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

Conditions for the efficient lithiation of the diynyl group in complexes Ru(Ctriple bond; length of mdashCCtriple bond; length of mdashCH)(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(Ctriple bond; length of mdashCCtriple bond; length of mdashCLi)(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(Ctriple bond; length of mdashCCtriple bond; length of mdashCR)(dppe)Cp* (R = Me, GePh3) are reported: there is significantly greater delocalisation along the Ru–C4–R chain in the GePh3 derivative.