Lithiation of diynyl-ruthenium complexes: Routes to novel metallated functional diynes

Conditions for the efficient lithiation of the diynyl group in complexes Ru(CCCCH)(PP)Cp′ (PP)Cp′ = (dppe)Cp* 1, (PPh₃)₂Cp 2] have been investigated. Addition of two equiv. LiBu to the diynyl complexes in thf solution at −78°C effects rapid conversion to putative Ru(CCCCLi)(PP)Cp′. Assays using subsequent reactions with either SiClMe₃ or AuCl(PPh₃) indicate that up to 80% conversion can be achieved. Reactions of the lithiated species with organic electrophiles MeI, MeC(O)Cl, PhC(O)Cl, ClC(O)OMe, PhCHO, Ph₂CO] and metal-containing substrates MClPh₃ (M = Ge, Sn), trans-RhCl(CO)(PPh₃)₂, cis-PtCl₂(PPh₃)₂, CuCl(PPh₃), (AuCl)₂(μ-dppm)] proceed to give functionalised diynyl complexes or bimetallic derivatives which are accessible only with difficulty or not at all from the parent diynes. Single-crystal X-ray diffraction molecular structures of Ru(CCCCR)(dppe)Cp* (R = Me, GePh₃) are reported: there is significantly greater delocalisation along the Ru-C₄-R chain in the GePh₃ derivative.