Aspects of Ligand and Electron-Acceptor Dependence of Magnetic Field Effects on Net Electron Transfer Efficiencies in Photooxidation of Ru(II)-trisbipyridyl Type Complexes

The heteroleptic series of Ru(bpY)n(dce)~:::n,with bpy = 2,2'-bipyridine, and dce = 4,4'diethoxycarbonyl-2,2'-bipyridine, has been investigated for the kinetic parameters of photo electron transfer, and for the magnetic field dependence of the net electron transfer efficiency (rIce) in photooxidations with methylviologen and propylviologen sulfonate (the latter only in the case n = 3) using ns-laser-flash spectroscopy and stationary illumination methods. Whereas the electric charge of the electron acceptor had no influence on the magnetic field effect on !Jceo the variation of ligands was found to result in a strictly linear (with n) increase of the magnetic field effect on kbet , the effective rate constant ofbackward electron transfer in the primary redox pair. The physical implications of these observations with respect to a previously developed magnetokinetic model are discussed.