Voltammetric, EPR and UV-VIS-NIR spectroscopic studies associated with thecharacterisation of electrochemically generated tris(dithiocarbamato)cobalt(IV) complexes in dichloromethane

Co-III (S2CNR2)(3) (R = Et, cyclohexyl) complexes were electrochemically ox idised by one-electron in CH2Cl2 containing Bu4NPF6 as the supporting elect rolyte. Voltammetric, EPR and UV-VIS-NIR spectroscopic data indicated that the cation complexes, [Co-IV(S2CNR2)(3)](+), formed by oxidation of the par ent Co-III compounds were stable for at least several hours at low temperat ures (T = 233 K), although instability was evident at higher temperatures a nd/or longer times. EPR spectroscopic data obtained by in situ electrogener ation of the oxidised species at low temperatures indicated that the unpair ed electron largely resided on the metal centre, thereby confirming a forma lly Co-IV state. The UV-VIS-NIR spectra of the [Co-IV (S2CNR2)(3)](+) compl exes showed a new set of low energy and moderate intensity series of bands at = 9600, 13300 and 15500 cm(-1) (epsilon = 700-1500 L cm(-1) mol(-1)) whi ch were interpreted as ligand- to-metal charge transfer excitations to the unfilled t(2g) orbital. The EPR spectra of [Co-IV(S2CNR2)(3)](+) (g(//) app roximate to 2.65 and g(perpendicular to) approximate to 1.90) required low temperatures to be detected (T < ca. 50 K) and displayed a high degree of a nisotropy consistent with a distorted octahedral structure.