The γ-polymorph of AgZnPO(4) with an ABW zeolite-type framework topology

Abstract

The γ-polymorph of the title compound, silver zinc orthophos-phate, was synthesized under hydro-thermal conditions. The structure consists of ZnO(4), PO(4) and AgO(4) units. The coord-ination spheres of Zn(II) and P(V) are tetra-hedral, whereas the Ag(I) atom is considerably distorted from a tetra-hedral coordination. Each O atom is linked to each of the three cations. An elliptic eight-membered ring system is formed by corner-sharing of alternating PO(4) and ZnO(4) tetra-hedra, leading to a framework with an ABW-type zeolite structure. The framework encloses channels running parallel to [100] in which the Ag cations are located, with Ag⋯Ag contacts of 3.099 (3) Å. This short distance results from d(10)⋯d(10) inter-actions, which play a substantial role in the crystal packing. The structure of γ-AgZnPO(4) is distinct from the two other polymorphs α-AgZnPO(4) and β-AgZnPO(4), but is isotypic with NaZnPO(4)-ABW, NaCoPO(4)-ABW and NH(4)CoPO(4)-ABW.

Fig. 1.

Plot of parts of the crystal structure of the title compound showing the most important interatomic bonds. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) -x + 1, -y + 2, -z; (ii) x - 1, y, z; (iii) x - 1/2, -y + 3/2, z - 1/2; (iv) -x, -y + 2, -z; (v) -x + 1, -y + 2, -z + 1; (vi) x - 1/2, -y + 3/2, z + 1/2.]

Fig. 2.

A three-dimensional polyhedral view of the crystal structure of the monophosphate γ-AgZnPO4. PO4 tetrahedra are pink, ZnO4 tetrahedra are light-blue and silver atoms are grey.