Spectroscopic and structural investigations of the ferrous and ferric high-spin state of a ''picket-fence'' porphyrinato acetato iron complex. A refined model for the P460 center of hydroxylamine oxidoreductase

Moessbauer investigations were performed in the ferrous and ferric form of the 'picket-fence' porphyrinato acetato iron complex vertical strokeFe(CH3CO2)(TPpivP)vertical stroke1-,0 at temperatures varying from 1.5-200K and in fields of 0.6-2T. The ferrous complex has an unusually large quadrupole splitting, ΔEQ= +4.25mms-1. The quadrupole splitting in the ferric species, ΔEQ= +1.1mms-1, is as normally found in ferric high-spin iron porphyrins. Spin-Hamiltonian analysis of the magnetic spectra yields zero-field parameters D=-0.9mms-1, E/D=0.33 and magnetic hyperfine parameters Ax,y=-17T, Az=-13.3T in the ferrous high-spin (S=2) complex, and D=7.5cm-1, E/D≅0 and Ax,y,z=20T in the ferric high-spin (S=5/2) species. (orig.)