. J. Foster and D. G. Hendricker Znorg. Chim. Acra 1972 6 371; R. J. Foster, R. L. Bodner and D. G. Hendricker J . Inorg. Nuclear Chem. 1972 34 3795. l 9 J. W. Moore M. D. Glick and W. A. Baker jun. J. Amer. Chem. SOC. 1972,94 1858 280 W. E. Smith and J. M . Winfield biX = dibenzoylmethide. An increase in charge density near Eu"' is suggested in the p-bromo-complex.20 (3) (4) The literature on lanthanide n.m.r. shift reagents appears to be increasing exponentially and several surveys of the use of Ln"' P-diketonate compounds, particularly the ligands 2,2,6,6-tetramethylheptane-3,5-dione (dpm) and 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,~dione (fod) have appeared.2 Attention has been drawn to the persistence of dimeric [Ln(biX),] species in solution the possibility of forming 1 1 or 1 2 shift reagent substrate complexes, and the importance in some cases of contact contributions to the observed shifts, as opposed to dipolar (pseudo-contact) contributions.The X-ray crystal struc-tures of two widely used reagents Ho(dpm),(4Mepy) and Eu(dpm),(py) have been determined.,' In both cases the LnO,N polyhedron is best described as a square antiprism (5). This may be compared with the structure of monomeric Er(dpm) in which Er has trigonal prismatic ~o-ordination.~~ 2o J.J. Degnan C. R. Hurt and N. Filipescu J.C.S. Dalton 1972 1158. 2 1 W. Dew. Horrocks jun. and J. P. Sipe tert. J . Amer. Chem. SOC. 1971 93 6800; J. K. M. Sanders S. W. Hanson and D. H. Williams ibid. 1972 94 5325; B. F. G. Johnson J. Lewis P. McArdle and J. R. Norton J.C.S. Chem. Comm. 1972 535. 2 2 W. Dew. Horrocks jun. J. P. Sipe tert. and J. R. Luber J . Amer. Chem. SOC. 1971, 93 5258; R. E. Cramer and K. Seff Acta Cryst. 1972 B28 3281. 23 J. P. R. de Villiers and J. C. A. Boeyens Acta Cryst. 1971 B27 2335 The Transition Elements 28 1 Single-crystal magnetic anisotropy measurements on [Ln(dpm),(4-Mepy),] (Ln = Pr-Tm) indicate that the susceptibility tensors are highly anisotropic and non-axial. Dipolar n.m.r. shifts calculated using the data agree satisfactorily with those obtained in solution.24 Exchange between 'free' substrate and that bound to Ln(biX) is normally fast on the n.m.r.time scale and separate reson-ances are not observed. An exception to this is the Eu('H,-fod) ,DMSO system in which separated DMSO signals were observed at 193 K and a 1 2 complex is indicated.25 2 1 Complex formation between optically active alcohols and Eu(fod) is indicated also from a c.d. study.26 While shift reagents may be used routinely for 'spreading out' n.m.r. spectra, more detailed work for example determining substrate binding enthalpies or conformations must be undertaken with caution. Commonly made assumptions of 1 1 complex formation and magnetic axiality may not be justified. A general approach using both shift and broadening effects to the use of Ln"' compounds in structural studies has been given2' Mossbauer spectroscopy has proved to be a useful technique for determining the oxidation states of Eu compounds.Thus the phases Eu,C3 EuC, and EuN,C, obtained from Eu and HCN or (CN) at high temperatures have been shown to be band systems while EuN is ionic and contains Eu3+. Reactions in liquid NH between Eu and HCN C,H,,or NH,SCN give Eu" and Eu"' cyanides Eu"' acetylide and Eu"' thiocyanate respectively. It has been suggested also that polymeric and monomeric Eu"' chelates may be differentiated by means of their Mossbauer spectra.28 The previously observed ferromagnetic properties of EuO EuS EuSe and GdN at low temperatures have been interpreted according to indirect exchange betweenfelectrons of different cations via their outer closed shells.This mechan-ism is expected to compete with superexchange via anions which would favour antiferromagnetic beha~iour.~' Electric deflection molecular beam studies' on LnF (Ln = Sm Eu or Yb) show that they are strongly polar molecules in the gas phase and therefore bent structures are indicated. A similar conclusion is drawn from the i.r. spectra of matrix-isolated LnX (X = F or Cl)30 (see also last year's report) and ClLnCl bond angles calculated from isotope frequency shifts are 130 O (Sm) 130 O (Eu) and 140 O (Yb). Complexation energies derived for the formation of Ln(NH3)62 '(8) from Ln2'(g) and NH,(g) are - 1250 and - 1352 kJ mol-' for Ed' and Yb" respec-tively.,' These values are comparable with complexation energies of Group I1 2 4 W.Dew. Horrocks jun. and J. P. Sipe tert. Science 1972 177 994. " D . F. Evans and M. Wyatt J.C.S. Chem. Comm. 1972 312. 2 6 N. H. Andersen B. J. Bottino and S. E. Smith J.C.S. Chem. Comm. 1972 1193. 27 B. Bleaney C. M. Dobson B. A. Levine R. B. Martin R. J. P. Williams and A. V. Xavier J.C.S. Chem. Comm. 1972 791. '* I. Colquhoun N. N. Greenwood I. J. McColm and G. E. Turner J.C.S. Dalton, 1972 1337; J. I. Mackey and N. N. Greenwood J . Inorg. Nuclear Chem. 1972 34, 1529. 2 9 E. Lombardi G. Tarantini R. Block R. Roel G. Ter Maten L. Jansen and R. Ritter, Chem. Phys. Letters 1972 12 534. 3 0 C. W. DeKock R. D. Wesley and D. D . Radtke High Temp. Sci. 1972,4,41. 3 1 R. H. Frisbee and N.M. Senozan J . Chem. Phys. 1972,57 1248 282 W. E. Smith and J. M . Winjeld cations of similar size. Bands in the spectra of transient species observed in the pulse radiolysis of Ln"' solutions have been assigned to transitions between the 4f" and 4P-l 5d levels of Ln2+. The reactions of Ln" with OH- O, N,O etc. indicate that the order of reactivity is Sm" > Yb" > Eu" which correlates with their electrode potential^.^^ 3 The Actinides The first hydrated complexes of UI'I U2(S04)3 ,5H20 (or 2H,O) and M,SO,,U,(SO,)3,xH,O (M = Na K Rb Cs NH, or N2H5; x unknown) have been prepared. A further series of hydrated chlorides divides into two sets : the red set MUCl,,SH,O (M = NH,,K or Rb) have more covalently bound chlorides compared with the green set MUCI,,xH,O (M = NH or Rb) which are ionic.The red set only have a U-Cl stretch in the i.r. spectra. In general, oxygen donor ligands do not give stable complexes of UIII but the compounds U(ph),Cl and U(dmaz),(Ph,B) have now been isolated (ph = phenazone, dmaz = dimethylphena~one).~~ Adducts of type UX,,RCN (X = C1 or Br; R = Me Et Pr" Pri Bn" or Ph) appear to be eight-co-ordinate from spectral and magnetic data. The complexes are weak and easily broken down thermally.34 M11U,VF,2 salts (M = Co Ni or Cu) also appear to be eight-co-ordinate from spectral and magnetic data.35 New preparations of U0,Cl and UOC1236 and the new compound UOF are reported.37 The structure of the complexes UO,(MeCS,) ,Ph3P0 shows that the uranium is seven-co-ordinate with a pentagonal-bipyramidal geometry,' and neutron diffraction data on [U0,H20{CO(NH2),),] (NO,) for which the structure has been uncertain, demonstrates that it has a similar geometry.39 The U02,+ group is linear and the plane has four urea oxygen groups and one water co-ordinating the uranium.The structure is connected by hydrogen bonds through the nitrates. of U(BH,) shows that the structure is polymeric with six BH groups per uranium. There are four bridging groups and two (cis) terminal groups. A neutron diffraction study shows that the four bridging groups are bonded through two U-H-B bonds and the cis terminal groups by three U-H-B bonds.40b The spectrum of Uv has been assigned using an intermediate coupling calculation for an f ' system in a tetragonal field.,' The An X-ray diffraction 32 M.Faraggi and Y. Tendler J . Chem. Phys. 1972 56 3287. 3 3 R. Barnard J. I. Bullock B. J. Gellatly and L. F. Larkworthy J.C.S. Dalton 1972, 3 4 P. Gans and J. Marriage J.C.S. Dalton 1972 46. 3s F. Montoloy P. Plurien and M. Capestan J. Inorg. Nuclear Chem. 1972.34 125. 3 6 S. S. Eliseev I . A. Glukhov and E. E. Vozhdaeva Russ. J . Inorg. Chem. 1972,17,627. 37 P. W. Wilson J.C.S. Chem. Comm. 1972 1241. G. Bombieri U. Croatto E. Forsellini B. Zarli and R. Graziani J.C.S.Ddton 1972, 560. 964 1932 1933, 3 9 N. K. Dalley M. H. Mueller and S. H. Simonsen Inorg. Chem. 1972 11 1840. 40 ( a ) E. R. Bernstein T. A. Keiderling S. J. Lippard and J. J. Mayerle J. Amer. Chem. SOC. 1972,94,2552; (b) E. R. Bernstein W. C. Hamilton T. A. Keiderling S. LaPlaca, S.J. Lippard and J. J. Mayerle Inorg. Chem. 1972 11 3009. 4 1 J. Selbin C. J. Ballhausen and D. G. Durrett Inorg. Chem. 1972 11 510 The Transition Elements 283 choice of coupling scheme to interpret the spectra of uranyl complexes has been considered and the Russell-Saunders scheme found to be superior to the inter-mediate coupling case.42 The new complexes (Et,N),M(NCS)* (M = Th Pa Np or Pu) have the metal at the centre of an almost perfect cube.43 An improved method of preparing trihalides of U Np and Pu by reduction of the tetrahalide with zinc metal at 900K and the preparation of the new oxyhalides NpOCl NpOBr and NpOI are The complex sulphates M2Np02(S04),,2H20(M = K or Cs) and [Co(NH,),] [NpO,(SO,),] xH20 have been prepared (x unknown)."' The di-positive oxidation state of the heavier actinides has become much better characterized this year.New compounds reported are : Am Cm Bk Cf Es Fm Compound AmI - BkH CfBr SmC12.Es2+ SmC12.Fm2+ Reference 46 - 47 48 49 50 Each of these is a first report of that particular oxidation state. The di-positive Es and Fm species are ions doped into SmCl . They were prepared by reduction with Mg of solutions of SmCl and EsCl or FmCl in aqueous ethanol. The rather insoluble SmCl crystallizes out. CfO, the second example of a Cf'" compo~nd,~' and Pull' formate the second example of an actinide(II1) f ~ r r n a t e ~ ~ have been reported. The high temperature form of curium metal has an oxidation state of +3 not + 4 as suggested previo~sly.'~ The crystal structure of Am2(SO,),,8H,O shows that the metal is co-ordinated to four oxygens of the SO, - group and four oxygens from water molecule^.'^ The unit cell dimensions of the actinides show changes which obey the 'tetrad' rule" as do the stability of mono- di- and tri-SCN derivatives of Amii1 CrnI" Bk"' Cf"' and Es~I'.'~ It 4 2 G.Gorller-Walrand and L. G. Vanquickenborne J. Chem. Phys. 1972,57 1436. 43 2. M. S. A1 Kauaz K. W. Bagnall D. Brown and B. Whittaker J.C.S.Dalton 1972, ** D. Brown and J. Edwards J.C.S. Dalton 1972 1757. " M. P. Mefodeva N. N. Knot L. N. Bugahava and A. D. Gelman Russ. J. Inorg. 46 R. D. Baybarz L. B. Asprey C. E. Strouse and E. Fukushima J. Inorg. Nuclear *' J. A. Fahey J. R. Peterson and R. D. Baybarz Inorg. Nuclear Chem. Letters 1972, 2273. Chem. 1972.17.736. Chem. 1972 34 3427. 8 101. J. R. Peterson and R. D. Baybarz Inorg. Nuclear Chem. Letters 1972 8 423. *' N. B. Mikheev V. I. Spitsyn A. N. Kamenskaya N. A. Rosenkevitch I. A. Rumer, and L. N. Auerman Inorg. Nuclear Chem. Letters 1972,8 869. " N. B. Mikheev V. I. Spitsyn A. N. Kamenskaya B. A. Gvodev V. A. Druin I. A. Rumer R. A. Dyachkova N. A. Rozenkevitch and L. N. Auerman Inorg. Nuclear Chem. Letters 1972 8 929. " R. D. Baybarz R. G. Haire and J. A. Fahey J. Inorg. Nuclear Chem. 1972,34,557. " L. R. Crisler J. Inorg. Nuclear Chem. 1972 34 3263. " R. D. Baybarz and H. K. Adair J. Inorg. Nuclear Chem. 1972,34,3127. " J. H. Burns and R. D. Baybarz Inorg. Nuclear Chem. Letters 1972,8,423. " S . Siekierski and I. Fidelis J. Inorg. Nuclear Chem. 1972 34 2225." H. D. Harman J. T. Peterson W. J. McDowell and C. F. Coleman J . Inorg. Nuclear Chem. 1972 34 1380 284 W. E. Smith and J. M. Winfield thus appears that this rule holds good for the heavy actinides as it does for the lanthanides. 4 The Titanium Group Titanium.-Compounds of the type Ti(biX)X have attracted some attention in recent years as they may contain five-co-ordinate Ti. Work reported last year suggested that this was not the case and an X-ray structure of Ti(acac)Cl, provides confirmatory evidence. The compound is a C1-bridged centrosym-metric dimer (6).57 X-Ray work has shown that TiCl,(NCH) has a cis con-figuration not trans as was suggested from its vibrational spectrum.58 Other work on Ti'" illustrates again the lability of its complexes in and the similarity of MeTiC1 to TiC1,.60 ,'Ti ( I = $ 7.3 % abundance) and 49Ti (1 = $ 5.5% abundance) n.m.r.have been used to examine tetrahalides in solution.59a The results are similar to those obtained from previous spectro-scopic work as monomeric TiX,(X = C1 or Br) and rapid exchange between TiCl and TiBr are indicated. A "F n.m.r. study of halide ligand redistribution between TiC1 and TiF in 1,2-dimethoxyethane indicates that all possible species in the series TiCl,-,F,(biL) can be formed but that isomers with a minimum number of Cl ligands trans to oxygen are favoured. This contrasts with previous work in THF and steric interactions between cis C1 and 0 atoms (THF) are deemed to be re~ponsible.~'~ MeTiCl reacts with Et,NCl in CH2C1 to give dark-violet light-brown or deep-blue salts depending on the mole ratio of reactants.60a Structures for the anions are formulated from their i.r.spectra as [MeCl,TiCl,TiCl,Me]-, [C13MeTiC1,TiC1,Me]2- and [MeTiClJ- respectively. The n.m.r. and i.r. spectra of MeTiCl,(biL) (biL = X'CH2CH,X2 where X',X2 are OMe NMe, or 5 7 N. Serpone P. H. Bird D. G. Bickley and D . W. Thompson J.C.S. Chem. Comm., 5 8 G. Constant J. C. Daran and Y . Jeannin Actu Cryst. 1971 B27 2388. 5 9 ( a ) R. G. Kidd R. W. Matthews and H. G. Spinney J. Amer. Chem. SOC. 1972 94, 6686. (b) R. S. Borden P. A. Loeffler and D . S. Dyer Inorg. Chem. 1972 11 2481. 6 o (a) R. J. H. Clark and M. Coles Chem. Comm. 1971 1587. (b) R. J. H. Clark and A. J. McAlees Inorg. Chem. 1972 11 342; J.C.S. Dalton 1972 640. 1972 217 The Transition Elements 285 SMe) complexes have been interpreted on the basis of rner configurations with the 'harder' X group trans to Me; m e r e fac exchange occurs readily and a twist mechanism is proposed to explain this.Reaction of MeTiCl,(biL) with 0 at room temperature gives the corresponding MeOTiCl,(biL) complexes which show similar behaviour.60b Little information is available about the solid-state structures of TiCl com-plexes but two X-ray structures of complexes with N-donor ligands have been reported this year.61 In the complex with NN-bis-(6-methyl-2-pyridylmethyl)-methylamine Ti"' has a distorted octahedral environment with a rner configur-ation (7). A similar configuration exists in [TiCl,py,]py and variations in the Ti-C1 and Ti-N bond distances are observed.Steric crowding about Ti appears to be responsible for the distortions observed in (7) but there is no simple Me T N - 7 explanation for the variable bond distances in the py complex although steric factors may be important. In py solution an e.p.r. study suggests that the most abundant species is [C12py2TiC1,Tipy,C1 3 an edge-sharing bioctahedral dimer with py ligands cis to the C1-bridges and a Ti-Ti distance of ca. 340 pm.62 The electronic spectrum of Ti2+ ions isolated in single-crystal NaCl is that expected for a d2 ion in an octahedral field. Values of Dq and B derived from the 77 K spectrum are 852 and 572 cm- ' re~pectively.~~ ZirconiumandHafnium.-In some of the work on these elements this year similarities to Ti chemistry are apparent.A vibrational study of MC14,2NOC1 compounds suggests that they should be formulated as [NO+],[MC162 -1 salts, like the Ti compound.64 Heats of formation of MC1,,2POC13 (s) are 88.6 (Zr) and 98.2 (Hf) kJ mol- l . The values are comparable with that reported for the Ti analogue last year and these compounds are also completely dissociated in the vapour phase.65 Stereochemical information on solid Hf(biX) species has been obtained using I8'Ta as a probe. Nuclear quadrupole interactions involving "'Ta were derived by measuring the differential perturbation in the angular correlation of 6 1 6 2 6 3 6 4 6 5 R. K. Collins M. G. B. Drew and J. Rodgers J.C.S. Dalton 1972,899; R. K. Collins and M. G. B. Drew Inorg. Nuclear Chem. Letters 1972 8 975. S.G. Carr and T. D. Smith J.C.S. Dalton 1972 1887. W. E. Smith J.C.S. Chem. Comm. 1972 1121. J. MacCordick C. Devin R. Perrot and R. Rohmer Compt. rend. 1972,274 C 278. E. K. Krzhizhanovskaya and A. V. Suvorov Russ. J . Inorg. Chem. 1971 16 1355, 1789 286 W. E. Smith and J. M. Winfield the y-y cascade of "'Ta fed by the /I decay of '"Hf. For the compounds where biX = N-benzo yl-N-phenylhydrox ylamine or N-nitroso-N-phenylhydroxylamine (cupferron) two "'Ta sites are observed in each case and it is suggested that isomeric configurations may be present. For biX = tropolone a rapid inter-conversion between isomeric forms is suggested and when CHCl is included in the lattice interaction between CHCl molecules and the ligand aromatic rings is proposed.66 The structural chemistry of Zr sulphates a field in which there has been recent activity has been reviewed,67 and further work relating to Zr molybdate gels, which are cation exchangers has been reported.68 Refluxing the gels in 1 4 M -HCl gives microcrystalline ZrMo,O,(OH),(H,O) whose X-ray structure comprises [Zr0,'9(OH),"q02"] pentagonal bipyramids and distorted cis-[MoO,(OH)(H,O)] octahedra.The units are cross-linked to give a three-dimensional network and one of the 0 atoms has the trigonal planar ZrOMo, co-ordination geometry. The crystalline form shows no ion exchange properties. 5 The Vanadium Group Vanadium.-Mass spectrometric studies have been reported on vanadium oxides and VOF3 .69 Species identified in the vapour over V,OS at 1000-1200 K include V,Ol0 and V,08 whereas VO, VO and V were found over V,O at 2270K.69" Following the detection of polymeric species in MF vapours (see last year's report) it has now been found that a similar situation obtains for VOF .Dimeric species were identified in its vapour at ambient temperature^.^" V0,XC (X = F or C1) anions have been isolated for the first time. They were prepared as their Ph4M+ (M = P or As) salts and CZv symmetry is indicated from their i.r. spectra.70 Vanadium oxides are reduced by liquid Li to the metal. This reacts with nitrogen which is present in the molten Li to give various products, e.g. V3N VN or Li,VN4.7' Stereochemistry of V 0 3 + and V 0 2 + complexes has been the subject of several reports. X-Ray work7 on two V03+ peroxo-complexes has shown that the geometry about Vv in [VO(O2),NH3]- is a distorted pentagonal pyramid with the terminal 0 atom axial and in [VO(O,)(dipicolinate)(H,0)]- is distorted pentagonal bipyramidal with 0 and H20 ligands occupying axial positions.The geometry of the former anion is very similar to that in [CrO(O,)py]. The X-ray structures of two VIVO(biX),L species have been reported; in both cases L is 6 6 P. Boyer A. Tissier J. I. Vargas and P. Vulliet Chem. Phys. Letters 1972 14 601 ; P. Boyer A. Tissier and J. I. Vargas Inorg. Nuclear Chem. Letters 1972 8 813. 6 7 I. J. Bear and W. G. Mumme Rev. Pure Appl. Chem. (Austral.) 1971,21 189. '* A. Clearfield and R. H. Blessing J. Inorg. Nuclear Chem 1972 34 2643. 69 ( a ) M. Farber 0. M. Uy and R. D. Srivastava J . Chem. Phys. 1972 56 5312; (b) ' O E.Ahlborn E. Diemann and A. Muller J.C.S. Chem. Comm. 1972 378. " C. C. Addison M. G. Barker and J. Bentham J.C.S. Dalton 1972 1035. " R. E. Drew and F. W. B. Einstein Inorg. Chem. 1972 11 1079; Acta Cryst. 1972, A. J. Edwards and D. R. Lloyd J.C.S. Chem. Comm. 1972 719. A28 S86 The Transition Elements 287 cis to the terminal 0 atom with the biX ligands mutually cis.73 The first species,73a the [VO(OX),(H,O)]~ - anion was previously formulated as five-co-ordinate because there was no i.r. evidence for ligated H,O. Its structure is similar to the six-co-ordinate anion [V0,(0x),]~ - whose sttucture was reported last year. It has been shown previously from i.r. spectroscopic work that VO(acac),L (L = substituted pyridine) complexes may have cis or trans configurations depending on the nature of the pyridine substituent.The structure of the complex where L = 4-~henylpyridine,~~~ however indicates that previous assignments should be reversed. A number of compounds of the type VO(S,PX,) have been isolated and their spectroscopic and magnetic properties depend on the nature of X. When X = Me Ph or OEt monomeric square-pyramidal structures are indicated but for X = F or CF the compounds appear to contain V-0 V chains.74 The crystal structure of V(S,CMe) contains two types of VSB dodecahedron, corresponding to the classes I d and V of the Hoard and Silverton notation. The I d type (rnrnrnrn chelation) has been found previously for V(S,CPh) (reported last year) but the V type (rnrngg chelation) which is unfavourable energetically, has apparently not been observed before in an MSs 1.r.and molar polarization measurements suggest that V(dpm),X (X = C1 or Br) have a trans configuration in the solid state but that in solution they exist in equilibrium with the cis form. The concentration of the latter increases with increasing dielectric constant of the solvent. This contrasts with the Ti" analogues which are exclu-sively cis and it is suggested that for V" steric factors play a greater role in determining the structure owing to the smaller central atom. Reaction of V(biX),Cl (biX = acac or dpm) with FeCl or SbCl gives [V(biX),]+Y-(Y = FeC1 or SbC1,) which are apparently the first well-characterized cationic complexes of V1v.76 The X-ray structure of K,[V(CN),],2H20 shows it to contain isolated V(CN)74- anions with approximate D, symmetry.There is no significant difference between axial and equatorial V-C bonds (214.4 and 214.9pm, respectively) and these distances are longer than those of other 3d cyano-complexes. The anion is believed to be the first example for d block elements of an MX group where X is not F and the anion appears to persist in A very thorough study of the magnetic properties of V(urea),13 has been made which has included crystal structure determinations at room temperature and at ca. 90 K. The compound is isomorphous with the Ti"' analogue (reported in 1970) and the cation has D symmetry at both temperatures. A temperature-7 3 ( a ) G. E. Form E. s. Raper R. E. Oughtred and H. M. M. Shearer J.C.S. Chem. Comm.1972 945; (b) M. R. Caira J. M. Haigh and L. R. Nassimbeni Inorg. Nuclear Chem. Letters 1972 8 109; J. Znorg. Nuclear Chem. 1972 34 3171. 7 4 R. G. Cavell E. D. Day W. Byers and P. M. Watkins Znorg. Chem. 1972 11 1591. " L. Fanfani A. Nunzi P. F. Zanazzi and A. R. Zanzari Acta. Cryst. 1972 B28 1298. 7 6 R. B. VonDreele and R. C. Fay J. Amer. Chem. SOC. 1972,94,7935. 77 R. L. R. Towns and R. A. Levenson J . Amer. Chem. SOC. 1972,94,4345. 7 8 B. N. Figgis and L. G . B. Wadley J.C.S. Dalton 1972 2 182 288 W. E. Smith and J. M. Winfield dependent distortion along the three-fold axis exists there being a small elonga-tion at low temperature and a zero or slight compression at room temperature. Magnetic susceptibility and anisotropy data (80-300 K) are interpreted on the basis of a 3T1s ground state with 1 = 45cm-' A = 450crn-' and k = 0.5.78 A study of the electronic spectra of VX (X = C1 Br.or I) crystals at various temperatures has shown that while the general features expected for isolated V2+ ions are observed additional sharp fine structure and intense spin-forbidden bands are the result of antiferromagnetic exchange between V" centres." Niobium and Tantalum.-Combustion calorimetry of Nb and Ta penta-alkoxides suggests that average M-0 bond energies for these compounds are in the range 4 1 8 4 3 8 kJ mol- Rather surprisingly there is little difference between Nb and Ta.80 Exchange processes in these compounds have been studied using 'H n.m.r. spectroscopy.81 Scrambling among terminal RO-groups occurs faster than scrambling between terminal and bridging.The activation energy for the latter process is fairly constant (ca. 4 2 4 8 kJ mol- ') although for Ta derivatives the activation entropy depends on the size of R. Possibly steric factors are important.81' M(OMe) are weaker Lewis acids than the corresponding halides and M(OMe),L (L = N- or 0-donor ligand) are in equilibrium with [M(OMe),] in solution.81b MF,-,,(NEt,) (n = 1 or 2) which from their i.r. spectra are believed to be polymeric via F-bridges are formed from reactions of MF with Me,SiNEt . Analogous reactions with Me3SiC1 give chlorofluorides which were precipitated from solution as py complexes.82 The i.r. spectrum of matrix-isolated NbF has been assigned on the basis of C, symmetry,83 although from work on other pentahalides D3, symmetry might have been expected.Isomeric complexes of MCl with MeNCS have been reported which from their i.r. spectra appear to be N- or S-bonded isomers. They can be interconverted at their melting points. TaCl reacts with PhNCS to give a compound formulated as Cl,(S)Ta 9 N(Ph) = CCl .84 Further compounds in the series NbCl -,,Me, have been identified from reactions between NbCl and Me,Zn. NbC13Me was isolated pure and forms complexes NbCl,Me,L (L = 0- N- P- or S-donor ligand) in which the Me groups are trans. NbC1,Me was not obtained pure but its complexes were isolated. The decomposition pressure of NbBr, corresponding to the equilibrium (5 - x)NbBr,(s) NbBr,(s) + (4 - x)NbBr,(g) at a given temperature is much lower than that for NbCl, suggesting that the former compound is significantly '9 W.E. Smith J.C.S. Dalton 1972 1634. ** V. I. Telnoi I. B. Rabinovich B. I. Kozyrkin B. A. Salamatin and K. V. Kirianov, Doklady Akad. Nauk S.S.S.R. 1972 205 364. ( a ) C. E. Holloway J. Co-ordination Chem. 1971 1 253; (6) L. G. Hubert-Pfalzgraf, J. Guion and J. G. Riess Bull. SOC. chim. France 1971 3855. '' J. C. Fuggle D. W. A. Sharp and J . M. Winfield J.C.S. Dalton 1972 1766. 83 N. Acquista and S. Abramowitz J. Chem. Phys. 1972,56 5221. 8 4 H. Bohland and F.-M. Schneider Z . Chem. 1972 12 28 63. G. W. A. Fowles D. A. Rice and J. D. Wilkins J.C.S. Dalton 1972 231 3 The Transition Elements 289 more stable.86 E.p.r. signals due to NbOClS3- and NbOCl,(H20)2- have been observed from solutions of NbCl in conc.HCl. NbC16,- can be isolated from solution (for example as the Cs’ salt) but no signal for this species was observed. Reduction of NbV by Zn in HC1 or HC1,EtOH gives solutions containing [NbOC1,LI2- (L = H 2 0 or EtOH). Considerable electron delocalization into the equatorial C1 pn-orbitals is suggested for these specie^.^' The first simple complexes of Ta”’ have been prepared by MeCN reduction of TaCl . Diamagnetic [TaCl,(NCMe),] has been isolated for which structure (8) is proposed from its spectra and by analogy with [WCl,(py),] . From MeCN N c1 N dl solutions of this complex diamagnetic TaCl,(biL) (biL = bipy or phen) and paramagnetic Ta(dibenzoylmethanate) were isolated. 13 A number of papers concerning (M6X12)A+ clusters have appeared.89 The crystal structures of [(Nb6C1 2)c16]2 - and [(Nb,Br ,)C1,l2 - have been deter-mined.89a,b Nb-Nb (301.8-307.2 pm) and Nb-C1 (terminal) distances are longer and shorter than those in the (Nb6Cll 2)2’ analogue as expected.Similarly, an n.q.r. study of [(Nb6Cll,)C1,]2- is consistent with the availability of 1k for Nb-Nb bonding.*’‘ (pyH),[(M6Br,,)C1,] undergo an exothermic irreversible rearrangement at 473 K to give (pyH),[(M,Br,Cl,)Br,] in which six Br ligands in two trigonal cluster planes are exchanged by Cl.89a.d M.c.d. studies89e on (M,Xl,)”+ (n = 2,3 or 4) clusters have been used to revise previous assignments of their electronic spectra. A bonding scheme is proposed which includes the effects of spin-orbit coupling and which has a different ordering of orbitals than in the scheme due to Cotton and Haas.The green-brown cations [(Me6C6)3M3X6]+ (x = c1 or Br) are readily oxidized to dipositive cations a 6 A. D. Westland and D. Lal Canad. J. Chem. 1972,50 1604. 8 ’ 8 8 D. G . Blight R. L. Deutscher and D . L. Kepert J.C.S. Dalton 1972 87. 8 9 ( a ) B. Spreckelmeyer and H. G. von Schnering 2. anorg. Chem. 1971 386 27; (b) F. W. Koknat and R. E. McCarley Inorg. Chem. 1972 11 812; (c) P. A. Edwards, R. E. McCarley and D. R. Torgeson Inorg. Chem. 1972 11 1185 ; ( d ) B. Spreckel-meyer C. Brendel M. Dartmann and H. Schafer Z . anorg. Chem. 1971 386 15; ( e ) D. J. Robbins and A. J. Thomson J.C.S. Dalton 1972 2350; cf) R. B. King, D. M. Braitsch and P. N. Kapoor J.C.S. Chem. Comm. 1972 1072. D. P. Johnson and R. D. Bereman J . Inorg.Nuclear Chem. 1972 34 679 290 W. E. Smith and J. M. WinJield which are isolated as PF6- or BPh,- salts. They are diamagnetic therefore their simplest molecular formula is [(Me,&)6M6X 214+ and the cations could be regarded as C6Me derivatives of [(M6X’ 2)X26]”- ~lusters.*~f The superconducting intercalation complexes of TaS and pyridine derivatives that were reported last year are representative of a large class of intercalates involving MX (M = Ta Nb V Hf Zr or Ti; X = S or Se) and aliphatic or aromatic amines NH hydrazine and substituted hydrazines or Bu3P.” Superconductivity is observed when the parent dichalcogenide is superconducting. The critical temperatures depend on the intercalate but are insensitive to the separation of the superconducting planes up to 5700 pm.’Oa The X-ray photo-electron spectra of NbSe and TaS with amine intercalates suggest that electron transfer from N to the metallic layers occurs possibly to a band derived from metal d, orbitals.90b Other materials with superconductor properties that have been reported are Li,Ti,.,S (0.1 < x < 0.3) which has the hexagonal Ti,S, ~trucfure,’~~ and rhombohedra1 Mo6-,M,S6 (M = Cu Ag Zn Cd Mg Sn or Pb).’ l b The transition temperatures of these materials are generally higher than those found in layered sulphides.6 The Chromium Group Chromium.-From a study of electron attachment and compound formation in H,-O,-N flames values for the electron affinities of CrO and HCrO of 390 and 229 kJ mo1-l respectively have been deduced.’ A study of the reactions of molecular oxygen evolved from the aqueous decomposition of K,CrO suggests that at least some of it is in an excited singlet state.This is probably the first example of singlet 0 production from a transition metal oxygen-containing ~ornplex.’~ Reduction of CrO,’- in the presence of perfluoropinacol leads to the formation of [CrVO{ (CF,),C(O)C(O)-(CF,),),I- which can be isolated as Cs’ K’ or Et,N’ salts. The compounds are remarkably stable to reduction and to hydrolysis and it is suggested that the bidentate ligand may stabilize other unusual oxidation states.’, The most widely studied Cr” species is probably CrO,,-. This year further salts of this anion KSrCrO and KBaCrO, have been reported. Their structures are derived from P-K,SO and the corresponding MnV salts are is~structural.~~ The electronic spectra of CrV and MnV doped in various phosphate and vanadate hosts have been interpreted in terms of the effects of the anion site size and possible 90 (a) F.R. Gamble J. H. Osiecki M. Cais R. Pisharody F. J. DiSalvo and T. H. Geballe Science 1971 174 493; H. Fernhndez-Morhn M. Ohstuki A. Hibino and C. Hough ibid. p. 498; ( 6 ) B. Bach and J. M. Thomas J.C.S. Chem. Comm. 1972, 301 ; (c) R. Schollhorn R. Ruthardt and A. Weiss 2. Nuturforsch. 1972 27b 1273, 1275 1277 1278. 9 1 (a) H. E. Barz A. S. Cooper E. Corenzwit M. Marezio B. T. Matthias and P. H. Schmidt Science 1972 175 884; (b) B. T. Matthias M. Marezio E. Corenzwit, A. S. Cooper and H. E. Barz ibid. p. 1465. 9 2 W. J. Miller J. Chem. Phys. 1972 57 2354.93 J. W. Peters J. N. Pitts jun. I. Rosenthal and H. Fuhr J. Amer. Chem. SOC. 1972, 94 C. J. Willis J.C.S. Chem. Comm. 1972 944. 9 5 R. Olazcuaga J.-M. Reau and G . LeFlem Compt. rend. 1972,275 C 135. 94 4348 The Transition Elements 29 1 Jahn-Teller distortion of CrV.' Further examples of CrIV stabilized as fluoro-complexes are Li,CrF (NazSnF6 structure) and A'tkF (A = Ba or Sr BaSiF, structure ; A = Mg Ca or Cd LiSbF structure ; A = Ni or Zn VF3 ~tructure).'~ Many papers dealing with Cr"' complexes have been concerned with the study of reactions and equilibria in solution. Some papers are dealt with in the Reaction Mechanisms Report.* Another interest has been the spectra and magnetic properties of exchange-coupled Cr"' species.98 The [Cr@(OAC),(H,0)3]+ cation is a particularly suitable model to study such effects.Transitions observed in the 690-750 nm region of its polarized electronic spectrum have been identified as originating from different ground-state spin levels and a highly structured band system between 330 and 365nm is assigned to double excitation of low-energy doublet states.980 The magnetic susceptibility of [(NH,),CrOCr(NH,),]-X,,H20 in which the Cr-0-Cr group is linear (see last year's report) has been redetermined because previous work had been performed using samples con-taminated with [(NH,),Cr(OH)Cr(NH3),(OH)]X,. The paramagnetic suscepti-bility in the range 50-300 K has now been fitted to an isotropic exchange model with S = 3 and J = 450cm-1.98b X-Ray work on [Cr(glycinate),OH] has shown the presence of a planar Cr(OH),Cr unit with LCr-0-Cr = 98.2'.Low-temperature (4.2-100 K) magnetic susceptibility data are consistent with previous work at higher temperatures and with the postulate formulated for Cu"(OH),Cu" complexes that 2J decreases with increasing M-0-M angle.g 8c The X-ray structures of two Cr" complexes with N(SiMe,) ligands provide further examples of unusual stereochemistries that can be produced by this ligand." [Cr{ N(SiMe,),),(THF),] prepared from CrC1 and LiN(SiMe,) in THF has a trans square-planar structure. The bond distances suggest that little or no N+ Cr x-bonding is present although the CrNSi and CrOC units are planar. The pseudo-tetrahedral C3" structure suggested previously (see 1970 report) for [Cr(NO) { N(SiMe,),),] has been confirmed.In this compound the CrNSi units are planar; the bond distances suggest considerable N - + Cr It-bonding and that NO is a It-acceptor. The structure of antiferromagnetic CsCrC1 features face-sharing [Cl*CrCl+], chains in which there is a small Jahn-Teller distortion from trigonal symmetry. The single-crystal polarized electronic spectra of CsCrC1 and of Cr" doped in CsMgCl contain spin forbidden bands whose intensities depend on the Cr" concentration and a band strongly polarized along the hexagonal crystal c axis 9 6 J. B. Milstein J. Ackerman S. L. Holt and B. R. McGarvey Inorg. Chem. 1972 11, 9 7 G. Siebert and R. Hoppe 2. anorg. Chem. 1972,391 113 126. 98 (a) L. Dubicki and P. Day Inorg. Chem. 1972 11 1868; (6) E. Pedersen Acra Chem. Scand. 1972 26 333.(c) D. J. Hodgson J. T. Veal W. E. Hatfield D. Y. Jeter and J. C. Hempel J . Co-ordinarion Chem. 1972,2 1 . 99 D. C. Bradley M. B. Hursthouse C. W. Newing and A. J. Welch J.C.S. Chem. Comm. 1972 567. 1178. 'Inorganic Reaction Mechanisms' ed. J. Burgess (Specialist Periodical Reports) The Chemical Society London Vol. 2 1972 and Chapter 1 1 of this volume 292 W. E. Smith and J. M . Winjield at ca. 2A. Both features are attributed to magnetic coupling between Cr" centres.' O0 Molybdenum and Tungsten.-Interest in eight-co-ordinate compounds and com-plexes formed by the tetrahalides of these elements continues and further consolidating work has appeared this year. Oxidation oftetrakis 5,7-disubstituted-8-quinolinolato (biX) compounds of W" (see last year's report) by Cl, Br, or HClO at room temperature or by HbiX above room temperature produces violet paramagnetic [W(biX),]Y (Y = C1 Br CIO, or biX)."' The compounds disproportionate in aqueous or alcoholic base to give W(biX) and Wvl but they are more stable than the analogous Nb" compounds.Their e.p.r. spectra imply distorted dodecahedra1 structures similar to the W" compounds. The reactions of Ag,M(CN) with alkyl iodides have been re-investigated independently by two groups.'02 Compounds of the type [M(CN),(CNR),] (R = Me Et Pr" Pr', But C,H Ph,CH or Ph,C) which are diamagnetic non-electrolytes are obtained. The X-ray structure of [Mo(CN),(CNMe),] shows an MoC triangular dodecahedron with CN groups (Mo-C, = 217.7 pm) at the n-donor positions and CNMe groups (Mo-C, = 214.8 pm) at the n-acceptor positions.'02"*b The vibrational spectra of the other products suggest that they have similar struc-fures.lozc An additional product formed from the reaction of Ag,Mo(CN) with Bu'I is the Mo" compound red-orange [Mo(CNBu'),I]I in which Mo has monocapped trigonal prismatic geometry with I above one of the square faces (9).Bond distances are Mo-I 286.2; Mo-C, (trans to I) 206; Mo-CC, (cis to I) 212 pm.lo2' 0 = MO (9) 0 =Br l o o G. L. McPherson T. J. Kistenmacher J. B. Folkers and G. D. Stucky J . Chem. Phys. 1972 57 3771. l o ' R. D. Archer W. D. Bonds jun. and R. A. Pribush Inorg. Chem. 1972,11 1550. I o 2 ( a ) M. Novotny D. F. Lewis and S. J. Lippard J . Amer. Chem. Soc. 1972,94 6961 ; (b) F. H. Can0 and D. W. J.Cruickshank Chem. Comm. 1971,1617; (c) R. V. Parish and P. G. Simms J.C.S. Dalton 1972 2389; ( d ) D. F. Lewis and S. J. Lippard Inorg. Chem. 1972 11 621 The Transition Elements 293 Another example of seven co-ordination in Mo chemistry is provided by X-ray work on [MoBr,(PMe,Ph),] (10) which is a mono-capped octahedron of ClV ~ymrnetry."~" Three Br ligands (Mo-Br = 256.0pm) occupy the uncapped face three P atoms (Mo-P = 258.0pm) the capped face and the fourth Br (Mo-Br = 242.5 pm) the capping position. Apparently the co-ordination geometry found in these complexes is determined by the steric requirements of the ligands. Seven co-ordination is suggested for WCl,(NMe,), which dissociates in solution to give [WC13(NMe3),]+ and Cl-,'03b and for WCl,(PMe,Ph),-(NCMe).lo3' They provide further examples of the ease with which an additional ligand may be added to MX,L complexes.MX,(NCMe)2 are widely used to prepare other complexes by ligand exchange under mild conditions but with more vigorous conditions reduction can occur. For example WC1,(NMe3) can be formed from WCl,(NCMe) and NMe (see also tantalum section). It has a low magnetic moment and a polymeric structure is indicated.'03b WCl,L (L = PR, or AsR,) may be prepared directly from WCl, by Zn-Hg reduction in CH,Cl, or THF in the presence of L (two moles). A related procedure is used for mer-Other complexes containing MI" include Mo(biX),X (biX = acac oxine or N-substituted salicylaldimines ; X = C1 or Br) prepared from MoCl,(NCMe), or MoX,(py) polymeric [MoC14(4,4-bipy)] for which a cis-MoC1,N2 configuration is suggested,' 03e and W(NCS),(py) and [M(NCS),bipy] which like A,[M(NCS),] and A[W(NCS),] have N-bonded isothiocyanate groups.lo4 K,WCI or a solution of WCl reduced by RLi in THF are good reagents for olefin synthesis for example via a cis deoxygenation of vicinal diols.The reason is believed to be the ready formation of Wvl-O bonds in these systems.'05 Mo,(02CCF,) which is prepared from Mo,(OAc) and a CF3C02H-(CF,CO),O mixture has the expected dimeric D, structure. The Mo-Mo (209.0pm) and C-0 distances are not significantly different from those in the acetate. The Mo-Mo distance in [pyMo(O,CCF,),Mopy] is 212.9 pm and LMo-Mo-N = 171.0 '. Corresponding v(Mo-Mo) frequencies in the Raman spectra of the solid compounds are 397 (trifluoroacetate) and 367 cm-(bis py adduct) compared with 406cm-' in the acetate.Formation of M0,-(02CCF3),L2 in donor solvents (L) is implied as both v(Mo-Mo) and the energy of the lowest electronic transition decrease with increasing donor ability of the solvent.'06 Rather surprisingly carboxylates of Wn have proved to be difficult to prepare. Dimeric compounds analogous to the Mo" series have not been [WOCl,L,]. Io3' l o 3 ( a ) M. G . B. Drew J. D. Wilkins and A. P. Wolters J.C.S. Chem. Comm. 1972 1278; (6) D. G . Blight D. L. Kepert R. Mandyczewsky and K. R. Trigwell J.C.S. Dalton, 1972 313; ( c ) A. V. Butcher J . Chatt G. J. Leigh and P. L. Richards ibid. p. 1064; ( d ) A. van den Bergen K. S. Murray and B. 0. West Austral. J . Chem. 1972,25,705; ( e ) W.M. Carmichael and D. A. Edwards J . Znorg. Nuclear Chem. 1972 34 1181. l o 4 T. M. Brown and C. J. Horn Inorg. Nuclear Chem. Letters 1972 8 377; C. J. Horn and T. M. Brown Znorg. Chem. 1972 11 1970. K. B. Sharpless and T. C. Flood J.C.S. Chem. Comm. 1972 370; K. B. Sharpless, M. A. Umbreit M. T. Nieh and T. C. Flood J . Amer. Chem. SOC. 1972 94 6538. l o 6 F. A. Cotton and J. G. Norman jun. J . Co-ordinarion Chem. 1971 1 161 ; J . Amer. Chem. SOC. 1972,94 5697 294 W. E. Smith and J. M. Winjield isolated and the products appear to be polymeric [W(O,CR),] or impure [W3(02CMe)90].'07 The chemistry of Mo W and Re with dinitrogen and related ligands continues to expand trans-[M(N,),(diphos),] (M = Mo or W) being useful intermediates!" Reactions of RC(0)Cl with trans-[W(N,),(diphos),] give [Cl,(diphos),-W=N-NH-C(O)R] from which HCl can be reversibly removed to give chelated [Cl(diphos),W(N,COR)].The chelate ring appears to have structure (1 la) rather than (1 lb) which has been suggested for related Re compounds (see 1971 report). [MX,(diphos),(N,H,)] (X = C1 or Br) and [WCl(N,H,)(diphos),]Y (Y = BPh or C10,) are formed from trans-[M(N,),(diphos),] and HX and are regarded as models for part of the N fixation process. Diamagneticorganoimido-complexes of Mo [(12) is regarded as one of the four possible canonical forms] are formed from [MoOCl,(PMe,Ph),] and 1 -aryl-2-benzoylhydrazines. O9 PMe,Ph I Molybdenum and Tungsten 0x0-compounds and Related Topics.-It is possible to include only a small fraction of the work that has appeared in this field.The isomorphous series of heteropolyanions [(H20)M1(*+)0,M2("+)0,(W or Mo) 03J(' - are valuable hosts to study magnetic effects between two isolated centres (MI M2 = Fe3+ Co2+ or Co3+). M'('"+)'occupies a distorted octahedral site M2("+) a tetrahedral site and the two ions are 0x0-bridged with /'-O-M2 ca. 125 O and M1-M2 cu. 330 pm. When S' # S2 the low-temperature susceptibilities follow a Curie law characteristic of IS' - S2( and l o ' F. A. Cotton and M. Jeremic Synrh. Inorg. Metal-org. Chem. 1971 1,265; G . Holste lo' J. Chatt G. A. Heath and G. J. Leigh J.C.S. Chem. Comm. 1972 444; J. Chatt, and H. Schafer Z . anorg. Chem. 1972 391 263. G. A. Heath and R. L. Richards ibid. p. 1010. J. Chatt and J. R. Dilworth J.C.S. Chem.Comm. 1972 549 The Transition Elements 295 the individual g values at high temperatures the susceptibilities tend towards another Curie law characteristic of the sum of the susceptibilities of the uncoupled ions whereas at intermediate temperatures little change in the susceptibilities is observed.' ' Crystal structures of simple 0x0-complexes reported include that of [Mo~O,(O-C,H,O~)~]~ -. Two cis-MoO,(biX) groups are linked uia an oxo-bridge a very distorted octahedral co-ordination about Mo being completed by two additional bridges involving an 0 atom from each o-C6H402 ligand to give an [O,MoO,MoO3] arrangement.' ' 1,2-Dimethoxyethane undergoes an oxygen abstraction reaction with WSC1 to give a dinuclear product (13) with an unsymmetrical bridge (W-0 = 172 and 226pm).The compound may be regarded as a donor-acceptor complex between(biL)Cl,(S)WO and WSCl . ' I 2 Crystal structures of several Mov'-peroxo-complexes have been determined ' ' including [MOO(O~)~(OP(NM~,),)L] (L = H 2 0 or py) which are pentagonal bipyramids with axial 0 and L groups. The compounds have been used to per-form an elegant oxidation of secondary amides R'C0.N(R2)SiMe, to hydrox-amic acids. ' ' 3b [R'C(b).N(R2)0],koO2 complexes are formed initially from which the free acids are readily liberated. A study by 19F n.m.r. spectroscopy of the reactions of WOF,- or MoOF,-(NCMe) with EtOH in MeCN suggests that F ligands cis to the M=O group are preferentially replaced by OEt ligands. Ligands trans to M=O might have been expected to be more labile and (pd)n-bonding is offered as an explanation of the observed 'cis' effect.' ' A thermodynamic and kinetic study of the reaction of 8-quinolinol with MoO,(dien) (dien = diethylenetriamine) yielded results identical with previous work with Although the complex is well characterized 1 LO 1 1 1 1 1 2 1 1 3 114 L.C. W. Baker V. S. Baker S. H. Wasfi G. A. Candela and A. H. Kahn J. Amer. Chem. SOC. 1972 94 5499. L. 0. Atovmian V. V. Tkachev and T. G. Shishova Doklady Akad. Nuuk S.S.S.R., 1972 205 609. D. Britnell M. G. B. Drew G. W. A. Fowles and D. A. Rice J.C.S. Chem. Comm., 1972 462. (a) J.-M. LeCarpentier R. Schlupp A. Mitschler and R. Weiss Acra Crysr. 1972, B28 1278 1288; (6) S . A. Matlin and P. G. Sammes J.C.S. Chem. Comm. 1972 1222. Yu. A.Buslaev Yu. V. Kokunov V. A. Bochkaryova and E. M. Shustorovich, J . Inorg. Nuclear Chem. 1972 34 2861 296 W. E. Smith and J. M . Winfield in the solid state it rapidly hydrolyses in aqueous solution giving Moo,'- and dienH + . The W analogue behaves similarly.' Several other papers have dealt with oxine and related ligands.'I6 Four distinct compounds of composition [MoO(oxine),],O have been reported from reactions of Mo"' with Hoxine under various conditions. It is suggested that the isomerism is due to differing configurations of the terminal 0 ligands.'16" 1 1 Complexes between MoV and oxine its mercapto- or amino-analogues or 3,4-dimercaptotoluene in DMF have been identified by e.p.r. spectroscopy. The expected order of ligand binding strength - S - > -0- > -NH2 is found and in the thiol complexes there is considerable electron delocalization.116b Information about electron transfer processes in Mo-oxine complexes has been obtained from an electrochemical study in DMSO. Reduction of MoVIO,-(oxine) occurs in two one-electron steps with solvent attack on the intermediates displacing oxine. The Mo" species formed catalytically reduces any excess oxine present. Mov,O,(oxine) is reduced in two reversible one-electron steps giving Mo~-Mo'~ and then Mo'; dimers. The latter intermediate decomposes to give a Mo" species identical with that produced from MoV1. Oxidation of Mov203(oxine) is an irreversible one-electron process producing a MoV1-MoV dimer which decomposes and is further oxidized to MovlO,(oxine) .' A series of dinuclear Mo"' complexes with bipy or acac ligands has been pre-pared from Mo,O,Cl,(H,O) .Their spectroscopic and magnetic properties indicate that Mo0,Mo groups are present. From similar evidence Mo,03(ox),-(H,O), is thought to contain Mo(OH)(O)Mo groups linked by bridging ox ligands. These is no evidence for terminal 0 ligands the presence of which had been suggested previo~sly."~ A compound of composition Mo(S2CNPrn) is produced from Mo" acetate and NH,S2CNPr" but its X-ray structure indicates that C-S bond cleavage has occurred to give a compound which contains Mo" (14) with a carbene type linkage (C-Mo = 206.6pm). The Mo-Mo distance (270.7 pm) and LMo-Sbridge-Mo (72.3 ") indicate direct interaction."' Much 'Is R. S. Taylor P. Gans P. F. Knowles and A.G. Sykes J.C.S. Dalton 1972 24. ( a ) W. Andruchow jun. and R. D. Archer J . Inorg. Nuclear Chem. 1972 34 3185; (6) G. R. Lee and J. T. Spence Inorg. Chem. 1972,11,2354; ( c ) A. F. Isbell,jun. and D. T. Sawyer ibid. 1971 10 2449. L. Ricard J. Estienne and R. Weiss J.C.S. Chem. Comm. 1972 906. '17 P. C. H. Mitchell and R. D. Scarle J.C.S. Dalton 1972 1809. ' I The Transition Elements 297 of the foregoing work has been undertaken with the expressed aim of investigating model systems for Mo-containing enzymes which have again been reviewed. '' Although none of the models can be considered to be definitive they have gener-ated much interesting co-ordination chemistry. 7 The Manganese Group Manganese.-The general chemistry of manganese in its oxidation states above two and the properties of manganese porphyrin complexes have been reviewed.'20 Manganate-(vI) and -(v) have attracted some interest this year.y-Irradiation of KMnO at 77 K produces an e.p.r. active species [MnV'0,2- . - MnV"On7 - 2 n ] in which there is interaction between Mn042- and a neighbouring species (MnO,- or MnO,'). On warming to room temperature a second species, probably 03- is formed.lZ Manganate-(vr) and -(v) may be observed in molten alkali metal nitrates nitrites or hydroxides. Whether MnV' or MnV species are stabilized depends on the identity of the alkali metal cation(s) and on the con-centration of other anions added to the melt.'22 For example in K,Na nitrate melts Mn0,2- is stabilized in the presence of OH- whereas MnO,,- is stabilized in the presence of 022- or 02- anions.'22u The MnV',MnV system is thus a convenient probe for comparing melt properties.Attempts to grow single crystals of [Mn(bipy),](ClO,) led instead to the isolation of [(bipy)2Mn(0)2Mn(bipy)2] (ClO,),. X-Ray work indicated that this is a Mn"' Mn" compound with the expected Jahn-Teller distortion for Mn"' producing a lengthening of the Mn-"(axial) relative to the Mn-N(equatoria1) bonds. The compound is antiferromagnetic and a superexchange mechanism is suggested.' 2 3 The chemistry of anhydrous metal nitrates has been extended by the preparation from N205 and MnF of a thermally unstable Mn"' derivative, which is believed to be high-spin. Adduct formation occurs with N205 {formu-lated as [NO,+][Mn(NO,),-]} and also with bipy phen MeCN or Ph,PO.The X-ray structure of Mn(N03) bipy shows the presence of seven-co-ordinate (approximately pentagonal bipyramidal) Mn"'. Axial positions are occupied by N (bipy) and a unidentate NO group equatorial positions by symmetrically and unsymmetrically co-ordinated bidentate NO ligands and the remaining N. ' 24 The M(S2C-) units in tris-NN-dialkyldithiocarbamato complexes usually have D symmetry but X-ray work has shown that this is not the case for Mn(S2CNEt2) The structure may be understood in terms of a tetragonal 120 W. Levason and C. A. McAuliffe Co-ordination Chem. Rev. 1972,7,353; L. J. Boucher, 12' S. Subramanian and M. T. Rogers J . Chem. Phys. 1972 57 2192. 1 2 2 ( a ) B. J. Brough D. A. Habboush and D. H. Kerridge Inorg. Chim. A m 1972,6,366; ( b ) R .B. Temple and G. W. Thickett Austral. J . Chem. 1972 25 6 5 5 ; ( c ) H. Lux and E. Renauer Z . anorg. Chem. 1972 390 303. P. M. Plaksin R. C. Stoufer M. Mathew and G . J. Palenik J . Amer. Chem. SOC., 1972 94 2121. D. W. Johnson and D. Sutton Canud. J . Chem. 1972 50 3326; F. W. B. Einstein, D. W. Johnson and D. Sutton ibid. p. 3332. 12' ( a ) P. C. Healy and A. H. White J.C.S. Dalton 1972 1883; ( 6 ) R. M. Golding E. Sinn, and W. C. Tennant J . Chem. Phys. 1972,56,5296. R. C. Bray and J . C. Swann Structure and Bonding 1972 11 107. ibid. p. 289 298 W. E. Smith and J. M . Winfield distortion superimposed on D symmetry arising from Jahn-Teller distortion of the 5E,(0,) ground state. This contrasts with previous work on Mn(acac) in which no distortion was found and a dynamic Jahn-Teller effect postulated.Interestingly the e.p.r. spectra of Mn(S,CR,) doped in their Co"' analogues contain no signals which can be obviously attributed to the Mn"' centres. The observed spectra are tentatively suggested to arise from electron delocalization to or near the ligand S atoms.'25b Mn" complexes continue to be widely studied. Mn(SP(Ph),NP(Ph),S) has been examined as a possible model for biologically important d5MS4 complexes, e.g. iron(1rr) rubredoxin. An approximately tetrahedral MnS core (Mn-S = 242.7-245.5pm) is evident from its X-ray structure and peff = 5.75 BM is consistent with an ,A ground state. Its electronic absorption spectrum is very similar to that of Mn2+ doped in ZnS but its emission spectrum shows a pro-nounced red shift.This contrasts with Mn2+ZnS and some flexibility of the s, environment in the complex is suggested.12 Other work includes a single-crystal e.p.r. study of [Mn(O(Me,N)2POP(NMe,)~O) ,] (ClO,) where a highly 'ionic' metal-ligand interaction is indicated,' 27 and an examination of the reduction of Mn(acac) by primary amines.'28 Normally [Mn(acac),(L or en)] (L = RNH,) are obtained but when L = CH,:CHCH,NH the product is [Mn(acac),L] a centrosymmetric dimer with octahedral Mn0,N co-ordination. The structure is analogous to [Co(acac),L] (L = H,O or cyclohexylamine). Technetium and Rhenium.-This year as last halogen compounds of these elements have proved a fruitful field of study. The reaction of Tc metal with C1, at 573 K has been re-investigated with the results that Tc0,Cl and TcOCl were isolated.TcC1 which with Tc03C1 has been reported previously from this reaction was not isolated and alternative routes to this compound would seem to be desirable. A good route to Tc0,Cl is from TcCl and O2 at 723 K and its vibrational spectrum is similar to Re0,Cl and Tcz07 suggesting a similar molec-ular s t r ~ c t u r e . ' ~ ~ The crystal structure of ReOCl shows that two types of square-pyramidal ReOCl molecules (both having Re-0 = 163 Re-Cl = 226 pm) are present.I3' They are weakly associated via Re - - - Cl contacts (355 and 365 pm) trans to Re-0 into dimers or endless chains. The absence of M-0 - - - M contacts contrasts with the structure of WOCl, but the dimeric units are similar to those found in WSX (X = C1 or Br).The formation of ReOC1,L complexes is now well e~tab1ished.l~~ X-Ray work (on ReOC1,. 0. Siiman M. Wrighton and H. B. Gray J . Co-ordination Chem. 1972 2 159. 12' G. M. Woltermann and J. R. Wasson Chem. Phys. Letters 1972 16 92. ''' Y . Nishikawa Y. Nakamura and S. Kawaguchi Bull. Chem. SOC. Japan 1972 45, 155; S. Koda S. Ooi H. Kuroya Y. Nishikawa Y. Nakamura and S. Kawaguchi, Inorg. Nuclear Chem. Letters 1972 8 89. l Z 9 A. Guest and C. J. L. Lock Canad. J . Chem. 1972,50 1807; A. Guest H. E. Howard-Lock and C. J. L. Lock J. Mol. Spectroscopy 1972,43 273. 130 A. J. Edwards J.C.S. Dalton 1972 582. ' 3 1 (a) P. W. Frais and C. J. L. Lock Canad. J . Chem. 1972,50,1811; (6) C . G. Barraclough and D. J. Kew Austral. J . Chem. 1972 25 27; ( c ) D.A. Edwards and R. T. Ward, J.C.S. Dalton 1972 89 The Transition Elements 299 (L = Et,O Me,CO or MeCN) indicates that co-ordination occurs trans to the 0 ligand although with NH ammono-lysis occurs to give [ReO(NH,),] which appears to be O-b~-idged.'~'' In non-co-ordinating solvents and in the vapour phase both ReOCl and OsOCl, appear to be monomeric. Square-pyramidal structures are favoured although the decision is not A re-investigation of the properties of A,ReOCl (A = Rb or Cs) indicates that they contain spin-paired ReV. The products previously reported in the literature appear to have been contaminated with ReC1,'- or ReO4-.l3 The disproportionation of ReIV to Re"' and ReV occurs readily in air but from re-actions of p-ReCl under rigorously anhydrous and O,-free conditions ReIV complexes may be isolated e.g.cis-ReCl,L (L = MeCN or py) and truns-ReCl,(PPh,),. Even so the reactions are complex and reduction to Re"' occurs also.133 One of several papers describing the use of boron halides to effect halogen-exchange reactions describes the isolation of Re,Br6C1 from Re,Cl, and BBr . Redistribution reactions occur on sublimation or in a mass spectro-meter and X-ray work on one product suggests that it is Re,Br,Cl. These compounds contain the triangular Re group and replacement of C1 by Br occurs preferentially in the terminal positions.'34 The crystal structure of [Pt11(NH3)4]2[ReV203(CN)8] confirms the structure of the anion previously suggested from solution work (see 1970 report). The cyano-ligands are believed to be C-bonded and bond distances in the linear OReOReO skeleton are 191.5 (bridge) and 169.8 (terminal) pm.These may be compared with Re-0 = 178.1 pm in tran~-ReO,(CN),~- whose structure has been redetermined. '' Arylimido-complexes of Mo are described in the Mo section and related work on Re compounds has led to two interesting reactions. The well-known ReV-arylimido-compounds e.g.[ReCl,(NPh)(PPh,),] are conveniently prepared from reactions of phosphinimines RN=PPh (R = Ph or PhCO) with ReOCl,(PPh,),. The route is useful since [ReCl,(NC(O)Phf(PPh,),] cannot be prepared by other methods and this work further demonstrates the analogy between ReV=O and X = O . [OsOCl,(PPh,),] and ArC(O)N=PPh give [OsCl,(NAr)-(PPh,),] .Io9 trans-[ReCl,(NMe)(PPh,R),] (R = Ph Me or Et) are deprotonated by py to give [ReCl,(N=CH,)py(PPh,R),] from which the original compounds are regenerated with HCl.These appear to be the first examples of transition-metal complexes containing the - N=CHZ ligand although its C-substituted derivatives are well known. Similar reactions using NEt and excess PR give mer-[ReCl,(N=CH,)(PR,),] in which -N=CH2 is trans to the unique PR, ligand. Linear Re-N-C groups are suggested in these corn pound^.'^^ and spectroscopic 1 3 2 J. E. Fergusson and J. L. Love Austral. J . Chem. 1971 24 2689. 1 3 3 R. A. Walton Inorg. Chem. 1971 10 2534. 1 3 4 M. A. Bush P. M. Druce and M. F. Lappert J.C.S. Dalton 1972 500. 1 3 ' R. Shandles E. 0. Schlemper and R. K. Murmann Inorg. Chem. 1971 10 2785; 1 3 6 J. Chatt R. J.Dosser and G. J. Leigh J.C.S. Chem. Comm. 1972 1243. R. K. Murmann and E. 0. Schlemper ibid. p. 2352 300 W. E. Smith and J. M. Winfield 8 The Iron Group Iron.-A simple preparation of the ferrates Rb,FeO and Cs,FeO and an improved preparation of K,FeO and BaFeO have been reported. 3 7 The K Rb and Cs salts are isostructural with P-K,SO and the magnetic susceptibi-lities are field-independent and obey the Curie-Weiss law. The new fluorides FeSnF613* and MFeF,13' (M = Na K Rb or Cs) have been prepared. The hydrolysis of dilute Fe"' chloride solutions has produced a new structural form of B-Fe2O3 .I4' An attempt to prepare isocyanate complexes by treating K,Fe(CN) with oxonium salts in acetone led to the formation of new cyano-complexes.141 The reaction appears to be an acid-catalysed aldol addition of the acetone Fe(CN):- + 12Me,CO + 6R30+BF Fe(CNCMe,CH,COMe),(BF,), + 4BFT + 6R,O + 6ROH (R = Et or Pr) The reduction of p-0x0-bis[tetraphenylporphyriniron(~~~)] by Na-Hg in THF yields several products the first being a compound characterized by e.p.r., magnetic susceptibility and electronic spectra as the first Fe' porphyrin sodium-[phenylporphyriniron(~)].', The five-co-ordinate high-spin Fe"' substituted porphyrins known to have a distinct out-of-plane displacement of the Fe"' should on addition of a sixth ligand effecting the transition to the low-spin state, have no such displacement. Structural verification of this has long been delayed because suitable crystals of a six-co-ordinate low-spin Fe"' porphyrin were not available.The structure of such a compound bisimidazole [a,P,y,&tetraphenyl-porphyrinatoiron(~~~)] chloride has now confirmed this prediction. The structure of an iron@) analogue with piperidine in place of imidazole is also reported.143 Attempts to use cysteine as a model for the reactions of non-haeme iron proteins require the use of low temperatures and non-aqueous solvents to prevent rapid oxidation reactions but the corresponding penicillamine has two methyl groups in blocking positions which inhibit these reactions. The results of an investigation of the controlled oxidation of Fe" penicillamine complexes to Fe"' with H20, are reported. Vapour-pressure and gas-chromatograph studies of P-diketo-nates of Fe" indicate that in solution the tris chelates interact with the solvent only by van der Waals forces with no evidence of hydrogen bonding but the bis chelates have a specific solvent interaction presumably at the sites above and below the chelate ring.14' Dimeric dialkoxo-bridged Fe"' chelates of the form 1 3 ' R.J. Audette and J. W. Quail Znorg. Chem. 1972 11 1904. 1 3 * R. Hoppe V. Wilhelm and B. Muller Z . anorg. Chem. 1972 392 1. 1 3 9 G. Ellinger A. Funke P. Kleinert P. Roseman and W. Keilig 2. anorg. Chem., 140 H. Braun and K. J. Gallagher Nature 1972 240 13. l d l 14* 1 4 3 (a) D. M. Collins R. Countryman and J. L. Hoard J . Amer. Chem. SOC. 1972. 94, 144 L. G. Stadherr and R. B. Martin Inorg. Chem. 1972 11 92. 1972 393 193. M. Shaul and W. Beck Agnew Chem. Internat. Edn 1972 11 527. I. A. Cohen D.Ostfeld and B. Lichtenstein J . Amer. Chem. SOC. 1972 94 4523. 2066; (6) L. J. Radonovitch A. Bloom and J. L. Hoard ibid. 1972,94 2073. W. R. Wolf R. E. Sievers and G. H. Brown Znorg. Chem. 1972.11 1995 The Transition Elements 30 1 [biL,FeOR] (L = acac or dipivaloylmethane R = Me Et or Pr') have been prepared and characterized. They are weakly antiferromagnetic with similar electronic spectra to the monomers but with peaks at slightly higher energies. 146 A number of papers on tetrahedral FeX,- ions have appeared. The crystal structure of (MeNH,),FeBr gives the first structural evidence for the tetrahedral FeBr,- ion.',' The first single-crystal electonic spectra of RFeBr (R = EtPhH', NMe,' NHMe,+ NH,Me,+ NH,Me+) have been reported and assigned using a crystal-field calculation.The spin-orbit splittings are much smaller than for the isoelectronic ion MnBr,'- and these and other differences from the man-ganese spectra are explained in terms of a larger Jahn-Teller effect due to the higher charge on Fe111.'48 The luminescence of Et,NFeBr and a series of complexes with FeC1,- ions has been studied.I4' Although iron nitrosyl compounds were among the first nitroso-complexes to be discovered there has been little systematic study of them. A number of new complexes including Fe(S,CEt,),,XNO (X = Br I or NO,) were reported this year.'" In each case the unidentate ligands are in the cis conformation. The five-co-ordinate complex Fe(S,CNEt,),I has an Fe-I distance of 259 pm, demonstrating that the iodine is covalently bonded to the iron."' Much work on the crossover between high- and low-spin ground states of iron has appeared.The complexes FeLX (L = rneso-5,5,7,12,12,14-hexamethyl-1,4,8,1l-tetra-azacyclotetradecane) (X = NO- NO - NCS- or MeCN) provide the first examples of low-spin Fe" with predominantly aliphatic nitrogen co-ordination. If X = OAc- C1- Br- or I- the complex is high-spin demon-strating that the crossover is dependent on ligand field strength.', Work on a series of substituted tridithiocarbonate complexes indicates that the crossover is sensitive to electron withdrawal rather than steric effects.', The crystal struc-tures of two similar complexes one low-spin tris-( 1-pyrro1idinecarbodithioato)-iron(m) and the other high-spin tris-(N-methyl-N-pheny1dithiocarbamato)iron-(111) indicate that the geometry round the iron is similar but that there is a sig-nificant reduction in the Fe-S bond distance in the latter.ls4 The inadequacy of considering the ground-state crossover to be a simple ,T, to 6Al in Fe" has been demonstrated by Mossbauer studies.'55 The ground states which may be expected to occur including the areas of mixed spin states have been calculated for D systems plotting D against D4.lS6 A series of complexes giving examples 146 C.S. Wu G. R. Rossman H. B. Gray G. S. Hammond and H. J. Schugar Znorg. 14' G. D. Sproul and G. D. Stucky Znorg. Chem. 1972,11 1647. 148 149 C. D. Flint and P. Greenough J . Chem. Phys. 1972 56 5771. Chem. 1972 11 971. M. Vala P. Mongan and P. J. McCarthy J.C.S. Dalton 1972 1870. H.Buttner and R. D. Feltham Znorg. Chem. 1972 11 971. P. C. Healy A. H. White and B. F. Hoskins J.C.S. Dalton 1972 1369. R. R. Eley R. R. Myers and N. V. Duffy Inorg. Chem. 1972 11 1128. l S z J. C. Dabrowiak P. H. Merrell and D. H. Busch Inorg. Chem. 1972 11 1979. 5 4 P. C. Healy and A. H. White J.C.S. Dalton 1972 1163. l S 5 P. B. Merrithew and P. G. Rasmussen Znorg. Chem. 1972 11 325. E. Konig P. Giitlich and R. Link Chem. Phys. Letters 1972 15 302 302 W. E. Smith and J. M . Win3eld of both a 'T2 and 6 A equilibrium and mixed spin states has been reported.157 The nature of the ground state of the (bipy),Fe"' ion is again discussed and assigned for what appear cogent reasons to an E ground state.'58 Oxygen-bridged Fe"' dimers have been investigated by magnetic susceptibility, Mossbauer electronic and i.r.spectra. It is concluded that a ligand field model incorporating spin-spin interactions of pairs of high-spin Fe"' ions is superior to the Dunitz-Orgel MO model for these systems.'59 The origin of the colour in naturally occurring sapphires has been elucidated. Yellow sapphire contains chromophores consisting of Fe3 + ions and Fe3 +-O2 -Fe3 + pairs ; blue and green sapphires have bands due to Fe3+-02-Ti4+ and more complex Fe2+-02-Fe3+ species.'6o The nature of the defects in Fe -,O suggest a cluster with four vacant cation sites round the iron; increasing the iron content increases the size of the cluster.'6' Ruthenium and Osmium.-The new compound OsOF has been prepared in good yield by the reduction of OsOF on a hot tungsten filament.'62 The first osmium-oxygen complex,163 the first example of a stable nitroso metal por-phyrin rnesoporphyrin-IX dimethyl [esterato dinitrosyl ruthenium (II)],' 64 and [OsH,en,]ZnCl the first osmium hydride with only saturated nitrogen co-ordination' 6 5 have been prepared.The nitrogen-bridged dimer [Cl(NH3),-OS'~NNOS'~(NH,),]~+ is easily oxidized to the mixed valence dimer [H20(NH3),-Os"NNOs"'(NH,),] which is kinetically quite stable and has a complex electronic spectrum at quite low energies owing to exchange coupling between the metals.'66 The crystal structure of [Os(NH3),N2]C12 is similar to the corresponding ruthenium derivative but it has been more accurately defined. Only a small change in the bond length of the co-ordinated nitrogen compared with gaseous nitrogen is noted but there is a large change in i.r.stretching frequency. The nitrogen is both 6- and n-b~nded.'~' The reaction of [Ru(NH~)~],+ in base with nitric oxide appears to proceed through the attack of the nitric oxide on the ruthenium to yield the nitrogen complex [Ru(NH3),N2]+. There is a rapid reaction a quantitative yield and the method does not need an external reducing agent.'68 Studies of the heat of reaction of [Ru(NH,),H~O]~+ and [Ru(NH3),-H20I2+ with o-donors and n-acceptors shows that the Ru"' bonds more strongly 1 5 7 A. J. Cunningham J. E. Ferguson H. K. J. Powell E. Sinn and H. Wong J.C.S. ' 5 8 R. E. De Simone and R. S. Drago Inorg. Chem. 1972 11 668. 1 5 9 H. J. Schugar G. R. Rossman C. G. Barraclough and H. B.Gray J. Amer. Chem. 160 J. Ferguson and P. E. Fielding Austral. J . Chem. 1972 25 1371. 1 6 1 1 6 * W. E. Falconer R. D. Burbank G. R. Jones W. A. Sunder and M. J. Vasile J.C.S. Dalton 1972 2155. SOC. 1972 94 2683. N. N. Greenwood and A. T. Howe J.C.S.Dalron 1972 110 116 122. Chem. Comm. 1972 1080. B. E. Cavert K. R. Grundy and W. R. Rohr J.C.S. Chem. Comm. 1972 60. 164 T. S. Srivastava L. Hoffman and M. Tsutsui J. Amer. Chem. SOC. 1972,94 1385. J. Maln and H. Taube Inorg. Chem. 1972 11 2403. 1 6 6 R. H. Magneson and H. Taube J. Amer. Chem. SOC. 1972 94 7213. J. E. Fergusson T. L. Love and W. T. Robinson Inorg. Chem. 1972 11 1662. 16' S. Pel1 and J. N. Armor J. Amer. Chem. SOC. 1972 94 686 The Transition Elements 303 to a-donors Ru" to rr-acceptors. The replacement of one NH group by H,O in [(RU(NH,),),N,]~+ decreases the heat ofbinding of the N by 6 kcal mol-1.169 Dinitrogen bridging between ruthenium and boron is demonstrated in a series of complexes ((Ph3P)3Ru(H2)N,),B,oH8.The yellow crystalline solids are either stable in air or oxidize slowly and the nitrogen triple bond is retained in the complexes even on treatment with NaBH, HCl KCN or MeCN."' The reaction [RuClNO(diars)]Cl + 2N,- -* [RuN,Cl(diars),] + N + N,O has been followed by isotopic labelling studies. An intermediate ring structure of the form is postulated. The azide complex is thermally stable and can be converted into the nitrogen complex by treatment with HC1-MeOH a reaction known for Ru"' but not previously for Ru".'~' The crystal structure of two similar phosphorus bridged ruthenium complexes gives examples of both bent and linear Ru-N-0 bonds.0 0 1 \ N / c1 \ / N / / RU -c1 c1 c1 Ru- Ru 'p' 'N \ 0 (15) 0 9 N P L \ / \ / Ru=Ru / \ / \ L P N \ 0 The Ru-N-0 bond angle in (15) is 16V but it is clear that rr-bonding does occur in the complex. 72 Significantly more metal-metal bonding occurs in (16) than in (15) as measured by the Ru-Ru distance. In (NH,),[RuNOCl,] the Ru-N-0 bond is again bent. l7 The series of compounds [Ru(NH,),(NO)L]X, (L = C1- Br- NCO- N3- OH- NH, or MeCO-; X = C1- Br- I - or 169 G. D. Watt J . Amer. Chem. SOC. 1972 94 7351. 170 W. H. Knoth J . Amer. Chem. SOC. 1972 94 104. "' P. G. Douglas and R. G. Feltham J . Amer. Chem. SOC. 1972,94 5254.1 7 ' R. Eisenberg A. P. Gaughan C. G. Pierpoint J. Reed and A. J. Schultz J . Amer. 1 7 3 J. T. Veal and D. J. Hodson Znorg. Chem. 1972 11 1420. Chem. SOC. 1972 94 6240 304 W. E. Smith and J. M. Winjield ClO,-) has been investigated by m.c.d. electronic absorption and i.r. spectra. The possibility of Ru"'N0 is ruled out the species are Ru"NO+.' 74 The X-ray photoelectron spectra of a series of complexes of Os Rh Ir and Pt are reported and caution in the interpretation of this type of result counselled. Only results from very similar molecules can reasonably be compared.' 75 The diffuse reflectance spectra at 4.2 K of OsF,- and IrF6- are reported and inter-preted.' 7 6 Charge delocalization on [Ru"(NH,),L]~+ ions by spectral and n.m.r. techniques has been studied.' 7 7 9 The Cobalt Group Cobalt-A new series of fluorides MCo"'F (M = Cs Rb Na or Li) has been reported. The Cs salt fluorinates benzene directly to give C6F as the product.' 7 8 Cs2CoF6 and the new compound Rb2CoF are ferromagnetic. ' 79 Ba2[Co,(CN),,],13H20 is the first air-stable crystal reported which contains the CO,(CN),~~- group. X-Ray studies of the compound have revealed that the structure is similar to Mn2(CO),,. The axial Co-CN bond is longer than the equatorial one in contrast to the manganese case and the infrared assignments are consequently altered.' 8o The novel CO,C~,~ - ion with the cobalt in approxi-mately tetrahedral geometry and bridged by two halides is reported.18' The species Co(N,) has been isolated and its i.r. spectrum obtained by matrix-isolation techniques.' 82 The reduction of a vitamin B12 analogue lY19-diethoxy-carbonyltetradehydrocorrincobalt(n) gives two products.A one-electron re-duction gives a very stable Co' species and a two-electron reduction gives a Co" species with two extra electrons on the ring so that the unusual pattern of oxida-tion states of the cobalt + I1 --* + I -+ + I1 appears.'83 Mono-dipeptide com-plexes of the type [Co(NH,),a,a,] are reported. The dipeptide is terdentate and planar having lost an amide proton.'84 The [Co"'dienI3+ moiety has been used to investigate the formation of peptides using glycine esters and glycine glycine esters. In one product [Co(dien)Gly-Gly-Gly-Gly-ORX]' + at low and neutral pH the cobalt is bonded to the glycines through the terminal amines and the oxygen of the carboxy-group in the third position is blocked so that the complex 1 7 4 A.F. Schreiner S. W. Lin P. J. Hauser E. A. Hopcus D. J. Hamm and J. D. Gunter, 1 7 5 G. J. Leigh and W. Bremner J.C.S. Dalton 1972 1216. 17' G. C. Allen G. A. M. El-Sharkaway and K. D. Warren Inorg. Chem. 1972 11 51. 1 7 7 (a) A. M. Zwichel and C. Creutz Inorg. Chem. 1971,10,2395; ( 6 ) D. K. Lavellee and 17' A. J. Edwards R. G. Plevey I. H. Sallomi and J. C. Tatlow J.C.S. Chem. Comm., Inorg. Chem. 1972 11 880. E. B. Fleischer J. Amer. Chem. SOC. 1972 94 2583. 1972 1028. J. W. Quail and G. A. Rivett Canad. J. Chem. 1972,50 2447. l S o (a) G. L. Simon A. W. Adamson and L. F. Dahl J. Amer. Chem. SOC. 1972 94, 7655; (6) L. D. Brown K. N. Raymond and S .2. Goldberg ibid. 1972 94 7664. I' * W. Harrison N. L. Paddock J. Trotter and J. N. Wingfield J.C.S. Chem. Comm. 1972, 23. J. K. Burdett. M. A. Graham and J. J. Turner J.C.S. Dalton 1972 1620. I. G. Browning R. D. Gillard J. R. Lyons P. R. Mitchell and D. A. Phipps J.C.S. Dalton 1972 1815. '*' N. S. Hush and J. S. Woolsey J. Amer. Chem. SOC. 1972 94 4107 The Transition Elements 305 must isomerize to give a metal-nitrogen rather than metal-oxygen bond before the third position is filled.'85 The macrocycle 3,3-dimethyl-1,5,8,1l-tetra-aza-cyclotridecane was prepared by a template reaction on Ni2+ and the nickel complex reduced with NaBH to give the fully unsaturated ligand. The nickel was removed with-cyanide and on addition of a Co"' solution the Co"' complex was formed.'86 Zwitterion com-plexes of the type M[Co(diphos),(CN),]X (M = Mn" Fe" Co" Ni" or Zn") have been prepared.The Co"' is linked with M" by a CN bridge.'87 Co" com-plexes of 2,2'-dithiodipyridine and 4,4'-dithiodipyridine are reported for the first time.'88 The structure of Co(NO)(S,CNMe,) has a bent Co-N-0 bond but the NO groups are disordered lying above one or other of the Co-S bonds of the same ligand. ' 89 Two low-spin five-co-ordinate Co" complexes [Co(diphos),-ClISnC1 and [Co(diphos),Cl]SnCl ,C,H,Cl are square-pyramidal and dis-torted towards trigonal-bipyramidal respectively. The spectra of both are very similar indicating the difficulties of assigning the structure of five-co-ordinate Co" complexes from spectral data.'" A spectral and magnetic study of Co" ions in distorted environments showed that these properties are rather insensitive to the distortion parameter Cp.' ' A low-spin calculation for tetragonally distorted octahedral systems suggests a ,Al ground state in cobalt(I1)phthalocyanine. 192 The e.p.r. spectrum of (Et,N),CoCI and CoCl, - doped into (Et,N),ZnCl, demonstrates that the axis of the ions is reoriented at the phase change." A discussion of the electronic Raman spectra of Co2+ in Co,GeO has appeared. 194 The three geometrical isomers of [Co(dien)J3+ have been resolved. The trans-isomer is the most stable and the u-cis and trans-isomers have been resolved into optical isomers by diastereoisomer formation. The trans-isomer exists as two optical isomers because of the non-planarity of the chelate rings and a discussion of the nature of the puckering of the rings and its optical consequences was given.' 95 Rhodium and Iridium.-The blue cation [Ir(MeNC),]+X (X = C1 PF, or BF,) associates with unidentate ligands (L = various solvents CO or MeNC) when irradiated with visible light to form a five-co-ordinate complex which dis-sociates in the dark back to the starting materials. The forward reaction appears to be the first proven example of the photochemical formation of a metal-ligand Y. Wu and D. H. Busch J . Amer. Chem. SOC. 1972 94 4115. lE6 N. F. Curtis and G. W. Reader J.C.S. Dalton 1972 1453. '" P. Rigo B. Longato and G. Favero Znorg. Chem. 1972 11 301. '" J. R. Ferraro B. B. Murray and N. J. Wieckowicz J . Znorg. Nuclear Chem. 1972, 34 231.J . H. Enemark and R. D. Feltham J.C.S. Dalton 1972 718. 1 9 0 J. K. Stalick P. W. R. Corfield and D. V. Meek J . Amer. Chem. SOC. 1972 6195. '" M. Gerloch J. Lewis and R. Richards J.C.S. Dalton 1972 980. L. M. Englehardt and M. Green J.C.S. Dalton 1972 755. 1 9 3 ( a ) G . E. Shankle J. N. McElearney R. W. Schwartz A. R. Kampf and R. L. Carlin, J . Chem. Phys. 1972,56 3750; ( b ) J. N. McElearney G. E. Shankle R. W. Schwartz, and R. L. Carlin ibid. 1972 56 3755. 19' J. A. Konigstein P. A. Grunberg J. T. Hoff and J. M. Preudhomme J . Chem. Phys., 1972 56 354 306 W. E. Smith and J. M . Winjield bond. Diphos does not react with the cation in the dark but on exposure to light the five-co-ordinate complex Ir(MeNC)(diphos) is formed. Five-co-ordinate d81r' complexes generally lose a ligand in oxidative additions but all five donor atoms are retained and no such reaction occurs in this case.196 There are very few examples of nucleophilic attack on the nitrogen of a co-ordinated nitrosyl although it is well known for carbonyl groups. The cationic nitrosyls [IrCI,NOL,]+(L = PPh or AsPh,) react with alcohols ROH to give neutral Ir"' complexes containing alkyl nitrites IrCl,(RONO)L (R = Me Et or Pr).19' A series of dioxygen complexes RhX(O,)(PPh,),(RNC) (X = C1 Br or I ; R = But; X = C1 R = cyclo-C6Hl or p-MeC6H4) RhCl(O,)(AsPh,),(Bu'NC), and [Rh(02)(PPh,),(ButNC),]C1 greatly extends the range of complexes of this type known. They are relatively thermally stable some hold oxygen reversibly, others do not.198 The synthesis of the first Rh' and Rh" porphyrins of interest as Co" analogues and as possible catalysts has been reported.'98 The photochemical dissociation of [Rh1"(NH,),XI2 + by irradiation of the ligand-field bands proceeds by two pathways giving as major product either [Rh(NH3),H,0]3+ if X = C1 or [Rh(NH3),(H2O)XI2+ if X = I ; with bromide both are found.The possibility that the different yields are due to different intersystem crossing yields or to different populations of singlet and triplet excited states has been ruled out. The most likely explanation is that two different triplet states of differing geometries can form one with an elongated Rh-X bond and one with an elongated Rh-NH bond."' The decomposition of [Ir"'-(NH3),N3] was postulated to go through a nitrene intermediate (see last year's report).Complex ions formed by reaction of HSO,- or C1- and the nitrene have now been isolated and characterized as [Ir1"(NH3),NH,0S03]2+ and [Ir"'-(NH,),NH2C1I3+ A new preparation of IrF has been reported.,' The m.c.d. and electronic absorption spectra of Ir4+ in Cs,ZnCI have been examined and in the light of the evidence a different interpretation of the spectra of Ir4+ is given.,' The luminescence spectra in eight different solvents of Ir"' complexes show both a solvent effect and a method of separating charge-transfer and ligand-localized transition^.^'^ A study of 31P n.m.r. in the complexes MX,L,(M = Rh or Ir, X = C1 Br or I L = tertiary phosphines) corrects a number of literature assignments. ,05 I g 5 F. R. Keene and G.H. Searle Znorg. Chem. 1972,11 148. '96 W. M. Bedford and G . Rouschias J.C.S. Chem. Comm. 1972 1224. 19' C. E. Reed and W. R. Roher J.C.S. Dalton 1972 1243. 198 A. Nakamura Y. Tatsuno and S. Otsuka Znorg. Chem. 1972 11 2058. I g 9 B. R. James and D. V. Stynes J . Amer. Chem. SOC. 1972,94 6225. 2 o o T. L. Kelly and J. F. Endicott J. Amer. Chem. SOC. 1972 94 278. 2 0 1 * 0 2 W. A. Sunder and W. E. Falconer Znorg. Nuclear Chem. Letters 1972 8 537. 203 S. B. Piepho J . R. Dickinson J. A. Spencer and P. N. Schatz J. Chem. Phys. 1972, *04 R. J. Watts G. A. Crosby and J. L. Sansregret Inorg. Chem. 1972 11 1475. ' 0 5 B. E. Mann C. Masters and B. L. Shaw J.C.S. Dalton 1972,704. B. C. Lane J. W. MacDonald F. Basolo and R. G . Pearson J. Amer. Chem. SOC., 1972 94 3786.57 982 The Transition Elements 307 10 The Nickel Group Nickel.-A complete series of complexes with macrocyclic ligands in which Ni" is co-ordinated to four nitrogens and the number of unsaturated nitrogens varies from one to four has been prepared (17)-(20). (19) is well known and the others were prepared by oxidation or reduction. The oxidation and reduction reactions of the series were investigated electrochemically and oxidation states ranging from 111 to 0 were found. In acetonitrile (17) undergoes only a one-electron reduction whereas (18) (19) and (20) undergo a second reduction. It is postulated that the first reduction involves addition of an electron to the ring, the second an addition to the Oxidative dehydrogenation of a known macrocycle produced a new type of unsaturation (21)207 and the template synthesis of a ligand containing two azo-groups gave the novel product (22).208 The encapsulating 'tripod' like ligands MeC(CH,PPh,) and MeC(CH2PEt2)3 are normally bidentate in nickel complexes but with nitrite ions the ligands become terdentate and an Ni-NO bond is formed.1.r. and electronic spectra and magnetic data gave no positive indication of the nature of the nickel nitrosyl bond but an X-ray crystal structure of [NiMeC(CH2PEt2)3NO]BF shows that the nickel is pseudo-tetrahedral with the Ni-NO bond linear. The complex is 206 E. K. Barefield G . V. Lovecchio N. E. Tokel E. Ochiai and D. H. Busch Znorg. 2 0 7 C. J. Hipp L. F. Lindoy and D. H. Busch Znorg. Chem. 1972 11 1988. 2 0 8 N. W. Alcock and P.A. Tasker J.C.S. Chem. Comm. 1972 1239. Chem. 1972 11 283 308 W. E. Smith and J. M . Winfield therefore formulated as Ni' with an NO+ group as a ligand.," An X-ray structure of the Nil complex [NiMeC(CH,PPh,),]I shows that the nickel is pseudo-tetrahedral ;'lo the C1 and Br complexes have been prepared. A series of Ni"' complexes with syn-2-benzoylpyridine oxime and syn-2-phenacyl-pyridine oxime ligands is reported and the difficulties of establishing the exist-ence of this oxidation state are discussed.212 The NilV complexes [Ni(PPh,),-(SnR,),]CI (R = Ph or Me) have been prepared. Preliminary X-ray studies indicate an octahedral structure with a trans-trans-trans arrangement of the The reactivity of the oxygen complex NiO,(Bu'NC) with a series of reagents demonstrates differences in the behaviour of co-ordinated and free oxygen and characterizes the nature of the reaction.214 The preparation of an aziridine complex with the nickel co-ordinated to the nitrogen of the aziridine ring and a novel ring-opening mechanism of the co-ordinated species are re-ported.215 The new oxide Li,NiO has been prepared.216 A high-power i.r.laser has been used to induce an octahedral-tetrahedral transition in a Ni" complex. This is the first example of a laser-stimulated chemical change involving an electronic excited state rather than a vibrational one.217 A convenient method of carrying out a magnetic titration developed from the Quinke method for measuring magnetic susceptibility has been applied to the elucidation of the intermediates in the formation of Ni(en),,+ complexes.21 The species Ni(0,) and O,Ni(O,) identified in matrix-isolation studies are the first examples of binary molecular oxygen complexes of the transition metals.Variable-concentration diffusion-controlled warm-up and isotope-labelling experiments confirm the existence of the species and show that the oxygen is co-ordinated side-on in contrast to the results for Ni(N,) where the nitrogen is bonded end-on.'lg A study of the matrix-isolated species produced when N U , and NiF gases are mixed with CO and N and quenched in solid argon has led to the first report of carbonyl halides of nickel NiC1,CO and NiF,CO. The i.r. stretching frequency of the CO is the highest yet observed suggesting that it is almost entirely o-bonded.2o An X-ray study of the boron hydride transition-metal complex (Me,N),-Ni(B ,H 2)2 is reported. There are eight metal-boron bonds with two different distances fusing the two Bl,Hl groups in a slightly open staggered position to '09 D. Berglund and D . W. Meek Inorg. Chem. 1972 11 1493. ' l o P. Dapporto G. Falloni S. Midollini and L. Sacconi J.C.S. Chem. Comm. 1972, 1161. 'I1 L. Sacconi and S. Midollini J.C.S. Dalton 1972 1213. ' I ' R. S. Drago and E. I. Baucom Inorg. Chem. 1972 11 2064. 2 1 3 P. E. Garrou and G. E. Hartwell J.C.S. Chem. Comm. 1972 881. 2 1 4 S. Otsuka A. Nakamura Y. Tatsuno and M. Miko J . Amer. Chem. SOC. 1972 94, 3761. 'I5 C. A. Root B. A. Rising M. C. Van Derveer and C . F. Hallmuth Inorg. Chem. 1972, 11 1489. R. Rieck and R. Hoppe 2.anorg. Chem. 1972 392. 193. K. J. Ivin R. Jamison and J. J. McGarvey J. Amer. Chem. SOC. 1972,94 1763. G. R. Grayhill J. W. Wrathall and J. L. Ihrig Inorg. Chem. 1972 11 723. ' I 7 2 1 9 H. Huber and G. A. Ozin Canad. J. Chem. 1972 SO 3746. "O C. W. DeKock and D. A. VanLeirsburg J. Amer. Chem. SOC. 1972,94 3235 The Transition Elements 309 each other.221 A theory of n.m.r. contact shifts as applied to tetrahedral Ni" complexes shows that the usual T-' temperature dependence would not be expected to hold and the available data is analysed on the new theory.222 An X-ray photoelectron study of nickel dithiolate complexes indicates that the Ni atom is best represented as Ni' not Satellite lines ('shake up' peaks) occur in the X-ray photoelectron spectrum of paramagnetic compounds and in particular are associated with the 2p photoelectron emission from nickel com-pounds.These peaks do not occur in the diamagnetic square-planar compounds and can be used to differentiate between the two.224 Palladium and Platinum.-Complexes of platinum and mercury are usually formulated as having a Pt-Hg bond although this has not been confirmed by structural evidence. A series of complexes of the type (Me,Ph),PtX,HgY, (X = Cl Br or I ; Y = Cl or Br) has been prepared and the structural analysis of one of them (X = Y = C1) shows that the platinum and mercury are bonded by a double halogen bridge with no evidence of direct metal-metal bonding. The platinum is in square-planar and the mercury in distorted-tetrahedral co-ordination. The i.r.spectra of the complete set of compounds suggest that the bonding between the metals is of a similar type in each case.22s A new set of Pto complexes with arylated polytertiary phosphines has been reported.226 The dinuclear species Pt,S,P4(CF3), is formed from the reaction of PtCl, or K2PtC1 with (CF3),PS2H. On the basis of mass spectra and "F n.m.r. studies it is formulated as (23),,,' i.e. two S groups have been eliminated in the course of the reaction. Most sulphur-bridged Pd complexes show low reactivity to organic halides but polymeric sulphur-bridged palladium complexes of 1,2-ethanedithiol and 1,3-propanedithiol react readily with organic halides. Many of the products are as yet unidentified.228 The X-ray crystal structure of 2 2 1 2 2 2 223 2 2 4 2 2 5 2 2 6 2 2 7 2 2 0 L.J. Guggenberger J . Amer. Chem. Soc. 1972 94 114. B. R. McGarvey J . Amer. Chem. SOC. 1972 94 1103. S. 0. Grim L. J. Matienzo and W. E. Swartz J . Amer. Chem. Soc. 1972,94 51 16. L. J. Matienzo W. E. Swartz and S. 0. Grim Znorg. Nuclear Chem. Letters 1972 8, 1085. R. W. Baker M. J . Braithwaite and R. S. Nyholm J.C.S. Dalton 1972 1924. R. B. King and P. N. Kapoor Znorg. Chem. 1972,11 1525. R. G. Cavell W. Byers E. D. Day and P. M. Watkins Znorg. Chem. 1972 11 1599. L. Cattalini J. S. Coe S. Degetto A. Dondoni and A. Vigato Znorg. Chem. 1972,11, 1519 310 W. E. Smith and J. M. Winfield Pt2(S2CC6H4p-C3H,)4 shows this compound to be the first example of a discrete Pt'l molecule with a Pt-Pt bond.229 The first structures of metal-metal bonded dithioline complexes of both Pd and Pt are reported,,' and the first structure of an azide-bridged Pd dimer (Ph,As),Pd,(N,) shows that the bridging is through one terminal nitrogen of the azido-gr~up.~~' There are few derivatives of unidentate amines known for Pd and Pt mainly due to preparative difficulties.The use of the bridged complex M2X4(PMeJ)2, has facilitated the preparation ofcomplexes MX,(NMe,) and Pr,NMX,(NMe,), (MX = PtCI PtBr or PdBr).232 A range of cationic Pd" isocyanide complexes has been ~repared.~ 33 The first all-oxygen co-ordinated sulphoxide of palladium, Pd(di-isoamylsulphoxide),(BF4)2 has been reported as one of a series of Pd" and Pt" complexes with S and 0 l i g a n d ~ . ~ ~ A novel series of hydroxo-bridged dimers has proved to be remarkably stable chemically resisting cleavage by tertiary phosphines under conditions which would easily cleave chloro-bridged species.235 Linkage isomerism in the hydride complexes L2PtHX (L = Ph,P; X = NO NCS CN or NCSe) was detected for NCS only.236 The product of the reaction of[PtF(PPh,),]HF with CS2 has beenshown tobe [Pt(S,CF)(PPh,),]-HF,.The CS has been inserted into the Pt-F bond.237 The new oxides Na,PtO and Na,Pt03 have been prepared2,* and a new series of compounds of formula PtCl,(SCN),,nH,O (x = 2,2.4 3.8 5.1 6.0; y = 2 1.6 1.2,0.9,0.5 resp) were identified from the action of liquid chlorine on Pt"(SCN) .239 The species Pd(N,) has been detected in matrix isolation There has been much work. on the conductivity of non-stoicheiometric platinum compounds in the solid state much of it directed towards Little's suggestion that conditions for high-temperature superconductivity could be found in materials of this type.The temperature dependence of the conductivity of K,.,,Pt(CN) ,1.8H20 is unusual in that a metal-insulator transition of the type previously found only in organic solids has been detected.,,' It seems likely that impurities play a large part in the conductivity of this type of platinum 2 2 9 J. P. Fackler J. Amer. Chem. SOC. 1972 94 1009. 230 K. W. Browall T. Bursh L. V. Interrante and J. S. Kasper Znorg. Chem. 1972 1 1 , 2 3 1 W. P. Fehlhammer and L. F. Dahl J. Amer. Chern. SOC. 1972,94 3377. 232 P. L. Goggin R. J. Goodfellow and F. J. S. Reed J.C.S. Dalton 1972 1298. 233 W.J. Cherwinski H. C. Clark and L. E. Mayer Znorg. Chem. 1972 1 1 1511. 2 3 4 J. H. Price A. N. Williamson R. F. Schram and B. B. Wayland Inorg. Chem. 1972, 235 G. W. Bushnell K. R. Dixon R. G. Hunter and J. T. McFarland Canad. J. Chem., 236 237 J . A. Evans M. J. Hacker R. D. W. Kemmitt D . R. Russell and J. Stocks J.C.S. 238 W. Urland and R. Hoppe Z . anorg. Chem. 1972 392 23. 2 3 9 S. S. Batsanov P. N. Kusnetsov and E. D. Ruchkin Russ. J. Inorg. Chem. 1972 17, 240 G. A. Ozin M. Moskovits P. Kiindig and H. Huber Canad. J . Chem. 1972,50,2385. 2 4 1 T. W. Thomas Chehsiung Hsu M. M. Labes P. S. Gomm A. E. Underhill and 1800. 11 1280. 1972 50 3694. M. W. Adlard and G. Socrates J.C.S. Dalton 1972 797. Chem. Comm. 1972 72. 168. D. M. Watkins J.C.S. Dalton 1972 2050 The Transition Elements 31 1 complex.242 K1.64Pt(o~)2 ,xH20 is suggested as a new solid-state proton battery2, and the nature of the oxidation-reduction reaction in this and related complexes has been Two reports question the present belief that PtC1 is tetrahedral.In a footnote on a study of organometallic platinum complexes spectroscopic and other evidence is summarized.245 A powder X-ray study suggests that it is in fact six-co-ordinate with a similar structure to PtBr and PtI .246 In K,Pd(SCN),, the Pd is in approximately square-planar co-ordination with two different Pd-S bond lengths and with infinite metal chains in the Two different syntheses of C1F,+PtF6- have been reported. The main interest is in the stabil-ization of the chloronium ion with chlorine formally Clv".248 In flash photolysis studies of the photochemical aquation of Na2PtC1, a similar intermediate to that found for the analogous bromide and chloride salts [PtCl,OHl2- is identi-fied but the new species [Pt"'Cl,]- is also found confirming the belief that a Pt"' species is also involved in the hydrolysis mechanism.249 11 The Copper Group Copper.-H,BCN- forms copper complexes of the type (Ph,P),Cu'NCBR, containing metal-nitrogen bonds.The dimeric complex [(Ph3P)2Cu(NCBH3)]2 was shown to have the structure (24) in both solid and solution.2s0 The conden-sation product of pyridine-2-carbaldehyde and 2-aminobenzothiazole (25) has been used as a ligand to produce a Cu" complex. An X-ray analysis indicates that it contains the biL (26) and a biL picolinic ion.The picolinic acid may be derived from hydrolysis of the ligand followed by oxidation of the pyridine-2-carbalde-hyde product at the expense of the ligand itself.251 2 4 2 L. V. Interrante J.C.S. Chem. Comm. 1972 302. 2 4 3 F. N . Lecrone and J. H. Perlstein J.C.S. Chem. Comm. 1972 75. 244 P. S. Gomm A. E. Underhill and D . M. Watkins J.C.S. Dalton 1972 2309. 2 4 s P. M. Cook L. F. Dahl and D. W. Dickerhoof J . Amer. Chem. SOC. 1972,94 5511. 2 4 6 2 4 7 A. H. Mawby and G. E. Pringle J. Inorg. Nuclear Chem. 1972,34 2213. 248 ( a ) F. Q. Roberto Znorg. Nuclear Chem. Letters 1972 8 737; (6) K. 0. Christe ibid., 249 R. C. Wright and G. S. Lawrence J.C.S. Chem. Comm. 1972 132. 2 5 0 S. J. Lippard and R. S. Welcher Znorg. Chem. 1972 1 1 6 . 2 5 1 A.Mangia M. Nardelli C. Pellizzi and G. Pellizzi J.C.S. Dalton 1972 996 2483. M. F. Pilbrow J.C.S. Chem. Comm. 1972 270. 1972 8 741 312 W. E. Smith and J. M . Winjield H A novel form of macrocycle (27) formed from two 1,lO-phen groups bridged by NH has been synthesized and the copper complex (28) prepared.252 H Histidyl groups are important as metal-binding sites in proteins. The crystal structure of the compound produced from the reaction of Cu" with the smallest peptide containing a histidyl group shows that it is basically a Cu" double oxygen-bridged dimer with six dimeric units forming a three-dimensional unit enclosing disordered water. A small-angle X-ray scattering study demonstrates that a similar species is present in solution.' Ammoniacal solutions containing Cu" ions oxalodihydrazide and acetaldehyde give a deep-blue solution on oxygena-tion.The solution is used in copper analysis and has been widely upheld as a copper-oxygen complex and a model for oxygen carriers in Cu protein complexes. The X-ray structure of the isolated product shows that it is not an oxygen complex, but that the ligands have undergone an extensive interligand condensation. The copper is co-ordinated to four nitrogens with an axial water ligand. Oxygen is involved in the condensation reaction. 54 A number of points of interest have appeared from the many X-ray crystal structure papers on copper compounds. The sulphur-bridged trimer, [Cu(Me,PS)Cl] has two copper atoms bridged through the sulphur of one ligand with an adjacent terminal chlorine whereas normally the chloride would be expected to be the bridging ligand.Presumably the larger bond angle in the trimer compared with the more widely studied dimer allows the sulphur to be more easily accommodated.255 2 5 2 S. Ogawa T. Yamaguchi and N. Gotoh J.C.S. Chem. Comm. 1972 571. 2s3 R. Osterberg B. Sjoberg and R. Soderquist J.C.S. Chem. Comm. 1972 983. 2 5 4 G. R. Clark B. W. Skelton and T. N. Waters J.C.S. Chem. Comm. 1972 1163. 2 5 5 J. A. Tethof J. K. Stalick P. W. R . Corfield and D. W. Meek J.C.S. Chem. Comm., 1972 1141 The Transition Elements 313 Dinitratobis-a-picolinecopper(r1) exists in two forms both of which belong to the same space group and have similar unit cells but quite different crystal-packing arrangements.,' The structures of Cu(NC,H,OMe),X (X = C1 or Br) were expected to be quite different from i.r.results but in fact have proved to be very similar.257 Anhydrous Na,Cu(CO,) consists of infinite sheets of Cu atoms bridged by carbonates through two of the oxygens the third CO distance is shorter than those involved in bridging.258 An assessment of antiferromagnetism in dinuclear Cu" carboxylate complexes has appeared. 140 compounds were considered some were rejected systematic trends were established among the rest using a singlet-triplet-singlet The mechanism of superexchange in Cu" dimers with bridging N-oxide groups has been discussed and the thermal population of excited states other than those predicted by the vector model is proposed.260 A summary of the magnetic data on a number of copper dimers and the evidence for spin-spin interaction have been discussed.261 The 4.2-300 K magnetic susceptibility of CuS has been reported and explained on the basis of a trimer of copper(rr) atoms.262 Magnetic susceptibilities for the tetrameric complexes cu4Ox& (x = c1 L = Ph,PO; X = Br L = Ph,PO or C,H,N) have been measured between 1.2 and 294K, and in each case a maximum susceptibility is found in the 40-60 K region.The results are significantly different from the related anion [CU,OC~,,]~- and it is suggested that the ground state of each ion is non-degenerate whereas for the neutral complex it is doubly degenerate. The theory for tetramers is developed using a spin-pair Hamiltonian for the doubly degenerate case and excellent agreement between theory and experiment is obtained.263 The triL N-2-pyridylsalicylaldimine7 gives rise to a tetranuclear Cu" cluster with two pairs of copper atoms bridged by a double oxygen bridge lying one above the other so that the coppers form a square.There is little interaction between the pairs of copper atoms.264 The relationship between structure and pressure-dependent magnetic susceptibility data has been studied. The sus-ceptibility is sensitive to bond-angle changes.265 The magnetic properties of hydroxo-bridged bipy complexes266 and Cu" quinoxaline complexes bridged either by chlorines or by the quinoxaline group have been The magnetic susceptibility from 4.2-300 K of Cu(NH,),CO indicates that it is an 2 5 6 A. F. Cameron D. W. Taylor and R. H. Nuttall J.C.S.Dalton 1972 5 8 . 2 5 7 P. Singh D. Y. Jeto W. E. Hatfield and D. J. Hodson Znorg. Chem. 1972 11 1657. 2 5 8 P. C. Healy and A. H. White J.C.S. Dalton 1972 1913. 2 5 9 R. W. Jotham S. F. A. Kettle and J. A. Marks J.C.S. Dalton 1972 428. 2 6 0 2 6 1 '" B. N. Figgis and D. J. Morton J.C.S. Dalton 1972 21 7. 263 M. E. Lines A. P. Ginsberg R. L. Martin and R. C. Sherwood J . Chem. Phys. 1972, 2h4 J . Drummond and J. S. Wood J.C.S. Dalton 1972 365. 2 6 5 2 6 6 J . A. Barnes D. J. Hodson and W. E. Hatfield Znorg. Chem. 1972 11 144. 2 6 7 C. V. Inman J. A. Barnes and W. E. Hatfield Znorg. Chem. 1972 11 765. R. W. Jotham S. F. A. Kettle and J. A. Marks J.C.S. Dalton 1972 1133. W. E. Hatfield Znorg. Chem. 1972 11,217. 57 1 . E. Sinn and W. T. Robinson J.C.S.Chem. Comm. 1972 359 3 14 W. E. Smith and J. M. Winfield antiferromagnet with a weak ferromagnetic interaction probably caused by slightly canted spins between magnetic sublattices.268 E.p.r. magnetic anisotropy and electronic spectral data on an eight-co-ordinate Cu" complex are in agreement with crystal-field theory.268 Complexes of the type Cu(Et,en),X (X = C104 BF, or NO3) are thermochr~mic.~~~ Physical properties indicate that there is a temperature-dependent interaction between the anion and the CuN plane giving a more square-planar geometry at low temperatures. Cu" benzoate dimers have been studied by n.m.r. The delocalization of electrons into the ligands is consistent with an exchange mechanism.271 Silver and Gold.-Compounds of AuV have been reported for the first time.[Xe,F J+[AuF,]- can be prepared by a direct reaction of XeF F, and AuF ; fluorination of CsAuF gives CSAUF, and fluorination with oxygen of CsAuF, gives O,+[AuF,]-. The CsAuF salt is isomorphous with other noble metal CSMF salts and Raman spectra are rather similar to those for AuF,-Well-defined compounds of formula MAu(NO,) (M = Na K Rb or Cs) were prepared by reaction with N" and NV oxide systems. All the nitrates are uni-dentate and square planar the first examples of solely unidentate NO3- in this type of compound.273 Although gold is inert to fluorosulphuric acid it has now been shown to react with bromine(1) fluorosulphate to form the complex Au(SO,F),(BrSO,F) . 274 The first ligand-induced disproportionation of Ag' in solution is reported.275 The addition of KOH-MeOH followed by C6H1 ,NC, to a Ph,PAuI suspension in methanol produces the novel complex (29).276 I -\A,.,Au N=C Tetrameric complexes of formula [(Me,P)AgCl] have been prepared and the new Si-0-Ag linkage is obtained from reactions of it and related complexes, with NaOSiMe,. A similar linkage has also been found for Cu and Au.277 2 6 8 D . Y. Jeter D. J. Hodson and W. E. Hatfield Inorg. Chem. 1972 11 185. 2 6 9 C. D. Garner P. Larnpert F. E. Mabbs and J. K. Porter J.C.S. Dalron 1972 320. * l o A. B. P. Lever E. Mantovani and J. C. Donini Inorg. Chem. 1971 10 2424. 2 7 2 7 2 K. Leary and N. Bartlett J.C.S. Chem. Comm. 1972,903. 2 7 3 C . C. Addison G. S. Brownlee and N. Logan J.C.S. Dalton 1972 1440. 2 7 4 W. M. Johnson R.Dev and G. H. Cady Inorg. Chem. 1972,11,2260. 2 7 5 M. A. Kestner and A. L. Allred J. Amer. Chem. SOC. 1972,94 7189. 2 7 6 G. Minghetti and F. Bonati Angew Chem. Internat. Edn. 1972 11 429. 2 7 7 H. Schrnidbaur J. Adhofer and K. Schwirten Chem. Ber. 1972 105 3382. P. A. Zelonka and M. C. Baird Inorg. Chem. 1972 11 134 The Transition Elements 315 A series of gold cluster compounds of the type Au,L8X3 has been prepared.278 The first crystal structure of one of these was reported last year. The structure of the first of a new type of cluster compound [AuP(tol),],[BPh,], shows that the Au atoms are arranged at the points of an ~ctahedron.,~' The bonding pattern of the compounds is considered and a rationalization proposed. The crystal structure of (Au(Pr'O),PS,) shows that although the molecule is dimeric a one-dimensional gold chain with each dimer linked by a slightly longer Au- Au distance is formed.280 The electronic spectrum of tetragonally distorted Ag" in the compounds MNAg"F (MIv = Sn Pb Zr or Hf) has been reported28' and other fluorides of the same type (MIv = Ti Ge Pb Pd or Pt) have been prepared.Some of them (MIv = Sn Pb; or Pd) have magnetic pro-perties which obey the Curie-Weiss law but for others (MIv = Zr or Hf) there is evidence of exchange occurring. The deep-blue colour of the latter two is further evidence of this. 82 12 The Zinc Group A range of selenourea complexes of Zn" Cd" Hg" and Co" have been synthesized. The donor properties of selenourea are similar to those of thiourea. The i.r. M-L stretching frequencies lie in the range 245-167 cm- ' about 20 % lower in frequency than equivalent thiourea complexes.283 A series of Zn" and Cd" complexes containing hydrazine has been reported.Cadmium complexes of the types [CdBr,(N,H4),],4H20 and [Cd(H20),(N2H4),]S04 have both been established.284 The complex Hg" cations [HgXL]+ [HgL2I2+ (L = PMe or AsMe,) [HgMepy]' and [MeHgSMe,]' have been synthesized as NO3- and BF4- salts and characterized by i.r. Raman and 'H n.m.r. spectra.28' The metal clathrates Cd(en),M(CN) ,2C,H,(M = Cd or Hg) have M ions in tetrahedral co-ordination.286 The U.V. spectra of Zn" Cd" and Hg" tetrahalides have been assigned to the t -P a transition with no evidence of transitions from t or e non-bonding The first direct observation of a polarized sharp-line porphyrin absorption spectra is reported at 77 K for zinc porphyrin doped into a triphenyl-ene crystal.* The thermodynamics of decomposition of mercury(1x) halide dioxan complexes have been re-examined. Previous thermodynamic data gave 2 7 8 F. Cariati and L. Naldini J.C.S. Dalron 1972 2286. 279 P. L. Bellon M. Manassero L. Naldini and M. Sansoni J.C.S. Chem. Cornm. 1972, 1035. S . L. Lawton W. J. Rohrbaugh and G. T. Kohotailo Inorg. Chem. 1972 11 2227. 2 8 ' G. C. Allen R. F. McMeeking R. Hoppe and B. Miiller J.C.S. Chern. Cornm. 1972, 291. B. Muller and R. Hoppe Z . anorg. Chem. 1972 392 37. 44 573. 647. 283 G. B. Aitken J. L. Duncan and G. P. McQuillan J.C.S. Dalton 1972,2103. 284 R. Y. Aliev N . N. Guseinov and N . G. Klyuchnikov Russ.J. Inorg. Chem. 1972 17, 2 8 5 P. L. Goggin R. J. Goodfellow S. R. Haddock and J. G. Eary J.C.S. Dalton 1972, 2 8 6 T. Iwamoto and F. Shriver Inorg. Chem. 1972 11 2570. 28' P. Day and R. H. Seal J.C.S. Dalton 1972 2054. 2 8 8 B. F. Kim J. Bohandy and C. K. Jen J. Chem. Phys. 1972 57 1792 316 W. E. Smith and J. M. WinjieId the bond order Br > I > C1 in contrast to the spectroscopic order C1 > Br > I. The new data are in agreement with the spectroscopic result.289 A structural investigation of the mode of bonding of Cd" and Hg" urea deriva-tives has begun. At present it is common practice to assume that they are oxygen-bonded if a shift in carbonyl frequency occurs on complexation. The crystal structure of hexakis-(2-imidazolidinone) Cd" perchlorate demonstrates that it is oxygen-bonded but no corresponding i.r.shift is found. Bis-(2-imidazolidinone)-Hg"C12 shows such a shift but it is a polymer with two oxygen and two nitrogen bonds to each mercury.290 [(Et,O),Cd(B,,H,,),] has been shown by an X-ray structural analysis to consist of two bridging B,,H, groups each bonded to the cadmium ions by two three-centre bonds with two other groups completing the co-~rdination.~" The existence of the ion [Cd2I6l2- has been confirmed by a structural determination on a [Cd,LI,] complex L = tris-(2-dimethylamino-ethy1)amine. The anion consists of two CdI tetrahedra linked by a common edge. The cations are five-co-ordinate Cd" complex ions.292 The first example of a linear chain polydentate complex with helical co-ordination is reported for a 1 1 complex.The ligand has 3N and 2s co-ordination and all are shown to be at bonding distances. There is only one molecule per unit cell and the crystal is optically active. 293 In spite of the wide use of zinc dithizonate in analytical chemistry no crystal structure has appeared until this year. The zinc is tetrahedrally co-ordinated to both S and N. The methyl derivative would be expected to be tetrahedral for Nil' but to be distorted for Zn" in agreement with the known stabilities.294 Mercury dehydrodithizone is a sulphur-bridged polymer with five-co-ordinate Hg.29s ZnSO ,2H,O crystals contain both octahedral and tetrahedral Zn'1,296 Hg3(A1Cl,) contains Hg,,' units of a type discussed last year297 and in Zn(OAc) ,2H20 the Zn" is co-ordinated to seven oxygen^.,^^ 13 Ligands Dithiophosphinic acids have been shown to form insoluble polymeric complexes with CO" and Ni".The co-ordination sphere of the metal can be expanded by the addition of base and depending on the nature of the acid selective absorbants for a series of amines have been prepared.299 Cyclic oxamides can isomerize as shown (30) and co-ordinate with Ni" giving product (31) in air and (32) in the 2 8 9 J. C. Barnes Znorg. Chem. 1972 11 2267. 2 9 0 ( a ) J. N. Brown A. G. Pierce and L. M. Trefonas Znorg. Chem. 1972 11 1830; (b) R. J. Majestic and L. M. Trefonas ibid. p. 1834. N. N. Greenwood J. A. McGinnety and J. D. Owen J.C.S. Dalton 1972 989. 2 9 2 P. L. Orioli and M. Campolini J.C.S. Chem. Comm. 1972 1251. 293 L.F. Lindoy D. H. Busch and V. Goedhen J.C.S. Chem. Comm. 1972 683. 2 9 4 A. H. Mawby and H. M. N. H. Irving J . Znorg. Nuclear Chem. 1972 34 109. 2 9 5 W. J. Kozarek and Q. Fernando J.C.S. Chem. Comm. 1972,605. 2 9 6 H. Quinares and S. Baggio J . Inorg. Nuclear Chem. 1972 34 2153. 297 R. D. Ellison H. A. Levy and K. W. Fung Znorg. Chem. 1972 11 833. 2 9 8 W. Harrison and J. Trotter J.C.S. Dalton 1972 936. 299 W. Kuchen J. Delventhal and H. Keck Agnew Chem. Internat. Edn. 1972 11 435 The Transition Elements 317 absence of air. With Co" and Cu" a product similar to (32) is obtained with or without air.300 A detailed investigation of fused-ring polymeric phthalocyanines prepared from 1,2,4,5-tetra-azabenzene (TCB) or pyromellitic anhydride (PMA) and metal salts showed that the present literature work-up methods lead to impure products.Pure compounds obtained from the reaction of TCB and metal salts were mono-meric with imide or carboxylate functional groups but PMA and metal salts gave polymers with imide not carboxy-groups at the ~eriphery.~" Template synthesis of compounds which represent corrins more faithfully than previous ligands302 and a series of octa-aza-annulenes together with the first metal complex of this type is reported.303 A simple and easy preparation of cyclam (1,4,8,1l-tetra-zizacyclotetradecane) giving a 20% yield,304 and direct methods of preparing related saturated tetra-aza macrocycles have been reported.305 A general mechanism for the incorpor-ation of a metal ion in a porphyrin which rationalizes the variety of kinetic results at present available has been proposed.It appears that a metal ion, proton or N-alkyl group on one side distorts the porphyrin ring and allows attack by a second metal ion on the other side.306 1.r. spectra of tri(bipy) and tri(phen) complexes of Fe"*"' Cu" and Co"*"' have been assigned from isotope studies. There are two distinct series those with t,, orbitals only filled and those with partially filled eg orbitals as well. It appears 300 H. Kanatomi and I . Murase Znorg. Chem. 1972 11 1356. 3 0 1 D. R. Boston and J. C. Bailar Inorg. Chem. 1972 11 1578. 302 D. St. C. Black and A. J. Hartshorn J.C.S. Chem. Comm. 1972 706. j o 3 J. E. Baldwin R. H. Holm R. W. Harper J. Huff S. Koch and T. J . True Inorg. 304 E. K. Barefield Znorg.Chem. 1972 11 2273. 305 A. M. Tait and D. H. Busch Inorg. Nuclear Chem. Letters 1972 8 491. 3 0 6 R. Khosropour and P. Hambright J.C.S. Chem. Comm. 1972 13. Nuclear Chem. Letters 1972 8 393 318 W. E. Smith and J. M . Winfield that significant electron delocalization occurs if antibonding eg orbitals are filled.307 M.c.d. spectra of octaethylporphyrins of Co Cu Ag Zn between room temperature and 8 K have been reported. The metal plays little part in the spectra and is only weakly coupled to the 7c-ring system. Vibronic fine structure is found on only one band.308 The electronic spectra of Zn" Ni" Fe" Mn" Mg" and Al"C1 porphyrins and their reduction products have been studied.309 The advantages of 13C n.m.r. and 'H n.m.r. in determining the stereochemistry of Ph,P and Ph,As complexes have been pointed out.310 A study of metal ring conformation for edta metal complexes shows that only two ring conformations will occur and ten conformational types of the complex are possible.311 3 0 7 Y. Saito J. Takemoto B. Hutchinson and K. Nakamoto Znorg. Chem. 1972,11,2003. 308 R. Gale A. J. McCaffery and M. D. Rowe J.C.S. Dalton 1972 597. 309 D. W. Clack and J. R. Yandle Znorg. Chem. 1972 11 1738. 310 B. E. Mann B. L. Shaw and R. E. Stainbank J.C.S. Chem. Comm. 1972 151. 3 1 1 B. Lee Inorg. Chem. 1972 11 1072