Variational Approach to Electron Transfer in Bridged Diruthenium Complexes

In this work, we address the energetics of electron transfer in bridged diruthenium complexes from a theoretical and numerical perspective. The electronic structure of the bridged complexes is described by a tight-bindingHamiltonian, which is extended by an on-site spin pairing energy. The coupling of the system to a polarizable solvent is taken into account by a nonretarded reaction field. The resulting nonlinear Hamiltonian is solved within the Hartree-Fock mean-field approximation, and the emerging potential energy surface is analysed using Marcus' theory of electron transfer reactions. For the systems studied here, the charge transfer rate depends on the chemical nature of the bridge rather than the intermetal distance. We discuss the special nature of the Creutz-Taube cation, which is on the border of charge delocalization.