Silver trimagnesium phosphate bis(hydrogenphosphate), AgMg 3(PO4)(HPO4)2, with an alluaudite-like structure

Abstract

The title compound, AgMg3(PO4)(HPO4) 2, which has been synthesized by the hydrothermal method, has an alluauditelike structure which is formed by edge-sharing MgO6 octahedra (one of which has symmetry 2), resulting in chains linked together by phosphate groups and hydrogen bonds. The three-dimensional framework leads to two different channels along the c axis, one of which is occupied by Ag + ions with a square-planar coordination. The Ag+ ions are disordered over two sites in a 0.89 (3):0.11 (3) ratio. The OH groups, which point into the other type of channel, are involved in strong O - H⋯O hydrogen bonds. The title compound is isotypic with the compounds AM 3H2(XO4)(HXO4)2 (A = Na or Ag,M = Mn, Co or Ni, and X = P or As) of the alluaudite structure type.