Synthesis and electrochemical properties of bis(bipyridine)ruthenium(II) complexes bearing pyridinyl- and pyridinylidene ligands induced by cyclometalation of N′-methylated bipyridinium analogs

Ruthenium complexes with bipyridine-analogous quaternized (N,C)-bidentate ligands [RuL(bpy)2](PF6)2 (bpy = 2,2′-bipyridine, (1), L = N′-methyl-2,4′-bipyridinium; (2), L = N′-methyl-2,3′-bipyridinium) were synthesized and characterized. The NMR and electrochemical studies indicate that the C-coordinated ring of (N,C)-ligands in 1 and 2 are linked to ruthenium(II) with pyridinium and pyridinylidene manners, respectively.