Structural and spectroscopic studies of reduced [Re(bpy-R)(CO)3]−1 species relevant to CO2 reduction

Spectroscopic and structural comparisons are made between the rhenium anions with bpy-R ligands spanning a wide range of electron-withdrawing and donating abilities (R = CF3, H, Me, tBu, OMe). The synthesis and characterization of the rhenium anions [Re(bpy-R)(CO)3]−1 (bpy-R = 4,4′-disubstitued-2,2′-bipyridine; R = CF3, Me, OMe) are reported. The anions [Re(bpy-R)(CO)3]−1 (R = Me and OMe) were structurally characterized. X-ray characterization of [Re(bpy-CF3)(CO)3]−1 was unsuccessful. However, the structure of a mono-reduced complex, [Re(bpy-CF3)(CO)3Cl][K(18-crown-6)] was obtained. This compound is a rare example of a structurally characterized “19e−” intermediate formed in the chemical and electrochemical reduction of a Re(bpy-R)(CO)3Cl species.

Graphical abstractSpectroscopic and structural comparisons are made between [Re(bpy-R)(CO)3]−1 anions with ligand substituents spanning a wide range of electron-withdrawing and donating abilities (R = CF3, H, Me, tBu, OMe). The anions [Re(bpy-R)(CO)3]−1 (R = Me and OMe) were structurally characterized. The structure of a mono-reduced complex, [Re(bpy-CF3)(CO)3Cl][K(18-crown-6)] was also obtained.Figure optionsDownload full-size imageDownload as PowerPoint slide