Synthesis and Reactivity of Labile MeCN Adducts of Diruthenium Bis(μ-methylene) Species, Cp₂Ru₂(μ-CH₂)₂(CO)_n(MeCN)_2-n (n = 1, 2):  Reaction with H Sources, H−X (X = SiR₃, SnR₃, H), and C−C Coupling with Alkynes and Diazoalkanes

Irradiation of the diruthenium bis(μ-methylene) complex Cp₂Ru₂(μ-CH₂)₂(CO)₂ (1), in acetonitrile gives the mono- and bis(acetonitrile) species Cp₂Ru₂(μ-CH₂)₂(CO)(MeCN) (2) and Cp₂Ru₂(μ-CH₂)₂(MeCN)₂ (3) in a successive manner. The mono-MeCN species 2 has been characterized spectroscopically and crystallographically, but the bis-MeCN species 3 is too unstable to be fully characterized. Reaction of 2 with hydrosilanes and hydrostannanes results in oxidative addition of the H−Si and H−Sn bond to give hydrido−μ-methylene complexes, Cp₂Ru₂(μ-CH₂)₂(H)(mR₃)(CO) (m = Si (7), Sn (9)). In the case of the reactions with dihydrosilane, phenylsilane, and triphenylstannane, one of the two methylene bridges is eliminated as methane (and benzene from phenylsilane) to give μ-methylene−μ-silylene complexes, Cp₂Ru₂(μ-CH₂)(μ-SiR₂)(H)(SiR₃)(CO) (8), and a tristannyl−μ-methylene complex, Cp₂Ru₂(μ-CH₂)(μ-H)(SnPh₃)₃(CO) (10). Treatment of 2 with alkynes (R¹C⋮CR²) and diphenyldiazomethane produces the metallacyclic products Cp₂Ru₂[μ-η³-C(R¹)C(R²)CH₂](μ-CH₂)(CO) (12), and the vinylidene complex Cp₂Ru₂(μ-CCPh₂)(μ-η³-CPh₂) (14), respectively, via C−C coupling. In contrast to 2, corresponding reactions of the bis-MeCN species 3 are sluggish and only the simple MeCN replacement reaction proceeds in a selective manner.