The synthesis, structure, reactivity and electrochemical properties of ruthenium complexes featuring cyanoacetylide ligands

The complex [Ru(Ctriple bond; length of mdashCCtriple bond; length of mdashN)(dppe)Cp*] (1) is readily obtained (ca. 70%) from the sequential reaction of [Ru(Cdouble bond; length as m-dashCH2)(dppe)Cp*]PF6 with nBuLi and phenyl cyanate. The complex behaves as a typical transition metal acetylide upon reaction with tetracyanoethene, affording a metallated pentacyanobutadiene. Complex 1 is a useful metalloligand, and its reactions with [W(thf)(CO)5], [RuCl(PPh3)2Cp], [RuCl(dppe)Cp*] or cis-[RuCl2(dppe)2] all afforded products featuring the M–Ctriple bond; length of mdashCCtriple bond; length of mdashN–M′ motif, for which ground state structures indicate a degree of polarisation. Electrochemical and spectroelectrochemical studies reveal moderate interactions between the metal centres in the 35-electron dications [{Cp*(dppe)Ru}(μ-Ctriple bond; length of mdashCCtriple bond; length of mdashN){RuL2Cp′}]2+ (RuL2Cp′ = Ru(PPh3)2Cp, Ru(dppe)Cp*).