Orbitally Nondegenerate Iron(III) Dithiocarbamates. II. Intermolecular Exchange in a Ferromagnetic Homolog

The chelate bis-(N,N-diethyldithiocarbamato)iron(III) chloride is known to exhibit a ferromagnetic transition at 2.43°K. The magnetism of this complex is of some interest since crystallographic data show the lattice to be composed of discrete molecules at normal van der Waal's radii, containing one iron atom per molecular unit. The magnetic exchange is primarily intermolecular in origin, since iron—iron separations rule out significant dipole—dipole contributions. Single crystal Mössbauer experiments are presented which may be analyzed to show the exchange to be of the form Fe–S··· S–Fe, the Fe–S units belonging to distinct molecules, and the actual geometry being nonlinear. The Mössbauer data are consistent with a spin polarization parallel to the major axis of the base of the rectangular pyramid formed by the immediate iron ligands.