Two types of dicarbonykuthenium(II) complexes bearing the unsymmetrical bidentate ligand 2-(2-pyridy1)-1,8-naphthyridine were prepared. The complexes undergo irreversible ligand-localized one-electron reduction to form redox-induced metal-lacyclization between the bidentate naphthyridyl ligand and the terminal CO ligand located nearby. Chemical reductions using NaBH4 were also performed to isolate the reaction products; the formation of both a metal hydride (Ru-H) and an organo hydride (C-H) species was confirmed.