Rhenium Complexes with a Pyridinyl-Naphthyridine Ligand: Synthesis, Characterization, and Catalytic Activity



Treatment of [Re2(CO)8(CH3CN)2] with 2,7-dipyridinyl-1,8-naphthyridine (bpnp) thermally provided mononuclear [(N,N′-bpnp)Re(CO)3Cl] (1). Further reaction of 1 with rhenium carbonyls yielded ortho-metallation dinuclear rhenium complex 2. Both complexes were characterized by spectroscopic analyses and single-crystal X-ray determination. Complex 1 also reacted with [PdMeCl(COD)] and [Ir(COD)Cl]2 by means of ortho-metallation to yield the corresponding heterodinuclear species. Complex 2 appears to be an excellent precatalyst to promote the insertion of terminal alkynes into acetoacetates, which subsequently undergo cyclization to form 2-pyranones.