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High-power proton decoupling, cross-polarization, and magic-angle spinning techniques have been employed to obtain high-resolution 31 3P NMR spectra of solid tertiary phosphines, tertiary phosphine oxides, and tertiary phosphine complexes of nickel(II), palladium(II), and platinum(II). Solid-state effects can result in nonequivalence of 31P shieldings in simple di-[PtCl2(PR3)2] complexes. The magnitudes of the scalar couplings, V(195Pt,31P), in platinum(II) complexes are comparable with those obtained by high-resolution solution 31P NMR measurements, allowing the geometry of such complexes to be determined in the solid state. The ligand Ph2PCH2CH2Si(OEt}3 and its Ni(II), Pd(II), and Pt(II) complexes have been immobilized on silica gel and high-surface-area glass beads and the immobilized species studied by solid-state 31P NMR. The results show that the geometry of surface-immobilized complexes may be determined and the surface reactions may be monitored. The merits of some preparative routes to supported transition-metal catalysts have been studied and some common representations of surface reactions and surface-immobilized species shown to be misleading.

Szn,ntniar-y Ready insertion of ethylene or propene into the Pt-H bond of PtII hydrido-complexes, which leads to good yields of ethyl or n-propyl derivatives, involves displacement of the ligand trans to the hydridic hydrogen in a cationic species, giving a cationic hydrido-olefin complex as intermediate.

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Trimethyltin fluoride differs considerably in its properties from other trimethyltin halides. The crystals are orthorhombic, with four molecules in a unit cell of dimensions a = 4.32, b = 10.85, and c = 12.84 A, space group Pmcn. The structure, which has been determined by Patterson methods, and refined by three-dimensional Fourier synthesis, consists of Me,Sn groups and F atoms arranged alternately in a chain-like manner along the a-axis. Two interpretations are given of the observed electron-density distribution ; both contain essentially five-co-ordinate tin atoms, and non-linear unsymmetrical Sn-F Sn bridges, consistent with a non-ionic type of compound.ON the basis of infrared spectroscopic studies, different structures have been proposed for trimethyltin fluoride, and the remaining trimethyltin halides. The former is considered to be ionic, Me,Sn+F-, and the latter are thought to consist of covalent tetrahedral molecules. However, no structure determinations for the solid compounds have been reported. Recently, it was suggested 2,3 that trimethyltin compounds may be associated, so that, for example, trimethyltin acetate may be composed of planar Me,Sn groups bridged by an aceto-group. The planarity of the Me,Sn portion of the molecule then no longer necessarily requires an ionic formulation. Such an associated structure would make the tin atom five-co-ordinate, and support for this less common co-ordination number is given by the recent reports 495 of the structure of chloro(trimethyl)pyridinetin(Iv), (C5H,N)M%SnC1, in which the tin atom is a t the centre of a trigonal bipyramid, the methyl groups being in the equatorial sites, and the chlorine atom and pyridine occupying the axial positions. It therefore seemed desirable to determine the crystal structure of trime t hyl tin fluoride. EXPERIMENTALCrystals of trimethyltin fluoride consist of bundles of very fine colourless needles, elongated along the a-axis. Almost all the crystals were multiple twins, but it was possible to obtain one or two suitable single crystals by breaking up the bundles and searching for a very small fragment. The crystal used for recording the X-ray data had cross-section 0-02 x 0.02 mm.The unit-cell dimensions and space group were determined from various rotation, oscillation, Weissenberg (all Cu Ka) , and precession films (Mo K,). Crystal Data [h(CuK a ) = 1.5418 A; A(Mo K,) = 0.7107 A].-Trimethyltin fluoride, Me,SnF, M = 182.8, m. p. >360° (decornp.), orthorhombic, a = 4.32 f 0.01, b = 10.85 f 0.02, c = 12.84 f 0.02 A, U = 601.8 Hi3, D, (2 = 4) = 2.017, D, = 2-01 g. cm." (by flotation in silver nitrate), F(000) = 344. Absent reflexions: h0l when l is odd, hkO when (h + k ) is odd. Space group is P2,cn (C,,e) or Pmcn (D,h16).

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Severaltitanium(III)complexesincorporatingthechelatingdiamidoamineligand[(Me 3 SiNCH 2 CH 2 ) 2 NSiMe 3 ] 2- [NN 2 ] are described. The reaction between Li 2 [NN 2 ] and TiCl 3 (THF) 3 (THF ) tetrahydrofuran) resulted in the formation of the dimeric titanium(III) chloride {TiCl[NN 2 ]} 2 1, from which the monomeric titanium(III) alkyl Ti{CH(SiMe 3 ) 2 }[NN 2 ] 2 could be synthesized via a salt metathesis route. The alkyl complex 2 was found to react with hydrogen gas to form the thermally stable, dimeric, diamagnetic titanium(III) hydride {TiH[NN 2 ]} 2 3; density functional calculations on a simplified model system of 3 indicated the presence of a weak Ti-Ti σ-interaction. The solid-state structures of 1, 2, and 3 are described.The characterization and reactivity of titanium(III) hydride complexes has been a recurring theme of research over the past 30 years, in part due to the high reactivity of such species in a variety of catalytic processes such as alkene hydrogenation and isomerization, 1 imine hydrosilylation, 2,3 and silane polymerization, 4,5 and also because of the uncertainty in describing "titanocene"; 6-11 only in 1992 was the original formulation of titanocene as the bridging fulvalene hydride confirmed by X-ray crystallography. 12 To date, however, all of the known titanium-(III) hydridic species that have been reported have been based around cyclopentadienyl-derived ligands; employing C 5 H 5 and other nonbulky cyclopentadienyl ligands causes dimeric species to be formed, 6,11,13,14 whereas the more sterically crowded environments dictated by C 5 Me 5 or alternatively C 5 Me 4 Ph result in the formation of monomeric Ti(III) hydrides. [15][16][17][18][19] Considering the recent upsurge in the chemistry of Group 4 complexes that incorporate noncyclopentadienyl ligands 20-28 and the high reactivity of Ti(IV) and Zr(IV) cations incorporating multidentate diamides toward processes such as alkene polymerization, [29][30][31][32][33][34][35][36] it seemed appropriate to develop the Ti(III) chemistry of the polydentate diamidoamine ligand, [(Me 3 SiNCH 2 CH 2 ) 2 NSiMe 3 ] 2- [NN 2 ]. This ligand has been shown to stabilize Zr and Ti(IV) oxidation states 37,38 and also to provide a suitable ligand Mach, K.; Cisarova, I.; Loub, J.; Hiller, J.; Sindelar, P. J. Organomet. Chem. 1995, 497, 33. (15) De Wolf, J. M.; Blaauw, R.; Meetsma, A.; Teuben, J. H.; Gyepes, R.; Varga, V.; Mach, K.; Veldman, N.; Spek, A. L.