An Iron Porphyrin Complex with Pendant Pyridine Substituents Facilitates Electrocatalytic CO ₂ Reduction via Second Coordination Sphere Effects

A bispyridylamine-based hanging unit within the ligand framework of a newly synthesized iron porphyrin complex (Py2XPFe) can act, on one hand, as hydrogen bonding site to facilitate proton transfer in catalysis and, other coordination for second Lewis acidic metal center. The bispyridylamine group close proximity center is able mediate electrocatalytic CO2 reduction anhydrous MeCN. interactions affect kinetics likely through stabilization [FeI(CO2H)]? intermediate, increasing overall rate when compared non-functionalized analog, TMPFe (TMP=tetramesitylporphyrin). constants (kapp) reaction were calculated using FOWA method which resulted higher TOFmax Py2XPFe with neat MeCN (1.7×102 vs. 1.1×101 s?1). addition weak Brønsted acids mixture (TFE or PhOH) shows an increase both complexes, yet analog displays at each relative acid concentration, suggesting beneficially impacts presence these sources. Sc3+ also results current density reaction. Resonance Raman well 1H-NMR spectroscopy indicates pyridine substituents.