The electrochemistry of the anions, radicals, and cations CpM(CO)3-/./+ (M = Cr, Mo, W) in acetonitrile has been reinvestigated by cyclic voltammetry and digital simulation techniques. For M = Cr, oxidation of the persistent radical to the cation is directly observed at a potential ca. 1.0 V more positive than the anion oxidation potential. For M = Mo and W, oxidation of the 17-electron radicals cannot be directly observed due to the rapid follow-up dimerization reactions. Thermochemical considerations establish that the generation of the cationic products CpM-(CO)3(NCMe)+ (M = Mo, W) even at the anion oxidation potentials cannot be due to the direct oxidation of the radicals CPM(CO)3.. Digital simulation results demonstrate that the 19-electron radicals CpM(CO)3(NCMe)., which are stronger reducing agents than CpM(CO)3. by about 1.4 V, are kinetically and thermodynamically competent intermediates for the production of the cations by heterogeneous and homogeneous electron transfer. Thermochemical cycle shows that acetonitrile binds more strongly to the 16-electron cations CpM(CO)3+ than to the 17-electron radicals CpM(CO)3. by ca. 135 kJ/mol.