A computational study of a cyano-bridged dinuclear ruthenium complex containing the non-innocent methylpyrazinium ligand
The properties of a series of complexes trans-[LRu(NH3)4-NC-Ru(NH3)4(methylpyrazinium)]n+ where L is an anion (Cl, F, CN, OH) or neutral ligand (CO, H2O, pyridine, CH3NO2) were analyzed using density functional theory. The objective was to probe the change in electronic coupling between the two ruthenium atoms and between ruthenium and the non-innocent methylpyrazinium ligand as L is varied. Molecular orbital coefficients and optical spectra were derived. The electronic interactions involved are seen to be quite sensitive to the charge on the ruthenium to which the ligand L is attached as L is varied. Exchange (K) and Coulomb (J) energies are also calculated, using the INDO/S model, for the various metal-to-ligand charge-transfer transitions. K correlates well with the energy and intensity of the transitions and specifically with the variation in delocalization induced by variation of L.Key words: DFT, ruthenium, non-innocent ligand, methylpyrazinium, ZINDO.