Communication of metal ions in the dinuclear ruthenium complexes containing 4,4′-bipyridine, 1,4-diisocyanobenzene, and pyrazine bridging ligands: Synthesis, characterization and structure determination

Reaction of [Ru(2,2′-bipyridine)(2,2′:6′,2″-terpyridine)Cl]PF6 (abbreviated to [Ru(bipy)(terpy)Cl]PF6) with 0.5 equiv of the bidentate ligand L produces the dinuclear complexes [{Ru(bipy)(terpy)}2(μ-L)](PF6)4 (L = 4,4′-bipyridine 1, 1,4-diisocyanobenzene 2 and pyrazine 3) in moderate yields. Treating [Ru(bipy)(terpy)Cl]PF6 with equal molar of 1,4-diisocyanobenzene affords [Ru(bipy)(terpy)(CNC6H4NC)](PF6)2 (2a). These new complexes have been characterized by mass, NMR, and UV–Vis spectroscopy, and the structures of 1–3 determined by an X-ray diffraction study. Cyclic voltammetric studies suggest that metal communication between the two ruthenium ions increases from 1 to 2 to 3.