Stable cyclopropenylvinyl ligands via insertion into a transient cyclopropenyl metal bond

Abstract

Treatment of the rhodium pincer complexes [RhCl(RPm)] (RPm = N,N′-bis(di-R-phosphinomethyl)perimidinylidene, R = Ph, Cy) with triphenylcyclopropenium hexafluorophosphate affords rhodacyclobutadiene complexes. These in turn react with activated alkynes (RCCCO₂Me, R = H, CO₂Me) to afford unusually stable cyclopropenylvinyls, implicating the intermediacy of σ-cyclopropenyl isomers. In contrast, treatment of [RhCl{py(NHP^tBu₂)₂-2,6}] with the same reagent instead results in double functionalisation (S_EAr) at the pincer backbone.