Reoxidation of transition metal substituted heteropoly blues in nonpolar solvents

CHED 1237

Arlie Rinaldi, rinaldia@canisius.edu and Mariusz Kozik, kozik@canisius.edu. Department of Chemistry and Biochemistry, Canisius College, 2001 Main Street, Buffalo, NY 14208
We showed in the past that Transition Metal Substituted Heteropolytungstates (TMSHTs) can act as electron reservoirs and that they form complexes with carbon dioxide in toluene. Therefore, they are potential catalysts for carbon dioxide reduction in nonpolar solvents. Unfortunately, the CVs of TMSHTs in nonpolar solvents are irreversible, and electrocatalytic reduction of carbon dioxide is impossible. Therefore, in 2000 we designed a new transfer procedure, in which the TMSHT is reduced in aqueous solution, the heteropoly blue is precipitated as potassium salt, washed with water, and eventually transferred into toluene in its reduced form. In this presentation we report that the reoxidation of TMSHTs in toluene solution requires protons. Without protons the decomposition of TMSHT takes place as the heteropoly blue is oxidized. On the other hand, the reoxidation is very clean in the presence of triflic acid.