Trialkylstibine Complexes of Boron, Aluminum, Gallium, and Indium Trihalides: Synthesis, Properties, and Bonding

Abstract

The reaction of BX3 (X = Cl, Br, I) with SbR3 (R = Et,iPr) in anhydrous hexane or toluene produced moisture-sensitive [BX3(SbR3)], whose stability increases with halide: Cl < Br < I. Unstable [BF3(SbR3)] species were also characterized spectroscopically but lose BF3 very readily. The [MX3(SbR3)] (M = Al, Ga, In) complexes were isolated from hexane solution; the Ga and In complexes can be recrystallized unchanged from CH2Cl2, but [AlX′3(SbR3)] (X′ = Br, I) undergoes X′/Cl exchange with the solvent. The new complexes were characterized by IR and multinuclear NMR spectroscopy (1H, 13C{1H}, 11B, 27Al, 71Ga, 115In, as appropriate). X-ray crystal structures are reported for [BX3(SbR3)] (X = Br, I; R = Et, iPr; X = Cl, R = iPr), [AlI3(SbiPr3)], [GaX3(SbR3)] (X = Cl, I; R = iPr), [GaBr3(SbEt3)], and [InX3(SbR3)] (X = Cl, I; R = Et, iPr); all contain pseudotetrahedral geometries at both the group 13 and antimony atoms, and comparisons with phosphine and arsine analogues are discussed. The donor–acceptor bond lengt...