A Stable Aminyl Radical Coordinated to Cobalt

Abstract A family of cobalt complexes bearing the trop 2 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(trop 2 N)(bpy)], [Co(trop 2 NH)(bpy)] + , and [Co(trop 2 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(trop 2 N)(bpy)] + : [Co II (trop 2 N − )(bpy)] + (Co II amido) and [Co I (trop 2 N ⋅ )(bpy)] + (Co I ‐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(trop 2 N)(bpy)] + . The results described here complete the series of Group 9 metal aminyl radical complexes bearing the diolefin amine ligand trop 2 NH.