Infrared Spectroelectrochemical Insights into Rhenium-Based Supramolecular Assemblies for Electron Storage and...

Three supramolecular square assemblies featuring Re(CO)₃Cl corners and monodentate pyridyl linkers [4,4'-bipyridine, (1a), pyrazine (2a), and 1,2-di(4-pyridyl)ethylene (3a), where a denotes the native state] were synthesized and studied via infrared spectroelectrochemistry (IR-SEC). IR-SEC revealed that the length of the bridging ligand and degree of electronic coupling in rhenium squares greatly impact the reduction pathway in both inert and CO₂ atmospheres; notably, the squares are capable of interacting with CO₂ after only ligand reduction, thereby avoiding the need for an additional reductive event to generate the rhenium anion. This mechanism differs from that of mononuclear complexes, highlighting how unique redox properties can be endowed by electronic coupling in supramolecular systems.