Synthesis and Characterization of Co Complexes Coordinated by a Tetraanionic Bis(amidateanilido) Ligand

High Resolution Image Download MS PowerPoint Slide The synthesis and characterization of a square planar Co II complex coordinated by the tetraanionic bis(amidateanilido) L 4– ligand, 1 2–, and its corresponding one-electron oxidized forms 2 –, 3, and 4 + are discussed herein. 1 2– undergoes aerobic oxidation to form 2 –, a square planar S = 1 Co III complex. This aerobic reactivity is attributed to a remarkably negative Co II /Co III potential, as observed in its cyclic voltammogram, which is among the most negative Co II /Co III couples reported. This supports the conclusion that the L 4– ligation is strongly stabilizing to the oxidized Co III center. The cyclic voltammogram of 2 – also reveals that further oxidations are possible at mild potentials. Indeed, the stoichiometric addition of a suitable chemical oxidant yields a ligand-oxidized S = 1/2 Co III complex, 3, while the addition of a further equivalent of the oxidant putatively yields 4 + . The formation of the ligand oxidized species 3 suggests that bis(amidateanilido) ligation can further behave as a redox-active ligand upon additional oxidation.