The Electronic States of Rhenium Bipyridyl Electrocatalysts for CO₂ Reduction as Revealed by X‐ray Absorption Spectroscopy and Computational Quantum Chemistry

Where are the electrons that allow a highly reduced rhenium bipyridyl catalyst to attack CO2, but not H+? XAS and computational quantum chemistry indicate that the negative charge in [Re(bpy)(CO)3]− and [Re(bpy-tBu)(CO)3]− is not stored in a localized Re 5d state, but rather in the bipyridine ligand . The active states of this family of catalysts possess formally Re0 metal centers with singly reduced bipyridine ligands.