87461-82-3Relevant articles and documents
A reexamination of the reactions of Ga(CH2SiMe3)3 and In(CH2SiMe3)3 with alkali-metal hydrides. The search for a reductive-elimination reaction
Hallock,Beachley Jr.,Li, Yong-Ji,Sanders, William Michael,Churchill, Melvyn Rowen,Hunter,Atwood
, p. 3683 - 3691 (2008/10/08)
The nature of the reactions that occur between Ga(CH2SiMe3)3 and In(CH2SiMe3)3 with alkali-metal hydrides has been reinvestigated. The previously reported results2,3 suggesting reductive elimination reactions have not been reproduced. The product from the reaction between Ga(CH2SiMe3)3 and KH in benzene at 45°C has been identified as KGa(CH2SiMe3)3H by an X-ray structural study, infrared and 1H NMR spectral data, and reaction chemistry. Thermal decomposition has not been observed until the temperature is above 200°C. The compound KGa(CH2SiMe3)3H crystallizes in the monoclinic space group P21/c with unit cell dimensions a = 14.560 (7) A?, b = 13.316 (6) A?, c = 23.592 (8) A?, β = 104.42 (5)°, and Z = 8 for dcalcd = 1.11 g cm-3. Full-matrix least-squares refinement led to a final R value of 0.076 for 3834 observed reflections. The geometry about each of the two gallium atoms is distorted tetrahedral with gallium-hydrogen distances of 1.49 and 1.36 A? and Ga-C(av) lengths of 2.04 (1) and 2.02 (1) A?, respectively. The infrared spectra of KGa(CH2SiMe3)3H and KGa(CH2SiMe3)3D have been compared in order to identify the bands associated with the gallium-hydrogen bond. The observed frequency for v(Ga-D) at 1075 cm-1 suggests that v(Ga-H) should be around 1500 cm-1, an unusually low frequency. The reaction chemistry of KGa(CH2SiMe3)3H also confirms the presence of a typical nucleophilic hydride. The reactions between In(CH2SiMe3)3 and KH or NaH have been reexamined under a great variety of experimental conditions. The primary products of reactions in pentane at room temperature are KIn(CH2SiMe3)3H and mixtures of NaIn(CH2SiMe3)3H and NaIn(CH2SiMe3)4. In one reaction between In(CH2SiMe3)3 and KH, colorless crystals were isolated and identified by an X-ray structural study as KIn(CH2SiMe3)4. The complex KIn(CH2SiMe3)4, crystallizes in the centrosymmetric monoclinic space group P21/n with a = 11.106 (4) A?, b = 19.712 (6) A?, c = 12.882 (3) A?, β = 91.65 (2)°, V = 2819 (1) A?3, and Z = 4. Diffraction data (Mo Kα, 2θ = 4.5-45.0°) were collected with a Syntex P21 automated four-circle diffractometer. All atoms were located, and the structure was refined to R = 3.6% and Rw = 3.2% for all 3520 independent reflections (none rejected). The complex is composed of discrete K+ cations and In(CH2SiMe3)4- anions; In-C distances range from 2.234 (4) through 2.251 (4) A?, averaging 2.239 [8] A?. The thermal decomposition reactions of KIn(CH2SiMe3)3H, KIn(CH2SiMe3)4, and mixtures of NaIn(CH2SiMe3)3H and NaIn(CH2SiMe3)4 have been investigated in detail under a variety of conditions by using benzene and saturated hydrocarbon solvents. The products of decomposition of the indium hydride derivatives, which include indium metal, SiMe4, biphenyl, and varying amounts of H2 depending on the reactant, solvent, and conditions, are indicative of reactions more complicated than a simple stoichiometric reductive-elimination reaction. All experimental observations including the formation of SiMe4 are consistent with the dissociation and reactions of alkali-metal alkyls, presumably KCH2SiMe3 and NaCH2SiMe3.
