Reversible Dioxygen Binding to Co(II) Complexes with Noninnocent Ligands.

A series of mononuclear Co(II) complexes with noninnocent (redox-active) ligands are prepared that exhibit metal-ligand cooperativity during the reversible binding of O. The complexes have the general formula, [Co()(Tp)] (R = Me, Ph), where is a bidentate -aminothiophenolate and Tp is a hydrotris(pyrazol-1-yl)borate scorpionate with R-substituents at the 3- and 5-positions. Exposure to O at room temperature results in one-electron oxidation and deprotonation of .