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

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 the P21/c space group. The zinc atoms are located on two crystallographically independent sites with tetra-hedral and distorted triangular-based bipyramidal geometries. Two edge-sharing triangular bipyramidal ZnO5 units form a dimer, which is linked to slightly deformed FeO6 octa-hedra via a common edge. The resulting chains are inter-connected through PO4 tetra-hedra to form a layer perpendicular to the b axis. Moreover, the remaining PO4 and ZnO4 tetra-hedra are linked together through common vertices to form tapes parallel to the c axis and surrounding a chain of Ca(2+) cations to build a sheet, also perpendicular to the b axis. The stacking of the two layers along the b axis leads to the resulting three-dimensional framework, which defines channels in which the Ca(2+) cations are located, each cation being coordinated by seven oxygen atoms.