Mononuclear ruthenium-water oxidation catalysts: discerning between electronic and hydrogen-bonding effects.

ABSTRACT

New mononuculear complexes of the general formula [Ru(trpy)(n,n'-F2-bpy)X](m+) [n = n' = 5, X = Cl (3(+)) and H2O (5(2+)); n = n' = 6, X = Cl (4(+)) and H2O (6(2+)); trpy is 2,2'6'2"-terpyridine] have been prepared and thoroughly characterized. The 5,5'- and 6,6'-F2-bpy ligands allow one to exert a remote electronic perturbation to the ruthenium metal center, which affects the combination of species involved in the catalytic cycle. Additionally, 6,6'-F2-bpy also allows through-space interaction with the Ru-O moiety of the complex via hydrogen interaction, which also affects the stability of the different species involved in the catalytic cycle. The combination of both effects has a strong impact on the kinetics of the catalytic process, as observed through manometric monitoring.