The polarographic reduction of rhodium(III) complexes

The absorption spectra, and E_p (peak potentials) determined by oscillographic polarography, of five different rhodium(III) complexes have been examined. From a comparison of E_p values, d-d transitions, and charge transfer peaks proposals have been made to describe the mechanism of reduction of metal complexes. A series of ligands has been drawn up in which the value of E_p becomes more negative as one moves from left to right across the series. Further, as E_p becomes more negative in crossing the series, the reduction becomes less reversible.