Paddlewheel Dicobalt Complexes with Metal Centers Having Various Oxidation States

Herein, we report the characterization of a family of two bidentate silyldiamide-stabilized digonal lantern dinuclear cobalt complexes [Co₂{μ-κ²-Ph₂Si(N-2,6-^<i>i</i>Pr₂C₆H₃)₂}]^<i>x</i>- (<i>x</i> = 0 (<b>1</b>), 1 (<b>2</b>), and 2 (<b>3</b>)) in order to study the interaction between two Co atoms. Complexes <b>1</b>-<b>3</b> can be interconverted by redox reactions. The Co₂-containing fragments in <b>1</b>-<b>3</b> are almost isostructural due to the steric congestion of the supporting ligands, leading to their high rigidity. In contrast to the reported shortest Co^I-Co^I bonds in similar digonal dicobalt complexes, the homounivalent dicobalt compound <b>3</b> instead has the longest Co-Co bond length among <b>1</b>-<b>3</b>. The calculated Co-Co bond orders are in agreement with the experimental data, with the order decreasing from 2 (<b>1</b>) to 1 (<b>3</b>) as the valence of the central Co₂ unit decreases.