Synthesis and crystal structures of anhydrous lithium and ammonium hypophosphites

Conditions of synthesis (temperature, precursors) have been selected to grow crystals of anhydrous lithium and ammonium hypophosphites. The crystal structure of LiH₂PO₂ has been determined. Cell parameters and atomic positions in (NH₄)H₂PO₂ at room temperature and at 100 K have been refined. By their oxygen atoms the hypophosphite anions serve to bridge the four cations. Each oxygen atom is bonded to two cations, creating puckered layers parallel to the (001) planes. The structures show much similarity in the general arrangement, but differ in the type of the tetrahedral cation-anion bonds. In LiH₂PO₂, the Li-O bond is ionic (1.933(4) Å); in (NH₄)H₂PO₂, N-H...O is a hydrogen bond (2.846(1) Å).Original Russian Text Copyright © 2004 by M. I. Naumova, N. V. Kuratieva, D. Yu. Naumov, and N. V. PodberezskayaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 491–496, May–June 2004.