Mössbauer spectroscopy on high-spin d5 iron complexes: Crystal field calculations

Mössbauer spectra of high-spin ferric Fe(EHPG) compounds in frozen solution have been recorded at 4.2 K in a small applied field. The spectra have been analyzed in terms of a spin Hamiltonian with S=5/2 used as an intermediate step for generating a crystal field model that has the ground sextet 6A1 and three excited quartet states appropriately spaced in energy. The model has been found to be appropriate for g=4.3 high-spin ferric complexes with spin Hamiltonian D values in the range 0.6–1.7 cm−1. It is shown that the model can provide a three-way correlation of the relevant data obtained by Mössbauer, EPR, and optical absorption spectroscopy.