title: Fe2(SO4)3·H2SO4·28H2O, a low-temperature water-rich iron(III) sulfate.
abstract: The title compound, diiron(III) trisulfate-sulfuric acid-water (1/1/28), has been prepared at temperatures between 235 and 239 K from acid solutions of Fe2(SO4)3. Studies of the compound at 100 and 200 K are reported. The analysis reveals the structural features of an alum, (H5O2)Fe(SO4)2·12H2O. The Fe(H2O)6 unit is located on a centre of inversion at (½, 0, ½), while the H5O2(+) cation is located about an inversion centre at (½, ½, ½). The compound thus represents the first oxonium alum, although the unit cell is orthorhombic.
authors.affiliation: Institute of Inorganic Chemistry, TU Bergakademie Freiberg, Leipziger Strasse 29, D-09596 Freiberg, Germany. horst.schmidt@chemie.tu-freiberg.de
authors.forename: Horst
authors.initials: H
authors.lastname: Schmidt
authors.forename: Erik
authors.initials: E
authors.lastname: Hennings
authors.forename: Philipp
authors.initials: P
authors.lastname: Zürner
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Voigt