Anodic oxidation of metal carbonyls in trifluoroacetic acid; stabilities of some 17-electron cations

The electrochemical oxidation of some metal carbonyls at a Pt electrode in trifluoroacetic acid–tetrabutylammonium tetrafluoroborate (0.2 mol dm–3) is reported. It is shown that the 17-electron cations [Cr(CO)6]+, [Fe(CO)5]+, [Mn(η-C5H5)(CO)3]+ and [MnBr(CO)5]+ may be prepared form their parent 18-electron carbonyls and that each has some stability in this medium. The complex [Mn2(CO)10] undergoes a two-electron oxidation and the product is [Mn(CO)5(O2CCF3)]. This latter product can also be prepared by direct air oxidation.