Coordination and Electrochemical Switching on Paddle-Wheel Complexes Containing an As-Ru or a Sb-Ru Axis.

Inspired by the known complex [PhP(μ-PyO)4Ru(CO)] (PyO = 2-pyridyloxy), the family of group 15 paddle-wheel complexes has been expanded to [PhPn(μ-PyO)4Ru(L)] (Pn = P, As, Sb; L = NCMe, CO). Solvent-dependent reversible switching between [PhAs(μ-PyO)4Ru(NCMe)] and [PhAs(μ-PyO)3Ru(κ2-PyO)] was detected. Electrochemical investigations of the [PhPn(μ-PyO)4Ru(L)] complexes showed reversible oxidation of the complexes with L = NCMe and back-formation of the complexes with L = NCMe upon oxidation of the complexes with L = CO in NCMe. In the series of [PhPn(μ-PyO)4Ru(L)] complexes, the Pn→Ru bonding mode is shifted from L-type Pn to X-type upon going from Pn = P and As to Pn = Sb, resulting in a pronounced electron-rich Ru site in the latter case. The easily accessible complex [PhSb(μ-PyO)4RuCl] exhibits reversible electrochemical and coordinative exchange with its reduced analogue [PhSb(μ-PyO)4Ru(NCMe)] under retention of the paddle-wheel motif and Sb-Ru bond properties.