Complementary Mössbauer, EPR and theoretical studies of the exchange-coupled oxoferryl porphyrin cation radical system [(Cl)Fe(IV)=O(TMP)̇]

We have applied Mössbauer- and EPR spectroscopy to [(Cl)Fe(IV)=O(TMP)^̇] which is a synthetic analog for compound I of the heme peroxidases. The temperature- and field-dependent Mössbauer- and EPR spectra were analyzed within the spin-Hamiltonian formalism. Spectral simulations with a unique parameter set are prohibited due to the fact that several of the spin-Hamiltonian parameters cannot be determined independently and, therefore, are covariant. Theoretical considerations are discussed to reduce the allowed parameter space.