CO2 to CO: Photo‐ and electrocatalytic conversion based on Re(I) Bis‐Arene Frameworks: synergisms between catalytic subunits

Abstract

Reduction of CO2 to CO and H2O is a two electron/two proton process. For this process, multinuclear complexes offer advantages by concentrating reduction equivalents more efficiently than mononuclear systems. We present novel complexes with [Re(η6‐C6H6)2]+ as scaffold conjugated to one or two catalytically active [Ru(dmbpy)(CO)2Cl2] subunits (dmbpy=5,5′‐dimethyl‐2,2′‐bipyridine). The [Re(η6‐C6H6)2]+ scaffold was chosen due to its very high photo‐ and chemical stability, as well as the multiple degrees of freedom it offers for any conjugated functionalities. High efficiency and selectivity for the reduction of CO2 to CO (over H2 or HCOOH) is reported. TONs and TOFs were found to be comparable or higher than for the catalyst subunit without the rhenium framework. Cooperativity in photo‐ and electrocatalysis is observed for the complex comprising two catalytic subunits. The synergistic communication between the two catalytic subunits is responsible for the observed enhancement in both photo‐ and electrocatalytic performance. Confirmation of electronic communication between the two [Ru(dmbpy)(CO)2Cl2] subunits as well as the elucidation of a possible mechanism was supported by electrochemistry, IR‐spectroelectrochemistry and DFT studies.