Investigation of the redox properties of a Cp*Co(dithiolene) complex.: Evidence of the formation of a dimeric dicationic species:: [Cp*Co(dddt)]22+

The synthesis and the electrochemical characterization of [(eta (5)-C5Me5)Codddt] (dddt(2-) = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) (1) are described. The chemical oxidation of 1 by AgBF4 leads to the formation of a bimetallic complex, [(eta (5)-C5Me5)Codddt](2)(2+) (2), which has been characterized by X-ray crystallography. The H-1 NMR study reveals that 2 is diamagnetic, and this has been rationalized by extended Huckel calculations. The addition of trimethyl phosphite on 2 gives the paramagnetic adduct [Cp*Co(dddt){P(OMe)(3)}](.+) (4) The dissociation of 2 has also been investigated electrochemically.