Spectroelectrochemistry of anthraquinone2-CO2ReI(CO)3(2,2′-bipyridine) and related complexes

The UV–vis/IR spectroelectrochemistry of anthraquinone2-CO2ReI(CO)3(2,2′-bipyridine), AQ2-CO2ReI(CO)3(bpy), has been studied with a view to making comparisons between the photochemical and spectroelectrochemical findings. The in-situ spectra of the electrochemically reduced radical anions, AQ− and bpy−, were in excellent agreement with those obtained from the products of reductive quenching of the corresponding photochemically-excited states. Charge transfer between different groups within the molecule was investigated by looking at shifts in the stretching frequency of the CO ligand in response to redox processes on other moieties. The poor electronic conductivity of the AQCO2-group, along with the low reactivity of the MLCTRe→AQ excited state, was related to the decoupling properties of the carboxylate group.