The inhibited reduction of different copper(II) complexes by phosphine oxides

The influence of hexyldiethyl- and octyldimethylphosphine oxide on the reduction of different Cu (II) complexes (ligands: oxalate, glycinate, EDTA, tartrate, malonate, citrate and alanin anion) was investigated by dc polarography. The mode of inhibition is changing as a function of the ligand. While the Cu(EDTA)]²⁻, Cu(ox)₂]²⁻, Cu(gly)₂] and Cu(ala)₂] complexes seem to cross the adsorption layer at the non-fully and fully covered electrode in the same way, all other complexes seem to change their structure before they are discharged, provided the electrode is fully covered with the surfactant. Both reaction channels were described by inhibition models, valid at the fully surfactant covered electrode.