Reactions of three-electron ση2-prop-2-ynyl ligands formed by deprotonation of four-electron η2-alkyne molybdenum complexes

Abstract

Reaction of [MoBr(η²-MeC₂R)₂(η-C₅H₅)](R = Me, or Ph) with Li[N(SiMe3)2] leads to a dehydrohalogenation reaction and unexpected formation or the three-electron σ,η²-prop-2-ynyl complexes [Mo(σ,η²-CH₂C₂R)(η²-MeC₂R)(η-C₅H₅)]; treatment of these reactive molcules with the proton source CF₃CO₂H affords the bis-alkyne complexes [Mo(O₂CCF₃)(η²-MeC₂R)₂(η²-MeC₂R)₂(η-C₅H₅)], whereas reaction with carbon monoxide leads to a novel carbon–carbon bone forming reaction, and formation of the X-ray crystallographically identified complex [Mo{η²,η³-[graphic omitted]–CH₂}(CO)(η-C₅H₅)].