{RuNO}(6)vs. co-ligand oxidation: two non-innocent groups in one ruthenium nitrosyl complex.

Recently, a new {RuNO}(6) complex, Ru(L)(PPh3)(NO)(Cl) (where L = 1-phenyl-1-(pyridin-2-yl)-2-(pyridin-2-ylmethylene)hydrazine), was reported which exhibits a one-electron quasireversible oxidation. The oxidized product, Ru(L)(PPh3)(NO)(Cl), was isolated and proposed to be a highly unusual {RuNO}(5) complex. In this paper, we investigate the electronic structure of both of these ruthenium complexes by DFT calculations and find that the oxidized species is best described as a {RuNO}(6) complex with a co-ligand radical. Ru(L)(PPh3)(NO)(Cl) is therefore oxidized to Ru(L(+˙))(PPh3)(NO)(Cl), i.e. this is an interesting example of a complex with two non-innocent ligands simultaneously bound to a ruthenium center.