Synthesis and characterization of half-sandwich Rh, Ir complexes containing mono-thiolate-ortho-carborane ligand

Two binuclear complexes [Cp∗M(Cl)CarbS]2 (Cp∗ = η5-C5Me5, M = Rh (1a), CarbS = SC2(H)B10H10, Ir (1b)) were synthesized by the reaction of LiCarbS with the dimeric metal complexes [Cp∗MCl(μ-Cl)]2 (M = Rh, Ir). Four mononuclear complexes Cp∗M(Cl)(L)CarbS (L = BunPPh2, M = Rh (2a), Ir (2b); L = PPh3, M = Rh (4a), Ir (4b)) were synthesized by reactions of 1a or 1b with L (L = BunPPh2 (2); PPh3 (4)) in moderate yields, respectively. Complexes 3a, 3b, 5a, 5b were obtained by treatment of 2a, 2b, 4a, 4b with AgPF6 in high yields, respectively. All of these compounds were fully characterized by IR, NMR, and elemental analysis, and the crystal structures of 1a, 1b, 2a, 2b, 4a, 4b were also confirmed by X-ray crystallography. Their structures showed 3a, 3b and 5a, 5b could be expected as good candidates for heterolytic dihydrogen activation. Preliminary experiments on the dihydrogen activation driven by these half-sandwich Rh, Ir complexes were done under mild conditions.