Ammonium diphosphitoindate(III)

The crystal structure of the title compound, NH4[In(HPO3)2], is built up from InIII cations (site symmetry 3m.) adopting an octahedral environment and two different phosphite anions (each with site symmetry 3m.) exhibiting a triangular–pyramidal geometry. Each InO6 octahedron shares its six apices with hydrogen phosphite groups. Reciprocally, each HPO3 group shares all its O atoms with three different metal cations, leading to [In(HPO3)2] layers which propagate in the ab plane. The ammonium cation likewise has site symmetry 3m.. In the structure, the cations are located between the [In(HPO3)2] layers of the host framework. The sheets are held together by hydrogen bonds formed between the NH4+ cations and the O atoms of the framework.