Abstract
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.