Synthesis and crystal structure of calcium dizinc iron(III) tris(orthophosphate), CaZn2Fe(PO4)3

Abstract

Single crystals of the title compound, CaZn2Fe(PO4)3, were synthesized by conventional solid-state reaction. In the asymmetric unit, all atoms are located in fully occupied general positions of theP21/cspace group. The zinc atoms are located on two crystallographically independent sites with tetrahedral and distorted triangular-based bipyramidal geometries. Two edge-sharing triangular bipyramidal ZnO5units form a dimer, which is linked to slightly deformed FeO6octahedraviaa common edge. The resulting chains are interconnected through PO4tetrahedra to form a layer perpendicular to thebaxis. Moreover, the remaining PO4and ZnO4tetrahedra are linked together through common vertices to form tapes parallel to thecaxis and surrounding a chain of Ca2+cations to build a sheet, also perpendicular to thebaxis. The stacking of the two layers along thebaxis leads to the resulting three-dimensional framework, which defines channels in which the Ca2+cations are located, each cation being coordinated by seven oxygen atoms.