Mössbauer studies in spin 3/2 iron complexes

Abstract

A series of penta-coordinate bis(N,N-dialkyldithiocarbamato) iron (III) halides have been prepared in which the ground iron (III) term is an orbital singlet and spin quartet. The quartet ground term results from the low symmetry (C_2v) local environment of the iron.

The Mössbauer technique was employed to study several homologues closely related to the basic unit, bis(N,N-diethyldithiocarbamato) iron (III) chloride, which exhibits a ferromagnetic ordering at low temperatures (T_C= 2.5°K). While the paramagnetic character of the ground quartet remains independent of small structural changes, no new magnetically ordered systems were found. However, low-temperature Mössbauer data show that the small zero-field splitting of the quartet manifold is markedly affected by the halo-constituent of the penta-coordinate complex. Effects of a small external polarizing field on the Mössbauer spectra of these complexes is also considered.