CRYSTAL STRUCTURE OF NOVEL LAYERED IRON ARSENATE-OXALATE (NH4)3K3[Fe2(HAsO4)2(C2O4)4]•2H2O

A new open-framework structure of iron arsenate-oxalate (NH4)(3)K-3[Fe-2(HAsO4)(2)(C2O4)(4)]center dot 2H(2)O (I) is synthesized by slow evaporation and structurally characterized by single crystal X-ray diffraction methods. It crystallizes in the triclinic space group P (1) over bar (No. 2), with a = 10.154(4) angstrom, b = 10.430(4) angstrom, c = 15.085(7) angstrom, alpha = 96.81(3)degrees, beta = 105.04(43)degrees, gamma = 93.93(3)degrees, V = 1523.7(11) angstrom(3) and Z = 2. Its crystal structure consists of two crystallographically independent bishydrogenarsenato tetraoxalato diiron(III) anions, both located on centres of inversion, while the potassium and ammonium cations and water molecules are located in general positions. These moieties are connected through N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds to form infinity of layers parallel to the (101) plane, thus leading to a two-dimensional open framework.