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) a 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) a 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. [ABSTRACT FROM AUTHOR]