Syntheses of new ruthenium carbonyl terpyridine o-phenylene complexes: strong interaction between carbonyl and o-phenylene ligands

Ruthenium carbonyl o-phenylene complexes, Ru(CO)(3,6-Bu2seq)(trpy)]PF6 ([1]PF6) and [Ru(CO)(o-monothiocat)(trpy)] (2), were prepared by the reaction of [Ru(CO)Cl2(trpy)] with the corresponding o-phenylenes in 2-methoxyethanol. X-ray crystallographic study of [1]BF4 indicated that the ruthenium center is coordinated by carbonyl, three nitrogens of trpy and two oxygens of 3,6-Bu2seq. ESR of [1]PF6 and 2 indicated that the electronic structures of ruthenium-o-phenylene unit of the complexes have Ru(II)-3,6-Bu2seq and Ru(II)-o-monothiocat forms, respectively. Significant differences in the redox behavior and the spectroscopical properties between [1]PF6 and 2 and [RuCl(3,5-Bu2seq)(trpy)] were ascribed to the strong interaction between o-phenylene and carbonyl ligands through Ru(II).