a-Ammonium Vanadium Hydrogen Phosphate, a-NH4V(HPO4)2.

Abstract

α-Ammonium vanadium(III) bis(hydrogen phosphate) is a new ammonium vanadium(III) phosphate built up from a three-dimensional framework of VO6 octahedra and HPO4 tetrahedra [dav(V—O) = 2.008, dav(P—O) = 1.538, dav(N⋯O) = 3.086 A and θav(V—O—P) = 139.5°]. It is isostructural with α-RbV(HPO4)2 and complements the previously described β-NH4V(HPO4)2: α-NH4V(HPO4)2 contains both four-ring (two VO6 and two HPO4) and lantern (two VO6 and three HPO4) groupings, whereas β-NH4V(HPO4)2 contains only four-ring polyhedral groupings.