List of authors Preface E. A. V. Ebsworth, A. G. Maddock and A. G. Sharpe 1. Organometallic cations Howard C. Clark 2. Unusual coordination numbers A. J. Downs 3. Gallium hydride and its derivatives N. N. Greenwood 4. Properties of donor solvents and coordination chemistry in their solutions V. Gutmann 5. Perfluoropseudohalides and the chemistry of chlorofluoromethylsuphenyl compounds Alois Haas 6. Polyfluoroalkyl silicon compounds R. N. Haszeldine 7. Fluoroalkylmercurials J. J. Lagowski 8. Catenationin inorganic silicon compounds A. G. MacDiarmid 9. Metal-metal interaction in paramagnetic clusters R. L. Martin 10. Amides as non-aqueous solvents R. C. Paul 11. Defect aggregation in solid state chemistry A. L. G. Rees 12. Transition metal derivatives of silicon, germanium, tin and lead F. G. A. Stone 13. Chemistry compounds of Schiff bases B. O. West 14. Fluorosulphates A. A. Woolf Author index Subject index.

The structures of a series of three triosmium carbonyl clusters containing closely related phosphorus ligands have been determined: decarbonyl-1kappa3C,-2kappa3C,3kappa4C-(dimethylphosphine-1kappaP)-mu-hydrido-1:2kappa2H-hydrido-2kappaH-triangulo-triosmium(3 Os-Os), [Os3(CO)10)H(mu2-H)(PMe2H)] (1), contains a terminal PHMe2 ligand; decacarbonyl-1kappa3C,-2kappa3C,3kappa4C-(mu-dimethylphosphino-1:2kappa2P)-mu-hy-drido-1:2kappa2H-triangulo-triosmium(3 Os-Os), [Os3-(CO)10(mu2-H)(mu2-PMe2)] (2), has a PMe2 group bridging two of the osmium centres; in nonacarbonyl-1kappa3C,2kappa3C,3kappa3C-bis-mu-hydrido-2:3kappa2H;1:3kappa2H-(mu3-methylphosphinidene-kappa3P)-triangulo-triosmium-(3 Os-Os), [Os3(CO)9(mu2-H)2(mu3-PMe)] (3), the PMe group caps all three metals. In (1) the terminal Os-P distance is 2.316 (18) angstrom and in (2) the two Os-P distances of 2.360 (4) and 2.365 (4) angstrom do not differ significantly. However, the mu3-PMe roup in (3) does not cap symmetrically: at 2.350 (5) angstrom, one of the Os-P distances is significantly lower than the remaining two, 2.318 (5) and 2.317 (5) angstrom.

Fluoroacyl complexes of iridium have been prepared by reaction of XeF2 with iridium carbonyl complexes [Ir(CO)3L2]+(L = PMe3, PMe2Ph, PEt2Ph or PEtPh2), [Ir(CO)2Cl(PMe3)2] and [Ir(CO)-(PMe3)4]+. The reaction can be viewed as an unusual type of oxidative addition and this is supported by the need for strongly electron-donating phosphines for reaction to occur. The complex [Ir(CO)2F(COF)-(PEt3)2]+ reacts with SiH3X (X = CN, NCS or NCO) to give acyl complexes [Ir(CO)2F(COX)(PEt3)2]+ and with BF3 to give [Ir(CO)3F(PEt3)2]2+. This dication reacts further with PMe3 to give an acyl product with PMe3 bound to a carbonyl ligand. The complex [Ir(CO)3(PPh3)2]+ reacts with XeF2+ BF3 to give [Ir(CO)3F(PPh3)2]2+. Products were characterised using 19F, 31P and 13C NMR spectroscopy.

The title compound is a four-coordinate Rh(I) complex in which the metal is ligated by two mutually trans triethylphosphines, a carbonyl and an isothiocyanate group. The molecule lies on a crystallographic twofold axis which passes through the metal, the carbonyl and the isothiocyanate group. Steric factors play a part in determining the coordination mode of the NCS- ligand: in particular, the bulk of the triethylphosphine ligands disfavours linkage through the larger S atom, whose preference for non-linear coordination would also cause steric problems.

The complex trans-[Rh(CO)X(PEt3)2] 1 (X = Cl, Br, I or NCS) reacts with PH3 in dichloromethane at 183 K to give [Rh(CO)(PH3)2(PEt3)2]+ 2 which in turn reacts with CO in dichloromethane at 213 K to give [Rh(CO)2(PH3)(PEt3)2]+. The complex [Rh(CO)Cl2H(PEt3)2], formed by reaction of 1 and HCl, reacts with PH3 in dichloromethane at 219 K to give [Rh(CO)Cl(H)(PH3)(PEt3)2]+; on warming, further displacement reactions with PH3 give first [RhCl(H)(PH3)2(PEt3)2]+ and then the tris(phosphine) species [RhH(PH3)3(PEt3)2 ]2+. Enrichment with C-13 in the carbonyl positions enabled the use of C-13 NMR spectroscopy to investigate these reactions and the parameters of eleven rhodium complexes observed in this work are given.

Oxidative additions of simple silanes and germanes of the type MH4−nXn, in which M  Si, Ge; X = halogen, to complexes of the type M(CO)X(PEt3)2, where M  Rh, Ir; X = halogen had previously been thought frequently to proceed in a trans fashion to give species with hydride trans to silyl or germyl. By using material enriched with 13C in the carbonyl position and studying the couplings between carbonyl and hydride by 13C NMR spectroscopy, we have found, in all the cases examined, that hydride is in fact situated cis to silyl or germyl and not trans. The same was found to be the case for the reaction of SiH2F2 with Ir(CO)Cl(PEt3) 2, which had not previously been investigated.

Carbonyldichloro(sulfur monoxide chloride)bis(triethylphosphine)iridium(III), [IrCl2(CO)-(C6H15P)2(SOCl)], M(r) = 610.96, monoclinic, P2(1)/c, a = 14.5752 (17), b = 9.7304 (8), c = 15.163 (5) angstrom, beta = 97.454 (15)-degrees, V = 2132 angstrom3, Z = 4, D(x) = 1.903 Mg m-3, lambda(Mo Kalpha) = 0.71073 angstrom, mu = 7.09 mm-1, F(000) = 1192, T = 183 K, R = 0.0448 for 2803 unique observed reflections. The coordinated SOCl group has Ir-S 2.304(3), S-Cl 2.168 (5), S-O 1.462 (10) angstrom and Ir-S-Cl 102.22 (17), Ir-S-O 113.9 (4), Cl-S-O 106.5 (4)-degrees.

C37H30ClIrOP2.2CD2Cl2, M(r) = 954.14, orthorhombic, Pcab (alternative Pbca, No. 61), a = 8.0054 (21), b = 20.669 (6), c = 23.170 (5) angstrom, V = 3834 angstrom-3, Z = 4, D(x) = 1.649 Mg m-3, lambda-BAR(Mo K-alpha) = 0.71073 angstrom, mu = 3.94 mm-1, F(000) = 1872, T = 298 K, R = 0.0253 for 1176 unique observed reflections. Despite disordering of the Cl- and CO ligands, it was possible to resolve the affected atoms and finally to refine without the need for geometric constraints. The solvate molecules associate with the metal complex via O...H and Cl...H contacts of 2.415 (25) and 2.672 (16) angstrom respectively.

Tellurium tetrafluoride reacts at 195 K in CD2Cl2 with Rh(CO)X(PEt3)2[X = Cl, Br, NCS, NCO] to give the novel complexes [Rh(CO)X(PEt3)2(TeF3)+][TeF5–], which have been characterised by 19F, 31P and 13C NMR spectroscopy; for X = Cl, Br and NCS the complexes are stable at ambient temperature but for X = NCO decomposition occurs at 215 K.

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Article Crystal structure of (chloromethyl)trimethylammonium tetrafluoroborate, (ClCH2)(CH3)3NBF4 was published on October 1, 1991 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 195, issue 1-4).