STANDARD ELECTRODE-REACTION RATES OF BIS(BIPHENYL)CHROMIUM(I) IN N,N-DIMETHYLFORMAMIDE

The electrode kinetics for the one electron reduction of bis(biphenyl) chromium(I) tetraphenylborate were studied in N,N-dimethylformamide as a function of the concentrations of the supporting electrolyte tetrab utylammonium perchlorate. Cyclic voltammetry on a hemispherical mercur y ultramicroelectrode as well as a.c. polarography on the dropping mer cury electrode were employed to obtain k(s)(app) and a values. An incr ease in the standard electrode reaction rate constants with increasing concentrations of the supporting electrolyte was observed. Measuremen ts in other supporting electrolytes (sodium perchlorate, tetrabutylamm onium hexafluorophosphate and tetrabutylammonium tetraphenylborate) sh owed only minor influences of the nature of the supporting electrolyte on the kinetics of the electroreduction of bis(biphenyl)chromium(I). The observed changes in the apparent reaction rate constants are discu ssed, together with the influence of the solvents and electrolytes on the kinetic behaviour of other organometallic redox systems.