Resonance Raman and Electrocatalytic Behavior of Thiolate and Imidazole Bound Iron Porphyrin Complexes on Self Assembled Monolayers: Functional Modeling of Cytochrome P450

Electrodes bearing thiolate and imidazole coordinated iron porphyrin catalysts are constructed and characterized using resonance Raman spectroscopy, absorption spectroscopy, and electrochemistry. The cyclic voltammetry data and their pH dependences are used to establish the nature of the exchangeable trans ligands in both of these cases. In situ monitoring of partially reduced oxygen species (PROS) produced during O2 reduction using rotating ring disc electrochemistry (RRDE) experiments provide direct insight into the “push-effect” of the thiolate ligand. The thiolate bound iron porphyrin electrode generates highly oxidizing species on the electrode during electrocatalytic O2 reductions which are very reactive. These surfaces can utilize these oxidants to catalytically hydroxylate strong C–H bonds using molecular O2 with turnover numbers as high as 200.