Mössbauer Spectroscopic and Magnetic Properties of Iron(II,III) Pyropheophytins

Abstract

The Mössbauer spectra and effective magnetic moments of (pyropheophytin a)iron(III) chloride and (pyropheophytin b) iron(III) chloride have revealed that the central iron(III) ion is in a high-spin state. The temperature-dependent asymmetry of the Mössbauer spectra is interpreted in terms of slow electronic spin relaxation. The Mössbauer parameters of these complexes are similar to those of corresponding iron(III) porphyrins. The central iron(III) ions in iron(III) pyropheophytins are autoreduced to the ferrous low-spin state in the presence of pyridine. The Mössbauer parameters of the bis-pyridine iron(II) adducts are also similar to those of corresponding iron(II) porphyrins.