Oxidation states cobalt tris complexes

Cobalt dithiocarbamate complexes are now known in oxidation states - -1 to +4, the first reported examples being the tris(dithiocarbamate) complexes [Co(S2CNR2)3], which were prepared in 1920 (1388). 

Chemical or photochemical oxidation of a nucleic acid is accomplished very efficiently by a variety of metal complexes. In the presence of hydrogen peroxide and thiol, bis(phenanthroline) cuprous ion very efficiently cleaves DNA (26). Tris(phenanthroline) complexes of cobalt(IIl) or rhodium(III) promote redox reactions in their excited states (27, 28). These photoac-tivated probes bind to the DNA helix in a fashion comparable to the spectroscopic probes described above and then, upon photoactivation, promote DNA strand cleavage. 

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