Nitrogen-nitrogen bond cleavage of hydrazine derivatives by a trinuclear pentahydride complex of ruthenium, (Cp′Ru)3(μ-H)3(μ3-H)2 (Cp′ = η5-C5Me5)

The reaction of (Cp'Ru)(3)(mu-H)(3)(mu(3)-H)(2) (1) with a monosubstituted hydrazine such as methylhydrazine and phenylhydrazine results in the exclusive formation of the nonsymmetrically capped bis(mu(3)-imido) complex (Cp'Ru)(3)(mu(3)-NR)(mu(3)-NH)(mu-H) (2, R = Me; 3, R = Ph) as a result of cleavage of the nitrogen-nitrogen bond. In contrast to the reaction with monosubstituted hydrazine, the reaction of 1 with 1,2-diphenylhydrazine predominantly yields the monocapped imido complex (Cp'Ru)(3)(mu(3)-NPh)(mu-H)(3) (4), due to the steric hindrance between the Cp' groups surrounding the reaction site of 1 and the incoming bulky 1,2-diphenylhydrazine. Kinetic studies were carried out to elucidate the reaction mechanism and proved that the methylhydrazine molecule was captured by the Ru-3 site from the more nucleophilic -NHMe terminus rather than the less bulky -NH2 terminus. Molecular structures of 2-4 and (Cp'Ru)(3)(mu(3)-NH)(2)(mu-H) (6) have been determined by means of X-ray diffraction studies.