Synthesis of Diruthenium μ‑Chloromethylidyne Complex: C–C Bond Formation at the Bridging Carbon Atom via the Reduction of a μ‑Chloromethylidyne Ligand

The μ-chloromethylidyne complex, [(Cp*RuCl)2(μ-CCl)­(μ-Cl)] (2) (Cp* = η5-C5Me5), was prepared by the reaction of a triruthenium pentahydrido complex, [{Cp*Ru­(μ-H)}3(μ3-H)2] (1), with CCl4. The reaction of 2 with Zn in an ethylene atmosphere resulted in the formation of a μ-ethylidyne-μ-propylidyne complex, [(Cp*Ru)2(μ-CMe)­(μ-CEt)­(μ-ZnCl2)] (3). Formation of a μ-propylidyne ligand was unambiguously confirmed by X-ray diffraction, and the μ-propylidyne ligand was probably formed via the migration of an ethyl group derived from ethylene to a transiently generated μ-carbido ligand. A linear μ-carbido complex, [(Cp*Ru)2(μ-C)­{μ-η1:η2-ZnCl­(−OC­(OEt)­CHCHC­(OEt)­O−}2] (4), was prepared by the reaction of 2 with diethyl maleate in the presence of Zn. Two ZnCl moieties were chelated by diethyl maleate, and the Zn-maleate moieties bridged the RuCRu skeleton in a head-to-tail fashion.