Controlled Synthesis of Dinuclear Acetylide-Bridged Ruthenium Complexes

A series of dinuclear and trinuclear, acetylide-bridged ruthenium(II) complexes was synthesized by the condensation of terminal acetylenes with methyl ruthenium complexes. Dinuclear ruthenium(II) complexes trans,trans-(RCC)Ru(dmpe)2(μ-CCC6H4CC)Ru(CCR′)(dmpe)2 (R = R′ = Ph; R = R′ = tBu; R = Ph, R′ = tBu; R = tBu, R′ = 3,5-tBu2-C6H3) were synthesized by the reaction of trans-(CH3)Ru(dmpe)2(CCR) with the unsymmetrical bis(acetylido)ruthenium(II) complex trans-(R′CC)Ru(dmpe)2(CCC6H4CCH) at ambient temperature and pressure. These complexes were fully characterized by NMR spectroscopy, and trans,trans-(tBuCC)Ru(dmpe)2(μ-CCC6H4CC)Ru(dmpe)2(CCtBu) was characterized crystallographically. The symmetrical trinuclear ruthenium(II) complexes trans,trans,trans-(RCC)Ru(dmpe)2(μ-CCC6H4CC)Ru(depe)2(μ-CCC6H4CC)-Ru(dmpe)2(CCR) (R = Ph, tBu, SiMe3) were also prepared and characterized, and the redox behavior of a subset of the complexes was studied using cyclic voltammetry.