Preparation, crystal structure determination and properties of adducts of indium methylene compounds with Group 15 donors

The reaction of InBr with CH2Br2 in 1,4-dioxane or acetonitrile yields the corresponding solvate of Br2InCH2Br, which on reaction with E(C6H5)(3) (E = P, As, Sb) gives the indium(III)-Group 15 dimetallo-methane derivatives, B r3InCH2E(C6H5)(3). The crystal structures of the two related compounds (E=A s, Sb) have been determined by X-ray crystallography. For Br3InCH2As(C6H5)( 3), cell constants a = 15.553(7), b = 21.646(8), c = 12.920 (10) Angstrom; space group Pbca, Z = 8, R = 0.064, R-w = 0.054, and for Br3InCH2Sb(C6H5)(3 ), a = 15.439(6) Angstrom, b = 22.016(4) c = 13.138(5) Angstrom; space grou p Pbca, Z = 8, R = 0.062, R-w = 0.049. Results are also reported for I3InCH 2As(C6H5)(3) (cell constants a = 12.0122(2), b = 15.8526(3), c = 13.4180(3) Angstrom, beta = 109.933(1)degrees; space group P2(1/n), Z = 4, R = 0.0481 , R-w = 0.0431) and Br3InCH2N(C2H5), (a = 7.362(2), b = 14.700(2), c = 13.0 49(1) Angstrom, beta = 98.90(1)degrees; space group P2(1/n), Z = 4, R = 0.0 418, R-w = 0.0368). The structural results are compared with those for othe r organoindium ylids with the same general structure Br3InCH2L (L = P(C6H5) (3); 1,1,3,3,-tetramethyl-2-thiourea; N,N,N',N'-tetramethylethanediamine). Semi-empirical quantum mechanical calculations, using the PM3 method, were carried out on the series Br3InCH2E(C6H5)(3) (E = P, As, Sb), and the calcu lated structural parameters are compared with the values determined by X-ra y crystallography. The presence of an ylid ligand H2Cdelta--(delta+) E(C6H5 )(3) in the organoindium compounds is confirmed. Mass spectra and thermogra vimetric analysis strongly suggest that the thermal decomposition of the co mpounds occurs via fission of the indium-carbon bond, leading to the corres ponding ylid, which can be trapped by reacting the X3InCH2E(C6H5)(3) compou nds with HBr to produce the onium derivative [CH3E(C6H5)(3)](+) [InX4](-) ( E = P, As; X = Br, I). (C) 2000 Elsevier Science S.A. All rights reserved.