Ferric Phosphite: Dimers of Face-Sharing Fe^IIIO₆ Octahedra. Crystal Structure Redetermination, Mössbauer Spectra, Magnetic Susceptibility, and Heat Capacity Data

Synthesis, structural characterization, and physical properties of Fe2(HPO3)3 are reported. The structure establishes the phosphite anion as a bridging unit producing dimers of face-sharing Fe(III)O6 octahedra. The Fe2O9 units are interconnected by sharing common apices with HPO3 tetrahedra, resulting in a three-dimensional arrangement. These structural characteristics determine the physical properties of the compound. A weak antiferromagnetic exchange interaction in the dimeric entities and a three-dimensional ordering below 20 K of antiferromagnetic nature can be detected using Mossbauer, susceptibility, and beat capacity data