NMR study of electron transfer between paramagnetic complexes Kinetics of the self-exchange reaction [Fe3O(O2CCMe3)6(py)3]+/0 (py = pyridine)

Abstract

The kinetics of the electron transfer self-exchange reaction [Fe₃O(O₂CCMe₃)₆(py)₃]⁺ + [Fe₃O(O₂CCMe₃)₆(py)₃] ⇄ [Fe₃O(O₂CCMe₃)₆(py)₃] + [Fe₃O(O₂CCMe₃)₆(py)₃]⁺ have been measured by NMR line broadening. Both reactants are paramagnetic and it was possible to measure broadening of lines of each component by exchange with the other. In dichloromethane at 23 °C the second-order rate constant is (3.7 ± 0.1) × 10⁴M⁻¹ s⁻¹. The ligand exchange reactions of [Fe₃O(O₂CCMe₃)₆(py)₃]ⁿ⁺ with pyridine are rapid for the mixed-valence complex (n = 0) but slow for the oxidised complex (n = 1).