Zn(AsO3)2, a unique structure among arsenates with composition M IIAsV 2O6.

Zinc bis-[catena-arsenate(V)] or catena-poly[zinc-di-μ-arsenato(V)-κ4 O:O], [Zn(AsO3)2] n , is isotypic with the low-temperature modification of Zn(PO3)2. The asymmetric unit comprises one Zn atom situated on a twofold rotation axis and one As and three O atoms in general positions. In the crystal structure, the principal building units, ZnO6 octa-hedra and AsO4 tetra-hedra, are condensed into 1 ∞[ZnO4/2O2/1] zigzag chains and (AsO3)2 polyarsenate chains with a periodicity of two AsO4 tetra-hedra, respectively. The two types of chains extend parallel to [001] and are fused into a compact framework structure. Compared with divalent transition metal arsenates and other arsenates of the formula M IIAs2O6, Zn(AsO3)2 is unique in that arsenic is present exclusively in a tetra-hedral coordination and not in a mixed tetra-hedral/octa-hedral or purely octa-hedral coordination.