Mononuclear Ruthenium–Water Oxidation Catalysts: Discerning between Electronic and Hydrogen-Bonding Effects

New
mononuculear complexes of the general formula [Ru­(trpy)­(n,n′-F2-bpy)­X]m+ [n = n′ = 5, X =
Cl (3+) and H2O (52+); n = n′ = 6, X
= Cl (4+) and H2O (62+); 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.