Heterobimetallic Polyhydride Complex, Cp*Ru(μ-H)₄OsCp* (Cp* = η⁵-C₅Me₅). Synthesis and Reaction with Ethylene

A novel heterobimetallic polyhydride complex containing ruthenium and osmium, Cp*Ru(μ-H)4OsCp* (1; Cp* = η5-C5Me5), was synthesized by the reaction of (Cp*RuCl)4 with an anionic hydrido complex, Li[Cp*OsH4]. Complex 1 was also obtained from the reaction of [Cp*Ru(OMe)]2 with Cp*OsH5. A single-crystal X-ray diffraction study established the dinuclear structure of 1, in which four hydride ligands bridged the ruthenium and the osmium atoms. The reaction of 1 with ethylene exclusively produces a divinyl-ethylene complex, Cp*Os(η2-CH2CH2)(μ-η1:η2-CHCH2)2RuCp* (3a), in which two vinyl ligands are σ-bonded to the osmium atom and π-bonded to the ruthenium atom. Thermolysis of 3a generates an ethylidyne complex, Cp*Ru(μ-CCH3)2OsCp* (4), together with liberation of ethylene. The molecular structures of 3a and 4 are determined by X-ray studies.