Iridium Complexes with a Naphthyridine-Based Si,N‑Ligand: Synthesis and Catalytic Activity toward Olefin Hydrogenation

16-Electron iridium complexes bearing a silyl-1,8-naphthyridine-based bidentate ligand (napySi), Ir(κ2Si,N-napySi)(H)(coe)X [X = Cl (1) and Me (2)], were synthesized and characterized. Single-crystal X-ray diffraction studies revealed that both 1 and 2 have a square-pyramidal geometry with the silyl moiety occupying the apical position and the nitrogen lone pair of napySi adjacent to the vacant metal center. Methyl complex 2 catalyzed hydrogenation of alkenes with H2 (1 atm) at room temperature. This hydrogenation proceeded significantly faster than that catalyzed by a related complex with no nitrogen lone pair adjacent to the metal. Based on this result, we suggest a possible catalytic cycle including cooperative activation of H2 between the nitrogen lone pair and the metal center for this system.