Sur les carbonates basiques de fer (III): II. Préparation, radiocristallographie et spectres IR. du (NH4)2Fe2(OH)4(CO3)2 · H2O

Abstract

AbstractThe obtention of the crystalline basic carbonate of iron (III) and ammonium, (NH4)2Fe2(OH)4(CO3)2 · H2O, is described and its formula is established by chemical analysis and infrared spectroscopy. The powder X‐ray diagram could be indexed tetragonally leading to a body centred elementary cell with a = 12,04 ± 0,02 Å and c = 6,62 ± 0,01 Å.The infrared spectra show that in the CO groups either one oxygen atom is linked to one iron atom or, rather, two oxygen atoms are linked to two iron atoms. The symmetry of the NH groups is lower than C3v. The OH‐groups are linked by hydrogen bonds of 2,75 Å. Two sorts of OH‐groups can be distinguished, with a radius of approximately 1,34 Å and 1, 48 Å, respectively. The iron atoms are octahedrally coordinated by oxygen atoms, but either the octahedra are deformed or the iron atoms are in part coordinated tetrahedrally.