14591-57-2Relevant academic research and scientific papers
Electrochemical reduction and oxidation of cobalt(III) dithiocarbamates
Bond,Hendrickson,Martin,Moir,Page
, p. 3440 - 3446 (2008/10/08)
The literature describing the oxidation and reduction of cobalt(III) dithiocarbamate complexes, Co(R2dtc)3, and the chemistry of formally cobalt(II) and cobalt(IV) dithiocarbamate complexes contains substantially conflicting data. An extensive investigation of the electrochemical reduction and oxidation of Co(R2dtc)3 leads to the following conclusions: (i) In CH2Cl2 and for R = cyclohexyl, controlled-potential oxidative electrolysis at platinum electrodes produces a complex that appears to be the elusive cobalt(IV) complex [Co(R2dtc)3]+ (or possibly [Co2(R2dtc)6]2+ or related species). In acetone, electrolysis of the cyclohexyl derivative at platinum electrodes produces the cobalt(III) dimer [Co2(R2dtc)5]+. At mercury electrodes, the oxidation process proceeds via a pathway different from that at platinum electrodes and [Co2(R2dtc)5]+ and mercury dithiocarbamate complexes are obtained as products. (ii) On the electrochemical time scale, oxidation of most Co(R2dtc)3 complexes is chemically reversible in CH2Cl2 but not always in acetone or acetonitrile, implying that [Co(R2dtc)3]+ has a finite stability for many complexes, at least in CH2Cl2. However, with the exception of R = cyclohexyl, noted above, this complex is not obtained from electrolysis experiments. While [Co2(R2dtc)5]+ rather than [Co(R2dtc)3]+ may be isolated from the oxidized solution in CH2Cl2, it is not formed at the electrode surface and results from a series of chemical reactions subsequent to electron transfer. (iii) Electrochemical reduction of Co(R2dtc)3 is extremely complex and depends markedly on the nature of the R group, solvent, and electrode. Formation of [Co(R2dtc)3]- is favored by solvents such as acetone or acetonitrile and is stabilized by adsorption on mercury electrodes. Thus, chemically reversible one-electron reduction steps are observed in some circumstances. By contrast, Co(R2dtc)2 appears to be significantly more stable in CH2Cl2 than [Co(R2dtc)3]-, and chemically irreversible reduction is generally associated with this solvent at platinum electrodes. The nature of further electrochemical reduction steps, which ultimately produce cobalt metal and dissociated ligands, also depends on numerous variables.
