Even though the catalyst is well-known since it is published, we have found that the TONs and TOFs were strongly influenced by the concentration of CO2 and DMF, and under the scCO2 conditions, the TON of 62 is >5� greater than under biphasic low-pressure conditions, and the TOFinit of 56 h-1 (up to a maximum of 72) represents a 2.3� improvement in the rate of CO formation. In this presentation, to explore the more effective reaction system of photoreduction of CO2 to CO under high pressure, single-phase scCO2 conditions in the presence of DMF and TEOA, we have investigated substituent effects of fac-ReCl(bpy)(CO)3 as a catalyst. To study the effects on bipyridine lingand, we have synthesized over 20 series Re catalysts with different substituents on the ligand. Table 1 shows the TON values and catalyst life times at selected ligands. As shown in the table, TON is drastically decreased by introducing methoxy group on 4 and 4' positions of bipyridine. Otherwise phenyl groups on 4 and 4' positions improve TON compared to that of alkoxy groups. The halogenes further improves the TON values otherwise the catalyst life time is not improved. When biquniline is used, the lifetime is extednded up to 180 min, but the TON is very small. In the presentation, we would like to discuss about the substituents effects with further data to develop the better reaction system.

Substituent effects of the fac-ReCl(bpy)(CO)3 in the photo reduction of CO2 to CO under supercritical CO2 conditions

248th National Meeting (2014)

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