Iridium Halide Complexes [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2 (X = Cl, Br, I): Synthesis, Reactivity and Catalytic Activity

The reactions of thallium salt Tl[7-SMe2-7,8-C2B9H10] with [(cod)RhCl](2) and [Cp*RuCl](4) are accompanied by room-temperature polyhedral rearrangement, giving rhoda- and ruthenacarboranes 1-cod-8-SMe2-1,2,8-RhC2B9H10 (2) and 1-Cp*-8-SMe2-1,2,8-RuC2B9H10 (3), respectively. According to DFT calculations, the rearrangement could be attributed to the triangular face rotation mechanism. The reaction of iridium derivative 1-cod-8-SMe2-1,2,8-IrC2B9H10 (1) with anhydrous hydrohalic acids HX (X = Cl, Br, I) results in the dimeric halide iridacarboranes [1,1-X-2-8-SMe2-1,2,8-IrC2B9H10](2) [4a-c; X = Cl (a), Br (b), I (c)]. Bromide 4b reacts with Tl[Tl(eta-7,8-C2B9H11)] and TlCp giving iridacarboranes 8 '-SMe2-1,1 '-Ir(2,3-C2B9H11)(2 ',8 '-C2B9H10) (5) and 1-Cp-8-SMe-1,2,8-IrC2B9H10 (6). The formation of the latter compound is accompanied by demethylation of the SMe2 substituent. The structures of 2, 3, 5 and 6 were determined by single-crystal X-ray diffraction. Iridacarboranes 4b and [1,1-Br-2-4-SMe2-1,2,3-IrC2B9H10](2) (7) catalyze the dimerization of diphenylacetylene, giving 1,2,3-triphenylnaphthalene in 20-24% yields. Compounds 4b and 7 also effectively catalyze the reductive amination reaction between aldehydes (or ketones) and primary (or secondary) amines in the presence of carbon monoxide, giving the corresponding secondary and tertiary amines in high yields (60-85%).