Assignments of the Mössbauer spectra of an inorganic [8Fe–7S] complex based on the first-principle calculations

First-principle calculations are made on the isomer shifts and quadrupole splitting parameters for 15 selected mononuclear iron complexes as a test of our procedure. Reasonable linear correlations with the corresponding experimental values corroborate the validity of our approach. Then the Mössbauer spectrum of an inorganic [8Fe–7S] complex is assigned. The results for this multi-nuclear iron complex reveal that the Fe(III) centers are the ones on both sides of the [8Fe–7S] core. This assignment is discussed in terms of a formal charge analysis, by which possible charge states of multi-nuclear metal centers are identified.