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

Abstract

Conditions for the efficient lithiation of the diynyl group in complexes Ru(C CC CH)(PP)Cp′ [(PP)Cp′ = (dppe)Cp* 1, (PPh 3) 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(C CC CLi)(PP)Cp′. Assays using subsequent reactions with either SiClMe 3 or AuCl(PPh 3) 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, Ph 2CO] and metal-containing substrates [MClPh 3 (M = Ge, Sn), trans-RhCl(CO)(PPh 3) 2, cis-PtCl 2(PPh 3) 2, CuCl(PPh 3), (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(C CC CR)(dppe)Cp* (R = Me, GePh 3) are reported: there is significantly greater delocalisation along the Ru–C 4–R chain in the GePh 3 derivative.