Synthesis, Structures, and Properties of Terphenyl Diamido Complexes of Cobalt(I)

Abstract To obtain a novel type of low‐coordinate, low‐valent complexes of cobalt, we performed synthesis and reactions of cobalt complexes supported by TDA R ligands, which possess highly electron‐donating amide groups with a terphenyl framework. Synthesis of TDA R Co(I) complexes 3 and 4 was successfully achieved by reducing Co(II) precursors 1 and 2 with potassium graphite. X‐ray crystallography revealed that the cobalt centers are located close to the central aromatic rings of the TDA R ligands, and the reduction of Co(II) to Co(I) strengthens this Co−arene interaction. Reaction of the cobalt(I) complexes with pyridine or DMAP provided N‐donor ligated complexes 5 and 6 . Surprisingly, the Co−aromatic ring interactions in these complexes were found to be even stronger than those in 3 and 4 . These interactions with the aromatic rings were investigated in detail using computational methods.