Water oxidation catalysed by iron complex of N,N'-dimethyl-2,11-diaza[3,3](2,6)pyridinophane. Spectroscopy of iron-oxo intermediates and density functional theory calculations.

摘要: The macrocyclic [FeIII(L1)Cl2]+ (1, L1 = N,N′-dimethyl-2,11-diaza[3,3](2,6)pyridinophane) complex is an active catalyst for the oxidation of water to oxygen using [NH4]2[CeIV(NO3)6] (CAN), NaIO4, or Oxone as oxidant. mechanism 1-catalysed was examined by spectroscopic methods and 18O-labelling experiments, revealing that FeIVO and/or FeVO species are likely be involved in reaction. redox behaviour 1 these high-valent FeO has been both cyclic voltammetry density functional theory (DFT) calculations. In aqueous solutions, voltammograms at different pH show a pH-dependent reversible couple (E1/2 +0.46 V vs. SCE 1) irreversible anodic wave (Epa +1.18 assigned FeIII/FeII FeIII FeIV oxidation, respectively. DFT calculations showed E value half reaction involving [FeV(L1)(O)(OH)]2+/[FeIV(L1)(O)(OH2)]2+ +1.42 1. Using CAN oxidant 1, formation intermediate suggested ESI-MS UV-vis absorption measurements, rate evolution linearly dependent on concentrations CAN. NaIO4 concentration reactive with formula [FeV(L1)(O)2]+ generated measurements. revealed capable oxidizing barrier 15.7 kcal mol−1.