Electrochemistry of the pyrazolate-bridged dirhodium(I) complex Rh2(CO)2(PPh3)2(μ-3,5-Me2pz)2

The dirhodium(I) complex Rh2(CO)2(PPh3)2(mu-3,5-Me2pz)2 undergoes two consecutive oxidation processes at a platinum electrode in dichloromethane. The first oxidation gives the corresponding cationic species, [Rh2(CO)2(PPh3)2(mu-3,5-Me2pz)2]+, as inferred from the electrochemical (voltammetric and coulometric) and spectroelectrochemical data and from spectroscopic (IR, ESR and visible) examination of the oxidized product. The more anodic process involves poisoning adsorptions on the electrode surface, which rules out any effective study. Suggestions concerning the electronic charge distribution inside the monocationic compound are advanced on the basis of the voltammetric and ESR data.