Ammonium diphosphitoindate(III)

The crystal structure of the title compound, NH(4)[In(HPO(3))(2)], is built up from In(III) cations (site symmetry 3m.) adopting an octa­hedral environment and two different phosphite anions (each with site symmetry 3m.) exhibiting a triangular–pyramidal geometry. Each InO(6) octa­hedron shares its six apices with hydrogen phosphite groups. Reciprocally, each HPO(3) group shares all its O atoms with three different metal cations, leading to [In(HPO(3))(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(HPO(3))(2)](−) layers of the host framework. The sheets are held together by hydrogen bonds formed between the NH(4) (+) cations and the O atoms of the framework.