Synthesis of Group IV (Zr, Hf)-Group VIII (Fe, Ru) Heterobimetallic Complexes Bearing Metallocenyl Diphosphine Moieties and Their Application to Catalytic Dehydrogenation of Amine-Boranes

A series of heterobimetallic complexes, including [(MMe)-Me-1(mu-eta(1)-C5H4PEt2)(2)(MCp)-Cp-2*] (5a, M-1 = Zr, M-2 = Ru; 5b, M-1 = Hf, M-2 = Ru; 5c, M-1 = Zr, = Fe) have been prepared and characterized by X-ray analyses. Dehydrogenation of Me2NH center dot BH3 takes place in the presence of a catalytic amount of these heterobimetallic complexes. Studies on the reaction pathway of the catalytic dehydrogenation of Me2NH center dot BH3 lead us to propose a catalytic cycle where two metal centers cooperatively participate in the catalysis. Here, heterobimetallic hydride species serve as key reaction intermediates.