Crystal structure of iron(III) perchlorate nona-hydrate.

Abstract

Since the discovery of perchlorate salts on Mars and the known occurrence of ferric salts in the regolith, there is a distinct possibility that the title compound could form on the surface of Mars. [Fe(H2O)6](ClO4)3·3H2O was crystallized from aqueous solutions at low temperatures according to the solid-liquid phase diagram. It consists of Fe(H2O)6 octa-hedra (point group symmetry -3.) and perchlorate anions (point group symmetry .2) as well as non-coordinating water mol-ecules, as part of a second hydrogen-bonded coordination sphere around the cation. The perchlorate appears to be slightly disordered, with major-minor component occupancies of 0.773 (9):0.227 (9).