The molten state of iron trichloride: A molecular ionic conductor

Abstract

Experimental and theoretical studies of molten FeCl3 provide a picture of its liquid structure as mainly consisting of closely packed Fe2Cl6 bitetrahedral molecules which have an internal atomic structure consistent with electron diffraction studies of the vapour phase. As for AlCl3, melting of FeCl3 is thus accompanied by a transition in bonding character from an ionic crystal to a molecular liquid. However, in contrast to AlCl3 the FeCl3 melt shows an appreciable ionic conductivity. A molecular-based interpretation is offered for this behaviour.