Hydrogen-Mediated Metal−Carbon to Metal−Boron Bond Conversion in Metal−Carboranyl Complexes

A hydrogen-mediated Ru−C to Ru−B bond conversion was observed experimentally and supported by the theoretical calculations. Treatment of [η5:σC-Me2C(C5H4)(C2B10H10)]Ru(COD) (1) bearing a Ru−C(cage) σ bond with PR3 in the presence of H2 gave Ru−B(cage) bonded complexes [η5:σB-Me2C(C5H4)(C2B10H10)]RuH2(PR3) (R = Cy (2), Ph (3)) (σC: Ru−C(cage) σ bond; σB: Ru−B(cage) σ bond). Complex 3 was converted to [η5:σB-Me2C(C5H4)(C2B10H10)]Ru(L2) in the presence of L2 (L2 = dppe (4), PPh3/P(OEt)3 (5), PPh3/pyridine (6)) via liberation of H2 upon heating. These complexes were fully characterized by various spectroscopic techniques, elemental analyses, and single-crystal X-ray diffraction studies. DFT calculations show that this conversion process is both kinetically and thermodynamically favorable and requires involvement of a hydride ligand.