Mössbauer spectroscopic study on valence-detrapping and trapping of mixed-valence trinuclear iron(III, III, II) fluorine-substituted benzoate complexes

Four mixed-valence trinuclear iron(III, III, II) fluorine-substituted benzoate complexes were synthesized; Fe3O(C6F5COO)6(C5H5N)3·CH2Cl2 (1), Fe3O(C6F5COO)6(C5H5N)3 (2), Fe3O(2H-C6F4COO)6(C5H5N)3 (3), and Fe3O(4H-C6F4COO)6(C5H5N)3 (4), in which valence-detrapping and trapping phenomena have been investigated by 57Fe- Mössbauer spectroscopy. The valence state of the three iron ions is trapped at lower temperatures while it is fully detrapped at higher temperatures for 1. Valence detrapping is not observed for 2, 3, and 4 even at room temperature, although Mössbauer spectra for 3 and 4 show complicated temperature dependence.