Redox properties of a bis-pyridine rhenium carbonyl derived from an anthracene scaffold

We report the synthesis of a novel bis-pyridine chelate derived from an anthracene scaffold. Complexation of the N2 ligand with rhenium carbonyl affords the Re tricarbonyl bromide complex [(Anth-N2)Re(CO)3Br]. In THF solution, the title complex exhibits two quasi-reversible reductions located near − 2.1 and − 2.5 V vs Fc/Fc+, which are similar to those observed in the free Anth-N2 ligand, suggesting the non-innocent behavior of the complexed anthracene scaffold. Under CO2 atmosphere, the title complex exhibits an electrocatalytic response consistent with CO2 → CO reduction, and the presence of electrocatalytically generated CO was confirmed by bulk electrolysis. These results suggest that alternate locations of redox activity (other than at the Re metal center, pyr donors, or bpy framework) can lead to interesting electrochemical behavior.

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