Synthesis, Structures and Fluxional Behavior of Ruthenium(II) Complexes Bearing a Bidentate 1,8-Naphthyridine Ligand

The ruthenium complexes bearing 1,8-naphthyridine (napy) and terpyridine analogous (N,C,N)-tridentate ligands were synthesized and characterized. The reaction of [RuCl2(napy-(kappa)^2N,Nʹ)(dmso)2] with 2 equiv of AgPF6 and subsequent addition of LH and CO gave [RuL(napy-(kappa)^2N,Nʹ)(CO)](PF6)n (6a: L = N-methyl-3,5-di(2pyridyl)-4-pyridyl, n = 2; 6b: L = 2,6-di(2-pyridyl)phenyl, n = 1) via [RuL(napy-(kappa)^2N,Nʹ)(dmso)](PF6)n (5a: L = N-methyl-3,5-di(2-pyridyl)-4-pyridyl, n = 2; 5b: L = 2,6-di(2-pyridyl)phenyl, n = 1). The crystal structures of 5a and 6a show distorted octahedral coordination with the tridentate (N,C,N)-ligand as mer-fashion, two nitrogens of bidentate napy and the sulfur of DMSO (5a) or the carbon of the CO ligand (6a). Detailed experiments for irradiation and variable-temperature 1H NMR studies reveal a fluxional process of the chelated napy ligand in solution.