title: Crystal structure of (NH4)2[Fe(II) 5(HPO3)6], a new open-framework phosphite.
abstract: Di-ammonium hexa-phosphito-penta-ferrate(II), (NH4)2[Fe5(HPO3)6], was synthesized under mild hydro-thermal conditions and autogeneous pressure, yielding twinned crystals. The crystal structure exhibits an [Fe(II) 5(HPO3)6](2-) open framework with NH4 (+) groups as counter-cations. The anionic skeleton is based on (001) sheets of [FeO6] octa-hedra (one with point-group symmetry 3.. and one with .2.) linked along [001] through [HPO3](2-) oxoanions. Each sheet is constructed from 12-membered rings of edge-sharing [FeO6] octa-hedra, giving rise to channels with a radius of ca 3.1 Å in which the disordered NH4 (+) cations are located. The IR spectrum shows vibrational bands typical for phosphite and ammonium groups.
authors.affiliation: Dpto. de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco, UPV/EHU, 48080 Leioa, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Berrocal
authors.affiliation: Dpto. de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco, UPV/EHU, 48080 Leioa, Spain.
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Mesa
authors.affiliation: Dpto. Mineralogía y Petrología, Facultad Ciencia y Tecnología, Universidad del País Vasco, UPV/EHU, 48080 Leioa, Spain.
authors.forename: Edurne
authors.initials: E
authors.lastname: Larrea
authors.affiliation: Dpto. de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco, UPV/EHU, 48080 Leioa, Spain.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Arrieta
keywords: IR spectroscopy; crystal structure; iron phosphite; mild hydro­thermal synthesis