A Stable Aminyl Radical Coordinated to Cobalt

A family of cobalt complexes bearing the trop₂NH [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(trop₂N)(bpy)], [Co(trop₂NH)(bpy)]⁺, and [Co(trop₂N)(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(trop₂N)(bpy)]⁺: [Co^II(trop₂N⁻)(bpy)]⁺ (Co^II amido) and [Co^I(trop₂N^⋅)(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(trop₂N)(bpy)]⁺. The results described here complete the series of Group 9 metal aminyl radical complexes bearing the diolefin amine ligand trop₂NH.