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). According to DFT-calculations, the rearrangement could be attained to the Triangular Face Rotation (TFR) 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-X2-8-SMe2-1,2,8-IrC2B9H10]2 (4a-c, X = Cl (a), Br (b), I (c)). Bromide 4b reacts with Tl[Tl(η-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 latter compound is accompanied by demethylation of the SMe2 substituent. Structures of 2, 3, 5 and 6 were determined by X-ray diffraction. Iridacarboranes 4b and [1,1-Br2-4-SMe2-1,2,3-IrC2B9H10]2 (7) catalyze the dimerization of diphenylacetylene giving 1,2,3-triphenylnaphthalene in 20-24% yields. 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%).