A Stable Aminyl Radical Coordinated to Cobalt.

A family of cobalt complexes bearing the trop2 NH [bis(5-H-dibenzo[a,d]cyclohepten-5-yl)-amine] and 2,2'-bpy (2,2'-bipyridine) chelate ligands were prepared and fully characterized. The compounds [Co(trop2 N)(bpy)], [Co(trop2 NH)(bpy)]+ , and [Co(trop2 N)(bpy)]+ are cobalt complexes interrelated by one-electron redox processes and/or proton transfer. Two limiting resonance structures can be used to describe the paramagnetic complex [Co(trop2 N)(bpy)]+ : [CoII (trop2 N- )(bpy)]+ (CoII amido) and [CoI (trop2 N⋅ )(bpy)]+ (CoI -aminyl radical). Structural data, DFT calculations, and reactivity toward H-abstraction indicate a slightly higher contribution of the aminyl radical form to the ground state of [Co(trop2 N)(bpy)]+ . The results described here complete the series of Group 9 metal aminyl radical complexes bearing the diolefin amine ligand trop2 NH.