摘要:

10 Transition-metal Carbonyl Organometallic and Related Complexes By P. S . BRATERMAN Department of Chemistry The University Glasgow G 12 800 The principal proceedings of the 5th International Conference on Organometallic Chemistry (Moscow 1971) have been published.' A personal survey by A. N. Nesmeyanov has appeared,' as has a guide to the literature of organo-transition-metal chemistry between 1950 and 1970.3 Reviews have appeared on hydride c~mplexes,~ the organic chemistry of rhenium,' the decomposition of organo-metallics in the mass spectrometer,6 sulphur dioxide insertion reactions,' 0-n rearrangements of organo-transition-metal species,8 and catalytic olefinic metathe~es,~ disproportionation,' and hydrogenation by complexes of Group VIII,' while hydroformylation processes have been reviewed twice.' 'a*b Reviews have also appeared on the catalytic activity of organometallic species in hetero-geneous systems,' the stabilities and structures of olefin and acetylene complexes of transition metals,' ring displacement reactions,' and some aspects of organic synthesis by transition-metal complezes,'6 and a review of cluster compounds' is in part devoted to organometallic and carbonyl species. Of general interest is the application of chemical ionization mass spectrometry to organometallic species. In this technique ions are generated indirectly by ion-molecule reactions between the sample vapour and independently generated cations such as the powerful proton donor CH5+. The method generally gives Pure Appl. Chem. 1972,30 pp.3 3 5 4 3 6 . ' A. N. Nesmeyanov Adv. Organometallic Chem. 1972 10 1. M. I . Bruce Adv. Organometallic Chem. 1972 10 274. H. D. Kaesz and R. B. Saillant Chem. Rev. 1972,72 231 H. C. Lewis jun. and B. N. Storhoff J . Organometallic Chem. 1972 43 1. ' J. Muller Angew. Chem. Internat. Edn. 1972 11 653. 'I A. Wojcicki Accounts Chem. Res. 1971 4 344. M. Hancock M. N. Levy and M. Tsutsui Organometallic Reactions 1972,4 1. N. Calderon Accounts Chem. Res. 1972 5 127. l o R. L. Banks Fortschr. Chem. Forsch. 1972 25 39. l 1 W. Strohmeir Fortschr. Chem. Forsch. 1972 25 71. l 2 ( a ) F. E. Paulik Catalysis Reviews 1972 6 49; (6) M. Orchin and W. Rupolius ibid., p. 85. l 3 J. Manassen Fortschr. Chem. Forsch. 1972 25 1. l4 L. D. Pettit and D. S. Barnes Fortschr. Chem. Forsch.1972 28 85. l 5 H. Werner Fortschr. Chem. Forsch. 1972 28 141. l 6 J. Tsuji Fortschr. Chem. Forsch. 1972 28 41. " R. B. King Progr. Inorg. Chem. 1972 15 287. 31 320 P. S. Braterman a spectrum rich in heavy fragments up to and including (P + l)+ and is parti-cularly useful for such systems as the tricarbonyliron complexes of delicate dienes. The detailed electronic pathways involved in rearrangements of organo-transition-metal and related species have been discussed and the form of the highest occupied orbital is predicted to be a dominating factor.Ig 1 Metal Carbonyls Inelastic neutron scattering has been used to locate bending as well as stretching motions of hydrogen in a range of carbonyl hydrides including H,Mn,(CO), , H,Fe(CO), and CoHFe,(CO)ll.20 The use of 13C n.m.r.spectroscopy in studies of carbonyls has been facilitated by the introduction of Cr(acac) (acac = acetylacetonate) as a shiftless relaxation agent,* and carbonyl force constants have been correlated with 13C chemical shifts.22 Mono- and Di-nuclear Carbonyk-CO stretching parameters in carbonyl halides correlate with the calculated occupancy of the ligand 50 (partly carbon lone-pair partly C-0 antibonding) orbital as well as on the occupancy of 2n.23 The intensity and frequency distributions of simple binary carbonyls prepared from isotopically enriched CO have been calculated as an aid to the assignment of ~tructures.~, Studies of i.r. intensities in metal carbonyls have been re~iewed.~' The Raman intensities of the octahedral metal carbonyls C,H,Mn(CO) and arenechro-miumtricarbonyl complexes have been discussed using the Wolkenstein26 bond-polarizability model to explain among other features the weakness of scattering by the fully symmetric CO stretching mode.27 Raman intensities fall on sub-stitution of CO in Ni(CO) by phosphines or phosphites and this fall may be related to falling CO bond order.28 The vibrational (Raman and i.r.) spectra of C,H,Fe(CO),SnPh Mn(CO),SnPh, and (Ph,P)Mn(CO),SnPh in the solid state have been analysed.In some cases fewer lines are found than the selection rules of factor-group analysis allow and the term situs group is introduced to represent the effective symmetry of the set of oscillators with non-negligible interaction^.^^ Similarly the spectrum of butadienetricarbonyliron also shows the effects of non-crystallographic ~ymmetry.~' * * D.F. Hunt J. W. Russell and R. L. Torian J. Organometallic Chem. 1972 43 175. l 9 C. C. Su J . Amer. Chem. Soc. 1971 93 5653. 2 o J. W. White and C. J. Wright J.C.S. Faraday ZI 1972 68 1423. 2 1 2 2 E. A. Gansow B. Y . Kimura G. R. Dobson and R. A. Brown J. Amer. Chem. SOC., 2 3 M. B. Hall and R. F. Fenske Znorg. Chem. 1972,11 1619. 2 4 J. H. Darling and J. S. Ogden J.C.S. Dalton 1972 2496. 2 5 S. F. A. Kettle and I. Paul Ado. Organometallic Chem. 1972 10 199. 2 6 M. Eliashev and M. Wolkenstein J. Phys. (Moscow) 1945 9 101. 2 7 S. F. A. Kettle I. Paul and P. J. Stamper J.C.S. Dalton 1972 2413. 2 8 M.-F. Koenig and M. Bigorgne Spectrochim. Acta 1972 28A 1693. 2 9 H. J. Buttery S.F. A. Kettle G. Keeling I. Paul and P. J. Stamper J.C.S. Dalton, 3 0 D. A. Duddell S. F. A. Kettle and B. T. Kontik-Matecka Spectrochim. Acta 1972, E. A. Gansow A. R. Burke and G. N. LaMar J.C.S. Chem. Comm. 1972,456. 1971,93 5922. 1972 2487. 28A. 1571 Transition-metal Carbonyl Organometallic and Related Complexes 32 1 The photochemical reaction between V(CO) - and CN - generates the anions [V(CO),CN]2 - and (probably dinuclear) [V(CO)4(CN),]2- ; ammonia gives [V(CO),(NH,)]- and the U.V. spectra of these species are presented and dis-cussed.31 Co-condensation of hexacarbonylchromium with sodium vapour in an argon host gives a species characterized by i.r. spectroscopy as [Cr(CO)5]-.32 The intensities of the bands assigned by earlier workers33 to 'trigonal-bipyramidal Mo(CO),' in matrices containing photolysed molybdenum hexacarbonyl are concentration-dependent confirming the suggestion34 that these bands are actually due to di- or poly-nuclear specie^.^' Microcalorimetry leads to revised values for the heat of formation of chromium he~acarbonyl.,~ In species LW(CO), for a given donor atom the stretching parameter for equatorial CO is sensitive to the basicity of L whereas that of the axial CO group is not (contrast however the interpretation offered in ref.23).37 The medium-range i.r. spectra of a range of species of the type M(CO),(LL) (M = Cr Mo or W; LL is an N- P- As- or S-donor chelating ligand) have been discussed. The metal-carbon stretching bands are assigned where possible and the relevance of the results to bonding is discussed.38 The full vibrational spectrum of benzene-chromium tricarbonyl has been discussed in detail by two separate groups; data presented include Raman spectra of the solid and of solutions low-tempera-ture i.r.spectra and spectra of the fully deuteriated d e r i ~ a t i v e . ~ ~ Interchange of cyclopentadienyl groups in the species (n-C,H,)Mo(CO),-Mo(CO),(CNMe)(n-C,H,) has been detected by n.m.r. It is inferred that co-ordinated CO and CNR groups on different metals can undergo interchange, presumably via some bridged intermediate.,' The carboxamide complex (n-C,H,)W(CO),.CO.NHMe is generated by the action of methylamine on the [(n-C,H,)W(CO),] + ion. Further reaction gives dimethylurea while bases reversibly cleave the metal-acyl bond to give [(n-C,H,)W(CO),]- and methyl cyanate.Similar amino-acyl formation from arenedicarbonylmanganese cations is reversible reflecting the less electrophilic nature of co-ordinated C0.42 Two aluminium(rI1) atoms can be co-ordinated by (phen)Mo(PPh,),(CO), (phen = o-phenanthroline) through the carbonyl oxygens and Ga"' may be 3 1 32 P. A. Breeze and J. J. Turner J. Organometallic Chem. 1972 44 C7. 3 3 I . W. Stolz G. R. Dobson and R. K. Sheline J . Amer. Chem. SOC. 1963,85 1013. 34 M. J. Boylan P. S. Braterman and A. Fullarton J . Organometallic Chem. 1971 31, 3 5 M. A. Graham R. N. Perutz M. Poliakoff and J. J. Turner J. Organometallic Chem., 3 6 J. A. Connor H. A. Skinner and Y . Virmani J.C.S. Faraday I. 1972 68 1754. 37 R. A. Brown and G. R. Dobson Inorg. Chim.Acta 1972 6,65. 3 8 G. R. Dobson and R. A. Brown J. Inorg. Nuclear Chem. 1972,34 2785. 39 ( a ) J. Brunvoll S. J. Cyvin and L. Schafer J . Organometallic Chem. 1972 36 143; (b) L. Schafer G. M. Begun and S. J. Cyvin Spectrochim. Acta 1972 28A 803; (c) P. J. Hymans and E. R. Lippincott Spectrochim. Acta 1972,28A 1741. D. Rehder J . Organometallic Chem. 1972 37 303. C29. 1971 34 C34. 40 R. D. Adams and F. A. Cotton J . Amer. Chem. Soc. 1972,94 6193. 4 1 W. Jetz and R. J. Angelici J. Amer. Chem. SOC. 1972 94 3799. 4 2 R. J. Angelici and L. J. Blacik Inorg. Chem. 1972 11 1754 322 P. S. Bratermun co-ordinated in the same The species [(n-C5H,)W(C0),A1Me,1 has been shown crystallographically to have the structure (l) in which the dimethyl-aluminium groups bridge ligand oxygen^.^^ Me Me \ / 0 A1 c\ /C5H5 O\ I o/ ‘ I / c’ W W / \ Me Me (1) Species of the typefuc-(NNN)M(CO) (M = Cr Mo or W ; NNN is a terden-tate nitrogen ligand) are oxidized by iodine to [@NN)M(CO),I]+I-.45 The decomposition of Group VI pentacarbonyl amine complexes occurs by a first-order dissociative mechanism the rate being lower for a more basic or for a n-accepting a ~ i n e .~ ~ The reaction of the anions [M2(C0)10]2- with the appro-priate mercury compounds provides a route to zerovalent metal carboxylates (e.g. [HCOOW(CO),] - )47 and to mononuclear mercaptides [RSM(CO),] - ;48 the mercury is reduced to the metal. The structure (2) has been found for the [W(CO),Br,] - anion in its tetramethylammonium salt.49 c I 0 (2) The weak high-frequency i.r.band of MnRe(CO), has been assigned to the fully symmetric CO breathing mode which in Mn,(CO), and Re,(CO), is Raman-active only.” The solid formed by condensing Mn,(CO), vapour on to a liquid-nitrogen-cooled finger gives an e.s.r. signal attributed to the Mn(CO), 43 D. F. Shriver and A. Alich Co-ordination Chem. Rev. 1972 8 15. 44 G. J. Gainsford,R. R. Schrieke and J. D. Smith J.C.S. Chem. Comm. 1972 650. 4 5 J. G. Dunn and D. A. Edwards J. Organometallic Chem. 1972,36 153. 46 R. J. Dennenberg and D . J. Darensbourg Inorg. Chem. 1972 11 72. ” W. J. Schlientz Y . Lavender N. Welcman R. B. King and J. K. Ruff J. Organo-48 W. J. Schlientz and J. K. Ruff Inorg. Chem. 1972 11 2265. 49 M. G. B. Drew and A. P. Wolters J.C.S. Chem. Comm. 1972,457.metallic Chem. 1971 33 357. S. A. R. Knox R. J. Hoxmeier and H. D. Kaesz Inorg. Chem. 1971,10,2636 Transition-metal Carbonyl Organometallic and Related Complexes 323 radical.51 y-Irradiated Mn,(CO), at 77 K givesrise to the species [Mn,(CO),,]-, the extra electron being in a metal-metal cr-antibonding orbital.52 The crystal structure of the salt [(phen),Ni] [Mn(CO),] has been determined. As expected, the anion is ideally trigonal-bipyramidal. The axial CO distance is slightly but not significantly larger than the mean value for the equatorial CO groups which differ appreciably among themselves. Two groups agree in calculating the highest occupied orbital of Mn(CO),CH to be that arising from the metal-carbon o-bond. The photoelectron can then be re-assigned closer to expecta-tion d(e) being placed at almost the same energy as d(b,) rather than being con-siderably more table.^^^^^ There is no evidence from these calculations for any n-acceptor character of the CF group when bound to pentacarb~nylmanganese.~ The electronic spectra of a range of pentacarbonyl derivatives of manganese and rhenium have been presented and discussed using a rather archaic molecular orbital diagram.57*58 The fragment (n-C,H,)Mn(CO) has been generated photochemically and characterized by i.r.spectroscopy in a hydrocarbon matrix at 80K.59 This fragment has been invoked as an intermediate in the reversible thermal conversion of (n-C5H5)Mn(C0),(SiPh,)H into (n-C,H,)Mn(CO),(PPh,) triphenylsilane being lost in one concerted step.60 The reaction sequence that converts (n-C,H,)Mn(CO) into (n-C,H,)-Mn(CO),(CS)6’ can be repeated to give (n-C,H,)Mn(CO)(CS) and even (n-C,H,)Mn(CS) .The CS stretching frequency rises with increased substitution, indicating that CS is a more electron-demanding group than C0.62 The rapid conversion of Mn(CO),Cl in liquid ammonia into cis-Mn(CO),(NH,)CONH, has been described as has the subsequent formation of a cyanide complex and of the cation [(NH,),Mn(CO),] + .63 Pentacarbonylmanganese halides have been shown by i.r. to complex such Lewis acids as AlCl and FeCl in solution by donation from halogen and halides (n-C,H,)Fe(CO),X (Me,P),Fe(CO),X , and (Me,P),Ni(CO)I react similarly.64 The thermal and photochemical exchange of 13C0 with Mn(CO),Br has been studied. There is a slight preference for loss of axial CO at least in the thermal process.65 ” E.0. Fischer F. OfThaus J. Muller and D. Nothe Chem. Ber. 1972 105 3027. 5 2 0. P. Anderson and M. C. R. Symons J.C.S. Chem. Comm. 1972 1020. 53 B. A. Frenz and J. A. Ibers Inorg. Chem. 1972 11 1109. 5 4 S. Evans J. C. Green M. L. H. Green and D. W. Turner Discuss. Faraday Soc., ’’ M. B. Hall M. F. Guest and I. H. Hillier Chem. Phys. Letters 1972 15 592. 5 6 M. B. Hall and R. F. Fenske Znorg. Chem. 1972,11 768. ’’ G. B. Blackney and W. F. Allen Znorg. Chem. 1971 10 2763. ’* H. B. Gray G. Billig A. Wojcicki and M. Farona Canad. J. Chem. 1963,41 1281. 5 9 P. S. Braterman and J. D. Black J. Organometallic Chem. 1972,39 C3. 6 o A. J. Hart-Davis and W. A. G. Graham J. Amer. Chem. SOC. 1971,93,4388.6 1 6 2 A. E. Fenster and I. S. Butler Canad. J . Chem. 1972,50 598. 6 3 H. Behrens E. Lindner D. Maertens P. Wild and R.-J. Lampe J . Organomerallic 6 4 M. Pankowski B. Demerseman G. Bouquet and M. Bigorgne J . Organometallic 6 5 A. Berry and T. L. Brown Znorg. Chem. 1972,11 1 165. 1969 No. 47 p. 112. I. S. Butler and A. E. Fenster Chem. Comm. 1970 933. Chem. 1972,34,367. Chem. 1972,35 155 324 P. S. Braterman The crystal structure of Hg[Mn(CO),] has been determined. The Mn(CO), groups are eclipsed and the HgMnC (equatorial) angle is 84.3°.66 Somewhat surprisingly electron-diffraction data indicate an eclipsed configuration in Re,(CO), also.67 The reaction of Re,(CO), with a limited amount of ReF, in HF leads to a material of empirical formula Re(CO),F,.68 The reaction of Ph,SiH,Re,(CO) with silicic acid gives H,Re,(CO) .This has been shown crystallographically to have the structure (3) (hydrogen atom positions assumed). 0 0 C O\ C O/ I I I I / O C / \ 0 c , 0 0 (3) The rhenium-rhenium distance of 290pm is the shortest on record as befits a 'double' or 'bis-3-centre hydrogenated' bond.69 The preparation and intercon-versions of the species [Re"'(CO),I,] - [Re11(CO),I,]2 - and [Re(CO),I,] - have been described and u.v. i.r. and magnetic data presented. It is found that the CO stretching parameters are more sensitive to the overall charge of the complex than to the formal oxidation state of the metal.70 Ion-cyclotron resonance studies of iron carbonyl fragments have revealed a variety of processes including replacement of CO from cations Fe(CO),+(n < 4) by CH3F or H,O and reaction between fluoride (or methoxide) anions and Fe(CO) to give [YFe(CO),]- and free C0.71 13C n.m.r.shifts of the carbonyl groups in compounds (n-C,H,)Fe(CO),X show a linear dependence of the 13C chemical shift on Taft's o1 for X.72 Di-iron enneacarbonyl reacts with HBr or HI to give species [Fe(CO),X] which can also be generated photochemically from iron pentacarbonyl and the hydrogen halide.7 The reaction of 1,2,3-thiadiazoles (4) with Fe,(CO) gives both 'normal' products (5) and crossover products (6). The occurrence of the latter may be explained by invoking intermediates (7) in which the original distinction between the sites of R1 and R2 has been lost.74 Indenyl-6 6 M.L. Katcher and G. L. Simon Inorg. Chem. 1972 11 1651. 6 7 N. I. Gapotchenko N. V. Alekseev N. E. Kolobova K. N. Anisimov I. A. Ronova, and A. A. Johansson J. Organometallic Chem. 1972 35 319. 6 8 T. A. O'Donnell and K. A. Phillips Inorg. Chem. 1972 11 2563. 6 9 M. J. Bennett W. A. G. Graham J. K. Hoyano and W. L. Hutcheon J . Amer. Chem. ' O M. Freni P. Romiti V. Valenti and P. Fantucci J . Inorg. Nuclear Chem. 1972 34, '' 72 0. A. Gansow D. A. Schexnayder and B. Y . Kimura J. Amer. Chem. SOC. 1972,94, 7 3 E. Koerner von Gustorf J. C . Hogan and R. Wagner Z . Nuturforsch. 1972,27b 140. 7 4 P. G. Mente and C . W. Rees J.C.S. Chem. Comm. 1972,418. SOC. 1972 94 6232. 1195. M. S. Foster and J. L. Beauchamp J . Amer. Chem. SOC. 1971 93 4924. 3406 Transition-metal Carbonyl Organometallic and Related Complexes 325 dicarbonyliron iodide undergoes CO substitution by an S,1 process that is rapid compared either with the cyclopentadienyl or with the tetrahydroindenyl ana-logues.It seems possible that the n-electrons of the indenyl C ring can reduce the unsaturation of the metal in the S,1 ir~termediate.~ In para-substituted deriva-tives of 2-phenylbutadienetricarbonyliron the CO stretching frequencies vary linearly with the oP parameter of the sub~tituents.~~ The cation RuH(CO),(PPh,) + and its osmium analogue react with methoxide to give species M(C0)2(PPh3)3 the i.r. spectra of which show the two CO groups to be mutually trans and thus to occupy the axial positions of a trigonal bipyra-mid.77 The product from the reaction of Ru,(CO) with rneso-tetraphenyl-porphin has been shown crystallographically to be trans-dicarbonyltetraphenyl-porphinatoruthenium(II) in which remarkably the average RuCO angle is 153°.78 There is 'H n.m.r.evidence for averaging of the cis- and trans-isomers of Os(CO),(SiMe,) above room temperature. The process is non-dissociative, since there is no exchange with ' 3C0 and Os(CO),(SnMe,) behaves similarly. The suggested rearrangement intermediate is a five-co-ordinate pseudo-acyl species and in accord with this suggestion ~eplacement of methyl by chlorine raises the coalescence t e m p e r a t ~ r e . ~ ~ The cis-isomer of Ru(CO),(SiCl,) ex-changes only those CO groups trans to silicon whereas the trans-isomer shows no thermal exchange under similar conditions but does exchange photochemically.It follows that the distinction between cis- and trans-CO groups is maintained in the reaction intermediates. The Ru-Ge analogues show similar specificity, though the related iron-silicon species does not.80 The rate and equilibrium constants of the reaction of dicobalt octacarbonyl with hydrogen giving tetracarbonylcobalt hydride have been reported. It is inferred that the rate-determining step in the forward reaction is a reaction '' D. J. Jones and R. J. Mawby Znorg. Chim. Acta 1972 6 157. 7 6 J. M. Landesberg and L. Katz J . Organometallic Chem. 1972 35 327. 7 7 '13 D. Cullen E. Myer jun. T. S. Srivastava and M. Tsutsui J.C.S. Chem. Comm., 79 R. K. Pomeroy and W. A. G. Graham J . Amer. Chem. SOC. 1972,94 274.B. E. Cavit K. R. Grundy and W. R. Roper J.C.S. Chem. Comm. 1972 60. 1972 584. R. K. Pomeroy R. S. Gay G. 0. Evans and W. A. G. Graham J . Amer. Chem. SOC. 1972 94 272 326 P. S. Braterman between CO,(CO) and dihydrogen.8 The heptacarbonyldicobalt intermediate has also been invoked in a re-evaluation of the reaction between Co,(CO) and alkynes to give Co,(CO),(alkyne) as the eventual product.82 The species [CO(CO),(CN),]~ - is formed by the reaction of aqueous [Co(CN),HI3 - with CO in the presence of hydroxide. The reaction is first-order in hydroxide and in the initial complex suggesting [Co(CN),I4- as a reaction intermediate.83 The integrated i.r. intensity of the CO stretching band has been proposed as a measure subject to certain reservations of n-bonding in the species trans-(Ph,P),Rh(X)CO and their iridium analogues.84 The crystal structure (8) of the II 0 (8) solvated bridged species [(Ph3P),Rh(C0)] ,2CH,Cl has been determined.Noteworthy features include the co-ordination geometry around rhodium and the asymmetry of the carbonyl bridges.85 The carbonylated species formed on dissolving rhodium trichloride in dimethylformamide reacts with chelating nitrogen ligand precursors HLL including Schiff s bases and imidazoles to give species (LL)Rh(CO) [e.g. (9) for HLL = f~rrnazan].~~ The crystal structure R2 -R‘ 0 / / /,,-- N-N /C \ -.__ N-N/ \C . C Rh C / _ - - - / (9) of the dicarbonyl(thiocarbonyl)bis(triphenylphosphine)iridium(I) cation as the acetone adduct of its hexafluorophosphate has been determined.The phosphine ligands are axial and the iridium-thiocarbonyl distance is shorter than those between Ir and C0.87 F. Ungvary J. Organometallic Chem. 1972,36 363. 8 2 P. C. Ellgen Inorg. Chem. 1972,11 691. 8 3 G. Guastalla J. Halpern and M. PribaniC J . Amer. Chem. Soc. 1972 94 1575. 8 4 R. Schlodder S. Vogler and W. Beck Z. Naturforsch. 1972 27b 463. 8 5 C. B. Dammann P. Singh and D. J. Hodgson J.C.S. Chem. Comm. 1972 586. 86 Yu. S. Varshavskii T. G. Cherkasova 0. A. Osipov N. P. Bednyagina A. D. Gar-novskii R. I . Ogloblina G. K. Mitina and G. N. Lipunova Russ. J. Inorg. Chem., 1972 17 726. J. S. Field and P. J. Wheatley J.C.S. Dalton 1972 2269 Transition-metal Carbonyl Organometallic and Related Complexes 327 Species NiF,(CO) and NiCI,(CO) and related dinitrogen complexes have been prepared by matrix-deposition methods,88 as have the long-sought-for tetracarbonyls of palladium and platinum.These show one polarized Raman-active mode in the CO stretching region at higher frequency and one other mode at lower frequency that is both i.r.- and Raman-active. This is as expected for tetrahedral species the modes corresponding to the A and T2 carbonyl-stretching motions. The actual wavenumbers found are of some interest being 2122 and 2066 cm-I for Pd(CO) in CO and 21 19 and 2049 cm-' for Pt(CO) in CO. These values compare with 2130 and 2043 cm-' for Ni(CO) under the same condi-t i o n ~ ~ ' so that the wavenumbers of Pd(CO) deviate from those required by simple interpolation in much the same way as do those of Mo(CO) .A range of cations of the type trans-[PtX(CO)L,]+ (L = e.g. PPh ; X = e.g. NO, SCN or halogen) have been prepared by the reaction of trans-L,PtCl with NaX followed by CO. The carbonyl group in these complexes is susceptible to nucleophilic attack reacting in various cases with methanol to give PtX(CO,Me)L and with water to give PtX(H)L .90 The first air-stable copper carbonyl complex HB(pz),Cu(CO) (pz = pyrazolyl), has been prepared by the reaction of KHB(pz) with copper (I) chloride under c0.91 Polynuclear Carbony1s.-The reaction of pentacarbonyliron with the anion [(z-C,H,)Mo(CO),] - gives the new species [Fe,C(C0),,I2 - isoelectronic with the long-established Fe,C(CO) .92 The reaction of the phosphinoacetylene Ph,PC-CCF with dodecacarbonyltri-iron gives a product that was character-ized crystallographically as (10) There is evidence from the broad-line n.m.r.spectrum of Ru,(cot),(CO), (cot = cyclo-octatetraene) that the cot rings are continually reorienting them-selves even in the solid.94 The reactions of Ru,(CO), with butylacetylene or with phenylacetylene give products of composition Ru,(CO),(RCCH) the 88 8 9 9 0 91 92 9 3 94 C. W. DeKock and D. A. Van Leirsburg J . Amer. Chem. SOC. 1972,943235. ( a ) H. Huber P. Kiindig M. Moskovits and G. A. Ozin Nature Phys. Sci. 1972, 235 98; (6) P. Kundig M. Moskovits and G. A. Ozin J . Mol. Structure 1972 14, 137. W. J. Cherwinski and H. C. Clark Inorg. Chem. 1971 10 2263. M. I. Bruce and A. P. P. Ostazewski J.C.S. Chem. Comm.1972 1124. A. T. T. Hsieh and M. J. Mays J. Organometallic Chem. 1972 37 C53. T. O'Connor A. J. Carty M. Mathew and G. J. Palenik J . Organometallic Chem., 1972 38 C15. C. E. Cottrell C. A. Fyfe and C. V. Senoff J . Organometallic Chem. 1972 43 203 328 P. S. Braterman 'H n.m.r. spectra of which show the presence of hydride as a ligand.95 When Ru,(CO), is allowed to react with sulphite in the presence of hydroxide ion a species H,Ru,(CO),S is formed; the selenium and tellurium analogues may be prepared similarly. These species are described as being paramagnetic with two unpaired electrons per molecule and as showing a single signal around z = 30 in their 'H n.m.r. spectra.96 Ru,(CO) reacts with bicyclo[3,2,l]octa-2,6-diene to give a product assigned from its physical properties as (1 1),97 and with cis,cis-or trans,trans-hexa-2,4-diene to give a product characterized crystallographically as (12).The central C fragment of (11) acts as a 7c-ally1 ligand to one of the ruthenium atoms while being a-bonded at each end to one of the other two. (1 1) (12) The 'H and I3C n.m.r. spectra have been analysed and the proposed position of the ligand hydrogen is compatible with the observed "CO-'H coupling.98 The reaction of a-H,Ru,(CO) with ethylene gives a product H,Ru,(CO),CCH . The structure (13) closely related to that of the range ofcompounds Co,(CO),CY, CH3 I (13) is inferred from 'H and I3C n.m.r. data.99 The structure of a-H,Ru,(CO), has been determined and found to be related to that of H,F~RU,(CO)~,.'~~ The reaction of H,Ru,(CO) with cyclo-octadiene gives rise to a range of species, 9 5 96 97 9 8 9 9 100 E.Sappa 0. Gambino L. Milone and G. Cetini J . Organometallic Chem. 1972 39, 169. E. Sappa 0. Gambino and G. Cetini J. Organometallic Chem. 1972 35 375. A. J. P. Domingos B. F. G. Johnson,and J. Lewis J. Organometallic Chem. 1972,36, c43. M. Evans M. Hursthouse E. W. Randall E. Rosenberg L. Milone and M. Valle, J.C.S. Chem. Comm. 1972 545. A. J . Canty B. F. G. Johnson J. Lewis and J. R. Norton J.C.S. Chem. Comm., 1972 1331. D. B. W. Yawney and R. J. Doedens Znorg. Chem. 1972 11 838 Transition-metal Carbony 1 Organometallic and Related Complexes 329 including one Ru,(CO) l(C,H,o) for which the structure (14) has been deter-mined. lo' The compound H,Ru,(CO) 8 is approximately octahedral with two opposed triangular faces being slightly larger than all the others and it is suggested that the hydrogen atoms (which cannot be located directly) are seated above the centres of these faces.", The pyrolysis of Ru,(CO), in a sealed tube gives Ru,(CO),,C showing that (under these conditions at least) the lone carbon atom is generated from carbonyl.Pyrolysis of Os,(CO), gives species which from their mass spectra appear Os,(CO) 5C4.103 The Raman and i.r. spectra of OS,O,(CO) 2 between 2200 and 67 cm- have been reported and the results for the CO stretching region have been analysed in some detail assuming tetrahedral symmetry. lo4 The reaction of Os,(CO), with triphenylphosphine gives no fewer than nine pro-ducts among them Os,(CO),(PPh,)(Ph)(PhPC,H,) (15a) Os,(CO),(PPh,),-to be OS&O),3 7 os5(co)16 7 osfj(c0),8 7 os7(co)21? os,(co)23 7 and (C6H4) (15b) (16a) HOs,(CO),(PPh,)(PPh,)-(C6H4) (17) HOS3(CO)8(PPh,)(PPh,C,H,) (18) and HOS,(CO),(PP~,)-(PPh,C,H,C,H,) (19).'05*'06 The range of differkg distances between formally bonded metals in compounds of this sequence is large.The compound (16b) contains two sets of magnetically non-equivalent methyl groups the separate signals from which are frozen out below 278 K but show averaging at higher temperature^."^ Related to the formation of the benzyne complex (15b) is the reported reaction of Os,(CO) with benzene to give H20S3(C6H4)(CO)9 . This is a more general reaction of species H,X where X can act as a four-electron l o l A. J.Canty B. F. G. Johnson and J. Lewis J . Organometallic Chem. 1972 43 C35; R. Mason and K. M. Thomas ibid. p. C39. M. R. Churchill and J. Wormald J . Amer. Chem. SOC. 1971 93 5670. l o 3 C. R. Eady B. F. G. Johnson and J. Lewis J. Organometallic Chem. 1972 37 C39. ' 0 4 W. van Bronswyk and R. J. H. Clark Spectrochim. Acta 1972 28A 1429. C. W. Bradford R. S. Nyholm G. J . Gainsford J . M. Guss P. R. Ireland and R. Mason J.C.S. Chem. Comm. 1972 87. C. J. Gainsford J. M. GUSS P. R. Ireland R. Mason C. W. Bradford and R. S. Nyholm J . Organometallic Chem. 1972,40 C70. l o ' A. J. Deeming R. S. Nyholm and M. Underhill J.C.S. Chem. Comm. 1972 224 330 P. S. Braterma Transition-metal Carbonyl Organometallic and Related Complexes 33 1 donor bridging three osmium atoms and the species H,Os,(C,H,)(CO) and H,OS,(CO)~S (cfi also ref.96) have been prepared in this way.''* However, crystallographic investigation of Ph,C,Os,(CO) shows it to possess the struc-ture (20) in which the backbone of the organic ligand is co-ordinated only to two osmium atoms. lo9 Ph Ph (20) The reaction of dicobalt octacarbonyl with trimethylamine-boron trichloride gives a species with one unpaired spin for which the structure (21) is suggested.' lo OBCl ,NEt, I I OBC1 ,NEt (21) The tetracarbonylcobaltate anion has been allowed to react with a number of metal halides in order to prepare compounds with heterometallic bonds. For example aluminium trichloride gives a product AlCo,(CO) while the bis-(cyclopentadienyl) dichlorides of titanium and zirconium give products (~-CsH5)2-TiCo,(CO) and (TC-C~H,),Z~,C~,(CO) .' ' The reaction with nickel(r1) chloride is more complicated giving at least the two products ~iCo,(CO) -and Co,Ni,(CO), .' l 2 The reaction of the Friedel-Crafts reagent Co,(CO),-CCl.* eAlC1 with a variety of species HX (X = e.g. RO PhS H,N or ferrocenyl) gives the unexpected products XCO-CCo,(CO) in high yield.' The crystal structures of Co,(CO),S and Co,Fe(CO),S have been compared and the ' 0 8 A. J. Deeming and M. Underhill J . Organometallic Chem. 1972,42 C60. l o 9 G. Ferraris and G. Gervasio J.C.S. Dalton 1972 1057. ' l o G. Schmid and B. Stutte J. Organometallic Chem. 1972,37 375. '' ' K. E. Schwarzhans and H. Steiger Angew. Chem. Znternat. Edn. 1972 11 5 3 5 . 1 1 3 D. Seyferth and G.H. Williams J. Organometallic Chem. 1972 38 C1 1. P. Chini A. Cavaliero and S. Martinengo Co-ordination Chem. Rev. 1972 8 3 332 P. S . Bratermun presence of an antibonding electron in the former compound is confirmed by scrutiny of bond lengths. ' l4 These studies have been extended to include Co,-(CO),Se and FeCo,(CO),Se.' " Treatment of dicobalt octacarbonyl with bis-dimethylphosphine disulphide gives products which from their mass spectra are formulated as SCO,(CO),(PM~~)~ and S,Co,(CO),PMe .' l6 A range of species of general type CO~(CO)~ -,[P(OMe),] has been prepared; they show temperature-dependent spectra which indicate the occurrence of some kind of exchange process. The i.r. spectra can be assigned and related to that of the parent carbonyl assuming this to have the same structure in solution as in the solid.' The conversion of [Rh(CO),Cl] into Rh4(C0),2 in alcoholic solvents in the presence of sodium carbonate has been shown to require the presence of critical amounts of water.'18 The 13C n.m.r. spectrum of Rh,(CO), is temperature-dependent and shows averaging of all bridging and terminal signals."' Rh4-(CO), is converted by mixtures of propene and hydrogen gas at room tempera-ture into RhJCO), with concomitant formation of the hydroformylation products CH,CH,CH,CHO and (CH,),CH-CHO. Both hydrogen and propene are necessary and CO inhibits the reaction suggesting reversible dissociation as a first step. In polar solvents [RhJCO) ,-COR] - is formed along with traces only of aldehydes.120 Carbonyl Phosphines.-The one-stage preparation of carbonyl phosphine and related species12' is improved by the use of potassium hydroxide in ethanol as a reducing agent ; cis-RuCl,(CO)(PPh,) and OsH,(CO),(PPh,) have been prepared in this way.'22 The redox system based on V(CO),(dppe) has been explored [dppe = 1,2-bis(dipheny1phosphino)ethanel.Thus treatment of the anion [V(CO),(dppe)] -with t-butyl chloride in water gives the hydride which decomposes to generate paramagnetic neutral V(CO),(dppe). This can be prepared directly from the anion using a suitable oxidizing agent (e.g. the tropylium cation which is con-verted into bitropyl) and reduced back again by sodium amalgam. Nucleo-philic attack by the anion on iodine or iodolysis of Ph,SnV(CO),(dppe) gives IV(CO),(dppe) which reacts with the anion to regenerate the neutral species and free iodide.' The phosphorus-phosphorus coupling constant can be found by analysis of the I9F 'H and 31P n.m.r.spectra of species [(CF,),P(R)],M(CO) (M = Cr Mo, or W) and falls in the order X = F > C1 > Br > I > H being unusually small 1 1 4 D. L. Stevenson C. H. Wei and L. F. Dahl J . Amer. Chem. SOC. 1971,93,6027. l 5 C. E. Strouse and L. F. Dahl J. Amer. Chem. SOC. 1971,93 6032. l 6 G. Natile S. Pignataro G . Innorta and G. Bor J . Organometallic Chem. 1972,40,215. l 7 D. Labroue and R. Poilblanc Inorg. Chim. Acta 1972 6 387. 1 1 * P. E. Cattermole and A. G. Osborne J . Organometallic Chem. 1972 37 C17. 119 F. A. Cotton L. Kruczynski B. L. Shapiro and L. F. Johnson J . Amer. Chem. SOC., l Z o P.Chini S. Martinengo and G. Garlaschelli J.C.S. Chem. Comm. 1972 709. l Z I z 2 N . Ahmad S. D. Robinson and M. F. Uttley J.C.S. Dalton 1972 843. l Z 3 A. Davison and J. E. Ellis J . Organometallic Chem. 1972 36 131. 1972,94,6191. J. J. Levinson and S. D. Robinson J . Chem. SOC. ( A ) 1970 2947 Transition-metal Carbonyl Organometallic and Related Complexes 333 for the (CF,),PH complexes. There is evidence in [(CF,),P(NMe,)J,Mo(CO), and [(CF,),P(NCS)],Mo(CO), for intermolecular exchange.’ 24 In tungsten carbonyl phosphorus trihalide complexes the tungsten-phosphorus coupling constant increases in magnitude with the electronegativity of the halogen but the relationship does not appear to be the same as that connecting PF complexes with those of phosphines and phosphite~.”~ Extensive chemistry based on nucleophilic displacement of chloride can be carried out on Ph,PClMo(CO) and the methyl analogue.Thus chloride can be replaced by dialkylamide alkoxide, mercaptide or sulphydryl while aqueous triethylamine generates the anion [(OC),MoP(O)Ph,] - . This species can couple with trimethylsilyl chloride to give (OC),MoP(OSiMe,)Ph or with excess starting material to generate the diphosphoxane complex (OC),MoPPh,~O~PPh,Mo(CO) . Photochemical substitution of CO in carbonyl phosphine complexes M(CO),L by phosphines L’ gives predominantly cis-Mo(CO),LL although photochemical ,CO exchange occurs in all positions and axial exchange is favoured over exchange at each equatorial site by a factor of around two.”’ Exhaustive photosubstitution of the neutral hexacarbonyls by phosphorus ligands gives as final products species M(CO)(PMe,) (M = Mo or W) and MCO[P(OMe),] and M[P(OMe),F], (M = Cr Mo or W).lZ8 Electrochemical reduction of the bis-p-phosphido-deriva-vatives [M(CO),PR,] of Cr Mo and W and the related species [M‘(CO),PR,], (M’ = Fe or Ru) leads to a large increase in phosphorus-phosphorus coupling, presumably because of the geometrical consequences of removing the metal-metal bonds.’ ,’ MoBr,(CO),(dppe),acetone has been found to possess a fairly regular CO-capped octahedral seven-co-ordinate structure.130 The structure of 2,4,6-triphenylphospholetricarbonylchromium (22) has been determined.The chromium atom lies below the centre of the ring and the chromium-phosphorus distance is long so that the complex seems to be a true aromatic species.13’ Ph (22) Pentacarbonylmanganese bromide reacts with phenylbis-(2-diphenylphos-phinoethy1)phosphine (Ph,PCH,CH,PPhCH,CH,PPh triphos) to give a 124 J.F. Nixon and J. R. Swain J.C.S. Dalton 1972 1038. l Z 5 E. 0. Fischer L. Knauss R. L. Keiter and J. G. Verkade J . Organometallic Chem., 1972 37 C7. (a) C. S. Kraihanzel and C. M. Bartish J . Amer. Chem. SOC. 1972,94 3572; (b) C. S. Kraihanzel and C. M. Bartish J. Organometallic Chem. 1972,43 343. 1 2 7 G. Schwenzer M. Y. Darensbourg and D. J. Darensbourg Znorg. Chem. 1972 11, 1967. R. Mathieu and R. Poilblanc Inorg. Chem. 1972 11 1858. 129 R. E. Dessy A. L. Rheingold and G. D. Howard J. Amer. Chem. Soc. 1972,94,746. 130 M. G. B. Drew J.C.S.Dalton 1972 1329. 131 H. Vahrenkamp and H. Noth Chem. Ber. 1972 105 1148 334 P. S. Braterman species (triphos)Mn(CO),Br in which one end of the triphos ligand is free. This reacts with Cr(CO),(THF) to give two isomers characterized crystallographically, of (OC),Mn(Br)P(Ph,)CH,CH,P(Ph)CH,CH,PPh,Cr(CO) .' 32 The photochemical reaction between phosphine and dimanganese deca-carbonyl gives Mn,(CO),(PH,) the i.r. spectrum of which shows that phosphine occupies one equatorial position.' 3 3 Orthoarsenite and orthoantimonite derivatives of (n-C,H,)Mn(CO) have been prepared by the indirect photo-chemical method in tetrahydrofuran. The order of CO stretching frequencies is (z-C,H,)Mn(CO),{Sb(OR),} 5 (n-C,H,)Mn(CO),{P(OR),} < (n-C,H,)Mn-(CO),(As(OR),).' 34 The reaction of (n-C,H,)Mn(CO),{ PPh(NMe,),} with hydrohalic acid leads to replacement of NMe by halogen.'35 The reactions of the ligand (CF,),PH with iron carbonyls have been described.Iron pentacarbonyl and Fe,(CO), both give rise to a mixture of Fe,(CO),-[P(CF,),] and H,Fe,(CO),[P(CF,),], this last being shown by n.m.r. to be a mixture of the cisoid and transoid species (23a,b). (n-C,H,),Fe,(CO) and Fe-(CO),(NO) give (n-CSH5)Fe(CO),[P(CF,),] and Fe,(NO),[P(CF,),] respec-tively while Fe,(CO) gives Fe(CO),[P(CF,),H]. This is decomposed by heat to give (23).'36 The reaction of a ligand with Fe,(CO) is a general route to H OC \ I Fe / I OC c 0 C0 / \ cO (23) (b) species of the type Fe(CO),(PR,H) and Fe(CO),(PRH,) although in most cases there is some formation of Fe,(CO),(PR,) and in the case of secondary phos-phines Fe,(CO),(PR,)(H).The species Fe(CO),(PR,H) are acidic enough to be lithiated by butyl-lithium as shown by their subsequent reaction with methyl iodide to give species Fe(CO),(PR,Me). ' The intermediates Fe(CO),PR,Li would presumably be very effective reagents for the formation of novel polynuclear species by nucleophilic displacement of halogen from metal. Such displacing ability is shown by (n-C,H,CH,)Fe(CO),(PPh,) which reacts with rhodium dicarbonyl chloride dimer to give the cation (24) in which the rhodium atom is co-ordinately unsaturated and of unusual geometry.' 38 Species (LLL)Fe(CO), [LLL = e.g. l,l,l-tris(diphenylphosphinomethyl)methane] cannot be formed 1 3 ' 1 3 3 E. 0. Fischer and W.A. Herrmann Chem. Ber. 1972,105,286. 134 T. B. Brill J. Organometallic Chem. 1972,40 373. 1 3 ' M. Hofler and M. Schnitzler Chem. Ber. 1972 105 1133. 136 R. C. Dobbie M. J. Hopkinson and D. Whittaker J.C.S. Dalton 1972 1030. 1 3 ' (a) P. M. Treichel W. K. Dean and W. M. Douglas Inorg. Chem. 1972 11 1609; 1 3 ' R. J. Haines R. Mason J. A. Zubieta and C. R. Nolte J.C.S. Chem. Comm. 1972,990. M. L. Schneider N. J. Coville and I . S. Butler J.C.S. Chem. Comm. 1972 799. (b) P. M. Treichel W. M. Douglas and W. K. Dean ibid. p. 1615 Transition-metal Carbonyl Organometallic and Related Complexes 335 \ / \ / F -Rh e \ CO Fe -/ \ PPh ' 'PPh C 0 -(24) directly from Fe(CO), which disproportionates but may be prepared by the reaction of the terdentate ligand with cyclo-octatetraenetricarbonyliron.39 There is spectroscopic evidence that solid Fe(CO)(PF,) exists as one isomer only, whereas in solution the isomer with CO equatorial is more stable by about 8 kJ While ruthenium trichloride is reduced on refluxing in 2-methoxyethanol in the presence of CO and normal phosphines to species RuCl,(CO),L, the bulky ligand bis-(t-buty1)phenylphosphine gives rise to (25).14' The photoreaction of mol- 1 140 c1 (25) Ru(trans-PPh,)2(cis-CO),cis-I gives the isomer in which all pairs of identical ligands are mutually trans ; this process is thermally rever~ib1e.l~~ Ru,(CO) , reacts with PF at high pressures to give species Ru(CO) -x(PF3)x (x = 3,4, or 5) which appear from their 19F n.m.r. spectra to be non-rigid. At lower pressures of PF and higher pressures of CO replacement of up to six CO ligands occurs without cleavage of the Ru skeleton.The controlled pyrolyses in decalin of Ru,(CO),(PPh,) and related species give rise to a variety of di- and tri-nuclear species containing bridging phosphido-groups and ortho-metallated phenyl rings (cf refs. 105,106 and 107);144 for example the product HRu,(CO),-[P(OC,H,) (OPh),],[OP(OPh),] formed by pyrolysis of the triphenyl phosphite species has the structure (26).14, Stereochemical non-rigidity has been demonstrated by H n.m.r. studies of cobalt carbonyl phosphine cations [Co(CO) -nLn]+. 146 Phosphites as well as 1 3 9 H. Behrens H.-D. Feilner and E. Lindner 2. anorg. Chem. 1971,385 321. 140 M. Bigorgne and J. B. Pd. Tripathi J . Mol. Structure 1971 10 449.14' R. Mason K. M. Thomas D. F. Gill and B. L. Shaw J . Organometallic Chem. 1972, 40 C67. J. Jeffery and R. J. Mawby J . Organometallic Chem. 1972,40 C43. 143 C. A. Udovich and R. J. Clark J . Organometallic Chem. 1972,36 355. M. I. Bruce G. Shaw and F. G. A. Stone J.C.S. Dalton 1972 2094. l C 5 M. I . Bruce J. Howard I . W. Nowell G. Shaw and P. Woodward J.C.S. Chem. Comm. 1972 1041. ' 4 6 S. Attali and R. Poilblanc Znorg. Chim. Acta 1972,6 475 336 P. S. Braterman Ph phosphines react with Hg[Co(CO),] to produce bis-axially substituted species Hg[Co(CO),L] but light must be excluded to prevent precipitation of mercury. Excess ligand reacts further to give species Hg[Co(CO),L,] . 14' Rhodium carbonyl halides [Rh(CO),X] react with phosphorus trifluoride under increasingly forcing conditions to give Rh,(CO),- x[PF,]xX,, [Rh(PF3)2X] and Rh(PF,),X.148 The oxidative addition reactions of sterically hindered species trans-IrX(CO)L, have been studied. For L = PBu'Me, the reaction occurs even with acyl and ally1 chlorides whereas for L = PBu'Et, methyl iodide and di-oxygen can be added but no larger species. The species with L = PBukMe very slowly adds dichlorine or dioxygen but the PBuiEt derivatives and those of even more hindered phosphines do not react at all.' 49 Oxidative addition of para-sub-stituted thiophenols to the species trans-(Ph,P),Ir(CO) is first-order in each component faster for the iodide than the chloride and accelerated by electron-withdrawing substituents on the phenyl ring of the species added.The addition is cis as shown by i.r. and n.m.r. spectra of the products.'50 Oxidative addition of toluene-2,3-dithiol to (Ph,P),Ir(CO)Cl gives (27).' ' Some 19,1r Mossbauer spectra have been collected for a series of compounds (Ph,P),Ir(CO)ClXY. In these compounds a high CO stretching frequency correlates in general with a large negative isomer shift and thus with a decrease in s-electron density at the nucleus. This is contrary to what would have been expected on simple arguments from electron density and shielding and some other effect such as distortion of the 'tZg1 orbitals must be invoked.'52 The five-co-ordinate Ni" carbonyl NiI,(CO) (PMe,) has been prepared both by iodine oxidation of Ni(CO),(PMe,) and by carbon monoxide addition to NiI,(PMe,) .' 53 Ni(CO),(PPh,) is a good catalyst for the cyclotrimerization 14' J .Newman and A. R. Manning J.C.S. Dalton 1972 241. 14' J. F. Nixon and J. R. Swain J.C.S. Dalton 1972 1044. 149 B. L. Shaw and R. E. Stainbank J.C.S. Dalton 1972 223. l S o J. R. Gaylor and C. V. Senoff Canad. J. Chem. 1972 50 1868 3085. l S 1 G. P. Khare and R. Eisenberg Inorg. Chem. 1972 11 1385. 1 5 2 H. H. Wickman and W. E. Silverthorn Znorg. Chem. 1971 10 2333. 1 5 3 M. Pankowski and M. Bigorgne J . Organometallic Chem. 1972 35 397 Transition-metal Carbonyl Organometallic and Related Complexes 337 PPh, / C \ 0 \ of diacetylenes RC-CC-CR to give the asymmetric product 1,2,4-trialkyl-3,5,6-trialkynylbenzene. More active catalysts are less useful since they activate the product.5 4 Carbonyl Nitrosy1s.-Nitrosyl chloride has been used to prepare carbonyl nitrosyl chlorides of the Group VI metals. For example the reaction of (CH,-CN),Mo(CO) with NOCl followed by treatment with dppe or bipyridyl, gives Mo(CO),(NO)(dppe)Cl or Mo(CO),(NO)(bipy)CI. ' Tetracarbonyl-nitrosylmanganese undergoes photochemical replacement of CO by other nucleo-philes the yield being dependent on the nature of the nucleophile.' 56 The solution i.r. and low-temperature n.m.r. spectra of [(n-C,H,)Mn(CO)(NO)] indicate the presence of a mixture of isomers (28a) (28b) and their enantiomers. Cisoid-(284 (28b) transoid interconversion occurs in solution and at least three separate averaging processes are involved. ' 5 7 The reaction of the (TC-C,H,)R~(CO),(NO)~ cation with borohydride does not give the expected hydride (n-C,H,)Re(CO)(NO)H, but rather the species (n-C,H,)Re(CO)(NO)CH,.The hydride can however be generated by treatment of [(n-C,H,)Re(CO),(NO)] + with aqueous trimethyl-amine presumably by addition of hydroxide to one CO group followed by elimination of CO . ' 5 8 A. J. Chalk and R. A Jerussi Tetrahedron Letters 1972 61. D. P. Keeton and F. Basolo Inorg. Chirn. Acta 1972 6 33. T. J. Marks and J. S. Kristoff J . Organornetallic Chem. 1972 42 C91. R. P. Stewart N. Okamoto and W. A. G. Graham J . Organornetallic Chem. 1972,42, C32. 15' W. R. Robinson and M. E. Swanson J. Organometallic Chem. 1972 35 315 338 P. S. Braterman The [Fe(CO),(NO)]- anion at a mercury electrode gives reversibly Hg[Fe-(CO),(NO)] with irreversible oxidation probably via the Fe(CO),(NO) radical occurring at more oxidizing potentials.At the platinum electrode one-electron oxidation to presumably Fe(CO),NO is observed as is a one-electron reduction. This latter it is suggested corresponds to the placing of an electron in the formally vacant NO(n*)orbitals.' 5 9 Displacement ofCO from Fe(CO)(NO),L by an entering phosphorus ligand or of CO + L by entering dppe occurs by an associative mechanism in contrast to similar reactions of Ni(C0)3L.160 The crystal structure of Hg[Fe(CO),(N0)(PEt3)1 has been determined. The apparent symmetry is D,, with presumably disordering of the positions of equatorial CO and NO groups.161 The reaction of Ru,(CO),~ or OS,(CO), with NO gives species M(C0) ,(NO) . X-Ray crystallography of the ruthenium derivative reveals the structure (29) with bridging NO groups.'62 0 oc c co \ I / RU oc /k\ / co \ ----N----OC -Ru Ru-CO 'CO / -N/ oc 0 2 Organometallic Complexes One-carbon Ligands.-Cyanides and Isonitriles.It has been shown by the use of optically active isonitriles to give resolvable species (z-C5H5)Mo(CO)(NO)-(CNR) followed by reaction with further isonitrile that replacement of one RNC group by another occurs with inversion.163 Voltammetric studies have been carried out on a range of complexes of the type Cr(CNR) and [Mn(CNR),] +. [Mn(CNMe),] + is more easily oxidized than [Mn(CNAr),]+ and the Mn2 + com-plexes so formed are capable of undergoing a further oxidation step. The Cro complexes can be oxidized by one step only without decomposition but may also be reduced by one step.' 64 The isonitrile tetracarbonyliron complex (OC),-FeCN(to1) (to1 = p-tolyl) is formed by elimination of triphenylphosphine oxide between iron pentacarbonyl and the reagent Ph,P N(to1); this is a rare example of the de-oxygenation of co-ordinated C0.'65 A 1,2 hydride shift converts species RuI(H)(CNR')(CO)(PPh,) in the presence of the carboxylate R2C02 -, l S 9 S.M. Murgia G . Paliani and G. Cardaci 2. Naturforsch. 1972 27b 134. I6O G . Cardaci and S. M. Murgia Inorg. Chim. Acta 1972 6 222. 1 6 1 F. S. Stephens J.C.S. Dalton 1972 2257. 1 6 2 J. R. Norton J. P. Collman G . Dolcetti and W. T. Robinson Inorg. Chem. 1972,11, 1 6 3 H. Brunner and M. Lappus Angew. Chem. Znternat. Edn. 1972 11 923. 164 P.M. Treichel and G. E. Dirreen J . Organometallic Chem. 1972,39 C20. 1 6 5 H. Alper and R. A. Partis J . Organornetallic Chem. 1972 35 C40. 382 Transition-metal Carbonyl Organometallic and Related Complexes 339 into R2C02Ru(CH :NR1)(CO)(PPh,)2 which can also be generated by the reaction of the primary alcohol R2CH,0H with RuO,(CO)(CNR'). The con-version of isonitrile hydride iodide into iminomethyl carboxylate is reversed by excess iodide. 66 Carbene Complexes. The range of available carbene complexes has been further extended by using novel nucleophiles to attack co-ordinated CO or carbene. Thus treatment of chromium or tungsten hexacarbonyl with LiPMe, followed by triethyloxonium fluoroborate gives the complexes (OC),MC(PMe,)OEt. 167 Thiocarbene complexes may be produced by the general route: (OC),M:C(OMe)R' + HSR2 + (OC),M:C(SR2)R1 + MeOH Lr.ionization potential and dipole-moment data indicate that thiocarbene as a ligand is intermediate between alkoxy- and amino-carbenes. 16* The crystal structure of one thiocarbene complex (OC),CrC(SPh)Me has been reported. The carbon-sulphur distance is short consistent with some multiple-bond character. In series of carbene complexes the force constant for CO trans to the substituent is sensitive to a-bonding between metal and carbene-carbon. 16' The reaction of dimethylphosphine with (OC),Cr C(0Me)Ph is not under the conditions used analogous to the thiol-alkoxycarbene reaction referred to above, but gives the nucleophilic addition product (30).I7O In (OC),Cr :C(OEt)NEt,, the CO and CN distances within the alkoxy(dialky1amino)carbene fragment are 134.6 and 132.8 pm respectively showing that there is more n-donation by nitrogen than by oxygen to the co-ordinated carbon atom.17' In the highly asymmetrical sterically hindered carbene complex (3 1) it has been shown by H /OMe (OC),Cr- -C-Ph I P+HMe, _ _ CHPhMe /N, (OC),Cr C I (30) (31) n.m.r.that rotation around each of the bonds (carbene carbon-nitrogen) and (carbene carbon-naphthyl) is slow. 72 The cis- and trans-isomers of Cr(CO),-(PEt,) C(Me)OMe and related species interconvert at ca. 335 K in hydrocarbon solvents by first-order kinetics without decomposition and with no inhibition 1 6 6 1 6 7 1 6 8 169 1 7 0 1 7 1 1 7 2 D. F. Christian G. R.Clark W. R. Roper J. M. Waters and K. R. Whittle J.C.S. Chem. Comm. 1972,458. E. 0. Fischer F. R. Kreissl C. G. Kreiter and E. W. Meineke Chem. Ber. 1972, 105,2558. E. 0. Fischer M. Leupold C. G . Kreiter and J. Miiller Chem. Ber. 1972 105 150. R. J. Hoare and 0. S . Mills J.C.S. Dalton 1972 653. F. R . Kreissl C. G. Kreiter and E. 0. Fischer Angew. Chem. Internat. Edn. 1972,11, 643. G . Huttner and B. Kreig Chem. Ber. 1972,105 67. H. Brunner E. 0. Fischer and M. Lappus Angew. Chem. Internat. Edn. 1971,19,923 340 P. S. Braterman by added CO or phosphine; thus the reaction is apparently intramolecular. 1 7 3 Two groups' 74* have studied the n.m.r. spectra of pentacarbonylmetal carbene complexes. The carbene-carbon is strongly deshielded and accepts charge from the lone pairs of attached oxygen and nitrogen.Thus the signals of the substituents in the carbene as well as that of the trans-carbonyl group, are shifted downfield. The results accord well with the general observation that electron-releasing groups stabilize carbene complexes. ' 74,175 Dicyanomethyl-enecarbene complexes can be formed from dicyanochlorovinyl precursors by reducing the electronegativity of the metal : (NC),C C(Cl)M(CO),(n-CSH,) + 2L (NC),C=C M(Cl)L,(n-C,H,) + CO (L = phosphine arsine or pho~phite).'~~ Carbene complexes react with phos-phorus ylides providing a useful path for vinyl ether formation e.g. 7 7 (OC)sW :C(OMe)Ph + RCH:PPh -+ C(0Me)Ph:CHR + (OC),W(PPh,) where R = H or Me. The reaction of the pentacarbonylmanganese( - I) anion with a,w-dichloro-organic species may prove to be a route of some generality to carbene complexes.The reaction proceeds by nucleophilic displacement of chloride and may require the presence of a second nucleophile. For example Mn(CO),- reacts with P-chlorobutyryl chloride to give (OC),MnCO(CH,),Cl which is converted by excess Mn(CO),- or by lithium iodide into (32a) or (32b) respectively. 178 1 7 3 174 1 7 5 1 7 6 1 7 7 178 1 7 9 180 (a) X = Mn(CO), (b) X = I (32) The methoxyphenylcarbene derivative of iron pentacarbonyl (OC),FeC(OMe)-Ph has been prepared by photochemical exchange between (n-C,H,)Mo-(CO)(NO)C(OMe)Ph and Fe(CO) . However the species (OC),FeC(OEt)R (R = C,F or NMe,) may be prepared by conventional routes at reduced temperatures.' 79 Ethoxy(dialky1amino)carbene derivatives have been prepared conventionally from Fe(CO),(NO) Co(CO),(NO) and Ni(CO) by treatment with dialkylaminolithium followed by Et30+BF4-.'80 The [HFe(CO),] - anion E.0. Fischer H. Fischer and H. Werner Angew. Chem. Infernat. Edn. 1972,11,644. C. G. Kreiter and V. FormaCek Angew. Chem. Internat. Edn. 1972 11 141. J. A. Connor E. M. Jones E. W. Randall and E. Rosenberg J.C.S. Dalton 1972,2419. R. B. King and M. S. Saran J.C.S. Chem. Comm. 1972 1053. C. P. Casey and T. J. Burkhardt J . Amer. Chem. Soc. 1972,94,6543. M. Green J. R. Moss I. W. Nowell and F. G. A. Stone J.C.S. Chem. Comm. 1972, 1339. E. 0. Fischer H.-J. Beck C. G. Kreiter J. Lynch J. Muller and E. Winkler Chem. Ber. 1972 105 162. E. 0. Fischer F. R. Kreissl E.Winkler and C. G. Kreiter Chem. Ber. 1972 105, 588 Transition-metal Carbonyl Organometallic and Related Complexes 341 reacts with 1,4-dimethyltetrazolium fluoroborate [CH :N(CH,).N N-N(CH,)]+-BF,- to give a salt which at raom temperature is converted into a mixture of the carbene complexes (33) and (34). There is restricted rotation around the carbene carbon-nitrogen bonds of (34) and the isomer shown is that actually present in solution since two distinct methyl resonances of equal intensity are observed.18' The crystal structure of the carbene complex CH,NCH=CH.N-(CH,)C Fe(CO) closely related to (33) has been determined. There is extensive delocalization within the ring of the carbene which occupies an apical position. 182 I + I i y 3 5333 I H (34) Nucleophilic addition to two co-ordinated ligands by one bifunctional reagent molecule occurs when the cation [(CH,NC),FeI2 + reacts with hydrazines to give (35).'83 The reaction of iron pentacarbonyl with the dimer of tris(dimethy-1amino)aluminium occurs with addition of Me,N-A1 across co-ordinated CO, giving the carbene complex [(OC),Fe C(NMe,).O-Al(NMe,),] Successive treatment of iron pentacarbonyl in THF with 2,6-dimethoxyphenyl-lithium, followed by Et,O+ BF,- gives the bridging carbene complex (36).18' (35) (36) The rhodium(1) carbene complex (37) has been identified on chemical evidence as the product of the reaction between [Rh(CO),Cl] and diphenylketen or diphenyldiazomethane.Thus (37) reacts with triphenylphosphine to give Ph,C : CPh and rhodium(1) complexes and with pyridine to give a species assigned as (py)ClRh( CPh,)[CO],Rh( CPh,)(py)Cl.This latter reacts with sodium "' K. 6fele and C. G. Kreiter Chem. Ber. 1972 105 529. G. Huttner and W. Gartzke Chem. Ber. 1972 105 2714. A. L. Balch and J. Miller J . Amer. Chem. SOC. 1972,94 417. E. 0. Fischer E. Winkler G. Huttner and D. Regler Angew. Chem. Internat. Edn., 1972 11 238. l S 4 W. Petz and G. Schmid Angew. Chem. Internat. Edn. 1972 11 934 342 /Ph Ph \ P. S. Braterman \ Ph Ph h (3 7) cyclopentadienide to give (n-C,H,)kh( CPh,)CO-Ikh (CPh2)(n-C5H5) which decomposes to give the carbene-bridged species (38).'86 Rhodium(1) carbene species are catalysts in the dismutation of (a=a) + (b=b) to give (a=b) [a is :dN(Ph).(CH,),-N(Ph); b is :CN(p-Me.C,H,).(CH,),.N(p-MeC,H,)].Com-plexes such as (Ph,P),RhCl :a (Ph,P),RhCl b are presumed intermediates and may be interconverted by excess of (a :a) or (b b).'87 The oxidative addition of imidoyl chlorides to rhodium(1) complexes provides a route to Rh"' carbene derivatives. Thus species L,RhCl react with ClC(R') NR2 to give L,(C1)RhCl2 :-C(R').NHR2 in the presence of HCl and L,(Cl)RhCl :C(R').NR,C(R'):NR2 in the presence of excess reagent.'89 I Ph Rh- Rh Ph\ / CSHS\ / c /C5H, CSH, (38) There is increasing agreement that the addition of species HA to isonitrile complexes of the Platinum Group metals giving derivatives of the carbene :C(A).NHR proceeds by way of nucleophilic attack by A on co-ordinated C. Thus reactions of this class are facilitated by electron-withdrawing groups attached to and by electron-donating substituents in the grouping A and (at least for addition of anilines to species of the type cis-[Pd(CN.C,H,.p-Y).LX,]} are first-order in each reagent.' 90 One would then expect the reaction to be further facilitated by net positive charge on the metal and indeed it is found that the tetrakis(methy1 isonitrile) complexes of Pd" and Pt" add dimethylamine to give the tetracarbene complexes [((MeNH),C),MI2 +.' ' The platinum(rr) carbenes formed by addition of hydrazine to (CH,CN),PtX, [compare ref. 183 and l S 6 P. Hong N. Nishii K. Sonogashiva and N . Hagihara J.C.S. Chem. Comm. 1972,993. '13' D. J. Cardin M. J. Doyle and M. F. Lappert J.C.S. Chem. Comm. 1972 927. l S 8 M. F. Lappert and A.J. Oliver J.C.S. Chem. Comm. 1972 274. G. A. Larkin R. P. Scott and M. G. H. Wallbridge J. Organometallic Chem. 1972, 37 c21. B. Crociani T. Boschi M. Nicolini and U. Belluco Inorg. Chem. 1972 11 1292. 1 9 1 J. S. Miller and A. L. Balch Inorg. Chem. 1972 11 2069 Transition-metal Carbonyl Organometallic and Related Complexes 343 (3511 undergo oxidative addition with halogen to give stable Pt" carbene com-plexes. ' 92 Alkyl and Aryl Complexes. The reaction of 2,6-dimethylphenyl-lithium with lutetium chloride in THF at 195 K gives the salt [Li(THF),]+[(aryl),Lu]- in which lutetium is tetrahedrally co-ordinated by aryl groups. 19,. Complexes of the type MeTiCl,(LL) have been prepared where LL is an asymmetric bidentate ligand. The complexes are in the mer-configuration with methyl trans to the 'harder' bonding atom of L.A band in the range 450-490 cm- ' is assigned to the titanium-carbon stretch.' 94 Bis-(n-cyclopentadieny1)zirconium dimethyl has been prepared from the dichloride and methyl-lithium. It is stable to heat (sublimes 385 K) dry O, and CO, but readily hydrolysed. The behaviour towards a variety of reagents is described. 195 Whereas vanadium oxytrichloride reacts with diphenylmercury to give VOC12C6H and phenylmercuric chloride, the only carbon products isolated from the reaction with tetramethyltin are trimethyltin chloride methyl chloride and methane. 96 Full details have been given of the preparation and properties of the trimethyl-silyl derivatives v(tsm), VO(tsm) Cr(tsm),- Cr(tsm), Mo,(tsm) and W,(tsm),.The ligand-field splitting A in the Cr" species is ca. 12 500cm-', compared with 9500 cm- for Cr(OEt),.'97 The related neopentyl compounds Ti(np) Zr(np) Ta(np),Cl and Cr(np) have been described ;' 98 as might be expected CrBu' which can decompose by the P-hydride mechanism is therm-ally much less stable.' 99 The reaction between niobium pentacarbonyl and dimethylzinc gives species MeNbC1 and Me,NbCl which are capable of adding on a further ligand.," Tetra-alkyl chromium compounds give a simple e.s.r. signal consistent with a regular tetrahedral structure and triplet configuration. At 77 K a second signal is observable corresponding to the transition Am = 2.*" The structure of a solvate of Na,CrPh has been determined and it has been found to contain distorted trigonal-bipyramidal [CrPh,12 -.'' Th e attempted sub-stitution of the ylid Ph,P:CHCH for CO in the Group VI hexacarbonyls gives products [Ph,PCH,CH,M(CO),] - .,03 Cyclic organometallic complexes of 1 9 2 1 9 3 1 9 4 1 9 s 1 9 6 1 9 7 1 9 8 1 9 9 200 2 0 1 2 0 2 2 0 3 A.L. Balch J. Organometallic Chem. 1972 37 C19. S. A. Cotton F. A. Hart M. B. Hursthouse and A. J. Welch J.C.S. Chem. Comm., 1972 1225. R. J. H. Clark and A. J. McAlees Inorg. Chem. 1972 11 342. P. C. Wailes H. Weigold and A. P. Bell J. Organometallic Chem. 1971 34 155. K.-H. Thiele W. Schumann S. Wagner and W. Briiser 2. anorg. Chem. 1972 390, 280. W. Mowat A. Shortland G. Yagupsky N. J. Hill M. Yagupsky and G. Wilkinson, J.C.S. Dalton 1972 533. W. Mowat and G. Wilkinson J.Organometallic Chem. 1972 28 C34. W. Kruse J . Organometallic Chem. 1972 42 C39. G. W. A. Fowles D . A. Rice and J. D. Wilkins J.C.S. Dalton 1972 2313. G. A. Ward W. Kruse B. K. Bower and J. C. W. Chien J . Organometallic Chem., 1972 42 C43. E. Miiller J. Krausse and K. Schmiedeknecht J. Organometallic Chem. 1972 44, 127. K. A. 0. Starzewski H. tom Dieck K. D . Franz and F. Hohmann J . Organometallic Chem. 1972,42 C35 344 P. S. Braterman molybdenum have been prepared by reductive coupling ,04 ( ~ - C H ) M O ( C O ) ( I ) A ~ M ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - ~ Hexamethyltungsten has been prepared from the reaction of tungsten hexa-chloride with methyl-lithium. The 'H n.m.r. signal occurs at z = 8.18. The compound is very air-sensitive and reacts with acids to give methane with halogens to give methyl halides and with CO and NO giving insertion products.205 The photoelectron spectrum of this compound shows bands at binding energies of 10.0 10.3 and 10.9eV assigned to the metalkarbon combinations a(e,), a(tl,) and a(al,) respectively.A broad band between 11.5 and 16 eV is assigned to the C-H framework. This would seem to imply a low electronegativity for Wv' The dichlorocarbene insertion product (n-C,H,),W(H)CHCl is formed when (n-C,H,),WH is heated with the carbene precursor sodium trichloroacetate. 2o The reaction between 1,2-dibromobenzocyclobutene and (n-C,H,)Fe(CO),Na gives (39) with no opening of the four-membered ring.,'* The product from the reaction between iron(rI1) chloride and phenyl-lithium is formulated as Fe(LiPh) .This species shows loss of hydrogen and it reacts with water to give iron@) benzene and biphenyl.209 The dependence of the methyl proton resonance on the nature of the trans-ligand L in cobaloxime complexes MeCo(dmgH),L (dmgH = dimethylglyoxime) has been compared with that in L-Me. It is found that in the cobalt complex the mqthyl group shows about 5 the sensitivity of the directly bounded series. l o The oxidative addition of for example 1-bromo-2-fluorocyclohexane to (Me,P),IrCOCl is greatly accelerated by 0 or other free-radical initiators and retarded by radical scavengers and there is loss of specific stereochemistry. However not all oxidative addition to Ir is of this type. l 1 The addition of a secondary acyl chloride to Ir' gives an n-alkyl carbonyl iridium(iii) complex, '04 K.P. Wainwright and S. B. Wild J.C.S. Chem. Comm. 1972 571. ' 0 5 A. Shortland and G. Wilkinson J.C.S. Chem. Comm. 1972 318. ' 0 6 S. Cradock and W. Savage Inorg. Nuclear Chem. Letters 1972 8 753. 207 K. S. Chen J. Kleinberg and J. A. Landgrebe J.C.S. Chem. Comm. 1972 295. '08 R. B. King A. Efraty and W. C. Zipperer J . Organometallic Chem. 1972 38 121. '09 B. Sarry and S. Noll Z . anorg. Chem. 1972,394 141. ' l o J. P. Fox R. Banninger R. T. Proffitt and L. L. Ingraham Inorg. Chem. 1972 11, 'IL J. S. Bradley D. E. Connor D. Dolphin J . A. Labinger and J. A. Osborn J . Amer. 2379. Chem. Soc. 1972,94,4043 Transition-metal Carbonyl Organometallic and Related Complexes 345 presumably formed via a s-alkyl species by an elimination-addition process., Tris(triphenylphosphine)iridium(I) methyl has been prepared from methyl-lithium and (Ph,P),IrCl.It decomposes presumably uia internal metallation followed by reductive elimination of methane to give ( P h 3 P ) I r m 6 H 4 or-Naphthyldimethylphosphine reacts with iridium(rr1) chloride with internal metallation of the naphthyl group at C-8 and loss of HCl; excess HCl reverses these processes.’ l 4 The preparations have been described of the nickel(r1) methyls (Me,P),NiMe, and (Me,P)NiMeCl both formed in the reaction of bis(ph0sphine)nickel dichlo-ride with methyl-lithium. Excess trimethylphosphine reacts further to give (Me,P),NiMe and [(Me,P),NiMe]+.’ The crystal structure of trans-(C,F,),-Ni(PMe,Ph) has been determined and compared with that of tranS-(C,F,)-(C,Cl,)Ni(PMe,Ph),.It is found that the C,Cl grouping has a greater trans-influence than C,F presumably because lower electronegativity leads to greater o-donation.’16 Aryls of the type trans-PdL,ArX (X = halogen) can be prepared by the Grignard route where L is SeEt or TeEt, but when L = SR, or SAr the method fails.21 The reaction between bis(tripheny1phosphine)-(dioxygen)palladium and keten gives (40) which reversibly loses keten (e.g. when water is present to convert lost keten into acetate) to give (41).’18 Ph,P Ph,P \ P \ O / ‘Pd’>O Ph,P Ph,P 0 (40) (41) The crystal structure of trans-(tsm)PtCl(PMe,Ph) (tsm = trimethylsilyl-methyl) has been determined and platinum-chlorine stretching frequencies and platinum-phosphorus coupling constants have been found for this species and for others containing different groups in place of tsm.It is concluded that the trans-influence of trimethylsilylmethyl is very similar to that of methyl and that there is no evidence for hyperconjugative electron release or for any other special bond-strengthening process.’ l 9 Platinum(r1) complexes of the o-tolylphosphines (o-tol)PBui and (less readily) of (o-tol),PBu’ undergo the internal metalla-tioq reaction at the CH group of the o-tolyl fragment.220 Similarly, M. A. Bennett and R. Charles J . Amer. Chem. SOC. 1972 94,666. ’I3 J. Schwartz and J. B. Cannon J . Amer. Chem. SOC. 1972,94,6226. ’I4 J. M. Duff and B. L. Shaw J.C.S. Dalton 1972 2219. ’ l 5 H.-F. Klein and H. H. Karsch Chem. Ber. 1972,105 2628.2 1 6 M. R. Churchill and M. V. Veidis J.C.S. Dalton 1972 670. 2 1 7 S. Sergi F. Faraone L. Silvestro and R. Pietropaolo J . Organornetallic Chem. 1971, 33 403. ”* S. Baba T. Ogura S. Kawaguchi H. Tokunan Y . Kai and N. Kasai J.C.S. Chem. Comm. 1972,910. ’ l 9 M. R. Collier C. Eaborn B. Jovanovic M. F. Lappert L. Manojlovic-Muir K. W. Muir and M. M. Truelock J.C.S. Chem. Comm. 1972 613. 2 2 0 A. J. Cheney and B. L. Shaw J.C.S. Dalton 1972 754 860 346 P. S. Braterman bis(benzonitrile)platinum(rI) chloride reacts with (BU‘)~P(~-C~H,.P~’) to give (42). 221 Ally1 acetate and ally1 ether (or alcohol) react with species [trans-PtH(PR,),(acetone)] -+ to give the cations (43) and (44) respectively. Cation (44) CH3-CHR I \ CH Et + eliminates propionaldehyde to give species [(h3-al1yl)Pt(PR3),] +.222 Cyclo-octadieneplatinum(r1) dimethyl is a useful starting material for the formation of platinum(1v) methyls which appear stable.Thus addition of halogen methyl iodide or acyl chloride gives products of composition PtMe2X2 PtMe31 and PtMe,(COR)CI respectively. However trifluoromethyl iodide gives the less expected product ( ~ o d ) p t ( C F ) . ~ ~ ~ The solvated solids CH,Cu(PPh,) ,toluene and CH,Cu(PPh,) ,iEt,O have been prepared from copper(r1) acetylacetonate and ethoxyaluminum dimethyl in the presence of excess triphenylphosphine. They are moderately stable materials but are decomposed by light to give methane.224 The physical and chemical properties of o-dimethylaminophenyl derivatives of copper have received attention the structures (45) and (46) being found by X-ray crystallo-graphy for 2-dimethylaminomethyl-5-methylphenylcopper tetrarner’” and (45) 2 2 1 D.F. Gill and B. L. Shaw J.C.S. Chem. Comm. 1972,65. 222 H. C. Clark and H. Kurosawa J.C.S. Chem. Comm. 1972 150. 223 H. C. Clark and L. E. Manzer J. Organomeiallic Chem. 1972 38 C41. 224 A. Yamamoto A. Miyashita P. Yamamoto and S. Ikeda Bull. Chem. SOC. Japan, 2 2 5 J. M. Guss R. Mason I. Sstofte G. van Koten and$. G. Noltes J.C.S. Chem. Comm., 1972,45 1583. 1972 446 Transition-metal Carbonyl Organometallic and Related Complexes 347 Me,N 1% I (46) tetrakis-(2-dimethylaminophenylcopper)biscopper(1) bromide,226 respectively. The related copper complexes Cu.C,H,.o-(CH,),NMe react with isonitriles to give species Cu.C(=NR).C,H,.o-(CH,),NMe .227 These are thermally stable, probably because of chelation through the terminal nitrogen atom.The reaction of (2-dimethylamino-5-pheny1)phenylcopper (RCu) with 1,2-bis(diphenylphos-phino)ethane in benzene solution is rather unexpected. With a molar ratio of 1 1 the product is RCu(dppe) but a 1 2 ratio gives Ph,PCu(dppe) Ph,PCH :-CH, and RH.228 Phenylsilver has been prepared by the reaction of silver nitrate with tin or lead phenyl a l k y l ~ . ~ ~ ’ Trimethylphosphinegold(1) methyl LAuCH reacts with methyl iodide to give trimethylphosphinegold iodide. Similarly LAuCH,-SiMe and LAuOSiMe react with methyl iodide to give LAuI and CH,CH,-SiMe and MeOSiMe respectively. No intermediate could be isolated,230 but in the case of triphenylphosphinegold(1) methyl there is kinetic evidence for a reaction sequence (L = PPh,):231 LAu’Me + Me1 + [Me,AuLI] (slow) [Me,AuLI] + MeAuL + Me,AuL + LAuI Me,AuL -+ MeMe + MeAuL 2 2 6 J.M. Guss R. Mason K. M. Thomas G. van Koten and J. G. Noltes J . Organo-2 2 7 G. van Koten and J. G. Noltes J.C.S. Chem. Comm. 1972 59. 2 2 8 G. van Koten and J. G. Noltes J.C.S. Chem. Comm. 1972,452. 2 2 9 C . D. M. Beverwijk and G. J. M. van der Kerk J . Organometallic Chem. 1972,43, 230 A. Shiotani and H. Schmidbaur J . Organometallic Chem. 1972,37 C24. 231 A. Tamaki and J. K. Kochi J. Organometallic Chem. 1972,40 C81. metallic Chem. 1972,40 C79. c11 348 P. S. Braterman Auration of arenes by gold(Ir1) chloride gives species [ArAuCl,] which are cleaved by suitable donors to give air-stable products of type L A u A ~ C ~ .~ ~ ~ The preparation and properties of a wide range of dimethylgold(III) derivatives have been described. All are square-planar and cis.233 Vinyl Alkynyl and Related Complexes. Unlike simple vinyl halides cyanovinyl halides react with metal carbonyl anions. Products of the general types (NC),-C CH(m) (NC),C C(CN)(m) and (NC),C C(Cl)(m) have been isolated [m = Mn(CO) or (n-C5H5)M~(C0)3]. With [(n-C,H,)Fe(CO),]- (NC),C :CC1 gives the bridged product (47) as a mixture of cisoid and transoid isomers. The dicyano-vinylidene group is apparently an even better net charge acceptor than C0.234 The structure (48) with vinyl units co-ordinated by both c- and n-bonds to different iron atoms has been found for [(bisbiphenylylidene)butadiene]-hexacarbonyldi-iron.’ NC CN \ / C he - he \ co (47) (48) Addition of carbonyltris(tripheny1phosphine)rhodium hydride across dialkyl-acetylenes gives products (OC)(Ph,P),RhC(R) CHR.These are presumed to be trans-vinyl derivatives since HCl cleavage produces the trans-alkene. The related addition to hexafluorobut-Zyne is however cis.236 HBr cleavage of (49) gives (50) the crystal structure of which has been determined. The vinylic C0,Me C0,Me Ph3P C0,Me C0,Me Ph3P $CO,Me I P d 7 C0,Me Br 232 K. S. Liddle and C. Parkin J.C.S. Chem. Comm. 1972 26. 2 3 3 G. C. Stocco and R. S . Tobias J . Amer. Chem. SOC. 1971,93 5057. 2 3 4 R. B. King and M. S . Saran J . Amer. Chem. SOC. 1972,94 1784. 2 3 5 D.Bright and 0. S. Mills J.C.S. Dalton 1972 2465. 236 B. L. Booth and A. D. Lloyd J . Organometallic Chem. 1972,34 195 Transition-metal Carbonyl Organometallic and Related Complexes 349 hydrogen could not be located directly. However if bond angles and distances at the terminal carbon are normal the distance between this hydrogen and the metal is only 230 pm whereas the sum of van der Waals radii is 310 pm. The hydro-gen resonates at an unusually low field and shows coupling with the phosphorus atoms of the ligands.,,’ Photolysis of bis(tripheny1phosphine)platinum dicyano-acetylene gives cis-(Ph,P),Pt(CN)C=C.CN the crystal structure of which has been determined.238 Species such as (Me,P),Pt(CCH) form dark 1 1 charge-transfer complexes with 7,7,8,8-tetracyanoquinodimethane (tcnq).It is argued that these complexes are held together by alkynyl to tcnq electron delocalization, this process being facilitated by metal to alkynyl n - d ~ n a t i o n . ~ ~ Complexes of Fluorinated Ligands. Perfluorophenyl-lithium reacts with tungsten hexachloride in ether to give a product LiW(C,F,) ,2Et20 and some bis(per-fluorophenyl). The tungsten complex is paramagnetic with some magnetic evidence for strong perturbation of the structure away from octahedral. Pyrolysis gives some (C,F,),W which is thermally stable.240 Hexafluorobut-2-yne inserts into a carbon-metal n-bond in (nbd)Rh’(acac) (nbd = norbornadiene; acac = acetylacetonate) to give (5 1) (detailed conforma-tion of addition to ring uncertain). With [(nbd)RhCl] however the reaction takes a totally different course to give (52) the structure of which has been determined.24 (51) (52) In series of complexes of the type [trans-(Me2PhP),Pt(CF,)L]+ and trans-(Me,PhP),Pd(CF,)X ,J(PtF) varies in the same way on the whole as does ,J(PtH) in the corresponding methyl complexes.242 The perfluoroalkynyl complexes cis-(Ph,P),Pt(C-CCF,) and cis-(Ph,P),Pt(C-CC,F,) are formed by the reaction of (Ph,P),Pt with the appropriate a l k ~ n e .~ ~ 2 3 7 2 3 8 2 3 9 2 4 0 2 4 1 2 4 2 2 4 3 D. M. Roe P. M. Bailey K. Moseley and P. M. Maitlis J.C.S. Chem. Comm. 1972, 1273. W. H. Baddley C. Panattoni G . Bandoli D. A. Clemente and U. Belluco J. Amer. Chem. SOC. 1971 93 5590. H. Masai K. Sonogashira and N. Hagihara J . Organometallic Chem. 1972 34 397.E. Kinsella V. B. Smith and A. G . Massey J . Organometallic Chem. 1971 34 181. J. A. Evans R. D. W. Kemmitt B. Y . Kimura and D. R. Russell J.C.S. Chem. Comm., 1972 509. T. G. Appleton M. H. Chisholm H. C. Clark and L. E. Manzer Inorg. Chem. 1972, 11 1786. W. R. Cullen and F. L. Hou Canad. J. Chem. 1971,49 3404 350 P. S. Braterman Acyl Complexes. Dicarbonyltitanocene undergoes oxidative addition with benzoyl and acetyl chlorides to give air-stable products (n-C,H,),Ti(CI)COR. Methyl iodide gives (n-C,H,)2Ti(COCH,)I.244 The anionic acyl complexes [(n-C,H,)Mo(CO),(CN)COR]- and the tungsten analogue and [(n-C,H,)Fe-(CO)(CN).COR]-(R = Me or Et) of type [(m)(CN)COR]- have been pre-pared by the reaction of cyanide with neutral (m)(CO)R. The reaction represents the first insertion reported into this type of molybdenum-methyl bond.In this case the initial insertion is cis but is followed by a slower conversion into the trans-isomer. Methylation of (m)(CN)COR - gives neutral (m)(CNMe)COR i.e. an isonitrile acyl rather than a carbene cyanide.,,’ Species (n-C,H,)Mo-(CO),(PR,)COCH decompose on heating by a first-order process to give (n-C,H,)Mo(CO),(PR,)CH . More basic phosphine ligands generally retard the reaction although PCx (Cx = cyclohexyl) promotes it presumably as a result of a steric effect.246 Acyliron tetracarbonyls may be prepared by the reaction of alkyl-lithium with pentacarbonyliron or by the action either of acyl chlorides or of alkyl halides followed by CO on the [Fe(C0),I2 - anion.247 This last process is an example of a more general reaction species [RFe(CO),] - being converted by added ligands into [RCO.Fe(CO),L]- at a rate that depends critically on the counter ion.248 Acyls of the types (n-C H ,)Fe(PPh ,) (C0)COR and (Ph ,P)Co(CO),COCH F show multiplet structure in the acyl v(C0) region indicating that more than one entity is present.It has been agreed that whereas the former case is due to restric-ted rotation about the iron -C(acyl) bond this can hardly be true for the latter so that restricted rotation about the C(acyl)-C(fluoroalkyl) bond is re~ponsible.~~’ Tetrakis( tripheny1phosphine)platinum reacts with 2,3-diphenylcyclopropenone (53a) to give the insertion product (54a) characterized crystallographically.250 This is in marked contrast to the reactions with 1,2-dimethylcyclopropene and species RC:CR.SO, which give n-complexes of the double bond.251 It is relevant that (Ph,P),Pt(C,H,) reacts with methylcyclopropenone (53b) at 210 K to give initially ( 5 9 which rearranges to (54b) on warming to 245 K.,’, Miscellaneous One-carbon Ligands.The chemistry of carbamoyl and alkoxy-carbamoyl complexes of the transition metals has been reviewed,253 and several preparations of such complexes have been reported. Cyclopentadienyliron I 244 G. Floriani and G. Fachinetti J.C.S. Chem. Comm. 1972. 790. 2 * 5 T. Kruck M. Hofler and L. Liebig Chem. Ber. 1972 105 1174. 246 K. W. Barnett T. G . Pollman and T. W. Solomon J . Organometallic Chem. 1972, 247 W. 0. Siegl and J. P. Collman J . Amer. Chem. SOC. 1972 94 2516.248 J. P. Collman J. N. Cawse and J. 1. Brauman J . Amer. Chem. SOC. 1972 94 5905. 249 K. H. Pannell and L. J. Rittman Z . Narurforsch. 1972 27b 1109. 2 5 0 W. Wong S. J. Singer W. D. Pitts S . F. Watkins and W. H. Baddley J.C.S. Chem. Comm. 1972,672. 2 5 1 (a) J. P. Visser A. J. Schipperijn J. Lukas D. Bright and J. J. De Boer Chem. Comm., 197 1 1266; (b) J. P. Visser C. G. Leliveld and D. N. Reinhoudt J.C.S. Chem. Comm., 1972 178. 36 C23. 2 5 2 J. P. Visser and J. E. Ramakers-Blom J . Organometallic Chem. 1972 44 C63. ”’ R. J. Angelici Accounts Chem. Res. 1972 5 335 Transition-metal Carbonyl Organometallic and Related Complexes 35 1 R' R2 ko (53) (a) R = R = Ph (b) R = Me R = H (Ph3P),PtM&0 H (55) Ph,P 1 R2 (54) (a) R' = R2 = Ph (b) R' = Me R2 = H dicarbonyl hydride adds across the CN bond of t-,uty isocyanate to give (~-CSH,)Fe(CO),CO-NH,Bu'.254 Carbamoyl complexes of Pt" can be prepared by the reaction of precursors [L,PtCl(CO)] + with amines or of bis(phosphine)-platinum dichloride with carbon monoxide in the presence of amines or by oxidative addition of N-alkylated chloroformamide to low-valent metal com-plexes.This last method may also be used to prepare thiocarbamoyl derivatives. Proton n.m.r. spectra show the complexes to be in the trans-configuration with a high barrier to rotation about the CO-NR bond.," The reaction between metal carbonyl anions [(m)CO] - [m = (.lr-C,H,)Mo(CO) Mn(CO), or(OC),-Mn(PPh,)] and ClC(S)NMe leads not to the expected (m)(CO)C(S)NMe , but to products (56a).These can be methylated at sulphur by trimethyloxonium fluoroborate to give cations (56b).256 C A I OC- Mo+S oc NMe, oc -/ oc Several reports have appeared of the formation of unusual a-bonded systems by insertion of isonitriles or nitriles into metal-carbon and other bonds. For example the species RCONi(X)(CNBu') reacts with excess isonitrile to give (57). Alternatively loss of CO generates RNiX(CNBu') which is converted into (Bu'NC)r'Si(X)NBu' CRC(=NB~').~(=NBU').~~~ The reaction between gold([), 2 5 4 W. Jetz and R. J. Angelici J. Organometallic Chem. 1972 35 C37. 2 5 5 C. R. Green and R. J. Angelici Inorg. Chem. 1972 11 2095. 2 5 6 P. M. Treichel and W. K. Dean J.C.S. Chem. Comm. 1972 804. 2 5 ' S. Otsuka M. Naruto T. Yoshida and A. Nakamura J.C.S.Chem. Comm. 1972, 396 352 P . S. Braterman (57) methanolic KOH and cyclohexyl isonitrile gives polymeric [AuC(OMe) N-(c6Hl1)-+ln ( n = 3 in chloroform).258 The reaction between the tetra-azido-gold(m) anion and isopropyl cyanide gives the tetrazolato complex ion [Au(CN,Pr'),] - characterized as its tetraphenylarsonium salt.259 Mechanistic Studies of Metal-Carbon Bonds. It has been argued that if transition metal-carbon bonds are labile this is for kinetic rather than thermodynamic reasons. Pathways readily available for the cleavage of such bonds include P-hydride elimination reductive elimination and processes involving dinuclear intermediates. The energies of d-d transitions it is argued are not directly related to thermal stability.260 A connection has been suggested between thermal lability and the availability of d + d excited states of the same symmetry as the ground state,261 but several objections have been raised to this view.262 The decomposition of (Ph,P),PtBu; gives butene butane and zerovalent platinum.The process is inhibited by small amounts of triphenylphosphine, and preceded by scrambling of hydrogen atoms on C-1 and C-2 of the butyl group but occurs without exchange with free butene. The initial process is thus dissociative loss of triphenylphosphine followed by rapid equilibria involv-ing a di-n-butyl complex and a butylplatinum hydride butene complex. This latter can revert reversibly either to a di-n-butyl or to its (s-buty1,n-butyl) isomer and more slowly eliminates butane followed by butene but does not exchange b ~ t e n e .~ ~ ~ The thermolysis of tetramethyltitanium to give methane is accompanied by the formation of titanium carbides suggesting intramolecular hydrogen abstraction rather than a simple free-radical mechanism.264 In accord with this view thermolysis of the perdeuteriated species in 10 1 hexane ether gives only CD while partially deuteriated methane results from the thermolysis of Ti(CD3)n(CH3)4-,.265 Relatedly the thermolysis of dimethyltitanium 2 5 8 G. Minghetri and F. Bonati Angew. Chem. Internat. Edn. 1972 11 429. 2 5 9 W. P. Fehlhammer and L. F. Dahl J. Amer. Chem. SOC. 1972,94 3370. 2 6 0 P. S. Braterman and R. J. Cross J.C.S. Dalton 1972 657. 2 6 1 D . M. P. Mingos J.C.S. Chem. Comm. 1972 165. 2 6 2 P. S. Braterman J.C.S.Chem. Comm. 1972 761. 2 6 3 G. M. Whitesides J. F. Gaasch and E. R . Stedronsky J . Amer. Chem. SOC. 1972,94, 2 6 4 F. S. Dyachkovskii and N. E. Khrushch Zhur. obshchei Khim. 1971,41 1779. 2 6 5 A. S. Khachaturov L. S. Bresler and I . Yu. Poddubnyi J . Organometallic Chem., 5258. 1972 42 C18 Transition-metal Carbonyl Organometallic and Related Complexes 353 dichloride in deuteriated solvents does not lead to deuteriated methanes, although some C,H,D is formed. There appear to be several competing paths in this system.266 There are however several examples of metal-carbon bond cleavage that still appear to involve free-radical intermediates. Thus although the stability of the chromium(II1) alkyls RCrC1 ,(THF) falls with increasing chain length there is no evidence for chromium hydride intermediates in pyrolysis and more alkane than alkene is produced in all cases.267 The thermolyses of neophyl (PhCMe,.CH,.) derivatives of copper(1) and silver(1) have been studied. The P-hydride shift mechanism is not available in these cases and accordingly the thermal stability is higher than that of copper or silver n-alkyls. The product distribution clearly indicates a free-radical mechanism.26 The oxidation of alkyl radicals by copper(1r) acetate involves the initial formation of RCu"' species. These decom-pose with reductive elimination of acetic acid from a copper(iI1) acetate hydride, to give R-H and copper(1) acetate. Alternatively attack of R+ on solvent can lead to solvent alkylation with again elimination of Cu' and of acetic acid.The corresponding oxidations by copper(i1) halides however involve atom transfer and lead to different products.269 The Cu'-catalysed decomposition of lead tetra-alkyls is consistent with transmetallation and decomposition of the copper(1) alkyls so produced.270 It then becomes significant that the products from the Cu" oxidation of lead tetra-alkyls are the same as those for the CU" oxidation of alkyl radicals. The implication is that Cu" alkyls are initially formed by transmetallation but that these then decompose by an internal formal redox reaction (ie. by homolysis) to give alkyl radicals and presumably C U ' . ~ ~ ' Radical loss from metal may be involved in the reaction of acyl halides with tetrakis(tripheny1phosphine)nickel to give eventually (Ph3P)3Ni'X.257 The stereospecificity with which (Ph,P),RhCl decarbonylates optically active aldehydes is variable but in some cases high.The results are attributed to the intermediacy of a cleavage radical pair.272 The reaction of cyclohexene with mixtures of palladium(r1) and copper(1r) in acetic acid gives rise to a range of products. These may be explained by cis-addition of Pd" acetate to the double bond followed by its rapid and reversible elimination. Decomposition of the intermediate species by Cu" may proceed directly by electron flow to Cu" from the carbon-palladium bond.273 It has been shown that the additions of Pd"0Ac and of PdI'Ph to cyclohexene proceed with differing stereochemistries. It must follow that generalizations about the 2 6 6 2 61 2 6 8 269 2 7 0 271 2 7 2 273 J.D. McCowan and J. F. Hanlan Canad. J . Chem. 1972,50 755. K. Nishimura H. Kuribayashi A. Yamamoto and S. Ikeda J . Organometallic Chem., 1972 37 317. G. M. Whitesides E. J. Panek and E. R. Stedronsky J . Amer. Chem. SOC. 1972 94, 232. C. L. Jenkins and J. K . Kochi J . Amer. Chem. Soc. 1972,94 843 856. N . A. Clinton and J. K. Kochi J . Organometallic Chem. 1972 42 229. N . A. Clinton and J. K. Kochi J . Organometallic Chem. 1972 42 241. H. M. Walborsky and L. E. Allen J . Amer. Chem. SOC. 1971 93 5465. P. M . Henry J . Amer. Chem. Soc. 1972,94 7305 354 P. S. Braterman detailed mechanisms even of closely related processes may be dangerous. 74a These studies are part of a series concerned with the interaction between Pd" and a l k e n e ~ .~ ~ ~ ~ ~ (see also ref. 291). Reversible oxidative insertion into a C-H bond of a molecule already com-plexed through a double bond is presumably responsible for the Pt"-catalysed deuteriation of 1-alkenes in aqueous solution. H-D exchange occurs most readily at C-5 presumably because of ring-size effects.275 Cleavage of the metal-carbon bond in trans-RCH CR.Mn(CO) by HMn-(CO) gives Mn,(CO), and specifically trans-RCH CHR. Cleavage with bromine must take place by a slightly different mechanism since it proceeds with retention where R = CF but with inversion where R = C02Et.276 The nucleo-philic displacement of cobalt from species containing organic groups bonded to cobalt(rr1) occurs with inversion of the configuration of C-1.A related process may account for the observed inversion on halogenation of the R-Cu bond. 77,27 8 The nucleophilic substitution of vinylic bromide by methyl, using lithium copper dimethyl proceeds with retention of stereochemistry in the vinyl group.279 Two examples from early in the transition series have been described of metal-carbon bond cleavage involving concomitant loss of part of another ligand. In the species (n-C,H,),UR prepared from (n-C,H,)UCl and LiR thermolysis is not a ready process and the rate does not seem to depend greatly on the nature of R. When the decomposition of the butyl derivative is carried out in ['H,]toluene, there is only 5 % incorporation of deuterium into the evolved butane and there is no formation of butene.280 Titanocene dibenzyl (n-C,H,),Ti(CH,Ph) , decomposes at 300 K in benzene or perdeuteriobenzene to give [Ti(C,H,),], and undeuteriated toluene.Addition of a nucleophile (CO) completely alters the course of this reaction the products being initially (n-C,H,),Ti(CH,Ph)CO. CH,Ph and finally (n-C,H,),Ti(CO) and PhCH,COCH,Ph.28 The reactions between (PhMe,P)AuCH 3 . and unsaturated fluorocarbons illustrate the importance of dinuclear species in metal-carbon bond cleavage. Tetrafluoroethylene which cannot bond to more than one metal at a time gives (Me,PhP),AuCF,CF,CH . The reaction with hexafluorobut-2-yne which can act as a bridging ligand is more interesting. The first product isolated is (58), which decomposes in ether to give the insertion product (59). In acetone the products isolated are (60) and ethane.Similar gold(rr1) methyl complexes are inert to these n-accepting ligands although both the gold(r) and the gold(1u) 2 7 4 ( a ) P . M. Henry J. Amer. Chem. SOC. 1971 93 3853; (b) P. M. Henry and G. A. Ward ibid. 1972 94 673; ( c ) P. M. Henry ibid. pp. 1527 4437; ( d ) P. M. Henry, J . Org. Chem. 1972 37 2443; (e) P. M. Henry Inorg. Chem. 1972 11 1867. 2 7 5 C. Masters J.C.S. Chem. Comm. 1972 1258. 276 B. L. Booth and R. J. Hargreaves J . Organometallic Chem. 1971 33 365. 277 S. N. Anderson D . H. Ballard J. Z . Chrzastowski D. Dodd and M. D. Johnson, J.C.S. Chem. Comm. 1972,685. "' F. R. Jensen V. Madan and D . H. Buchanan J . Amer. Chem. SOC. 1971,93 5283. 2 7 9 J. Klein and R. Levene J . Amer. Chem. SOC. 1972,94 2520. 2 8 0 T.J. Marks and A. M. Seyarn J . Amer. Chem. SOC. 1972,94 6545. 2 8 1 G. Fachinetti and C. Floriani J.C.S. Chem. Comm. 1972 654 Transition-metal Carbonyl Organometallic and Related Complexes 355 Au(PMe,Ph) F3C 1 F3C-C C-CF, \\ I (PhMe,P)Au(CH,) Au(CH,)(PMe,Ph) Au(PMe,Ph) CH3 CF3 CF3\ / /c=c\ (PhMe,P)Au species insert SO, and undergo elimination reactions with HCZCCF to give (Me,PhP)AuC i CCF and cis-(Me,PhP)Au(Me),C i CCF respectively.282 Rearrangements of or involving Metal-Carbon a-Bonded Species. The catalysis by silver cations of the rearrangement of strained cyclic systems has been re-viewed.,' Bis(benzonitri1e)palladium dichloride causes isomerization of bicyclo-[6,1,0]non-4-ene in non-polar solvents to the PdCl complex of cis,cis-1,5-cyclononadiene.The reaction presumably proceeds by oxidative addition of the strained ring to Pd followed by a 1,2-hydrogen shift.284 The n-cyclopenta-dienyldicarbonyliron derivative of cyclopropane is cleaved by acid to give a cationic complex of propene. A deuterium label at C-1 is specifically incorporated into the propene cis to the methyl group as required by Scheme l.285 D -& H '$-CH3 H Scheme 1 2 a 2 A. Johnson R. J. Puddephatt and J. L. Quirk J.C.S. Chem. Comm. 1972 938 and 283 L. A. Paquette Accounts Chem. Res. 1971,4 280. 284 G. Abelo and M. F. Rettig J. Organometallic Chem. 1972 42 183. 2 8 5 A. Cutler R. W. Fish W. P. Giering and M. Rosenblum J . Amer. Chem. SOC. 1972, references therein. 94. 4354 356 P . S . Braterman The rearrangements of bicyclobutanes and related systems continue to attract much interest.There is spectroscopic evidence for a palladium-alkene derivative [(61) or (62)] in the (PhCN),PdCl,-catalysed rearrangement of tricycloheptane to 3-methylenecyclohexene (63).286 The differing effects of different transition-(61) (62) (63) metal catalysts on the rearrangements can be rationalized in terms of a dif-ference in the identity of the bonds initially cleaved. Thus (64) rearranges in the presence of dicarbonylrhodium chloride dimer to give (65) and various other cyclization products whereas [C,F,Cu] and AgBF both give a mixture of (66) and (67). This is as expected if the rhodium reagent cleaves bonds ac bc of (64) to give(68) whereas Cu'and Ag'both cleave bonds ac,ab to g i ~ e ( 6 9 ) .~ ~ It has been discovered that a change of solvent can lead to a total change of mechanism and of products. Thus in methanol (64b) is converted either by [Rh(CO),CI] or by AgBF into (70b; X = H),288 presumably oia (71b). In [hydro~y-~HImethanol, (64a) is converted either by [Rh(CO),Cl] or by AgBF, into (70a; X = D) and an approximately equimolar mixture of (72) and (73). These products are thought to arise through nucleophilic attack by solvent on an intermediate (71a; m = D) formed by solvolysis of the metal-carbon bond in (71a; m = Ag or Rh). Such attack can proceed directly at C(a) to give (70a; X = D) or else at either of the equivalent homoallylic sites C(c) C(d) to give (72) or (73) respectively ; remarkably, the formation of carbene-metal intermediates such as (68) and (69) appears to be totally suppressed.289 The metal-catalysed rearrangement of 3-methyl-lP-penta-diene to 1,4-hexadiene under the influence of a transition metal has been shown by labelling experiments also to involve the repositioning of carbon atoms 4 and 5 [(74) + (75)].These results are explainable by metal insertion into the C-2-C-3 bond generating an ally1 and an alkene fragment which can alter their mutual orientation before re~ombining.~~' Crotyl propionate undergoes two distinct reactions in acetic acid under the influence of Pd". The first of these isomerization together with exchange of proprionate by acetate is simply the expected acyloxy-palladation-deacyloxypalladation process. The second isomerization without exchange involves transfer of ' 8O from carbonyl to alkoxy carbon in accord with Scheme 2.29 Two groups have studied the temperature-dependent ' 3C n.m.r.spectrum of (n-C,H,)Fe(CO),(o-C,H,). The spectrum has been explained in 2 8 6 S. Masamune M. Sakai and N . Darby J.C.S. Chem. Comm. 1972 471. 2 8 7 P. G. Gassman and T. Nakai J . Amer. Chem. SOC. 1972,94 2877. P. G. Gassman and F. J. Williams J.C.S. Chem. Comm. 1972 80. 2 8 9 P. G. Gassman and T. Nakai J . Amer. Chem. SOC. 1972,94 5497. 290 R. G. Miller H. J. Golden D. J. Baker and R. D. Stauffer J . Amer. Chem. SOC., 2 9 1 1971,93,6308. P. M. Henry J . Amer. Chem. SOC. 1972,94 5200 Transition-metal Carbonyl Organometallic and Related Complexes Me *&R R (64) (a) R = Ph (b) R = Me Ph M e d P h (67) R (70) (a) R = Ph (b) R = Me H D Ph $+ Ph OMe Me (73) Ph +Ph Me (65) 9 3 &R R 0 Ao* L I - - J Pd (71) (a) R = Ph (b) R = Me I L 7 /Ao* jll Pd 357 Ph OMe Me (72) Me J2 * ( 7 5 ) Pd Scheme 358 P.S. Braterman terms of ring ~ h i z z i n g ~ ~ ~ ~ ~ ~ and the more ambitious analysis fits the tempera-ture variation of lineshape to a 1,2 shift with an activation energy of 45 & 2 kJ mol- The reaction of 1,4-dilithiobutane with tungsten hexachloride gives (76) which decomposes to yield ethylene. Rearrangement takes place involving exchange of labelled sites consistent with (76) being an intermediate in olefin metathesis processes.’ 94 (76) Two-carbon Ligands.-Reviews have appeared on metal-olefin and metal-acetylene bonding in complexes,295 and on olefin oxidation and related reactions, of Group VIII noble-metal compounds.296 Akene Complexes.Alkene complexes (n-C,H,)Cr(CO)(NO)L have been pre-pared from (n-CSHs)Cr(CO),NO by a photochemical method.297 The n.m.r. spectrum of the complex (n-C,H,)Cr(CO)(NO)L (L = acetylene) is temperature-dependent above room temperature showing the onset of rotation of the co-ordinated The product of the reaction between butadiene and dintanganese decacarbonyl has been characterized crystallographically. Contrary to what had earlier been thought the organic ligand is not bonded to one manganese but is bridging (77). ’ coco OC ,co I / OC-Mn oc/ I (77) The vibrational spectrum of ethylenetetracarbonyliron has been assigned. The in-plane symmetric deformation of the CH groups is principally responsible for a band at 1510cm-’ but there is coupling between this motion and the C=C stretching band at 1193 cm- 1.300 Tetracarbonyliron alkene complexes 2 9 2 Yu.K. Grishin N. M. Sergeyev and Yu. A. Ustynyuk Org. Magn. Resonance 1972, 293 D. J. Ciappenelli F. A. Cotton and L. Kruczynski J . Organometallic Chem. 1972, 294 R. H. Grubbs and T. K. Brunck J . Amer. Chem. SOC. 1972,94. 2538. 2 9 5 F. R. Hartley Angew. Chern. Znternat. Edn. 1972 11 596. 2’96 R. Jira and W. Freisleben Organometallic Reactions 1972 3 1 . 2 9 ’ M. Herberhold and H. Alt J . Organometallic Chem. 1972 42 407. 298 M. Herberhold H. Alt and C. G. Kreiter J . Organometallic Chem. 1972,42,413. 299 H. E. Sasse and M. L. Ziegler Z .anorg. Chem. 1972,392 167. 300 D. C. Andrews and G. Davidson J . Organometallic Chern. 1972 35 161. 4 377. 42 159 Transition-metal Carbon yl Organometallic and Related Complexes 359 in general react with carbon monoxide to give iron pentacarbonyl. The reaction is dissociative and shows mass-law retardation by added alkene. In this situa-tion since the reversible dissociation step is common to all the species studied it is possible to derive relative thermodynamic stabilities for the alkene complexes. The stability order found for 1-alkenes is on the whole one of increas-ing electronegativity CH,CHOEt < hex-1-ene < styrene < CH,CHCO,Me < CH2CHCN.301 The hydrolysis of the tetracarbonyliron complex of vinyl-trimethylsilyl ether at 185 K gives the corresponding complex of vinyl alcohol.Not surprisingly in view of the dissociation equilibria already referred to this species is stable to evolution of acetaldehyde only below 195 K. Previous claims 302 to have trapped thevinyl ether asa Pd'Icomplex have been challenged.303 Epoxides may be converted by the anion [(.n-C,H,)(CO),Fe]- into alkenes the reaction taking place with retention of the alkene configuration by successive nucleophilic attack by the iron(0) complex on both carbon atoms of the ep~xide.~' The reaction of the insoluble polymeric material [(cod)RuCl,], with hydrazine gives a cationic complex [(co~)Ru(N,H,),]~ + which is a useful general precursor for cationic Ru" species.305 The n.m.r. spectra of alkene complexes are known to show temperature variation indicative of rotation of the olefin to give left-right exchange.What has not hitherto been known is the detailed nature of the rotation which could be either around the ligand-metal bond or around the double bond of the ligand. This problem has now been solved at least in the case of the cation truns-[(Ph,P),-Os(CO)(NO)(C,H,)]+ by a combination of 'H and I3C n.m.r. data. The two carbon atoms of the ethylene ligand are in chemically different environments, whereas the two phosphines are equivalent. These facts suffice to specify the struc-ture (78). The coalescence of signals from both ends of the molecule can only be (78) explained by rotation around the ligand-metal The barrier to rotation presumably then arises through a reduction in metal-olefin Tc-bonding at unfa-vourable angles.This suggestion receives further support from studies of the spectrum of (T~-C,H,)R~(C,H,) which show that rotation of the olefin is facilitated by electron-withdrawing groups on the ring. 307 In this complex one ethylene is readily displaced by a range of donors by an S,1 mechanism.308 The 30' G. Cardaci and V. Narciso J.C.S. Dalton 1972,2289. 302 Y . Wakatsuki S. Nozakura and S. Murahashi Bull. Chem. SOC. Japan 1969,42,273. 3 0 3 H. Thyret Angew. Chem. Znternat. Edn. 1972 11 520. 304 W. P. Giering M. Rosenblum and J. Tancrede J. Amer. Chem. SOC. 1972,94 7170. 3 0 5 J. J. Hough and E. Singleton J.C.S. Chem. Comm. 1972 371. 306 B. F. G. Johnson and J. A. Segal J.C.S. Chem. Comm. 1972 1312. 3 0 7 R. Cramer and J. J. Mrowca Inorg.Chim. Acta 1971 5 528. 3 0 8 R. Cramer J. Amer. Chem. SOC. 1972,94 5681 360 P. S. Bratermun tendency of Rh' in unsaturated phosphine complexes to become five-co-ordinate is so great that phenylbis-(0-vinylphenyl)phosphinerhodium(I) chlorides are dimeric with halogen bridges.309 The n.m.r. spectra of silver rhodium and iridium complexes of propene have been discussed. There is little metal-olefin n-bonding with silver but more with rhodium at least in rhodium(1) acetylace-tonato-complexes. Comparison of (CH,CHCH,),Rh(acac) with (C,H,)Rh(acac) shows that ethylene is a better acceptor than p r ~ p e n e . ~ ~ ' The crystal structure of the mixed olefin complex (z-C,H,)Rh(C,H,)(C2F4) has been reported. The dihedral angle between the two CF groups is 74" and the carbon-carbon dis-tance is 140 pm (as opposed to 136 pm in the C2H4 ligand).The trans-influence of the C2F4 ligand is great enough to cause asymmetry in the bonding between the metal and the cyclopentadienyl ring.,' Iridium(1) tetrakis-alkene complexes IrL4X (X = C1 or Br) may be prepared by the reaction of the alkene with the iridium cyclo-octene halide. Ir(C2H4)4Cl loses ethylene to give chlorine-bridged [(C,H,),IrCl] . 1.r. data indicate that metal-carbon as well as metal-halogen bonding is stronger in the chloride than in the bromide.312 The crystal structure of IrCl(CO)(tcne)(AsPh,) has been determined (tcne = tetracyanoethylene). The arsenic atoms and the central carbon atoms of the tcne ligand are coplanar with the metal while the tcne ligand itself is severely distorted from A range of activated alkene com-plexes of Ir' such as IrH(CO)(PPh,),(fumaronitrile) may be prepared from the alkene and iridium(1) carbonyl triphenylphosphine hydride~.~ l 4 The bis(trichlorosily1)stilbene complex (79) has been prepared by the reaction of (Ph,P),Ni(SiCl,) with diphenylacetylene.The structure is confirmed by treatment with methylmagnesium iodide followed by dilute hydrochloric acid, which produces the free bis(trimethylsily1)stilbene. The olefinic ligand in (79) is firmly held not being easily displaced even by triphenylph~sphine.~ The crystal structure of tricyclohexylphosphinebis(ethylene)nickel(O) has been deter-mined. The co-ordination of the nickel is trigonal planar the C2H ligands both lying surprisingly in the co-ordination plane.316 8 / \ >Ni + (79) SiCI, II c\ Ph 309 D.1. Hall and R. S. Nyholm J.C.S. Dalton 1972 804. K. R. Ark V. Ark and J. M. Brown J . Organometallic Chem. 1972 42 C67. l 1 L. J. Guggenberger and R. Cramer J . Amer. Chem. SOC. 1972,94 3779. A. L. Onderlinden and A. van der Ent Inorg. Chim. Acta 1972,6,420. J . B. R. Dunn R. Jacobs and C. J. Fritchie jun. J.C.S. Dalton 1972,2007. ' l 4 M. S . Fraser and W. H. Baddley J . Organornetallic Chem. 1972 36 377. l S Y. Kiso K. Tamao and M. Kumada J.C.S. Chem. Comm. 1972 1208. 3 1 6 C. Kriiger and Y.-H. Tsay J . Organometallic Chem. 1971,34 387 Transition-metal Carbonyl Organometallic and Related Complexes 361 Virtually planar crystal structures have been confirmed for ethylenebis-(triphenylphosphine)nickel(O) and the platinum analogue.The platinum complex does not dissociate in solution but does exchange with deuterioethylene although this exchange is slow on the n.m.r. timescale. The ethylene 'H n.m.r. spectrum is of type [A2X] (X = ,'P) rather than simple A4X2 indicating that rotation of the ethylene ligand is slow. The nickel complex however does exchange ra-pidly. ' Heats of reaction of alkenes and phosphines with bis(benzonitri1e)palladium dichloride have been determined. Cyclo-octadiene and norbornadiene give values of 54 and 57 kJ mol- respectively as against 210 kJ mol- for d ~ p e . ~ ' ~ cis,cis-l,3-Cyclo-octadiene (cod = cyclo-octadiene) attaches itself to platinum(I1) with rearrangement giving known 1 ,5-cis,cis-cod complexes. The 1 ,5-cisYtrans-species however complexes as such and in solution it co-ordinates through one double bond only.319 The diene 5-methylenecycloheptene forms a platinum dichloride complex by reaction with [PtCl4I2- in methanol.It is thought that, of the two double bonds one lies in and the other perpendicular to the co-ordination plane.320 Hydrolysis of vinyl trimethylsilyl ether acetylacetonato-platinum(r1) chloride is said to generate a vinyl alcohol complex (cf ref. 302 but see ref. 303 for a more sceptical view). Whereas the trimethylsilyl ether complex gives an ABX pattern in the n.m.r. spectrum the spectrum of the hydrolysis product is of type A2X and a species Pt-CH,-CHO formed by reversible deprotonation is suggested as an intermediate.,, Platinum(0) complexes of cyclo-hepta- -octa- and -nona- 1,2-dienes have been piepared.In these the steric strain in the cyclic allene is presumably relieved by the change in bond angles at the co-ordinated carbon atoms that occurs in ligand a l l e n e ~ . ~ ~ The thiiren dioxide complexes L2M(R'C :CR2S02) referred to earlier rearrange on heating to sulphur dioxide complexes and free acetylenes. This process may be relevant to the catalysis by transition-metal ions of the de-composition of thiiren l l - d i o ~ i d e s . ~ ~ ~ ~ Heats and activation energies have been determined for the loss of C2F or C,F from PtClCH,(AsMe,),L and a range of related complexes. The loss of L is endothermic by between 50 and 80 kJ mol-and the activation energies are far higher.323 Barriers to rotation have been determined in a series of platinum(I1) complexes of C,H, and have been compared with the CO stretching frequencies of the related complexes in which carbonyl has replaced ethylene.It is clear from the results that both steric and electrqnic factors are involved in determining the height of the barrier to alkene rotation.324 ' 1 7 P.-T. Cheng C. D. Cook S. C. Nyburg and K. Y. Wan inorg. Chem. 1972 10, 2210. 3 1 8 W. Partenheimer Inorg. Chem. 1972 11 743. H. A. Tayim and A. Vassilian inorg. Nuclear Chem. Letters 1972,8,659. 320 C . B. Anderson and J. T. Michalowski J.C.S. Chem. Comm. 1972,459. 3 2 1 M. Tsutsui M. Ori and J. Francis J . Amer. Chem. SOC. 1972 94 1414. 322 J. P. Visser and R. E. Ramakers J . C.S. Chem. Comm. 1972 178. 3 2 3 C. T. Mortimer J.L. McNaughton and R. J. Puddephatt J.C.S. Dalton 1972 1265. 3 2 4 J. Ashley-Smith I . Douek B. F. G. Johnson and J. Lewis J.C.S. Dalton 1972 1776 362 P. S. Braterman I3C n.m.r. data for an assortment of alkene complexes of platinum have been determined. As expected the alkene carbon signal is shifted further upfield in those species likely to show greater d -+ n* back-donation ; but there is no dis-continuity between complexes of formal Pt" and those of Pt'. The photoaquation of Zeise's anion gives the trans-aquated species.325 The Raman and i.r. spectra of silver alkene complexes lead to the conclusion that in general double-bond stretching character resides to varying extents in bands around 1500 and 1240cm-' and that changes in the positions of these bands should be combined in order to get a meaningful measure of bond-strength change.32 Alkyne Complexes. Cyclo-octyne (C8H 2 ) is converted thermally by hexacar-bonylmolybdenum into the benzenoid trimer in 100 % yield. The photochemical reaction gives in addition the products (80) and (81) in which CO from the metal OH 0 complex has been incorporated into the final product. The tris(a1kyne)metal carbonyl (C8H,2)3MO(CO) is also formed in the photochemical reaction.327 The crystal structure of the related complex tris(diphenylacety1ene)carbonyl-tungsten has been reported. The ligands describe an approximate tetrahedron round the metal with the angles at acetylenic carbon being approximately It has been shown crystallographically that in diphenylacetylenebis-(t-butyl-isonitrile)nickel(O) the acetylene lies in the co-ordination plane.The bonds between acetylenic carbon and the phenyl groups deviate by 31" from the direction of the acetylene bond and the central carbon-carbon bond length is 128pm, intermediate between normal double and normal triple bond lengths.329 Thermo-lysis of complexes (ArNC),(PhC i CPh)Ni gives principally the cyclopentadienone imine 6Ph :CPhCPh CPh-C( NAr) although the reaction of (ArNC),Ni with diphenylacetylene gives the cyclobutene derivatives CPh :CPh.C( NAr)d-( :NAr).330 The n.m.r. spectra have been obtained of (Ph,P),Pt(PhCi CH) deu-teriated at all sites except for the alkyne hydrogen. The acetylenic hydrogen is coupled to phosphorus showing that exchange of acetylene ligands is slow on the 140" 328 323 P.Natarajan and A. W. Adamson J. Amer. Chem. SOC. 1971,93 5599. 326 D. B. Powell J. G. V. Scott and N . Sheppard Spectrochim. Acta 1972,28A 327. 327 H. Kolshorn H. Meier and E. Muller Tetrahedron Letters 1972 1589. 328 R. M. Laine R. E. Moriarty and R. Bau J . Amer. Chem. SOC. 1972,94 1402. 329 R. S. Dickson and J. A. Ibers J. Organometallic Chem. 1972,36 191. 330 Y. Suzuki and J. Takizawa J.C.S. Chem. Comm. 1972 837 Transition-metal Carbonyl Organometallic and Related Complexes 363 n.m.r. time~cale.~~ ' Species [R,R,C(OH)-Ci CC(OH)R,R,],Pt are mono-nuclear diamagnetic and non-ionic. There is spectroscopic evidence that the triple bond is modified by complex formation.332 The complex Rh2(PF3),-(PhC ! CPh) reacts with triphenylphosphine to give (82) the structure of which, Ph F3 p, (82) entirely analogous to those of the dicobalt hexacarbonyl acetylenes has been determined crystallographically.The 'H n.m.r. spectrum of the related species Rh,(PF,),(HC i CMe) shows symmetrical septets thus demonstrating time-averaging of the ligand phosphorus positions.333 Threecarbon Ligands.-n-Ally1 Complexes. The reaction of the cyclopenta-dienyl tricarbon ylmolybdenum anion with 5- bromopen t- 1 -ene takes place with subsequent rearrangement to give (n-crotyl)(cyclopentadienyl)dicarbonyl-molybdenum. The suggested mechanism involves an indirect 1,2 hydrogen shift, via a metal hydride intermediate (Scheme 3).334 The crystal structure of bis-CH2' CH2 CH2 I 'CH CH -+ C H Mo(CO),- I NCH 5~ H / C H M O( CO) -CH CH C,H,Mo(CO), Scheme 3 (tripheny1phosphine)bis-(n-ally1)ruthenium has been determined.The ruthenium is approximately tetrahedrally co-ordinated (taking n-ally1 as occupying one site) and bonded most strongly to the central carbon atoms of the 71-ally1 ligand~.,~' The i.r. and Raman spectra of tetracarbonylmanganese n-ally1 have 3 3 1 C. D. Cook and K. Y . Wan Inorg. Chem. 1971 10,2696. 332 F. D. Rochan and T. Theophanides Canad. J . Chem. 1972,50 1325. 3 3 3 M. A. Bennett R. N. Johnson G. B. Robertson T. W. Turney and P. 0. Whimp, 334 J. Y . Merour C. Charrier J. Benaim J. L. Roustan and D. Commereuc J . Orguno-335 A. E. Smith Inorg. Chem. 1972 11 2306. J . Amer. Chem. SOC. 1972,94,6540. metallic Chem. 1972 39 321 364 P. S. Braterman been reported and assigned using the actual (C,) symmetry of the molecule.336 By contrast the vibrations of the Co(CO) fragment of tricarbonylcobalt n-ally1 can be satisfactorily assigned and predictions of i.r.and Raman activities made, in an idealized C symmetry.337 Azobenzenecobalt tricarbonyl reacts with hexafluorobut-2-yne to give the addition product (83) as well as the substituted quinolinone (84) that presumably arises from this.,,* II NPh (83) (84) Ally1 nickel chloride and bromide dimers result from the interaction in matrices of nickel atoms and the ally1 halide.339 The product from the reaction of bis(tri-isopropy1phosphine)methylnickel bromide and butadiene has been shown crystallographically to be the centrosymmetric species (85).340 Allene reacts Br ,PPrj Ni / Ni, PriP Br (85) with species L,Ni* where L is a sterically demanding ligand such as tricyclo-hexylphosphine or tri-2-biphenyl phosphite.The products are the n-ally1 complexes (86). These are remarkable for showing two n-ally1 groups in the cis-3 3 6 G. Davidson and D. C. Andrews J.C.S. Dalton 1972 126. 3 3 3 3 8 339 M. J. Piper and P. L. Timms J.C.S. Chem. Comm. 1972 50. 340 T. S. Cameron and C. K. Prout Acta Crysr. 1972 B28 2021. D. C. Andrews and G. Davidson J.C.S. Dalton 1972 138 1 . M. I. Bruce B. L. Goodall A. D. Redhouse and F. G. A. Stone J.C.S. Chem. Comm., 1972 1228 Transition-metal Carbonyl Organometallic and Related Complexes 365 conformation. The terminal ally1 groups are in fact highly a ~ y m m e t r i c a l . ~ ~ ~ . ~ ~ The chemistry of the familiar343 nickel dodecatrienyl complex (87) continues to yield new features of interest.Thus treatment of (87) with acetaldehyde followed (87) by aqueous cyanide leads to addition of the elements of ethanol across the carbon chain giving trans,trans,trans-CH,CH(OH).(CH,CH CH.CH,),.H. Ally1 halides also react in various (87) reacts with allene to give (88) which exhibits a further complex chemistry of its own. Treatment of (88) with CO at 200K gives (88a) which may be hydrogenated to give m u ~ c o n e . ~ ~ ~ Allylic nickel cationic species are thought to be implicated in such reactions as the coupling of crotyl chloride ethylene carbon monoxide and water to give CH,CH CHCH,.-R ' A R 2 ,- GQ rNi,j _- R/Ni PPh, 0 (88) (884 (89) CH2CH2C02H.346 n-Ally1 intermediates [of type (89)l are thought from the stereospecificity of reaction to be involved in the coupling of RICH:CHCH-(OH)R2 and RMgX in the presence of catalytic amounts of bis(tripheny1phos-phine)nickel(rI) Aluminium-nickel-phosphine systems catalyse the coupling of ethylene to butadiene yielding 1,4-hexadiene.Halide ions play an essential role and the active species is thought to be a n-crotyl nickel complex with nickel-aluminium halide bridges. 348 3 4 1 M. Englert P. W. Jolly and G . Wilke Angew. Chem. Internat. Edn. 1972 11 136. 3 4 2 B. L. Barnett C. Kriiger and Y . - H . Tsay Angew. Chem. Internat. Edn. 1972 1 1 137. 343 G . Wilke B. BogdanoviC P. Hardt P. Heimbach W. Keim M. Kroner W. Ober-kirch K. Tanaka E. Steinrucke D. Walter and H.Zimmermann Angew. Chem. Internat. Edn. 1966 5 151. 344 R. Baker B. N. Blackett R. C. Cookson R. C. Cross and D. P. Madden J.C.S. Chem. Comm. 1972 343. 345 R. Baker B. N. Blackett and R. C. Cookson J.C.S. Chem. Comm. 1972,802. 346 G. P. Chiusoli and G. Cometti J.C.S. Chem. Comm. 1972 1015. 3 4 7 H. Felkin and G . Schierezewski Tetrahedron Letters 1972 1433. 348 A. C. L. Su and J. W. Collete J. Organometallic Chem. 1972,36 177 366 P. S. Braterman Base hydrolysis of allylpalladium chloride dimer in water gives acetone ; this suggests a reaction mechanism of some complexity.349 Insertion of hexa-fluorobut-2-yne into a palladium-carbon bond of (dimethylpheny1phosphine)-n-allylpalladium chloride gives the species (90) and (9 1) in equilibrium.350 I . I H d / c l \ ] 2 F,C CF F 3 p c l I \ PMe2Ph PhMe,P (90) (91) Palladium(r1) acetate catalyses a reaction between formic acid and butadiene to give 1,6-octadiene and carbon dioxide.It is argued that the mechanism of this reaction involves palladium(r1) hydride formation addition of this hydride to butadiene to give a bis-(n-crotyl) complex and finally the coupling of two crotyl units to give the observed products.351 N.m.r. spectra of ring protons in aryl-substituted allylpalladium compounds show the n-allylmetal fragment as an electron-withdrawing The temperature-dependent n.m.r. spectrum of n-crotylpalladium chloride 2,4,6-trimethylpyridine shows three distinct pro-cesses ; intramolecular rotation of the amine intermolecular exchange of amines, and at still higher temperatures the rearrangement of the n-crotyl ligand which occurs by a 0-n process.353 Complexes of the type [(n-C,H,)Pd(LL)]+ where (LL) is an asymmetric bidentate ligand such as oxinate show a left-right inter-change that is catalysed by surplus base.Kinetic data support a mechanism for exchange uia partial substitution of LL in the transition state.3s4 Competition experiments show that the reactivity of cyclic 3-bromoalkenes with palladium, to give n-allylpalladium bromide complexes increases in the order C < C < C . This parallels the series of ease of catalytic hydr~genation.~~, Homoallyl p-Allyl Oxa-allyl and Cyclopropenium Complexes. The ethanolysis of norbornadienepalladium(r1) chloride by solvent gives the homo-ally1 complex (92) characterized by carbonylation in ethanol to give (93).356 The reaction of allylpalladium iodide dimer with three moles of triphenylphosphine gives allyltriphenylphosphonium iodide and (94) which has been characterized crystallographically.Of interest are the dimensions which imply a real palla-dium-palladium covalent bond. 349 F. R. Hartley and M. D. Higgs J . Organometallic Chem. 1972,44 197. 3 5 0 T. G. Appleton H. C. Clark R. C. Poller and R. J. Puddephatt J. Organometallic 3 5 1 S . Gardner and D. Wright Tetrahedron Letters 1972 163. 352 Y. Takahashi A. Akahori S. Sakai and Y. Ishii Bull. Chem. SOC. Japan 1971 44, 353 J. W. Fuller and M. J. Mattina Inorg. Chem. 1972 11 1296. 3 5 4 E. Ban A. Chan and J. Powell J . Organometallic Chem. 1972 34 405. 3 5 5 H. A. Quinn W.R. Jackson and J. J. Rooney J.C.S. Dalton 1972 180. 356 L. R. Hines and J. K. Stille J. Amer. Chem. SOC. 1972,94 485. 3 5 7 Y. Kobayashi Y. Iitaka and H. Yamazaki Acta Crysr. 1972 B28 899. Chem. 1972,39 C13. 2703 Transition-metal Carbonyl Organometallic and Related Complexes 367 (92) (93) (94) The crystal structure of tris(methy1 vinyl ketone)tungsten has been deter-mined and found to be trigonal prismatic (95). The oxygen and terminal carbon atoms are closer to the metal than are the intermediate carbon atoms, suggesting that the canonical structure (96a) plays as great a role if not greater, than the less remarkable (96b).358 Di-iron enneacarbonyl reacts with ap-unsaturated ketones to give such species as (97). The organic fragment is easily displaced by dienes providing a convenient synthetic route to diene tricarbonyl complexes.359 One particular example of a complex of this sort is pinocarvone-tricarbonyliron which has been prepared photochemically and characterized crystallographically.360 A 2-oxa-ally1 intermediate (98) has been suggested for the Fe,(CO),-induced reductive coupling of a,a'-dibromo-ketones to olefins and d i e n e ~ .~ ~ The 1,2-di-t-butyl-3-methylcyclopropenium cation reacts with nickel tetracarbonyl in the presence of bromide cations to give (99). This reacts further with sodium cyclopentadienide to give ( Me 358 R. E. Moriarty R. D. Ernst and R. Bau J.C.S. Chem. Comm. 1972 1242. 3 5 9 J. A. S. Howell B. F. G. Johnson P. L. Josty and J. Lewis J. Organometallic Chem., 3 6 0 E. Koerner von Gustorf F.-W.Grevels C. Kriiger G. Olbrich F. Mark D. Schulz, 3 6 1 R. Noyori Y. Hayakawa M. Funakura H. Tayaka S. Murai R. Kobayashi and S. 3 6 2 1972 39 329. and R. Wagner Z . Naturforsch. 1972 27b 392. Tsutsumi J. Amer. Chem. SOC. 1972,94 7202. W. K. Olander and T . L. Brown J. Amer. Chem. SOC. 1972,94,2139 368 P. S. Braterman Four-carbon Ligands.-Cyclobutadiene Complexes. Cyclic diynes of appropriate ring size react with cyclopentadienyldicarbonylcobalt to give products of type (101).363 For example 1,7-cyclododecadiyne gives (101; x = y = 4). Similarly, c o (101) the reaction of trimethylsilylacetylenes with (n-C,H,)Co(CO) produces bis-(trimethylsilyl)cyclobutadienecyclopentadienylcobalt complexes. Both cis- and trans-isomers are formed ; the crystal structures have been determined and are devoid of unusual features.364 A more interesting structure is that of the cation (102) in which two tricarbonylironcyclobutadienyl fragments are bonded to a Fe(C0)3 (102) cationic centre.The two four-membered rings are coplanar with each other and with the bridging carbonium carbon and the tricarbonyliron fragments are above and below the centres of their respective rings. It follows that the carbonium centre ct to the rings is stabilized at least in this species and presumably more generally only by conjugation to the rings and not by direct interaction with metals.36s Butadiene Complexes. A vibrational analysis of butadienetricarbonyliron has been carried out,366 and extended to bis(butadiene)monocarbonyliron.367 There seems to be little coupling between the butadiene ligands of the latter complex, which are very similar in their properties to those in the former.367 The cyclo-pentadienylrhodium complex of cyclohexa- 1,3-diene is a nucleophile being protonated specifically endo in strong acid as shown by the stereochemistry of 3 6 3 R.B. King and A. Efraty J . Amer. Chem. SOC. 1972,94 3021. 364 (a) H. Sakurai and J. Hayashi J . Organometallic Chem. 1972 39 365; (6) C. Kabuto, J. Hayashi H. Sakurai and Y. Kitahara J . Organometallic Chem. 1972,43 C23. 365 R. E. Davis H. D. Simpson N. Grice and R. Pettit J . Amer. Chem. SOC. 1971 93, 6688. 3 6 6 D. C. Andrews and G. Davidson J . Organometallic Chem. 1972 36 349. ' 6 7 G. Davidson and D . A. Duce J . Organornetallic Chem.1972 44 365 Transition-metal Carbonyl Organometallic and Related Complexes 369 d e ~ t e r i a t i o n . ~ ~ ~ Bis(butadiene)nickel has been prepared in 2 % yield by the co-condensation of nickel atoms with butadiene. The principal product is involatile and is formulated on chemical evidence as a polymer of the same composition with butadiene groups linking nickel atoms.369 Complexes of Modified or Conjugated Butadienes. The structure (103) has been found crystallographically for isopropenylbenzenebis(tricarbony1iron). The two C,Fe(CO) fragments are non-interacting. The Fe(CO) groups are on opposite Fe(C0) (103) sides of the common ligand and the two C units are connected by normal single bonds with loss of aromaticity from the C ring.370 The crystal structure of the diene complex (104) has been determined; the detailed geometries of the C, fragments which are described as the most accurately determined to date are shown in (105).It is noteworthy that the central bond of the C fragment is 1 4 2 c Jl.7 139.8 (A B 140.3 142.5 142.1 *-Fe(CO), (104) (105) actually slightly shorter than the two outer bonds both in ring A which is dis-torted by interaction with the oxygen atom of the ligand and in ring B which is not.3 The reactions of 2-methoxy-3-bromopropene and of the iodo-analogue, with di-iron enneacarbonyl give 2-methoxyallyliron tricarbonyl halides as expected for insertion of an iron carbonyl fragment into the allylic carbon-halogen bonds (cf ref. 361). The chloride however reacts rather differently to give (106) a stabilized vinylketen formed by carbonylation of the ally1 The low-temperature 3C n.m.r.spectrum of cyclo-octatetraene tricarbonyliron is assignable in terms of the rigid structure in which Fe(CO) is co-ordinated to one C fragment (but contrast ref. 447). There is also splitting of the signal from the carbonyl groups which are averaged by a different process from those of the 3 6 8 B. F. G. Johnson J. Lewis and D. Yarrow J.C.S. Chem. Comm. 1972,235. 3 6 9 P. S. Skell J. J. Havel D. L. Williams-Smith and M. J. McGlinchey J.C.S. Chem. 370 F. H. Herbstein and M. G. Reisner J.C.S. Chem. Comm. 1972 1077. 371 G. I. Birnbaum J . Amer. Chem. SOC. 1972,94,2455. 372 A. E. Hill and H. M. R. Hoffmann J.C.S. Chem. Comm. 1972 574. Comm. 1972 1098 370 MeO 0% (OC),Fe 0 P.S. Bratermun (106) ring.,' Photolysis of (cot)Fe(CO) occurs with loss of cot to give (107) which is also accessible photochemically from (cot) [Fe(CO),] .374 0 (107) Trimethylenemethane Complexes. An assignment has been offered for the vibra-tional spectrum of trimethylenemethanetri~arbonyliron.~~~ This complex may be substituted to give [C(CH,),]Fe(CO),(PF,) in which restricted rotation about the ligand-iron bond may be detected from the 'H n.m.r. spectrum below room temperature.376 The reaction of Fe,(CO) with 1-methylene-2-vinylcyclo-propane takes place to give vinylmethylenedimethylenemethanetricarbonyl-iron,lo8 rather than a .n-complex of the existing diene grouping.377 F~(co), (108) Five-carbon Ligands.-Reviews have appeared on electronic effects in metal-l ~ c e n e s ~ ~ and on their chemical reactions.379 Particularly timely in view of current interest is a review of the chemistry of cyclopentadienyls of chromium, molybdenum and tungsten.380 Acetylpentamethylcyclopentadiene has been 373 G.Rigatti G. Boccalon A. Ceccon and G. Giacometti J.C.S. Chem. Comm. 1972, 3 7 4 J. Schwartz J.C.S. Chem. Comm. 1972 814. 375 D. C. Andrews and G. Davidson J. Organometallic Chem. 1972,43 393. 376 R. J. Clark M. R. Abraham and M. A. Busch J . Organometallic Chem. 1971 35, 377 W. E. Billups L.-P. Lin and 0. A. Gansow Angew. Chem. Internat. Edn. 1972 11, 3 7 8 D. W. Slocum and C. P. Ernst Adv. Organometallic Chem. 1972 10 79. 379 E. G. Perevalova and T. V. Nikitina Organometallic Reactions 1972,4 163.380 K. W. Barnett and D. W. Slocum J. Orxanometallic Chem. 1972,44 1 . 1165. c33. 637 Transition-metal Carbonyl Organometallic and Related Complexes 37 1 used as a source of the pentamethylcyclopentadienyl grouping which is not readily accessible in other ways. Chromium and molybdenum hexacarbonyls react in each case to give the formally triple-bonded dimers [(x-C,Me,)M(CO),], (see also ref. 393) and in addition molybdenum hexacarbonyl gives (n-C,Me,)-Mo(CO),CH . The tungsten analogue of this compound has been prepared from tr is(ace toni tr i1e)tricarbonyl tungs ten tungsten hexacarbon y 1 itself having failed to react. The dimeric carbonyls of manganese and cobalt react to give (n-C,Me,)-Mn(CO) and (n-C,Me,)Co(CO) . Di-iron enneacarbonyl gives a mixture of at least three products ; the simple tricarbonyliron adduct (109) the acyl species Me (109) (n-C,Me5)Fe(CO),COCH formally derivable by oxidative insertion into the ring-acyl bond and the dimer [(n-C,Me,)Fe(CO),] .381 A study has been carried out of the n.m.r.spectra of bis(methylcyclopentadieny1) compounds of vanadium chromium cobalt and nickel. In the vanadium and chromium compounds the rings are found to bear negative spin density. This is ascribed principally to exchange between the half-filled metal orbitals and the full orbitals of the rings. There is direct positive spin delocalization for the nickel species, while the cobalt species shows what may be the effects of dipolar pseudocontact terms.382 It has been shown by extensive crystallographic studies that in species of the type (z-C,H,),MXY the XMY angle falls on going from do to d’ to d2 systems.This somewhat surprising result may be explained by so choosing the coefficients of the various metal atomic orbitals in the lowest energy ‘d’ orbital that its lobes of greatest density lie outside the angle in question while a further ‘d’ orbital of the same symmetry with its greatest density within this angle lies at higher energy. An additional ligand can however alter the nature and energies of these two orbitals so as to account for the ability of (n-C,H,),MoH to add on a proton.383 Solid bis(cyclopentadieny1)scandium chloride consists of discrete chlorine-bridged dimers. The C,H5 rings are symmetrically bound to the scandium atoms, which are thus in a pseudo-tetrahedral environment.384 The potential shift-reagents (CH,C,H,),Sm and (C5H,),Er form discrete complexes with the oxygen atoms of carbonyl or nitrosyl ligands in (C,H,),Fe,(CO) (bridging CO), CH,C,H,Mn(CO), and C,H,Cr(NO),Cl as shown by the appearance of new CO and NO stretching bands some 50-60 cm- ’ to lower frequency of the 3 8 1 R.B. King and A. Efraty J . Amer. Chem. Soc. 1971 93,4950. 382 S. E. Anderson jun. and N. A. Matwiyoff Chem. Phys. Letters 1972 13 150. 3 8 3 J. C. Green M. L. H. Green and C. K. Prout J.C.S. Chem. Comm. 1972,421. 384 K. D. Smith and J. L. Atwood J.C.S. Chem. Comm. 1972 593 372 P. S. Braterman bands of the parent compound.385 Uranium tetrachloride reacts with cyclopen-tadienylthallium in dimethoxyethane to give C,H,UCl ,DME.This is claimed as the first organometallic derivative of uranium with only one carbon-bonded ligand.386 Bis(cyclopentadieny1) (n-croty1)titanium exchanges ring hydrogen atoms with D gas ; a methyl group introduced into the ring is P-directing for this exchange.,” Pure [(n-C,H,),TiCl] may be obtained either from the reaction of(n-C,H,),TiCl, and (n-CSH,)2TiBH4 or from zinc reduction of the former compound in a polar solvent such as THF. The chlorine bridge may be broken by donors in the normal way.388 The crystal structure of (C,H,),Hf has been determined. It contains two pentahapto rings and two that are attached by a single a-bond thus resembling (C,H,),Ti rather than the zirconium compound.389 The e.s.r. spectrum of (n-C,H,),VCl has been obtained in a (n-C,H,),TiCl host.The odd electron is in an orbital of symmetry type a, built up mainly from 3d, and 3 d 2 - y 2 orbitals with some admixture of 4s.390 ‘Niobocene’ dimer has been shown crystallographically to be in fact the hydride (1 A route has been discovered to the chemistry of bis(cyc1openta-(1 10) dienyl) complexes of niobium(r11). The reaction of (~-C,H,),NbCl with boro-hydride gives (n-C,H,),NbBH,. Phosphines PR extract the elements of borane from this system as well as complexing to the metal giving products (n-C5H5)2-Nb(H)PR . These react with butyl bromide to give (n-C,H,),Nb(Br)PR, and with dilute aqueous HCl giving [(n-C,H,),NbH,(PR,)] +.jg2 385 A. E. Crease and P. Legdzins J.C.S. Chem. Comm. 1972 268. 386 L. Doretti P. Zanella G. Faraglia and S.Faleschini J . Organometallic Chem., 1972 43 339. 3 8 7 H. A. Martin M. van Gorkom and R. 0. De Jongh J. Organometallic Chem. 1972, 36 93. 3 8 8 M. L. H. Green and C. R. Lucas J.C.S. Dalton 1972 1000. 3 8 9 V. I. Kulishov E. M. Brainina N. G. Bokiy and Yu. T. Struchkov J . Organometallic Chem. 1972,36 333. 3 9 0 D. P. Bakalik and R. G. Hayes lnorg. Chem. 1972 11 1734. 3 9 1 L. J. Guggenberger and F. N. Tebbe J . Amer. Chem. SOC. 1971,93 5924. 3 9 2 C. R. Lucas and M. L. H. Green J.C.S. Chem. Comm. 1972 1005 Transition-metal Carbonyl Organometallic and Related Complexes 373 The crystal structure of [(n-C,Me,)Cr(CO),] has been determined. The molecule is centrosymmetric and all the CO groups are terminal. The short metal-metal distance (228 pm) is ascribed to multiple metal-metal bonding as required by the 18-electron rule.393 In solid (C,H,),Mo(CH,)NO the two cyclopentadienyl rings are similarly and asymmetrically bonded in accord with the requirement of the 18-electron rule that if equivalent they should be inter-mediate in character between trihapto and p e n t ~ h a p t o .~ ~ ~ The 19F n.m.r. spectra of species (n-C,H,),MoAr and the tungsten analogue (Ar = m- or p-fluoro-phenyl) are interpreted as showing that the bis(cyclopentadieny1)metal systems are net donors to the C5 ring by an inductive rather than a mesomeric route.395 The bis(cyclopentadieny1)dichlorides and dibromides of molybdenum and tungsten react with such nucleophiles as hydroxide sulphate and sulphite to give species formulated on spectroscopic and general grounds as (n-C,H,),MO, (n-C,HS),MS04 (1 ll) and (n-CsHs)2MS203 (1 12).With tin dihalides, (1 11) (1 12) insertion reactions occur giving (n-C,H,),M(X)(SnX,),396 and the crystal struc-ture of a compound of this class (M = Mo X = Br) has been determined.397 Several reports have appeared of reactions of bis(cyclopentadieny1)molybdenum dihydride and related species. Sodium amalgam reduction of (n-C,H,),MoCl, gives a mixture of the dihydride and ‘molybdenocene polymer’ [CloHloMo] . If the reduction is carried out in the presence of carbon monoxide or of dinitrogen, (n-C5H5),MoCO [v(CO) = 1905 cm- ‘3 or (n-C,H,),MoN (characterized by decomposition) are formed. Permethylmolybdenocene is a dimer [(C,Me,),-Mo] which is presumably very readily cleaved to monomer since the mass spectrum contains no fragments larger than required by [(C,Me,),Mo]+.In addition the dimer reacts with dihydrogen and with carbon monoxide generating (z-C,Me,),MoH and (n-C,Me,),MoCO respectively.398 (n-C,H,),MoH, reacts with bis(methoxycarbony1)acetylene to give (n-C,H,),Mo(H)C(CO,Me) :-CHCO,Me which reacts further with HCl giving (n-CsH,),MoClCH(C02Me)-CH,CO,Me. Hexafluorobut-2-yne also inserts into a metal-hydrogen bond but diphenylacetylene gives rise to a metallacyclopropene (n-C,H,),‘MoCPh :CPh as well as a mixture of cis- and t r ~ n s - s t i l b e n e . ~ ~ ~ Bis(cyclopentadieny1)molybdenum 3 9 3 J. Potenza P. Giordano D. Mastropaolo A. Efraty and R. B. King J.C.S. Chem. 394 F. A. Cotton and G. A. Rusholme J. Amer. Chem. SOC. 1972,94,402.3 9 5 A. N. Nesmeyanov L. G. Makarova Yu. A. Ustynyuk B. A. Kvasov and L. V. 396 M. L. H. Green A. H. Lynch and M. G . Swanwick J.C.S. Dalton 1972 1445. 397 T. S.Cameron and C. K. Prout J.C.S. Dalton 1972 1447. 3 9 8 J. L. Thomas and H. H. Brintzinger J . Amer. Chem. SOC. 1972 94 1386. 399 A. Nakamura and S. Otsuka J . Amer. Chem. SOC. 1972,94 1886. Comm. 1972 1333. Bogatyreva J . Organometallic Chem. 1971 34 185 374 P. S. Braterman dichloride and its tungsten analogue react with excess AlEtCl to give the cations [(2r-C,H,),MH(C,H4)]+. These are reversibly converted by base into (~-C,H,),M(~C-C,H~).~~~ Thermolysis of bis(cyclopentadieny1)tungsten di-hydride in E2H,]-benzene gives (2r-C5H,),W(D)C,D5 presumably via a tungstenocene in termediate.40 The crystal structure has been determined of [(CH,C,H,),Fe]+IS.The rings are almost eclipsed inclined at 7" to each other with the substituents occupying adjacent positions.402 Unlike ferrocene itself protonated ferrocene, [(n-C,H,),FeH]+ is oxidized by dioxygen to the ferricenium cation. Sulphur dioxide will also act as an oxidizing agent in this reaction being reduced to In 1,l'-disubstituted ferrocenes protonation introduces a ring tilt that inhibits free rotation of the rings.404" The protonation in the above cases is generally thought to occur at the metal but one group has claimed spectroscopic evidence for protonation of ferrocene at a ring.404b 'H n.m.r. spectra have been reported for the complexes (n-C,H,)Fe(CO),X (X = CH, Ph COCH, C1, Br I or CN) as well as for a variety of species (n-C,H,)Fe(CO)(PPh,).C,H,-R.It is concluded from an analysis of the results that the effects of X and R on the signal of the C ring are inductive.405 13C n.m.r. results have been obtained for (7c-C5H,),Fe,(CO) over a range of temperatures. Cisoid-transoid inter-conversion occurs as does the exchange of bridging and terminal CO groups. In methylene chloride the transoid-bridged isomer is less favoured and shows bridge-terminal interconversion at lower ternperat~re.~'~ The cluster tetramer [(7c-C5H,)FeCO] has been prepared with overall charges of +2 +1 0 and -l.407 The crystal structures have been determined of the neutral species, and of the singly charged cation (as its PF - salt). The neutral species is cubane-like with (z-C,H,)Fe fragments and CO groups at alternate corners of the cube in a structure of overall symmetry .408 The cation shows a slight shrinkage of iron-iron distances and a distortion towards D, symmetry.409 The reaction of dilithium pentalene (1 13) with nickel chloride gives the two-stack sandwich species (1 14a) directly related to nickelocene.With cobalt(rr) chloride the product is (1 14b) in which the cobalt atoms have become tervalent by forming a metal-metal bond. Oxidation of this species with hydrogen peroxide gives the bispentadienyl complex (1 1 Sa) whereas iron@) chloride gives (1 15b) 400 F. W. S. Benfield B. R. Francis and M. L. H. Green J. Organometallic Chem. 1972, 401 C. Giannotti and M. L. H. Green J.C.S. Chem. Comm. 1972 1114. 402 J. W. Bats J. J. de Boer and D.Bright Inorg. Chim. Acta 1971 5 605. 403 T. E. Bitterwolf and A. C. Ling J. OrganometaNic Chem. 1972,40 C29. 404 (a) T. E. Bitterwolf and A. C. Ling J . Organometallic Chem. 1972 40 197; (b) B. Floris G. Illuminati P. E. Jones and G. Ortaggi Co-ordination Chem. Rev. 1972 8, 39 B. Floris. G. Illuminati and G. Ortaggi Tetrahedron Letters 1972 269. 405 A. N. Nesmeyanov I. F. Leshcheva I . V. Polovyanyuk. Yu. A. Ustynyuk. and L. G. Makarova J. Organometallic Chem. 1972 37 159. 406 0. A. Gansow A. R. Burke and W. D. Vernon J. Amer. Chem. SOC 1972,94 2550. '07 J . A. Ferguson and T. J . Meyer J . Amer. Chem. SOC. 1972,94 3409. 408 M. A. Neuman Trinh-Toan and L. F. Dahl J. Amer. Chem. SOC 1972.94. 3383. 409 Trinh-Toan W. P. Fehlhammer and L. F. Dahl J. Amer. Chem.Soc. 1972 94, 3389. 44 C13 Transition-metal Carbonyl Organometallic and Related Complexes 375 (114) (a) M M = Fe Fe (115) [ a 1 M = C o + dire~tly.~" The 'H n.m.r. spectrum of the cobalticinium cation has been com-pared with those of ferrocene and of substituted ferrocenes and cobalticinium derivatives. In general substituents on one ring affect the protons on both rings to some extent. A notable exception is t-butyl and it is inferred that these interan-nular effects are mainly mesomeric rather than inductive in origin.,' ' The crystal structure of (C,CI,),Ru shows the chlorines to be displaced out-wards from the planes of the C rings by some 10 pm. This effect must be due to bonding effects since there is no steric The spectrum of solid ruthenocene is complex but has been reinterpreted with the help of solution spectra and single-crystal Raman data.All modes have been assigned including the totally inactive ones. Contrary to the accepted order the symmetric metal-ring frequency is higher than the asymmetric ring tilt.,' Cyclododecatriene reacts with bis(trimethylgermyl)tetracarbonylruthenium to give the trihydro-pentalenyl complexes (116) and (117) (which can also be obtained using cyclo-b M = F e (1 13) (b) M M = CO-CO Ru(CO),GeMe3 (116) I / GeMe,, Ru(CO),GeMe (OCIRU / GeMe, (1 17) ocatdiene as a starting material). This reaction is an interesting example of ring contraction presumably with loss of C fragments although these have not as yet been detected.414 The electrochemical oxidation of ruthenocene at a mercury anode leads to the cation [(C,H5)2RuHgRu(C,H,),]Z+.415 4 1 0 T.J. Katz N. Acton and J. McGinnis J . Amer. Chem. SOC. 1972 94 6205. 4 1 1 A. N. Nesmeyanov N. S. Kochetkova E. V. Leonova E. I. Fedin and P. V. Petrovskii, J . Organometallic Chem. 1972,39 173. G. M. Brown F. L. Hedberg and H. Rosenberg J.C.S. Chem. Comm. 1972 5 . 4 1 3 D. M. Adams and W. S. Fernando J.C.S. Dalton 1972 2507. 4 1 4 S. A. R. Knox R. P. Phillips and F. G. A. Stone J.C.S. Chem. Comm. 1972 1227. 4 1 5 D. N. Hendrickson Y . S. Sohn W. H. Morrison jun. and H. B. Gray Inorg. Chem., 4 1 2 1972 11 808 376 P. S . Braterman The kinetics have been investigated of the known reaction of cobaltocene with alkyl halides to give cobalticinium halides and (em-C,H,R)CoC,H . The reaction is first-order in each component and the favoured mechanism is a slow initial charge transfer to give the cobalticinium cation in conjunction with an alkyl halide radical anion.The latter would then decompose to give halide anion and neutral alkyl radicals which would rapidly add in the exo-position to a further molecule of c~baltocene.~ l6 The triangular tris(cyclopentadieny1cobalt) species [(n-C,H,),Co,(CO)S] [(n-C,H4),CO3S2] and [(n-C5H5),Co3S2]+ have been prepared and their crystal structures determined. The bis(su1phur) species has two more electrons than the 18-electron rule requires for triangular M, systems and at room temperature it is paramagnetic with two unpaired spins. Below 173 K however it is diamagnetic indicating a crossover of electronic states.The cationic bis(su1phur) species is deformed with one cobalt-cobalt distance of 247 pm the other two being 265 pm. In the electron-rich disulphide, and in the rule-obeying sulphide carbonyl the cobalt-cobalt distances are 269 and 245 pm re~pectively.~' Pentamethylcyclopentadienylrhodium bis(phos-phorus trifluoride) undergoes oxidative addition-elimination reactions to give (n-C,Me,)Rh(PF,)I and C,Me,Rh(PF,)(I)(RF) (RF = perfl~oroalkyl).~'~ The crystal structure has been determined of [(n-C,H,)Ni(n-C,H4)1, a centrosymmetric n-allylic cyclopentadienylnickel dimer. There are significant bond-distance irregularities within the C rings suggesting some localization of C and C ligand fragment^.^'^ Contact shifts are apparent in the 'H n.m.r. spectra of nickelocenium [(n-C,H5)2Ni]+ and methyl- and t-butyl-substituted derivatives indicate a strong first-order d e l ~ c a l i z a t i o n .~ ~ ~ [2Hlo]Nickelocene has been used as a probe for kinetic lability in metallocenes. Thus the bis(cyc1o-pentadienyl) complexes of chromium manganese and nickel all readily exchange rings with (C,D,),Ni but ferrocene cobaltocene and vanadocene react slowly, if at all.421 The bridged carbonyl species (n-C,H,),Ni,(CO) is known to react with phosphines to give products L,Ni(CO), and with alkynes to give bridged species [(n-C,H,)Ni] (alkyne). Despite earlier confusion it now seems that both these reactions proceed by an S,2 mechanism although the analysis of the alkyne reaction is complicated by d e c o m p ~ s i t i o n . ~ ~ ~ The reaction of nickelocene with benzylmagnesium chloride gives a product [(n-C,H,)Ni],CPh presumably structurally related to [(OC),CO],CP~.~~ The reaction of the dihalides of nickel palladium and platinum with the cyclopentadienyl anion in the presence of cyclopentadiene gives products of type (1 18).424 Nickelocene reacts with Lewis 4 1 6 G.E. Herberich and J. Schwarzer J . Organometallic Chem. 1972,34 C43. 4 ' 7 P. D. Frisch and L. F. Dahl J . Amer. Chem. SOC. 1972,94 5082. 4 1 8 R. B. King and A. Efraty J . Organometallic Chem. 1972 36 371. 419 A. E. Smith Znorg. Chem. 1972 11 165. 4 2 0 H. P. Fritz and F. H. Kohler Z . anorg. Chem. 1971,385 22. 4 2 1 M. E. Switzer and M. F. Rettig J.C.S. Chem. Comm. 1972 687. 4 2 2 (a) P. L. Stanghellini R. Rossetti 0. Gambino and G.Cetini Znorg. Chem. 1971 10, 4 2 3 T. I . Voyevodskaya I. M. Pribytkova and Yu. A. Ustynyuk J . Organometallic Chem., 4 2 4 E. 0. Fisher P. Meyer C. G. Kreiter and J. Muller Chem. Ber. 1972 105 3014. 2762; (6) P. C. Ellgen Znorg. Chem. 1972 11 2279. 1972 37. 187 Transition-metal Carbonyl Organometallic and Related Complexes 377 acids to give three-layer sandwich compounds. For example species R+BF4-(R = PPh or tropylium) give [(C5H5)3Ni2]+BFi and R.C,H,.425 Under suitable conditions even proton acids (such as HBF in propionic anhydride) will react giving [(n-C,H,),Ni,] + and cy~lopentadiene.~~~ Ligands with Six or More Carbon Atoms.-The hexamethylbenzene complexes ‘[(Me6C6)3M3X6]+’ where M is niobium or tantalum and x is chlorine or bromine can be oxidized to ‘[(Me,C,)3M3X,]2f’.All these species are dia-magnetic strongly suggesting a dimeric formulation and an analogy with the chemistry of the M chloride cluster complexes.427 Helium photoelectron spectra have been obtained for the bis-benzene complex of chromium and the related species (toluene),Cr (n-C,H,)(C,H,)Cr and (n-C,H,)(C,H,)Mn. The binding energies of the ‘d-electrons’ (in the 5-7 eV region) and of the ‘ring electrons’ at higher energies are presented and The crystal structure of benzenechromium tricarbonyl at 77 K has been reported to show the existence of slight but significant bond-length alternation in the benzene ring.429 The species (OC),Cr(.n-C,H,.Hg.C,H,-.n)Cr(CO) has been prepared from diphenylmercury and hexacarbonylchromium.430 Bis(benzene)chromium and bis(to1uene)chromium exchange hydrogen for solvent deuterium both in the ring and in the side-chain in ethanolic alkali.Bis(arene)chromium cations exchange even more readily for example in aqueous solution. The exchange rates are increased by added alkali and seem to be reduced by electron-donating sub-stituents. These facts can be explained in terms of abnormal acidity in the rings,43 and a species formulated as [(n-C,H,)Cr(n-C,H,)] - on the basis of its e.s.r. spectrum can in fact be identified.432 Electron-donating substituents in the arene facilitate the ion-molecule reaction (arene)Cr(CO) + (arene)Cr(CO) + (arene),Cr,(CO) + + 3CO in mass-spectroscopic studies of (arene)Cr(CO) .433 4 2 5 A. Salzer and H. Werner Angew. Chem. Internat. Edn. 1972 11 930.4 2 6 H. Werner and A. Salzer Inorg. Metal-org. Chem. 1972 2 239. 4 2 7 R. B. King D. M. Braitsh and P. M. Kapoor J.C.S. Chem. Comm. 1972 1072. 4 2 8 S. Evans J. C. Green and S. E. Jackson J.C.S. Faraday II 1972 68 249. 429 B. Rees and P. Coppens J . Organornetallic Chem. 1972,42 C51. 430 G. A. Razuvaev G. G. Petuchov A. N. Artemov and N. I. Sirotkin J . Organo-metallic Chem. 1972 37 3 13. 4 3 1 D. N. Kursanov V. N. Setkina and B. G. Gribov J . Organometallic Chem. 1972 37, c 3 5 . 4 3 2 C. Elschenbroich F. Gerson and J. Heinzer Z. Naturforsch. 1972 27b 312. 4 3 3 J. R. Gilbert W. P. Leach and J. R. Miller J. Organometallic Chem. 1972 42 C51 378 P. S. Braterman Arenechromium tricarbonyls react with quaternary ammonium salts to give the halide-bridged species [(OC),CrX,Cr(C0),I3 - .434 Bis(hexamethy1benzene)ruthenium has been shown crystallographically to contain one ring symmetrically bonded to the metal whereas the other is bonded through four carbon atoms only leaving two carbon atoms connected by a more or less localized double bond.43 In (C,H,)RuCl,(PMePh,) and (p-CH3-C6H4-CHMe,)RuCl,(PMePh,) the arene and other ligands are mutually staggered.The arene rings are slightly bent an effect attributed to the differences in trans-influence among the other ligand~.~, The reaction of cyclohexadiene with ruthenium trichloride in water or ethanol leads to the formation of soluble (C,H,)RuCl, which is a 1 2 electrolyte in water. This species adds one mole of a phosphine ligand to give (C6H,)RUC1,L which at least in acetonitrile is a n~n-electrolyte.~~~ Dimeric [(C,H6)RUCl2] is inert to such nucleophiles as Grignard reagents or organolithium compounds but reacts with a range of organometallic electro-philes to give eventually species in which chlorine has been replaced by a carbon ligand.Thus its reaction with R,Hg followed by triphenylphosphine gives (C,H,)-RuCl(R)(PPh,) (R = Me or Ph). Tetra-allyltin gives (C,H,)Ru(n-allyl) and Several transition-metal halides have been shown to react with cycloheptadiene and the corresponding triene to give V(C7H& [bis(cycloheptatriene)vanadium-(O)] Cr(C7H,)(C7HIo) [cycloheptatrienyl-1,3-cycloheptadienechromium(1)] Fe-(C,H,) (dicycloheptadienyliron) and Co(C7Hg) (C7H [(cycloheptadienyl-1,3-cycloheptadiene)cobalt(1)].~~~ Cycloheptatrienedi-iron hexacarbonyl has been shown crystallographically to have the symmetrical structure (1 19) in the (C H ,)TI gives [c6 H RUC,H 5] + c1- .4 * solid.This is in marked contrast to the behaviour of most other di-iron hexa-carbonyl cyclopolyene complexes in which there is time-averaging of two closely related distinct Fe(CO) fragments.440 434 J. F. White and M. F. Farona J . Organometallic Chem. 1972 37 119. 4 3 5 G. Huttner and S. Lange Acta Cryst. 1972 B28 2049. 436 M. A. Bennett G. B. Robertson and A. K. Smith J . Organometallic Chem. 1972, 437 R. A. Zelonka and M. C. Baird J . Organometallic Chem. 1972,3S C43. 438 R. A. Zelonka and M. C. Baird J. Organometallic Chem. 1972,44 383. 439 (a) J. Muller and B. Mertschenk J . Organometallic Chem. 1971,34 C41; (b) J.Muller 440 F. A. Cotton B. G. DeBoer andT. G. Marks J . Amer. Chem. SOC. 1971,93,5069 and 43 c41. and B. Mertschenk Chem. Ber. 1972,105 3346. references therein Transition-metal Carbonyl Organometallic and Related Complexes 379 Many new examples have been reported of cyclo-octatetraene (cot) complexes in which this ligand is symmetrically bound to the metal so that the complexes may formally be regarded as derivatives of the planar aromatic 10-electron system C8Hg2 -. The chloride-bridged dimer [(cot)TiCl] reacts with l-methyl-allylmagnesium chloride to give (h8-~ot)Ti(h3-1-methylallyl) the structure of which is inferred from its i.r. Hafnium tetrachloride reacts with Na,(cot) to give (cot),Hf. This forms a complex with diethylaluminium hydride, and reacts with alcohols or with hydrogen chloride in THF to give hafnium(1v) alkoxides and cyclo-octatriene or cyclo-octatriene and (cot)HfCl .The latter reacts with ally1 Grignard reagents to give the species (cot)Hf(n-allyl) .442 The crystal structure. of (cot),Zr(THF) (120) has been determined. One of the cot rings is symmetrically bonded to the metal whereas the other is bonded in a novel way through four carbons. Thus the complex could be said to obey the 18-electron rule though thermal anisotropy precludes the making of firm conclu-sions about the bonding of the h4-ring.443 E.s.r. spectra have been obtained for (C,H,)Ti(cot) and for (cot),V. Both of these may be regarded as derivatives of planar C8Hs2- and the odd electron is in a d, orbital and plays little part in bonding.444 X-Ray crystallography confirms a planar octahapto structure for the cot ring in [(cot)Ce(THF),Cl] .445 (cot),Th has been prepared from Li,(cot) in THF and thorium dichloride and it is assigned a sandwich structure from its i.r.spectrum.446a 1,3,5,7-tetramethylcyclo-octatetraene (tmcot) reacts in the usual way to give (tmcot),U and (tmcot),Np. The 'H n.m.r. spectrum of these species suggests that f-orbital involvement in ring-metal interaction is 441 H. K. Hoftsee H. 0. van Oven and H. J. de Liefde Meijer J . Organometallic Chem., 442 H.-J. Kablitz R. Kallweit and G. Wilke J. Organometallic Chem. 1972 44 C49. 443 D. J. Brauer and C. Kriiger J . Organometallic Chem. 1972,42 129. 444 J. L. Thomas and R. G. Hayes Znorg. Chem. 1972,11 348.445 K. 0. Hodgson and K. N. Raymond Znorg. Chem. 1972,11 171. 446 ( a ) J. Gottart J. Fuger B. Gilbert B. Kanellekopulos and G. Duyckaerts Znorg. Nuclear Chem. Letters 1972,8,403; (6) A. Streitwieser jun. D. Dempf G. N. La Mar, D. G. Karraker and N. Edelstein J . Amer. Chem. Soc. 1971 93 7343. 1972,42,405 380 P. S. Braterman The broad-line n.m.r. spectra of (h4-cot)Fe(CO) and of (cot)Fe,(CO) (107) show that in the solid the C,H rings retain some freedom of rotation but that [h4,(h')"-cot] [Fe(CO),] is rigid in the solid.447 3 Main Group Ligands Hydride Complexes.-There is i.r. evidence (raising of CO frequency) for protonation of the metal in trifluoroacetic acid solutions of species Ar-Cr(CO),-(PPh,). Ar-Cr(CO) is not protonated in trifluoroacetic acid itself but frequency raising (and splitting) of the v(C0) bonds does occur when acidity is further increased by the addition of boron trifluoride.Protonation also occurs in trifluoroacetic acid solutions of (n-C,H,)Mn(CO),(PPh,) although less than in the (n-C,H,)Cr analogue.448 The ' H n.m.r. spectrum of H,Mo(PPh,Me), has been analysed and in the hydride region indicates a fluxional system with an [AX] low-temperature limit.449 cis-HMn(CO),(PPh,) has been studied as a reducing agent for halogeno-organic species. Behaviour is irreproducible with an induction period and ethanol inhibition indicating a radical mechanism.450 The 'H and ,'P n.m.r. spectra of FeH,[P(OEt),] provide evidence for fluxional behaviour. Detailed topological analysis implies that the hydrogens traverse faces of the near-tetrahedron defined by the four phosphorus ligands and that in this case at least no major role is played by any trigonal twist mechanism.451 The related phosphine complexes H,Fe(PR,) and H,Ru(PR,) show dissocia-tive exchange with free ligand on the n.m.r.timescale and chemically observable replacement of one ligand by another.452 Zinc amalgam reduction of [OsO,-(en),]Cl (en = ethylenediamine) gives [OsH,(en),] [ZnCl,] in which the two hydrogens have been shown by their coupling with the ethylenediamine bridge protons to be mutually cis and exchangeable with aqueous D2O.,,, Complexes of type [Co(bipy)(PR,),]+ reversibly add H, the loss of H, being accelerated by light.,, There is spectroscopic evidence that RhClH,-(PPh,) is not appreciably dissociated in solution [nor is the precursor RhCI-(PPh,),] and that the reversible addition of hydrogen to the precursor is not preceded by diss~ciation.~~ Spectroscopic and kinetic evidence has been presented that the reaction of rhodium(r) carbonyl chloride dimer with cyanide 447 A.J . Campbell C. A. Fyfe and E. Maslowski jun. J . Amer. Chem. SOC. 1972 94, 2690. 448 (a) B. V. Lokshin V. I. Zdanovich N. K. Baranetskaya V. N. Setkina and D. N. Kursanov J . Organometallic Chem. 1972,37 331 ; ( 6 ) D. N. Kursanov V. N. Setkina, P. V. Petrovskii V. I . Zdanovich N. K. Baranetskaya and I . D. Rubin ibid. p. 339; (c) B. V. Lokshin A. G. Ginzburg V. N. Setkina D. N. Kursanov and I. B. Nemirov-skaya ibid. p. 347. 449 J. P. Jesson E. L. Muetterties and P. Meakin J .Amer. Chem. Soc. 1971 93 5261. B. L. Booth and B. L. Shaw J. Organometallic Chem. 1972,43 369. 4 5 1 P. Meakin E. L. Muetterties F. N. Tebbe and J. P. Jesson J . Amer. Chem. SOC. 1971, 93 4701. 4 5 2 D. H. Gerlach W. G. Peet and E. L. Muetterties J . Amer. Chem. Soc. 1972 94, 4545. 4 5 3 J. Malin and H. Taube Znorg. Chem. 1971 10 2403. 4 5 4 A. Camus C. Cocevar and G. Mestroni J . Organometallic Chem. 1972 39 355. 4 5 5 P. Meakin J. P. Jesson and C. A. Tolman J . Amer. Chem. Soc. 1972 94 3240 Transition-metal Carbonyl Organometallic and Related Complexes 38 1 to give [HRh'1'(CN)5]3- proceeds by way of an intermediate.456 The hydride IrHCl,(PBu~Pr"), although severely sterically hindered can nevertheless add on small ligands such as CO or acetonitrile.With the isopropoxide anion reduc-tion occurs to give IrH,(PBu\Pr") which reacts with carbon monoxide to give (OC)IrH,(PBu\Pr") .457 The known chemistry of the platinum(r1) hydrides has been further extended. Phosphine hydrides may be obtained by borohydride reduction of species cis-PtX,(PR,) . Cationic hydride derivatives are obtainable by the action of ligands on trans-[PtH(PPh,Me),acetone]+ or from complexes of the type trans-[PtH(CO)(PR,),]+ with strong neutral donors. The trans-influence of SCN in species such as trans-Pt(H)(PPh,Me),SCN is stronger than that of NCS. trans-PtH(CN) (PPh,Me) like trans-Pt(CN),(PPh,Me) undergoes facile phos-phine-exchange reactions.458 Ligand exchange has been shown to be responsible for broadening of the hydride n.m.r. signal in a range of species of the type L,Pt-HX.459 Oxidative addition of halogen acids to (Ph,P),Pt gives salts (Ph,P),-PtH'X- the hydride n.m.r.spectra of which have been discussed. Addition of triphenylphosphine causes loss of coupling between hydride and cis-phosphorus, presumably by rapid exchange so that the hydride 'H signal becomes a sharp doublet. Addition of PMePh or of PMe,Ph causes loss of both cis- and trans-coupling. 460 Group 11.-The reaction of (n-C,H ,)Ni(PPh,)Br with magnesium metal gives a 'nickel Grignard reagent' which reacts with oxygen to give (n-C,H,)Ni-(PPh,)OMgBr and with methyl toluene-p-sulphonate to give (n-C,H,)Ni(PPh,)-CH . With carbon dioxide presumed intermediates [(n-C,H,)Ni(PPh& CO-OMgBr] and [(n-C,H,)Ni(PPh,)CO]+ cannot be isolated and the eventual product is (Ph,P),Ni(CO) .461 A wide range of metal magnesium derivatives (m,)Mg(base) have been prepared from m2 magnesium amalgam and base (m2 = e.g* (nn-C,H,)2Fe2(C0)4 [(Ph,P)CO(CO),I (n-C5H5)2Ni2(CO) or [(Ph 3 P)Mn(CO)4I 2 > .46 ' A full-range analysis has been carried out of the i.r.and Raman spectra of [(OC),Co],Zn and the cadmium and mercury analogues. There is significant coupling between the two halves of these complexes which is attributed to n-donation from cobalt to the central atoms. The cobalt-metal force constants, unlike parameters derived from more approximate treatments appear to be very similar.46 Zinc metal carbonylates are solvolysed to varying extents by methanol ; for example Zn[Co(CO),] gives the (presumably cubane-like) tetrameric 4 5 6 R.A. Jewsbury and J . P. Maher J.C.S. Dalton 1972 2089. 4 5 7 B. L. Shaw and R. E. Stainbank J.C.S. Dalton 1972 2108. 4 5 8 H. C. Clark and H. Kurosawa J . Organometallic Chem. 1972 36 399. 4 5 9 M. W. Adlard and G. Socrates J.C.S Chem. Comm. 1972 17. 460 K. Thomas J. T. Dumler B. W. Renoe C. J. Nyman and D. M. Roundhill Znorg. "' H. Felkin and P. J. Knowles J. Organometallic Chem. 1972,37 C14. 4 6 2 G. B. McVicker and R. S. Matyas J.C.S. Chem. Comm. 1972 972. 4 6 3 R. J. Ziegler J. M. Burlitch S. E. Hayes and W. D. Risen jun. Inorg. Chem. 1972, Chem. 1972 1 1 1795. 11 702 382 P. S. Braterman species [MeOZnCo(CO),] and tetracarbonylcobalt hydride. The order of reactivity is that of carbonylate nucleophilicity [(x-C,H,)Fe(CO),],Zn > [( OC) Mn] ,Zn > [(n-C,H ,)Mo(CO),] ,Zn > [( OC),Co] 2Zn.464 The crystal structure has been determined of the 2,2’ 6‘,2”-terpyridyl complex of Cd[Mn(CO),] .The co-ordination of cadmium is trigonal-bipyramidal, with the manganese groups in the equatorial plane subtending an angle of 132.5’ at cadmium. The co-ordination around the manganese atoms is highly dis-t~rted.,~’ Whereas the 1 1 adduct of mercury(r1) chloride with cyclopentadienyl-dicarbonylcobalt is (n-C,H,)Co(CO),+HgCl, the 1 3 adduct is (n-C,H,)-Co(C0),-HgC1+C1-,2HgC12 .466 The nucleophile [Ir(CO),PPh,]- reacts with arylmercuric chloride to give products of the type Ir(CO),(PPh,)HgAr. The rhodium analogue behaves in a similar way.467 Group III.-(See also Chapter 8). B6H 0 reacts with di-iron enneacarbonyl to give B,H,,Fe(CO), in which it is suggested the iron atom is co-ordinated to the boron-boron bond of hexaborane( The structures have been deter-mined of bis(methoxyborinato)- and bis(methy1borinato)-cobalt (121).The borinate rings are almost planar (contrast cyclohexadienyl derivatives) and apparently ~onjugated.,~’ In the pyrazolyl derivative (122) the molybdenum atom was originally thought to be surrounded by sixteen valence electrons only but in fact the 18-electron rule is obeyed the molybdenum atom being hydrogen-bridged to R-c o The reaction of Fe,(CO) with dimethylaminoaluminium dibromide gives a product (Me,NAl)Fe(CO),Br, considered by the authors to be a derivative of 464 J. M. Burlitch and S. E. Hayes J. Organometallic Chem.1972 42 C13. 4 6 5 W. Clegg and P. J. Wheatley J.C.S. Chem. Comm. 1972 760. 466 I. W. Nowell and D. R. Russell J.C.S. Dalton 1972 2393 2396. 467 G. M. Intille and M. J. Braithwaite J.C.S. Dalton 1972 645. 468 A. Davison D. D. Traficante and S. S. Wreford J.C.S. Chem. Comm. 1972 1155. 469 ( a ) G. Huttner and B. Krieg Angew. Chem. Internat. Edn. 1972,11,42; ( 6 ) G. Huttner, 470 F. A. Cotton J. L. Calderon M. Jeremic and A. Shaver J.C.S. Chem. Comm. 1972, B. Krieg and W. Gortzke Chem. Ber. 1972 105 3424. 777 Transition-metal Carbonyl Organometallic and Related Complexes 383 All in the same sense that carbene complexes derive from C11.471 Dimanganese decacarbonyl reacts with metallic indium in a sealed tube to give In[Mn(CO),] , assigned a planar structure from its vibrational spectrum.Metallic gallium gives a product Ga,[Mn(CO),],. This last is assigned an asymmetrical structure, since a band assigned as v(Ga-Ga) is i.r.-a~tive.,~’ Thallium(r) tetracarbonyl-cobaltate (accessible from thallium metal and dicobalt octacarbonyl in toluene) has been advocated as a convenient source of the [Co(CO),] - anion.,’, Group IV.-The compounds (7c-CSH,),Zr(C1)MPh (M = Si Ge or Sn) and their hafnium analogues have been prepared from the metallocene dichloride and triphenylmetalloid lithium or sodium salts. They show high thermal stability despite the high oxidation state of the transition metal and the absence of d-electrons.474 The compounds (n-C,H,)M(CO),SiR (M = Mo or W) have been successfully prepared from the transition-metal anion and organosilicon halides in non-polar solvents ; in polar solvents the products are labile.475” Catenated derivatives e.g.(n-C,H,)Mo(CO),Si,Me have been prepared similarly.475b The reaction of hexacarbonyltungsten with dialkylsilanes gives products W,(CO),H,(SiEt,) for which the structure (123) has been determined.476 The photochemical reaction of Re,(CO) , with alkyldichlorosilanes gives products such as RCl,SiHRe,(CO), in which it appears that the RC1,Si group occupies an equatorial position and that the hydrogen is bridging the two rhenium atoms.477 Et, H? 2 Si El2 (1 23) Di-iron enneacarbonyl reacts with the strained ring molecule (CH,),SiMe, to give (OC),FkSiMe,CH,CH,~H .478 Nucleophilic attack by the [Co(CO),-(PPh,)] - anion on triphenylchlorosilane proceeds as expected to give (Ph,P)-Co(CO),-SiPh, but [Mn(CO),]- reacts to give (Ph,Si),O and a polynuclear anion.479 It has been shown that in one case at least silyl groups can displace ethyl groups from metal.Bipyridylnickel diethyl reacts with three moles of trichlorosilane (methyldichlorosilane reacts similarly) to give the air-sensitive 471 W. Petz and G. Schmid J . Organometallic Chem. 1972,35 321. 4 7 2 H.-J. Haupt and F. Neumann Z . anorg. Chem. 1972,394,67. 473 S . E. Pedersen W. R. Robinson and D. P. Schussler J . Organometallic Chem. 1972, 4 7 4 B. M. Kingston and M. F. Lappert J.C.S. Dalton 1972 69. 475 ( a ) W. Malisch H. Schmidbaur and M. Kuhn Angew. Chem. Znternat. Edn. 1972,11, 516; (6) W. Malisch J . Organometallic Chem. 1972 39 528.476 M. J. Bennett and K. A. Simpson J . Amer. Chem. SOC. 1971,93,7156. 4 7 7 J. K. Hoyano and W. A. G. Graham Znorg. Chem. 1972,11 1265. 4’8 C. S . Cundy and M. F. Lappert J.C.S. Chem. Comm. 1972 445. 4 7 9 M. D. Curtis Znorg. Chem. 1972 11 802. 43 c44 384 P. S. Braterman material (bipy)Ni(SiCl,) together with EtSiCl, ethane and hydrogen.480 Silicon-platinum bond cleavage by hydridic or by protonic agents or by acyl chloride or alkyne occurs with retention of configuration around silicon and is therefore almost certainly an oxidative elimination process.48 The crystal structures of cis- and trans-isomers of Cl,GeRu(CO) have been determined and compared. There is little difference in the various metal-carbon bond lengths so that the CI,Ge- grouping appears to be about as good a charge acceptor as C0.482 Germanium(Iv) tin@) and tin(rv) halides react with (n-C,H,),Fe,(CO) and (n-C,H,),Ni,(CO) .Among the products are (n-C,H,)Fe(CO),GeX (X = C1, Br or I) and (n-C,H,)NiCOMX and [n-C,H,Ni(CO)],MX (X = C1 or Br, M = Ge or Sn).483 Tin(1r) halides also insert into the metal-metal bond of [(n-C,H,)Mo(CO),] to give products [(n-C,H,)Mo(CO),],SnX (n-C5H5)-Mo(CO),X and (~-C,H,)MO(CO)~S~X .484 Species of the type (n-C,H,)-Fe(CO),SnX and [(n-C,H,)Fe(CO),],SnX are also obtained as are mixed derivatives such as [(n-C,H,)Fe(CO),][(n-C,H,Me)Fe(CO),][(Bu,P)Co(CO)4]-SnCl by further reaction. The compounds (Me,GeCl)Co(CO) (Me,GeCl)-Mn(CO) and (Me,GeCl)Fe(CO),(n-C,H,) have been obtained from Me,GeCl, and the appropriate metal carbonylate anion.Photolysis of these species gives the products (124a b) and (125). The reaction product of [Fe(CO,)(NO)]- with Me,GeCl is (126).48s Me2 M / \ M-\ / Ge Me 2 Ge Me Me\ / Ge / \ ( 125) (n-C5Hs)(OC),Fe - Fe(C0)2(n-C5H 5 ) (124) (a) M = Co(CO), (b) M = Mn(CO), / (C1) \ Me,Ge - Fe(CO),NO (126) "'Sn Mossbauer spectra have been reported for some fifteen species with tin-iron or tin-manganese bonds. It is concluded that the order of tin 5s charac-ter in Sn-X bonds is Sn-halogen < Sn-C < Sn-Mn(CO) < Sn-Fe(CO),-(n-C,H,) while the donor capacity to the Sn(5p) orbital of groups bonded to tin increases in the order halogen -= C,F < Mn(CO) < (n-C,H,)Fe(CO) < 480 Y . Kiso K. Tamao and M. Kumada J.C.S. Chem. Comm. 1972 105.4 8 1 C. Eaborn D. J. Tune and D. R. M. Walton J.C.S. Chem. Comm. 1972 1223. 4 8 2 R. Ball and M. J. Bennett Znorg. Chem. 1972 11 1806. 4 8 3 R. C. Edmondson E. Eisner M. J. Newlands and L. K. Thompson J . Organometallic Chem. 1972,35 119. 484 ( a ) P. Hackett and A. R. Manning J.C.S. Dalton 1972,2434; (b) P. Hackett and A. R. Manning J. Organornetallic Chem. 1972 34 CIS. 4 8 5 M. D. Curtisand R. C. Job J . Amer. Chem. SOC. 1972,94 2153 Transition-metal Carbonyl Organometallic and Related Complexes 385 C,H < alk~l.,~ Me,SnMn(CO),(PPh,) and the related triphenylarsine com-plex show a drop in quadrupole splitting relative to Me,SnMn(CO), but no detectable change in isomer shift. These effects are attributed to changes in the tin-manganese n-b~nding.,~~ However other workers ascribe changes in the "'Sn Mossbauer spectra of species [(CO),Mn],SnR,- to bond-length effects rather than to changes in n-bonding as such.Quadrupole splitting data fit the change in tin-manganese polarity from Mn(6 + )-SnHal,(G -) towards Mn(6 -)--SnR,(6 +).488 The species Ph,Sn.M(CO) (M = V Nb or Ta) and the related species (Ph,P)Au.M(CO) and EtHg.M(CO) have been described. These are all very prone to heterolytic cleavage by donor solvents with [M(CO),]- acting as a leaving group but as expected this tendency is less in M(CO),(PPh,) deriva-t i v e ~ . ~ ~ ~ The reaction of trimethylstannane with Mn,(CO), gives Me,SnMn-(CO) (which is best prepared in other ways). Unlike Me,SiMn(CO), this species is unaffected by water methanol or aqueous alkali.1,2-Dibromoethane gives Me,SiBr BrMn(CO) and ethylene while mercury(r1) chloride displaces tin to give Me,SnCl and Hg[Mn(CO),] . Trifluoroacetyl chloride and trichloro-silane both displace one methyl group to give Me,ClSnMn(CO), while tin tetrachloride gives Cl,SnMn(CO) .490 The crystal structure has been deter-mined of [Fe(CO),],[Me,Sn], in which the Me,Sn fragments bridge two Fe(CO) groupings. The tin-iron bonds are long (263 pm) suggesting little iron-tin n-b~nding.,~ ' Species described as (Ph,P),NiC1,(SnR,),4g2a have been properly identified as R ,SnCl( OPPh 3).492b Group V.-Dinitrugen Complexes. A strong correlation has been established for a range of dinitrogen complexes between the intensity of the N-N stretching absorption and the lowering of its frequency.493 The codeposition of metal atoms with dinitrogen in frozen matrices has been used to prepare dinitrogen complexes of chromium nickel palladium and platinum as well as dinitrogen adsorbates on small clusters of chromium nickel or copper a t o r n ~ .~ ' ~ ~ ~ ~ Ni(CO),(N,) has been generated by photolysis of tetracarbonylnickel in a solid dinitrogen matrix.496 The reduction of titanocene dichloride in toluene by metallic sodium generates a possibly dimeric true titanocene [(C,H,),Ti], which reacts with dinitrogen to 4 8 6 G. M. Bancroft K. D. Butler A. T. Rake and B. Dale J.C.S. Dalton 1972 2025. 4 8 7 S. Onaka and H. Sano Bull. Chem. Soc. Japan 1972,45 1271. 488 S. R. A. Bird J. D. Donaldson A. F. Le C. Holding B. Ratcliff and S. Cenini Inorg.489 A. Davison and J. E. Ellis J. Organometallic Chem. 1972 36 113. 490 R. A. Burnham F. Glockling and S. R. Stobart J.C.S. Dalton 1972 1991. 4 9 1 492 ( a ) P. E. Garrou and G. E. Hartwell J.C.S. Chem. Comm. 1972,881 ; ( b ) P. E. Garrou 493 D . J. Darensbourg Inorg. Chem. 1972 11 1436. 494 J . K. Burdett M. A. Graham and J. J. Turner J.C.S. Dalton 1972 1620. 4 9 5 G. A. Ozin M. Moskovits B. Kundig and H. Huber Canad. J. Chem. 1972 50, 496 A. J. Rest J. Organometallic Chem. 1972 40 C76. Chim. Acta 1972 6 379. C. J. Gilmore and P. Woodward JIC.S. Dalton 1972 1387. and G. E. Hartwell ibid 1973 100. 2385 386 P. S. Braterman give a species that may be hydrolysed to give ammonia.497 A possible inter-mediate in this nitrogen-fixation process [(7c-C,H,),Ti],N, has been isolated from the reaction of (.n-C,H,),TiCl methylmagnesium iodide and dinitrogen.The compound is non-centrosymmetric with an i.r.-active N-N stretching band at 1280 cm- (1240 cm- in the 15N derivative) and is formulated tentatively as a ~is-di-imide.,~~ Dinitrogen complexes m(N,) have been prepared by the oxidation using hydrogen peroxide-copper(I1) ion mixtures of hydrazine-complexed precursors (m)N,H [m = (C6H6)Cr(CO), (n-C,H,)Mn(CO) or (n-C,H,)Re(CO),]. The related species (C6Me6)Cr(CO),N has been prepared by an indirect photochemical route as have species [C,Me,Cr(C0)2]2N, for which the N-N stretch is not observed in the i.r. spectrum. The reaction of (n-C,H,)Mn(CO),(N,) with THF to give (7c-C5H,)Mn(CO),(THF) is reversible in solution under 500 atm pressure of dinitr~gen.~”-~’~ N .m.r.intensities have been used to determine equilibrium constants for the formation of a range of species MNNAlMe . The order of basicities towards trimethylaluminium is found to be mer-OsC1,(N2)(PEt2Ph) < Et,O < trans-ReCI(CO)(PMe,Ph) < trans-ReCl(N,)(PMe,Ph),[P(OMe),] < trans-W(N,),(dppe) < trans-Mo(N,)-(dppe) < trans-ReCl(N,) (PMe,Ph) < THF.,’ Two novel and presumably related addition reactions of chromium group dinitrogen complexes have been reported. The species trans-W(N,),(dppe) adds halogen acids to give products MX,(N,H,) (dppe) (a reaction shared by the molybdenum anal~gue),”~ and also reacts with acyl chlorides to give products of composition (dppe),Cl,W-(N,HCOR). These last lose the elements of HC1 on treatment with triethylamine, to give species (127) as products.506 A range of molybdenum phosphine dini-(1 27) trogen complexes including trans-Mo(N,),(dppe) have been prepared by aluminium alkyl reduction of tris(acety1acetonato)molybdenum in the presence of suitable ligands.,07 The crystal structure of trans-Mo(N,),(dppe) gives no evidence for any appreciable degree of molybdenum-nitrogen It-bonding.497 E. E. van Tamelen W. Cretnery N. Klaentschi and J. S. Miller J.C.S. Chem. Comm., 1972 481. 498 Yu. G. Borodko I. N. Ivleva L. M. Kachapina S. I. Salienko A. K. Shilova and A. E. Shilov J.C.S. Chem. Comm. 1972 1178. 499 D. Sellmann and G . Maisel Z . Naturforsch. 1972 27b 465. D. Sellmann and G. Maisel 2. Naturforsch. 1972 27b 718. D. Sellmann Angew.Chem. Internat. Edn. 1971 10,919. D. Sellmann J . Organometallic Chem. 1972 36 C27. D. Sellmann Angew. Chem. Internat. Edn. 1972 11 534. J. Chatt R. H. Crabtree and R. L. Richards J.C.S. Chem. Comm. 1972 534. J. Chatt G. A. Heath and R. L. Richards J.C.S. Chem. Comrn. 1972 1010. J. Chatt G. A. Heath and G . J. Leigh J.C.S. Chem. Comm. 1972 444. M . Hidai K. Tominari and Y . Uchida J . Amer. Chem. SOC. 1972 94 110 Transition-metal Carbonyl Organometallic and Related Complexes 387 The molybdenum-nitrogen distance of 201 pm corresponds to a single bond, while the nitrogen-nitrogen separation of 110 pm is comparable with that in free dinitrogen. The MoNN angle is 172".'08 Mo(N,),(dppe) is oxidized by iodine to [Mo(N,),(dppe),] +I - the first known cationic molybdenum(1) dini-trogen complex.509 The sign of the quadrupole splitting in the Mossbauer spectrum of [FeH(N,)-(dppe),]+ C104- has been determined making possible a comparison of the bonding of dinitrogen with that of other ligands.It appears that N is a far poorer a-donor than p-methoxybenzonitrile or even than CO. It is also a better n-acceptor than the former but inferior to the latter.' l o Triethylaluminium reduction of (Ph,P),RuHCl in ether under N gives rise to the complex (Ph,P),-Ru(N,)H, which may be equilibrated with (Ph,P),RuH and hence converted into (Ph,P),RuH ." ' Nitrosyi Complexes. (See also carbonyl nitrosyls above.) The bonding correla-tion between complexes with bent MNO groupings (formal NO- complexes) and those with linear MNO groups (formally NO') has been stated.512 The reaction of RuCl,(NO)(PPh,Me) with diphenylphosphine gives two products, (128) and (129) of which the crystal structures have been determined.'' Tri-Ph,P ,PPh, ON\ //\\ NO Ru' \\ PPh2 carbonylcobalt nitrosyl reacts with NO to give Co,(NO),(N02),(N,0,) (1 30)? 5 0 8 J.Uchida Y. Uchida M. Hidai and T. Kodama Bull. Chem. SOC. Japan 1971 44, 5 0 9 T. A. George and C. D. Seibold J . Amer. Chem. SOC. 1972,94 6859. ' l o G. M. Bancroft R. E. B. Garrod A. G. Maddock M. J. Mays and B. E. Prater J . ' I 2 C. G. Pierpont and R. Eisenberg J . Amer. Chem. SOC. 1971 93 4905. ' I 3 R. Eisenberg A. P. Gaughan jun. C. G. Pierpont J. Reed and A. J. Schultz J . Amer. 2883. Amer. Chem. SOC. 1972,94 647. W. H. Knoth J . Amer. Chem. SOC.1972,94 104. Chem. SOC. 1972,94,6240. R. Bau I. H. Sabherwal and A. B. Burg J . Amer. Chem. SOC. 1971,93,4926 388 P. S. Braterman 0 - N \ N - 0 i (ON ),Co ko(NO), 0’ I 0 N \ ( 1 30) Complexes of Other Nitrogen Ligands. The role of nitrogen donor groups in metal carbonyl chemistry has been re~iewed.~ The crystal structure of the tricarbonylchromium complex of N-methylpyrrole has been determined. There is little bond lengthening relative to the free ligand, but the methyl group is bent away from the metal by about 9°.516 Phosphonitrilic complexes of the Group VI carbonyls have attracted some attention. Thus Cr(CO),(Cl,P,N,) has been prepared from tricarbonylchromium tris(acetonitri1e) and Cl,P,N .517 It would however be a mistake to assume that such complexes are closely related to arene derivatives and in [(Me,N),P,N,]-W(CO) it has been shown crystallographically that the phosphonitrilic ligand is acting merely as a bidentate o-donor being co-ordinated by two nitrogen atoms of which one is in the ring whereas the other belongs to a ~ide-chain.~’ The question of o- as against 7c-bonding (and the related question of formal oxidation state and degree of ligand unsaturation) also arises with diazabutadiene complexes.In this connection it has been shown crystallographically that [Me,N-N C-(Me)C(Me) N.NMe,]Ni(CO) is a tetrahedral complex of Ni’ in which nickel is attached to the diacetylbis(dimethy1hydrazone) grouping by a-bonds from the two unsaturated nitrogen atoms.’ Diphenyldiazomethane reacts with Ni(CNBu‘) to give a complex Ph,CN,-Ni(CNBu‘) from which diphenyldiazomethane may be recovered by treatment with dioxygen or with triphenylph~sphine.~” Metal oxy-complexes can be converted into imido-derivatives by their reaction with phosphinimines.For example ReCl,O(PPh,) is converted into ReCl,( NR)(PPh,) on treatment with Ph,P:NR (R = Ph or COPh). However OsCl,O(PPh,) reacts with Ph,P NCO-Ph to give OsCl,( :NR)(PPh,) whereas MoCl,O(PMe,Ph) does 5 1 5 M. Kilner Adu. Organometallic Chem. 1972 10 115. G. Huttner and 0. S. Mills Chem. Ber. 1972 105 301. ’ N. K. Hoton and R. 0. Harris J.C.S. Chem. Comm. 1972,407. 5 1 8 H. P. Calhoun N. L. Paddock J. Trotter and J. N. Wingfield J.C.S. Chem. Comm., 1972 875. H. D. Hausen and K. Krogmann Z . anorg. Chem. 1972 389 247.1105. 5 2 0 S. Otsuka A. Nakamura T. Koyama and Y. Tatsuno J.C.S. Chem. Comm. 1972 Transition-metal Carbonyl Organornetallic and Related Complexes 389 not react with triphenylphosphine phenylimine. However this molybdenum complex does react with compounds of the type Ar'CONHNHAr to give (131).521 The reaction of the [(n-C,H,)Mo(CO),]- anion with diazoacetic ester, and treatment of the product successively with base methyl iodide and hexa-fluorophosphonic acid gives (132) which can only be written as a non-classical .* H \ PMe2Ph 0' 0 I cl 1 ,O=CAr' " c Mo I E t d C \ C (-A N\Arl Me N c1/ )I 'NSN I ( + Mo(CO),(C,H,) Ar2 N<-'/ (131) (132) sydnone as its PF - salt.522 The reaction of pentacarbonylmanganese bromide with R2N CR'.NR2Li gives (OC),kn.N(R2) CR'.NR2d0 presumably by initial nucleophilic attack of the lithium complex on co-ordinated CO.Heating this species leads to loss of CO and the formation of (OC),&nNR2CR'NR2; treatment of this with CO under pressure leads for R' = R2 = Ph to a species assigned as (OC),Mn.NPhCPh :NPh.523 (n-C,H,)Mn(CO),NH NHMn(CO),(n-C,H,) is among the products of hydrogen peroxide oxidation of (.lt-C,H,)Mn(CO),(N,H,). The complex possesses a trans-configuration since v(N N) is i.r.-inactive. The imine protons are very acidic resonating in the n.m.r. spectrum at 7 z The reaction of trimethylsilyl azide with di-iron enneacarbonyl gives (133) the structure of which has been confirmed ~rystallographically.~ SiMe, I WCO), (OC) 3 Fe & Fe(CO), N I SiMe, (133) Phosphine and Related Ligunds.Phosphorus-phosphorus virtual coupling can with advantage be detected by its effect on ligand 13C n.m.r. spectra which are 5 2 1 J. Chatt and J. R. Dilworth J.C.S. Chem. Comm. 1972 549. 523 T. Inglis M. Kilner and T. Reynoldson J.C.S. Chem. Comm. 1972 774. 5 2 4 D. Sellmann J . Organometallic Chem. 1972 44 C46. 5 2 s (a) E. Koerner von Gustorf and R. Wagner Angew. Chem. Internat. Edn. 1971 10, 910; (6) B. L. Barnett and C. Kruger ibid. p. 910. C. K. Prout T. S. Cameron and A. R. Gent Acta Cryst. 1972 B28 32 390 P. S. Braterman simpler than 'H spectra of the same species.526 Tetrakis(trifluorophosphine)-nickel now commercially available is of value as a trifluorophosphinating agent, and also acts in some cases as a halogen abstractor.For example it converts [(n-C,Me,)RhCl,] into (n-C,Me,)Rh(PF,),. The iridium analogue gives both a product of this kind and the isomeric (n-C,Me,)Ir(PF,)(PF,)F. Mn(CO),Br is converted into a mixture of Mn,(CO),(PF,) and related compounds while (n-C,H,)Mo(CO),CH undergoes simple replacement of one CO group by PF .527 Titanocene dichloride reacts with Na,P,Ph to give (n'C5H5)2-TiPPh.PPh-PPh.528 Fe(PF,) reacts with halogens to give cis-Fe(PF,),X, (X = C1 Br or I) the stereochemistries of which were determined by I9F n.m.r. spectroscopy. These are somewhat more stable than the iron carbonyl analogues.529 (n-CSH,)Fe(CO),P(CF,) is oxidized by NO or by sulphur to (n-C,H ,)Fe(CO),.P(O)(CF,) or (n-C5H ,)Fe(CO),-P(S) (CF,) . 30 The reaction of nickel@) bromide with diphenylphosphine gives Ni(PPh,H) (and not despite earlier claims nickel phosphide complexes).On heating this shows loss of benzene at moderate temperatures and eventual formation of (NiPPh) . The palladium analogue behaves similarly.531 (Ph,P),Pt acts as a base towards silicon tetrafluoride giving (Ph,P),Pt.SiF, and towards boron trichloride, giving (PhJP),Pt(BC1,) .532 Au(NO),(Ptol,) (to1 = p-tolyl) is reduced by sodium borohydride to the octahedral cluster cation [ A ~ ( P t o l ) ~ ] ~ + .533 Oxygen-group Ligands.-Dioxygen Complexes. The cations [Co(edpe)]' + , [Rh(edpe),]+ and [Tr(edpe),] + (edpe = tvans-1,2-bisdiphenylphosphinoethylene) add dioxygen the order of reactivity being Co >> Ir > Rh. This may be ration-alized by reference to the d-orbital energies (Rh < Ir < Co) if the process is regarded as an oxidation.534 The crystal structure of Co(edpe),O,+ BF,- has been determined.The cation is trigonal-bipyramidal with 0 occupying one corner of the equatorial plane and lying in that plane.535 The uptake of 0 from air by RhX(PPh,),CNR (X = halogen) to give a dioxygen adduct is reversible for R = p-tolyl but irreversible for R = t - b ~ t y l ' ~ ~ (this is consistent with the view that 0 is a net charge-remover). Dioxygen bis-(t-butylisonitrile) complexes of the nickel group react in the following ways (L = Bu'NC) (i) oxygen-atom-transfer redox reactions [L,MO, +4RNC* (RNC),M + 2Bu'NCO; L,NiO + 4CO -+ Ni(CO),L + 2C0,; s26 B. E. Mann B. L. Shaw and R. E. Stainbank J.C.S. Chem. Comm.1972 151. s2' R. B. King and A. Efraty J. Amer. Chem. SOC. 1971,93 5260. s28 K. Isslieb G . Wille and F. Krech Angew. Chem. Internut. Edn. 1972 11 527. s29 T. Kruck R. Kobelt and A. Prasch Z . Nururforsch. 1972 27b 344. s30 R. C. Dobbie P. R. Mason and R. J. Porter J.C.S. Chem. Comm. 1972 612. s 3 1 C. M. Watson G . W. Bailey J. H. Nelson and H. B. Jonassen J. Inorg. Nuclear 5 3 2 T. R. Durkin and E. P. Schram Inorg. Chem. 1972 11 1048 1054. s33 P. L. Bellon M. Manassero L. Naldini and M. Sansoni J.C.S. Chem. Comm. 1972, s 3 4 L. Vaska L. S. Chen and W. V. Miller J. Amer. Chem. SOC. 1971 93 6671. 53s N. W. Terry tert. E. L. Amma and L. Vaska J . Amer. Chem. SOC. 1972 94 653. s36 A. Nakamura Y. Tatsuno and S. Otsuka Inorg. Chem. 1972 11 2058. Chem. 1972,344 1752.1035 Transition-metal Carbonyl Organometallic and Related Complexes 39 1 L,NiO + 2Ph,P -+ L,Ni(PPh,) + 2Ph3PO] ; (ii) atom-transfer oxidation reactions [L,NiO + CO -* L,NiCO ; L,PdO + SO -+ L,PdSO,] ; (iii) substitution reactions [L,NiO + tcne-+ L,Ni(tcne) + 0,; tcne = tetra-cyanoethylene] ; and (iv) metal-assisted electrophilic peroxidations [L,NiO + 2PhCOCl-* L,NiCl + PhC0.0.0C0.Ph].537 Carbon dioxide reacts with FeH,L and FeH,(N,)L (L = PPh,Et) to give Fe(O,CH),L regarded on chemical evidence as a formate complex formally derived by insertion of OC(0) into a metal-hydrogen bond.538 Whereas Fe,-(CO),(COPh) reacts with thiols as expected to give Fe,(CO),(SR) and alde-hydes its reaction with triphenylphosphine gives the dibenzoyl complex (PhCOCOPh)Fe(CO),(PPh3) in addition to Fe(CO),(PPh,) .5 3 9 Nitric oxide reacts with hexamethyltungsten to give a quantitative yield of (134). At room temperature this shows two ‘H n.m.r. signals z 5.97 and z 8.42 assigned to N-Me and W-Me respectively. The latter signal is split below 225K in CH,Cl into two equal components?40 Some alkyl(pyridinato)cobaloximes take up dioxygen when irradiated with visible light to give stable peroxides ROO[CO].’~~ IrC1(PPh3),(CO)(OOBut), and related species are isolable from the reaction of t-butyl hydroperoxide with complexes trans-IrXL,CO. The latter are catalysts for the decomposition of organic hydroperoxides to alcohols and oxygen but the t-butyl peroxide com-plexes are catalytically inactive and therefore not in fact intermediate^.'^, Complexes of Sulphur Ligands.The crystal structure has been determined of [Ir(S,)(dppe),]Cl,CH,CN. The cation is closely related to its dioxygen ana-log~e.’~ The reaction of (n-C,H,)Mo(CO),Cl with trimethylstannyl sulphide gives [(lr-C,H,),Mo3S,]+[SnMe3C1,]- in which the cation has been shown to have the structure (135). The cation is two electrons short of the predictions of the 18-electron rule and there is indeed some evidence that it may be reversibly 5 3 7 S. Otsuka A. Nakamura Y . Tatsuno and M. Miki J. Amer. Chem. SOC. 1972 94, 538 V. D. Bianco S. Duronzo and M. Rossi J . Organometallic Chem. 1972 35 337. 5 3 9 W. Keiner and E. 0. Fischer J. Organometallic Chem. 1972,42 447. 540 S. R. Fletcher A. Shortland A. C. Skapski and G. Wilkinson J.C.S. Chem. Comm., 5 4 1 C .Fontane K. N. V. Duong C. Merienne A. Gaudemer and C. Giannotti J . Orguno-5 4 2 B. L. Booth R. N . Haszeldine and G. G. R. Neuss J.C.S. Chem. Comm. 1972 1074. 543 W. D. Bonds,jun. and J. A. Ibers J . Amer. Chem. SOC. 1972,94 3413. 3761. 1972 922. metallic Chem. 1972 38 164 392 P. S. Bratermn 1' reducible.544 The reaction of the known compound [Re(CO),SSnMe,] with (I~-C,H,)MO(CO),CI gives (136).545 The [(n-C,H,)Fe(CO),]- anion reacts with sulphur dioxide in THF to give (7r-C5 H,)Fe(CO),.S( O) .Fe( CO),( n-C H ,) the crystal structure of which has been determined.546 Sulphonyl chlorides react with Ir(N,)Cl(PPh,) to give species (Ph,P),CI,IrS(O),R. These undergo a rearrangement that is facilitated by electron-withdrawing substituents in R to give RIrCl,(PPh,),(S0,).547 The tetrakis(trip'heny1phosphine) complexes of Pdo and Pto react with sulphur dioxide to give products (Ph,P),MSO, which are converted by dioxygen into sulphate complexes.The tris(tripheny1phosphine) carbonyl hydrides of rhodium and iridium also take up SO to give products MH(SO,)(CO)(PPh,),. These do not give a detectable high-field proton resonance possibly because of reversible isomerization to give (Ph3P)2(CO)M.S(0)2H.548 trans-L,PtPhCl (L = e.g. Et,P or Et,Se) take up SO at 320K under moderate pressure to give the S-sulphinate L,Pt(Cl).S0,Ph.549 However the SO adduct of trans-(Ph,P),-544 P. J. Vergamini H. Vahrenkamp and L. F. Dahl J . Amer. Chem. SOC. 1971,93,6327. 5 4 5 P. J . Vergamini H. Vahrenkamp and L. F. Dahl J . Amer. Chem.Soc. 1971,93,6326. 546 M. R. Churchill B. G. DeBoer K. L. Kalva P. Reich-Rohrwig and A. Wojcicki, 5 4 7 M. Kubota and B. M. Loeffler Inorg. Chem. 1972,11,469. '*' J. J. Levison and S. D. Robinson J.C.S. Dalton 1972 2013. 5 4 9 F. Faraone L. Silvestro S. Sergi and P. Pietropaolo J . Organometallic Chem. 1972, J.C.S. Chem. Comm. 1972,981. 34 c55 Transition-metal Carbonyl Organometallic and Related Complexes 393 Pt(CH,)I has been shown crystallographically to be trans-(Ph,P),MePtI.SO,, in which SO is co-ordinated by iodine through (n-C,H,)Ni(PBu,)SR undergoes carbon disulphide insertion into the metal-sulphur bond to give (~-C,H,)(BU,P)N~C(S)-SR.~~~ Irradiation of (CF,S), with near U.V. light in the presence of suitable metal carbonyl halides or dinuclear metal carbonyls gives (n-C,H,)Mo(CO),(SCF,) (n-C,H,)W(CO),(SCF,) [Mn-(CO),( SCF ,)I [Fe(CO),( SCF ,)I and (71-C5H ,)Fe(CO),( SCF,).’ Niobocene dithioalkylate acts as a ligand to metals of the nickel group forming complexes [(CSH5),Nb(SMe),Nil2+.These like their palladium and platinum analogues, contain the Group VIII metals in tetrahedral environments and thus presumably, in the formal oxidation state zero whereas the side groups are best regarded as [(n-C,H,)Nb(SR),]+ fragments. 553 Alkyl(pyridinato)cobaloximes react with S , in methanol under the influence of visible light (cf. ref. 541) to give R-S,[CO].~~~ The product from the reaction of ‘molybdenum(I1) acetate’ with dipropyl dithio-carbamate gives a product of composition [Pr,NCS2],Mo but it has been shown crystallographically that this is in fact (137; R = Pr).555 R,N’ (1 37) \ ‘NR, 4 Compounds Containing Bonds between Different Transition Metals The anions [(n-C,H,)Mo(CO),] - and [(n-C,H,)W(CO),] - react with di-iron enneacarbonyl to give species [(C,H,),M,Fe,(CO),o]2-.These do not show bands due to bridging CO and a cluster structure is suggested.556 Complexes of the type (n-C,H,)Ni(L)X react with the anion [(n-C,H,)Fe(CO),]- to give (n-C,H,)Fe(L) [CO],Ni(n-C,H,) in which there is presumably a metal-metal bond as well as two bridging carbonyl groups. The metal-metal bond of this complex is susceptible to chemical attack e.g. by tin(I1) chloride to give (for 5 5 0 M. R. Snow J. McDonald F. Basolo and J. A. Ibers J. Amer. Chem. SOC. 1972, 5 5 1 F. Sato K.Iida and M. Sato J. Organometallic Chem. 1972 39 197. 5 5 2 J. L. Davidson and D. W. A. Sharp J.C.S. Dalton 1972 107. ’ 5 3 W. E. Douglas and M. L. H. Green J.C.S. Dalton 1972 1796. 5 5 4 C. Giannotti C. Fontaine B. Septe and D. Doue J. Orgunometallic Chem. 1972, 5 5 5 L. Ricard J. Estienne and R. Weiss J.C.S. Chem. Comm. 1972 906. 5 5 6 A. T. T. Hsieh and M. J. Mays J. Organometallic Chem. 1972 39 157. 94 2526. 39 c74 394 P. S. Braterman L = CO) (n-C5H5)Fe(CO),~SnCl~-Ni(CO)(n-C5H5).557 Similarly nickel com-plexes of this type are attacked by the [Co(CO),]- anion with formation of (n-C,H,)NiCo(CO),L the i.r. spectra of which are taken to show a mixture of bridged and non-bridged forms.558 Ir(CO)(PPh,),Cl reacts with silver nitrate to give a species [Ir(CO)(PPh,),(NO,),Ag] which from molecular weight measurements appears to be monomeric in chloroform but to dissociate into three particles in a c e t ~ n i t r i l e . ~ ~ ~ With copper(1) phenylacetylide Ir(C0)-(PPh,),Cl gives the remarkable mixed metal cluster compound ( 138).560 PPh, PPh, (138) R = PhCiC-5 5 7 5s8 A. R. Manning J. Organometallic Chem. 1972,40 C73. 5 5 9 D. N. Cash and R. 0. Harris Cunud. J . Chem. 1972,49 3820. s60 0. M. Abu Salah M. I. Bruce M. R. Churchill and S. A. Bezman J.C.S. Chem. Comm., K. Yasufuku and H. Yamazaki J . Organometallic Chem. 1972 38 367. 1972 858

ISSN:0069-3022    

DOI:10.1039/GR9726900319

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

I 1 Mechanisms of Inorganic Reactions By A. McAULEY Department of Chemistry University of Glasgow Glasgow G12 8QQ The scope and format of the Report resemble that of previous years with a restriction to the reactions of inorganic compounds in solution. With the publica-tion of the second Specialist Periodical Report in this area,' references have been chosen as being representative of areas of current interest with a view to general reader coverage. 1 Electron-transfer Reactions Transition-metal Complex Ions.-The nature of the electron-transfer step in redox reactions involving two metal-ion complexes is the subject of a continuing examination the most popular reductants being the aquated Cr" V" and Eu" species. In the reactions of twenty cobalt(I1r)-penta-ammine complexes' with Eu" and Cr" the ratio of the specific rate constants kEuII/kCrlI was in the range 8-25 in many cases with deviations from this value noted for oxidants with ligands where the electron transfer can take place only via remote attack.The role of co-ordinated water as a potential bridging ligand has also been investi-gated,3a the H +-independent term previously identified in the reaction of Cr" with [(H3N)sCo(OH,)]3+ being found to be due to medium effects. An important consequence of this study is that a comparison of outer-sphere reactions of V" and Cr" has been made with the relative rates kcrI1/kvII x 0.02. Similar ratios have been observed in the reactions of bridged p-amido-p-carboxylatodicobalt(x1x) ions.3b The large preference for Cr" to react via an inner-sphere pathway accounts for the differences in rate ratio between the H +-independent and -dependent paths.Evidence for an intermediate complex in the Cr" reduction of p-formyl-benzoatopenta-amminecobalt(m) has been given4 whereas in the corresponding reduction of thioether complexes there is a high reactivity when the mechanism is outer-sphere.' The presence of sulphate ion yields kinetically active ion-pairs 'Inorganic Reaction Mechanisms' ed. J . Burgess (Specialist Periodical Reports) The Chemical Society London 1972 vol. 2. E. R. Dockal and E. S. Gould J. Amer. Chem. SOC. 1972,94 6673. (a) D. L. Toppen and R. G. Linck Inorg. Chem. 1971 10 2635; (6) K. L. Scott and A. G. Sykes J.C.S. Dalton 1972 1832. A. Zanella and H. Taube J . Amer. Chem. Soc.1972,94,6403. M. Gilroy F. A. Sedor and L. E. Bennett J.C.S. Chem. Comm. 1972 181. 39 396 A . McAuley in the C~"-[CO(NH,),C~]~+ reaction with acceleration of the rate,6 and in the reaction with di- and tetra-nuclear cobalt(II1) complexes the relative inner- and outer-sphere paths have been disc~ssed.~ The formation of cobalt(III)-chromium-(111) intermediates has also been described. The reduction of the cluster ion [Ta,Brl2l3+ by Cr" in the presence of halide ions has been reported' and in the reaction with tetraphenyIporphineiron(rr1) chloride studied in benzene,' tracer studies are consistent with quantitative transfer of the halide to the reductant with no significant role of the delocalized porphyrin system as a route for electron transfer. In the corresponding reduction of the strongly oxidizing [Co(H20),l3 + ion lo some chloride-ion catalysis has been observed ; the reduction with vanadium-(11) is however too rapid for direct measurement.The V" reductions of azido-ammine cobalt(Ir1) complexes' are several orders of magnitude slower and are considered as inner-sphere with intermediate formation of the unstable VN32 + ion. The first step in the reduction of chromium(v1) in the presence of excess V" involves direct formation of V"' with no evidence for a V'" ion." Linear free energy correlations in the outer-sphere reductions of cobalt(II1) complexes con-taining macrocyclic ligands by VII Cr" and [ R u ( N H ~ ) ~ ] ~ + have been dis-c ~ s s e d . ' ~ " ' ~ Where corrections are made for variations of redox potentials in the oxidants the rate increases of - 100 when the quadridentate ligand is changed from a tetra-amine to a tetra-imine suggest that reorganization parameters on the reductant are important.A cross-correlation reaction for redox systems of this type based on a modified Marcus model has been discussed.'4 The reduction rate of acetatopenta-amminecobalt(II1) with Fe" is greatly enhanced in the presence of N-methyliminodiacetate L2 - the effective reactant in glycine buffer being Fe"L," with no evidence for intermediates. Such species are found however in the rapid two-stage reactions of vanadium(v) with [Fe(bipy)-(CN),12- and [Fe(bipy),(CN)2].'6 In the oxidation of vanadium@) by [Fe-(bipy),I3' the mechanism is considered to involve both V 0 2 + and VO(OH)+ as reactants.The nature of vanadium(1v) compared with iron@) as a reductant in aqueous electron-transfer reactions has recently been reviewed. ' ' The reacti-vity of different forms of p-amido-p-peroxo-bis(ethylenediamine)cobalt(m) com-plexes with [Fe(phen),13 + has been reported.' ' In the acidity range studied, three forms a aH and /3 of the peroxo-complex are present. Only the a-form is reactive with the oxidant [Fe(phen),13 + however the pattern being somewhat ' P. A. Jones and C. B. Monk J.C.S. Dalton 1972 1721. M. R. Hyde K. L. Scott and A. G. Sykes Co-ordination Chem. Rev. 1972 8 121. J . H. Espenson and T. R. Webb Inorg. Chem. 1972 11 1909. I . A. Cohen C. Jung and T. Governo J. Amer. Chem. SOC. 1972,94 3003. l o M. R. Hyde R. Davies and A. G. Sykes J.C.S.Dalton 1972 1838. K. W. Hicks D . L. Toppen and R. G. Linck Inorg. Chem. 1972 11 310. j 2 K. L. Bridges S. K. Mukherjee and G. Gordon Inorg. Chem. 1972 11 2494. I ' ( a ) D . P. Rillema J. F. Endicott and R. C. Patel J . Amer. Chem. SOC. 1972 94, ' 4 D. R. Rosseinsky J.C.S. Chem. Comm. 1972 225. 394; (6) D. P. Rillema and J. F. Endicott Inorg. Chem. 1972 11 2361. R. D . Cannon and J . Gardiner J.C.S. Dalton 1972 887. J . P. Birk and S. V. Weaver Inorg. Chem. 1972 11,95. D. R. Rosseinsky Chem. Rev. 1972,72 21 5 . D . P. Keeton and A. G. Sykes J.C.S. Dalton 1972 2530 Mechanisms of Inorganic Reactions 397 . . . . H I OH different from that for Ce" and for the reductants I- and Cr". The redox kinetics of U'" with [Fe(CN),I3- have been studied," the rate being acid-dependent and the reactive species UOH3+.The intermediate formation of Uv with two one-electron steps is suggested as a possible mechanism. In the reaction of this oxidant with diaquocobalt(I1)-oxime complexes," [Co(dmg),(H,O)] the anionic complex [(NC),F~CNCO(~~~),(H~O)]~ - is formed very rapidly. Adduct formation is also exhibited in the reaction of [Fe(CN),I3 - with hydridopentacyanocobaltate-(III)," where at high pH the rate-determining step is considered to involve the generation of the cobalt(1) ion [Co(CN),I4- and in the corresponding reaction with the carbonyl complex [Co'(CN),(PEt,),CO] - .22 The oxidation of copper-(11) by alkaline [MnO,] - and [Fe(CN),] - has been described,' the copper(II1) ion being stabilized as the tellurato-complex. In the non-complementary redox reaction 24 [PtL,X,] + 2Fe"' + 2X- S [PtL,X,] + 2Fe" where L = NH, NH,Me or NH,Et and X = C1 or Br the mechanism is consistent with two one-electron steps and the intermediate formation of Pt"'.A similar mechanism is postulated for the reaction of platinum(1v) complexes with ferrocene in hydroxylic solvents the reductions being strongly solvent-dependent. The forward reaction has a complex rate law the presence of Fe" being considered important." The transient absorption spectrum of Pt"' has been recorded, in the flash photolysis of [PtC1J2-. The reaction with Fe" has been studied the variation of rate with ionic strength being used to confirm the charge of - 1 on the Pt"' species consistent with the ion [PtCl,]-. The com-plex disproportionates in a second-order reaction : 2Pt"' + Pt" + PtIV l 9 L.Adamcikova and L. Treindl Cull. Czech. Chem. Comm. 1972 37 762. 2 o A. Adin and J. H. Espenson Inorg. Chem. 1972 11 686. * l J. Halpern and M. Pribanic Inorg. Chem. 1972 11 658. '' J. E. Bercaw L. Y. Goh and J. Halpern J . Amer. Chem. SOC. 1972,94 6534. " G. 1. Rosovskii A. K. Misyarichyus and A. Y. Prokopchik Zhur. neorg. Khim., 24 A. Peloso and M. Basato J.C.S. Dalton 1972 2040. " A. Peloso and M. Basato Co-ordination Chem. Rev. 1972,8 1 1 1 . 2 6 R. C. Wright and G . S. Laurence J.C.S. Chem. Comm. 1972 132. 1972 17 420 398 A . McAuley In contrast to Co"' Mn"' shows no reaction with TI' except in the presence of chloride ions,27 the mechanism being consistent with the prior formation of MnC12+ and its subsequent reaction with C1- to yield the active C1,- ion, formation of intermediate TI" being indicated.This species is also formed in the reduction of T1"' by As"' in perchlorate media28 where two one-electron steps are preferred to a two-electron exchange. The cerium(1v) oxidation of vanadium-(IV) has been de~cribed,~' the predominant reaction being CeOH3+ + V 0 2 + + Ce"' + V 0 2 + + Ht In the corresponding oxidation of neptunium(v) however the rapid reaction shows a more complex acidity pattern,30 and in the reaction with ferrocene-1,l'-disulphonic acid31 in sulphate media three moles of oxidant are consumed with decomposition of the sandwich structure. The same oxidant has been used in redox reactions with hexamethylbenzene cluster compounds of niobium and tantalum,32 [(Me6C6)M6X1J2+ (X = C1 or Br) which are formally analogous to the chloro-complexes previously described.The electron exchange between Cr" and [Cr(H,O),(ox)]+ (ox = oxalate) has been studied using 51Cr labelling the redox reaction occurring with transfer of an oxalate group.33 The corresponding reactions with oxalatotetra-ammine and maleatopenta-ammine complexes have also been investigated ;34 the latter system shows an acidity dependence consistent with reaction of both protonated and unprotonated ions. In the Tl'-Tl"' exchange rea~tion,~ the presence of organic complexing ligands such as pyridine induces substantial decreases in the rate, probably owing to the formation of unreactive T1"' species. The reaction is, however catalysed by iron(^^),^^ where it is suggested that intermediate formation of TI" takes place.The self-exchange rates for complexes of the type [CON,-(OH2)2]2+/3+ where N is a quadridentate macr~cycle~~ vary by a factor of - 1O'O on variation of the ligand the fastest reaction occurring with the vitamin-B couple. Reactions of rhodium(1) with the rhodium(u1) complex [Rh(dmg)-(dmgH)CI,] (dmg = dimethylglyoximate) have been observed38 in the auto-catalytic reduction of the latter species in aqueous alkaline ethanol. 2 Metal-ion Ligand Oxidations and Reductions The interactions of both aquated and complexed metal ions in high oxidation states with organic and inorganic substrates continue to be of interest. In some '' D. R. Rosseinsky and R. J. Hill J.C.S. Dalton 1972 715.2 9 N. A. Daugherty and R. L. Taylor J. Inorg. Nuclear Chem. 1972 34 1756. 30 A. Ekstrom and A. McLaren J. Inorg. Nuclear Chem. 1972 34 2015. '' R. B. King D. M. Braitsch and P. N. Kapoor J.C.S. Chem. Comm. 1972 1072. 3 3 T. Spinner and G. M. Harris Inorg. Chem. 1972,11 1067. " R. Davies and R. B. Jordan Inorg. Chem. 1971 10,2432. " 3 6 B. Warnqvist and R. W. Dodson Inorg. Chem. 1971 10 2624. 37 D. P. Rillema J. F. Endicott and N. A. P. Kane-Maguire J.C.S. Chem. Comm. 1972, P. D. Sharma and Y. K. Gupta J.C.S. Dalton 1972 52. J. Holecek K. Handlin and I. Pavlik Coll. Czech. Chem. Comm. 1972 37 1805. 0. Farver Acta Chem. Scand. 1972 26 534. 495. J. D. Miller and F. D. Oliver J.C.S. Dalton 1972 2469 Mechanisms of Inorganic Reactions 399 cases intermediate complex formation has been observed and with more detailed studies of a variety of systems now becoming available possible patterns of behaviour are beginning to emerge.The oxidations of thiocyanate thiourea and alkyl-substituted thioureas are all inner-~phere,~~ the rate-determining process being substitution on the manganese@) ion. Like the corresponding cobalt(w) systems the rate constants cover a fairly small range although in the former study protonation of the organic reagents has been described. Spectrometric evidence has been obtained for complex formation in the slower oxidation of formic acid4' under conditions of high ligand concentration and in this system the reaction of two complexes related by acid-base equilibria is considered. The oxidizing nature of manganese(n1) co-ordinated to aminopolycarboxylate ligands has also been investigated.In methanol as solvent:' the trans-1,Zdiamino-cyclohexanetetra-acetate complex oxidizes both the solvent and sterically hindered phenols and the reaction with hydrazine in aqueous media has also been discussed.42 The oxidation of halide ions by cobalt(Ir1) in strongly acidic media has been described43 and in the corresponding reaction with s a l i ~ y l a t e ~ ~ both 1 1 and 1 2 complexes have been identified as intermediates. The nature of the transient complex formed in the reaction between iron@) and ascorbic acid has been discussed45 and a mechanism for the second-stage process is considered to involve an intramolecular electron transfer from the ascorbate ion to the metal centre followed by a fast metal-ion oxidation of the radical ion produced.No such intermediate is observed in the iron(I1IFiodide system,46 which exhibits strictly second-order behaviour over very large concentration ranges. The interactions of iron(II1) with sulphur-containing ligands continue to be investi-gated. The aerial oxidation of the iron@)-penicillamine complex has been de-scribed4' and a mechanism suggested for the metal-ion-catalysed oxidation of sulphydryl groups by 0 in alkaline conditions. Kinetic and equilibrium studies of the reactions of iron(111)- and iron(1v)-maleonitriledithiolate (mnt) complexes with organic bases (L) in acetonitrile have been reported:8 e.g. FeIv(mnt),,- + 2L * 2LFe"'(mnt),- + (mnt),2-where there is a change in co-ordination geometry and a formal reduction at the metal centre with formation of the disulphide.The electron-transfer reaction between [Fe(~hen)~]~ + and sulphur(1v) (HS03-S20,2-) in aqueous media has been discu~sed:~ the mechanism involving the intermediate formation of sul-3 9 G . Davies Inorg. Chem. 1972 11 2488. 40 C. F. Wells and D . Whatley J.C.S. Faraday I 1972,68 434. 4 1 B. L. Poh and R. Stewart Canad. J. Chem. 1972,50,3432; R. Stewart and B. L. Poh, 4 2 A. Brown and W. C. E. Higginson J.C.S. Dalton 1972 166. 4 3 B. Sramkova J . Sramek and J. Zyka Coll. Czech. Chem. Comm. 1972 37 518. 44 R. G. Sandberg J. J. Auborn E. M. Eyring and K. 0. Watkins Inorg. Chem. 1972, 4 5 G . S. Laurence and K. J. Ellis J.C.S. Dalton 1972 1667. 46 G . S. Laurence and K.J. Ellis J.C.S. Dalton 1972,2229. 4 7 L. G . Stadtherr and R. B. Martin Inorg. Chem. 1972 11 92. 48 J. K. Yandell and N. Sutin Inorg. Chem. 1972,11 448. 49 D . W. Carlyle J . Amer. Chem. SOC. 1972 94 4525. ibid. p. 3437. 11 1952 400 A . McAuley phur(v) and no catalysis by copper(I1) is observed. In the oxidation of substituted benzyl alcohols with ferrate(v1) ion," the presence of electron-withdrawing substituents is seen to increase the rate. The relative rates of Mn"' and Ce" oxidation of radical intermediates in the reactions of aliphatic ketones have been investigated' and in the one-electron reaction between cerium(1v) and cyclo-butanol' the rate is lo3-lo' greater than that with cyclopentanol and yields products derived from the ring-opened free radical CH,(CH,),CHO.The two-electron process to give cyclobutanone is on the other hand much slower the effects of 1-methylcyclobutanol being very similar. The thiosulphatochromium-(VI) ion is sufficiently stable towards an intramolecular redox process that the mechanism of formation may be studied using rapid-reaction techniques,' and a general mechanism for substitution on [HCrO,]- has been postulated. E.s.r. studies of the chromium(v) species formed in the Cr"'-ethylene glycol reaction have been describeds4" and complexes of this intermediate with malic malonic, and salicylic acids have been identified,54b whereas with oxalic and or-mercapto-carboxylic acids there is no evidence for complexing. The co-oxidation of oxalic acid and isopropyl alcohol by chromium(v1) proceeds much faster than the reaction with either alone," both substrates being oxidized in a mechanism postulated to involve a single-step three-electron-transfer process.Several studies have been made on the redox reactions of halogens and oxy-halate ions. The reactions of vanadium(1v) with hypochlorous acid and chlorine have been de~cribed,~~" the latter proceeding oia two pathways one of which involves hydrolysis of the halogen. The corresponding reaction with chlorate' 6b is however inhibited by chloride ion. The oxidation of iron(I1) by chlorine(II1) involves both protonated and unprotonated C10 -," the mechanism involving a one-electron transfer with rapid subsequent reduction of the [Cl"] intermediate formed. Ionic-strength effects in the corresponding metal-ion reduction of chlorate have been described with slight differences between Na + and Li + as the counter ions in perchlorate media.'* The oxidation of iodide by vanadium(v) is c~rnplex'~ and is considered to involve rapid protonation of the tetrahydroxo-vanadium(1v) ion and its complex formation with the substrate.In the non-complementary reaction6' 2VOH2+ + Br -+ 2V02+ + 2Br- + 2H+ R. J. Audette J. W. Quail and P. J. Smith J.C.S. Chem. Cornm. 1972 38. K. Meyer and J. Rocek J . Amer. Chem. SOC. 1972,94 1209. 5 ' E. I . Heiba and R. M. Dessau J. Arner. Chem. SOC. 1972,94 2888. 5 2 5 3 K. A. Muirhead G. P. Haight and J. K. Beattie J . Amer. Chem. SOC. 1972,94 3005. 5 4 ( a ) P. R. Boutchev A. Malinovski M. Mitewa and K. Kabassanov Znorg. Chim. Acta, 1972 6 499; (b) M.Mitewa P. R. Boutchev and V. Bojinov Inorg. Nuclear Chem. Letters 1972,8 5 1 . F. Hasan and J. Rocek J. Amer. Chem. Soc. 1972,94 3181. G. Gordon Znorg. Chem. 1972 11 1912. M. G. Ondrus and G. Gordon Inorg. Chern. 1972 11 985. 5 5 5 6 ( a ) K. Dreyer and G. Gordon Znorg. Chem. 1972 11 1174; (6) W. S. Melvin and 5 7 5 8 K. P. Ang G. A. Creak and W. L. Kwik J.C.S. Dalton 1972 2560. 5 y F. Secco S. Celsi and C. Grati J.C.S. Dalton 1972 1675. 6 o A. Adegite and M. H. Ford-Smith J.C.S. Dalton 1972 21 13 Mechanisms of Inorganic Reactions 401 the mono-hydroxy-complex is thought to be much more reactive than the aquated vanadium(II1) ion chloride enhancement of the rate also being observed. Redox reactions of Br, Cl, and ICI with Prlr and As"' have been investigated in fluorosulphuric acid.61 The oxidative addition of 1 to the dicyanoaurate(I), [Au(CN),]- anion has been reported,62 a feature of the system being that the rates of reaction of I,- are substantially greater than that for I, which is the reverse order to that commonly observed for these species.The oxidation of propan-2-01 by Br in acidic media has been investigated amper~rnetrically.~~ Pulse radiolysis studies on inorganic systems have been continued. The Br,-ion has been reported in the hydrolysis of Br- in aqueous media by interaction with hydroxyl radicals.64". In the corresponding one-electron oxidation of hydra~ine,~~ the reaction rates are dependent on the protonation of the molecule, the U.V. spectrum of the hydrazyl radical being obtained in alkaline media.The second-order rate constant for the reaction of nickel@) dimethylglyoxime com-plex with NH2* radicals has been derived66" and the Ni"'-ammine complexes produced in this way have been characterized spectroscopically.66b These un-stable intermediates undergo second-order decomposition to the nickel(I1) ions. The methylpenta-aquochromium(rI1) cation has been prepared by chromium(r1) reduction of the t-butyl alcohol radical :67 t-C,H,O* + Cr" + Me,COMe + [Cr(H,O),MeI2+ Evidence has also been obtained for cation-radical intermediates6* in the Cr'I-ion reduction of pyrazinecarboxylatopenta-amminecobalt(II1) complexes, resulting from an internal electron transfer from the initial precursor complex. Reactions of the solvated electron have been reviewed6 and in its reaction with p-nitrobenzoatopenta-amminecobalt(m) the electron transferred is localized on the co-ordinated p-nitrobenzoato-ligand." Similar transient species which are radical anions and not excited spin states of the metal are observed" in the corresponding reactions with [Co(bipy),13 + and [Ru(bipy),]' +.The mechanisms of oxidation of low-spin d6 metal complexes by peroxodi-phosphate and peroxodisulphate have been and comparisons made " R. C. Paul S. K. Sharma K. K. Paul and K. C. Malhotra J. Inorg. Nuclear Chem., 1972,34,2535. " M. H. Ford-Smith J . J . Habeeb and J. H. Rawsthorne J.C.S. Dalton 1972 2116. '3 J. G. Mason and L. G. Baird J . Amer. Chem. SOC. 1972 94 61 16. 6 4 ( a ) D. Zehavi and J. Rabani J. Phys. Chem. 1972,76,3 12; (b) D.Behar J . Phys. Chem., 6 5 E. Hayon and M. Simic J . Amer. Chem. SOC. 1972,94,42. '' J. Lati and D. Meyerstein ( a ) Israel J . Chem. 1972 10 735; (6) Inorg. Chem. 1972, " '* E. S. Gould J. Amer. Chem. Soc. 1972,94 4360. 69 F. S. Dainton 'M.T.P. International Review of Science Physical Chemistry' vol. 9, ed. J. C. Polyani Butterworth London 1972. 'O M. Z. Hoffman and M. Simic J. Amer. Chem. SOC. 1972,94 1757. " J. H. Baxendale and M. Fiti J.C.S. Dalton 1972 1995. 72 J. 0. Edwards Co-ordination Chem. Rev. 1972 8 87. 1972,76 18 15. 11,2393,2397. M. Ardon K. Woolmington and A. Pernick Inorg. Chem. 1971 10 2812 402 A . McAuley of rate and activation parameters. The reduction of the corresponding d5 species 4[Fe@ipy),l3+ + 40H- -P 4[Fe(bipy),12+ + O2 + 2H,O by hydroxide ion has been inve~tigated~~ using a stopped-flow system the overall rate law being second order.A radical mechanism is postulated with H0,- as an intermediate. The slower re-oxidation of the iron@) products has been confirmed using an oxygen electrode. The mechanism of formation of the 'brown' complex between Pu" and H,02 has been the main reaction pathway being ascribed to interaction between a dimeric cationic species and the neutral H202 molecule. The reduction of H,02 by Cr" Ti''' and V'' has been reported;75 the rate depends on pH and in the case of the vanadium ion there is formation of both mono- and di-peroxovanadium(v) complexes. In the catalysis76 of the chlorine-hydrogen peroxide reaction by Mn"' and Mn" at saturation concentrations of the metal ion the reaction is first-order with respect to both C1 and H202 the hydrogen-ion dependence being indicative of the possible formation of MnOOH' which might be involved in electron transfer with Mn"'.There is little sign of reaction between phosphine and H 0 2 although in the presence of Br- as a catalyst77 it is suggested that oxidation to Br takes place with subsequent reaction with the phosphine possibly via the intermediate [PH,*Br]. The interaction of metal-ion complexes with molecular oxygen is also of interest and it has been reported that iron(rI)-cyanate complexes formed in methanol7 give rise to oxidized bridged dinuclear species although chloride ion retards complete oxidation. Reversible monomeric oxygen adducts of cobalt(1rk Schiff bases have been identified in methylene chloride-pyridine solutions7 and an e.s.r.studys0 has shown that such reversible room-temperature reactions occur only when the electronic configuration is (dxy2) (dxZ2)(dz2 ' ) ( d X 2 - y20) whereas no reaction takes place in solvents such as dimethylformamide where the con-figuration is altered. Dinuclear cobalt chelates with bridging oxygen ligands are found on reaction of complexes containing ethylenediamine and SCN- or ClO,-.* In acid media however there is spontaneous liberation of the oxygen. In the aerial oxidation of 1,2,4-trimethylbenzene in the presence of cobalt(I1) picolinate however,' a mixture of dialkyl-substituted benzoic acids is produced. 7 3 G. Nord and 0. Wernberg J.C.S. Dalton 1972 866. 7 4 A. Ekstrom and A.McLaren J . Inorg. Nuclear Chem. 1972 34 1009. 7 5 A. Samuni D. Meisel and G. Czapski J.C.S. Dalton 1972 1273. 7 6 J. I. Morrow and L. Silver Inorg. Chem. 1972 11 231. 77 D. V. Sokolskii Y. A. Dorfman and T. L. Rakitskaya Zhur. fiz. Khim. 1971 45, 277 1. 7 8 M. Quastlerova-Hvastijova J. Kohout and J . Gazo Coil. Czech. Chem. Comm., 1972,37,289 1. 79 E. W. Abel J . M. Pratt and R. Whelan Inorg. Nuclear Chem. Letrers 1971 7 910. E. I. Ochiai J.C.S. Chem. Comm. 1972 489. M. Zehnder and S. Fallab Helu. Chim. Acra 1972 55 1691. 8 2 A. D. Stefanova D. I. Dimitrov and L. K. Jankov Monatsh. 1972 103 1011 Mechanisms of Inorganic Reactions 3 Substitution Reactions 403 Solvent Exchange and Ligand Exchange.-The hydration number of the sodium ion has been determineda3 using n.m.r.methods by titration of sodium tetra-phenylborate in THF with water the data being consistent with the formulation [Na(H,O),] + in solutions over the concentration range up to 0.7M-sodium ion. In the temperature range 2 7 3 4 2 3 K there are six equivalent water molecules in the aqueous nickel@) ion.' 27Al resonance studies have shown hydrolysis and polymerization of the [Al(H20)6]3+ cationa5" and the presence of a sulphato-aluminium cation in sulphuric acid media.85b Complex formation has also been observed in erbium(rI1) and cerium(m) perchlorate solutions,86 although other lanthanide ions are six-co-ordinate. Similar effects have been observed for other tripositive metal ions in trimethyl phosphate solutions.87 Solvent exchange rates for dipositive metal ions in methanola8 have been reported with a relationship between ASs and AH$ ; an S,1-type mechanism is suggested for complex formation in this solvent.At low temperatures however,89 a stopped-flow study of manganese(i1) complexes with N-donor ligands yields activation parameters which are not in accord with the Eigen-Wilkins approach where for uncharged ligands AH*formation x AHtexchange. A temperature-jump study of lanthanide-murexide complexing in 50 % aqueous ethanol shows little difference from the rates in aqueous media unlike the behaviour for Ni" where under comparable conditions a five-fold increase in rate is observed." The formation of nickel(II)-terpyridine complexes in DMSO has been investigated, the reactions being essentially irreversible" and the rates parallel to those of DMSO exchange.The T-jump technique has also been used to study successive steps in the reaction of Dy"'-acetate complexesg2 where the rate of formation of the second (1 2) complex is significantly greater than that for the mono-species. Ligand-exchange studies on some eight-co-ordinate yttrium(1Ir) com-plexes have also been described.93 A 35Cl n.m.r. study of the chloride-ion exchange in the tetrachlorogallate(II1) ion9 has been made whereas under similar conditions no relaxation is observed for [AlCl,] - consistent with an upper rate limit of - lo4 s-'. The chlorine exchange between Et,NCl and Me(ClCH,)Si(CI)(NMe,) in CH,CI has been in~estigated,~' the rate being first-8 3 A. L. Van Geet J. Amer. Chem. Soc.1972,94 5583. 8 4 J. W. Neely and R. E. Connick J. Amer. Chem. Soc. 1972 94 3419. " ( a ) J. W. Akitt N. N. Greenwood B. L. Khandelwal and G. D. Lester J.C.S. Dalton, 1972 604; ( 6 ) J. W. Akitt N. N. Greenwood and B. L. Khandelwal ibid. p. 1226. 86 A. Fratiello V. Kubo S. Peak B. Sanchez and R. E. Schuster Inorg. Chem. 1971, 10 2553. J . Crea and S. F. Lincoln Inorg. Chem. 1972 11 1131. F. Dickert P. Fischer H. Hoffman and G. Platz J.C.S. Chem. Comm. 1972 106. 8 9 D. J. Benton and P. Moore J.C.S. Chem. Comm. 1972 717. y o J. L. Bear and C. T. Lin J . Inorg. Nuclear Chem. 1972,34 2368. y 1 P. A. Cook C. E. Cottrell and R. K. Boyd Canad. J . Chem. 1972 50 402. 92 M. Doyle and H. B. Silber J.C.S. Chem. Comm. 1972 1067. 9 3 N. Serpone and R. Ishayek Inorg. Chem.1971 10 2650. y 4 S. F. Lincoln A. Sandercock and D. R. Stranks J.C.S. Chem. Comm. 1972 1069. " S. Di Stefan0 and H. Goldwhite J.C.S. Chem. Comm. 1972 1195 404 A . McAuley order with respect to each component and the reaction occurring with inversion of configuration. In the tri-iodide-iodide I -I - exchange reaction a linear activated complex has been po~tulated,~~ the rate constant derived from the transfer diffusion method agreeing well with that from n.m.r. line broadening. The acid-catalysed exchange of oxalate oxygen between oxalatotetra-aquo-chromium(III) and solvent water has been discussedg7 and in the corresponding reaction with the trisoxalato-complexg8 the carbonyl oxygens exchange at a rate greater than the carboxyl oxygens at 25 "C. The rate of exchange of the oxygen atoms in trans-[Re(en),O,]+ and waterg9 has been reported and is generally dependent on the nature of the cation of the supporting electrolyte.On oxidation of the ion however a general feature is the complete transfer of the ReO unit to the product ReO,- ion. The corresponding reaction with bromate has been studied"' using '80-labelled halate and over the range 1.7 < pH < 14.3 both acid- and base-catalysed paths are observed the rates being generally slower in D20. No exchange occurs between SO4,- and H,O in neutral or alkaline conditions at 373 K over nine weeks."' Metal-ion Complexes.-A review of relaxation techniques used in solution chemistry has been published.102 The trans activation and limiting S,1 mechan-ism for substitution reactions of cobalt(II1) complexes in aqueous media have been des~ribed."~ From a consideration of the transition-state enthalpies in the aquation of acidopenta-amminecobalt(m) complexes,'04" it has been suggested that dissociative processes are important with considerable solvation of the leaving group but a similar treatment'04b for acidopenta-aquochromium(1n) species indicated a less strongly dissociated transition state.In tfie acid-catalysed hydrolysis of [Co(en),(OAc),] + ion^,''^ the cis-isomer is more labile than the trans- the acid dependence arising from a protonation pre-equilibrium step. In the corresponding reaction of [Co(bipy),CO,] + l8O tracer studies suggest that Co-0 bond cleavage is involved in the rate-determining ring-opening path.'06 Alkaline hydrolysis of co-ordinated nitriles in penta-amminecobalt(n1) complexes yields the corresponding N-bonded carboxamido-products,' ' the reactions being first order with respect to hydroxide ion concentration.The aquation of trans-[Cr(en),F,] + has been shown to proceedlo8 via the formation of an isolable 96 I. Ruff V. J. Friedrich and K. Csillag J . Phys. Chem. 1972 76 162. y 7 S. G. Gourley and R. M. Milburn Inorg. Chem. 1972,11,2262. 9 y L. B. Kriege and R. K. Murmann J . Amer. Chem. Soc. 1972,94,4557. A. L. Ode11 and D. B. Rands J.C.S. Dalton 1972 749. l o o H. Gaunsjager A. Griitter and P. Baertschi Helu. Chim. Acta 1972 55 781. l o ' R. Radmer Inorg. Chem. 1972 11 1162. J. E. Crooks 'M.T.P. International Review of Science Physical Chemistry' vol. 9, ed.J. C. Polyani Butterworth London 1972 p. 299. l o 3 J. E. Boyd and W. K. Wilmarth Znorg. Chim. Acra Rev. 1971 5 7. l o 4 ( a ) H. K. J. Powell Inorg. Nuclear Chem. Letters 1972 8 157; ( b ) H. K. J. Powell, l o ' T. P. Dasgupta and M. L. Tobe Inorg. Chem. 1972 11 1011. lo' D. J. Francis and R. B. Jordan Inorg. Chem. 1972 11 461. l o ' D. Pinnell G. B. Wright and R. B. Jordan J . Amer. Chem. Soc. 1972,94 6104. S. C. Pyke and R. G . Linck Inorg. Chem. 1971,10,2445. Austral. J . Chem. 1972 25 1569 Mechanisms of Inorganic Reactions 405 unidentate ethylenediamine complex [Cr(en)(enH)(H,0)F,]2 + where the fluorides are trans to one another the path being unusual in that Cr-N bond rupture is preferred to loss of an acido-ligand. Several examples of metal-ion-catalysed aquations of complexes have been reported.In the iron(m) acceleration of the reaction of [Cr(ox),(H,O),] - the iron(II1) co-ordinates to the leaving oxalate group,'0g which is consistent with the observed failure of the inert Cr"' ion to act in a similar manner. Linear free-energy relationships have been discussed in the Hg"-catalysed aquation of halogenopenta-amminechromium(Ir1) species' where it is suggested that there is a substantial breaking of the Cr-X bond and making of the Hg-X bond in the transition state. Similar activation states are described in the corresponding reactions of analogous Rh"' perchlorates.' ' ' Reactions of [1r(NH3),Xl2+ (X = C1 or Br) with NaOH have been studied", and a linear free-energy relationship has been found between the entropies of activation for the reaction [M(NH3),XI2+ + OH- + [M(NH3),0HI2+ + X-and the hydration entropy of the anion X- where M = Co Cr Rh or Ir.In the reaction of [Ir(NH3),N3l2 + with acid however intermediate formation of a co-ordinated nitrene [Ir(NH,),NHI3 + has been observed.' l3 Outer-sphere effects in the solvent-ammonia exchange in methanol-water mixtures have been reported for nickel@) species with quinquedentate ligands where only one site is available for exchange.' l4 The rates increase with increasing MeOH concentration but no correlation with bulk properties of the solvent as described previously is observed. An example of a trans effect in a low-spin nickel@) complex is exhibited in the reaction of CN- with nickel triglycine with the formation of a ternary complex.' ' The kinetics of ternary complex formation involving Mg2+ and Mn2+ species have been reported,"6" where it is suggested that in the case of Mg2+ the first ligand has little influence on the kinetics of incorporation of the second in marked contrast to reactions of nickel(@ com-plexes.1'6b A T-jump study has also been made of the Cu"-en-histamine com-plex formation,' l7 and using the same technique the formation and dissociation of Cu"-adenosine and -D-ribose complexes have been investigated.' l 8 A review of catalysis by metalloenzymes has been presented'lg which deals with both lo' S. N. Choi and D. W. Carlyle Inorg. Chem. 1972 11 1718. ' l o J. P. Birk and C. M. Ingerman Inorg. Chem. 1972,11,2019. I I * G. C. Lalor and T. Carrington J.C.S.Dafron 1972 55. ' l 3 B. C. Lane J. W. McDonald F. Basolo and R. G. Pearson J . Amer. Chem. SOC., S. C. Chan and S. F. Chan J . Inorg. Nuclear Chem. 1972,34,23 1 1. 1972,94 3786. F. R. Shu and D. B. Rorabacher Inorg. Chem. 1972,11 1496. ' I s G . K. Pagenkopf J . Amer. Chem. Soc. 1972,94,4359. l l 6 (a) D. N. Hague S. R. Marton and M. S. Zetter J.C.S. Furaduy I 1972 68 37; ( 6 ) M. A. Cobb and D. N. Hague ibid. p. 932. l 7 V. S. Sharma and D. L. Leussing Inorg. Chem. 1972,11 1955. l 8 G. Boivin and M. Zador Cunud. J . Chem. 1972,50 3 1 17. l R. J. P. Williams Inorg. Chim. Acra Rev. 197 1 5 137 406 A . McAuley acid-base and electron-transfer catalysts and in several other studies the impor-tance of metal ions in biological systems has been considered.A general mechan-ism for metal-ion incorporation into porphyrin molecules has been described. 2o In the catalysis of the hydration of acetaldehyde by Zn2 + in the presence of ace-tate12' the mechanism is considered to involve the formation of a bond between the metal ion and a carbonyl group which undergoes attack by OH- ions. Zinc ions have also been shown to catalyse the transesterification of N-(B-hydroxy-ethy1)ethylenediamine by p-nitrophenyl picolinate. ' 22 Al"' and Gal'' have been shown to feature uniquely in a transamination reaction'23 in that only these metal ions of M" and MI1' species yield an intermediate in neutral methanolic solutions of pyridoxamine and ethyl pyruvate. The kinetics and mechanism of formation of alkali-metal complexes in solution have been reviewedlZ4 and temperature-jump studies have been made on the equilibria in acetonitrile solutions between metal chlorides MCl (M = Fe In, Ga or Al) and triphenylchloromethane,' 2 5 the relaxation spectra being inter-preted in terms of the reactions (s = solvent): The influence of donor solvents on the corresponding ionization of SbCl has also been examined.'26 Relaxation effects on molybdate polymers in solution show pH-dependent effects which are consistent with heptamer formation' via protonated monomeric molybdate ions.A kinetic study of the first two hydrolysis reactions of the hexachloromolybdate ion has been described.' 28 A general mechanism for the rate-determining proton transfer in substitution reactions of the tetrahedral hydrogen chromate ion'29 has been proposed and influences of environment on the acid-catalysed hydrolysis of [Cr207]2- have been in~estigated'~' in dioxan and electrolyte solutions although effects are less pronounced than might have been expected from dielectric constants.The rever-sible interaction between iodine and thiocyanate ion has been studied using stopped-flow rnethod~'~' and a laser-Raman T-jump study of the kinetics of the tri-iodide equilibrium reported'32 where relaxation times of 10- 7-10-8 s were observed using a stimulated Raman effect in liquid nitrogen to shift the wave-length of the neodymium-glass laser radiation to 1.41 pm where water absorbs R. Khosropour and P. Hambright J.C.S. Chem. Comm. 1972 13. R . H. Prince and P. R. Woolly J.C.S. Dalton 1972 1548.D . S. Sigman and C. T. Jorgensen J . Amer. Chem. SOC. 1972,94 1724. S. Matsumoto and Y. Matsushima J . Amer. Chem. SOC. 1972,94 721 1. R. Winkler 'Structure and Bonding' Springer Verlag 1972 vol. 10 p. 1. V. Gutmann and R. Schmidt Monatsh. 1971,102,798; R. Schmidt and V. Gutmann, ibid. p. 805. V. Gutmann and R. Schmidt Monarsh. 1971 102 1217. D. S. Honig and K. Kustin. Inorg. Chem. 1972 11 65. W. Andruchow and J. Di Liddo Inorg. Nuclear Chem. Letters 1972 8 689. C. Lin and J. K. Beattie J . Amer. Chem. SOC. 1972 94 3011. IJO R. Koren and B. Perlmutter-Hayman J . Phys. Chem. 1972,76 582. I J 1 I . Orszagh G . Bazsa and M. T. Beck Inorg. Chim. Acta 1972 6 271. 13' D. H. Turner G . W. Flynn N. Sutin and J. V. Beitz J. Amer. Chem. Soc. 1972,94, 1554 Mechanisms of Inorganic Reactions 407 strongly. The equilibrium between octahedrally and tetrahedrally co-ordinated cobalt(I1) ions in NN'-dimethylacetamide has been studied spectrophoto-metrically'33 and T-jump studies of the reaction in pyridine and nitr~rnethane'~ indicate a two-stage process with evidence for a five-co-ordinate intermediate following loss of one pyridine molecule. * 3 3 V. Gutmann R. Beran and W. Kerber Monatsh. 1972 103 764. 1 3 4 R. D. Farina and J. H. Swinehart Inorg. Chem. 1972,11 645

ISSN:0069-3022    

DOI:10.1039/GR9726900395

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

ERRATA Volume 68A 1971 Pp. 41 1,412. In the last three lines of p. 41 1 and the first line of p. 412 : for “rhodium” and “Rh” read “ruthenium” and “Ru

ISSN:0069-3022    

DOI:10.1039/GR9726900408

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

Author Index

ISSN:0069-3022    

DOI:10.1039/GR9726900409

出版商:RSC    

年代:1972

数据来源: RSC