Electroreduction of carbon dioxide catalyzed by iron-sulfur clusters (Fe/sub 4/S/sub 4/(SR)/sub 4/)/sup 2 -/

The use of the tetranuclear iron-sulfur cluster (Fe/sub 4/S/sub 4/(SR))/sup 2 -/ (where R = CH/sub 2/C/sub 6/H/sub 5/ or C/sub 6/H/sub 5/) for the catalysis of the electroreduction of CO/sub 2/ in nonaqueous dimethylformamide (DMF) solution is reported. Controlled-potential electrolyses were performed in a CO/sub 2/-saturated 0.1M tetrabutylammonium tetrafluoroborate/DMF solution on Hg pool cathode referred to SCE at room temperature. Since the product current efficiency of 50% corresponded to 15 electrons per catalyst molecule, the reduction evidentally preceeded catalytically. The view that CO/sub 2//sup -/ would be generated through the electron transfer from the reduced clusters to CO/sub 2/ in the bulk solution, not on the electrode, and consequently undergo the protoniation rather than the self-coupling was supported by the fact that formate was obtained preferentially in the presence of the cluster. (BLM)