Ru-NO and Ru-NO2 bonding linkage isomerism in cis-[Ru(NO)(NO)(bpy)2](2+/+) complexes - a theoretical insight.

Ruthenium nitrosyl complexes have received considerable attention due to the fact that they are able to store, transfer and release NO in a controlled manner. It is well-known that the NO reactivity of ruthenium nitrosyl complexes can be modulated with the judicious choice of equatorial and axial ligands. In this piece of research we elucidate the nature of the Ru-NO and Ru-NO2 bonding in a cis-[Ru(NO)(NO2)(bpy)2](2+) complex energy decomposition (Su-Li EDA) and topological (e.g., QTAIM) and natural bond orbital analysis. It was observed that the strength of these bonds is directly correlated with the relative stability of isomers involved in nitro-nitrito and nitrosyl-isonitrosyl isomerism, as described previously by Coppens and Ooyama.