A new borophosphate compound with helix structure:: (NH4)0.5(H3O)0.5Mg(H2O)2BP2O8

A new borophosphate compound, (NH4)(0.5) (H3O)(0.5)Mg(H2O)(2)BP2O8, was prepared by hydrothermal synthesis and characterized by X-ray single crystal diffraction. The title compound belongs to hexagonal system,. space group P6(5)22, a = 0. 94507 (19) nm, c = 1. 5803 (5) nm, gamma = 120degrees, V = 1. 2224 (5) nm(3), M-r = 279.06, Z = 6, D-c = 2.258 g/cm(3), F (000) = 834, R-1 = 0.0360, wR(2) = 0.1070, mu = 0.663 mm(-1). The crystal structure of the compound contains infinite one-dimensional borophosphate ribbons (1)(infinity) {[BP2O8](3-)} built of corner sharing BO4 and PO4 tetrahedra arranged around 6(5) screw axes. The borophosphate helices are interconected. by MgO4(H2O)(2) coordination octahedra to form a three-dimensional framework. The elemental analysis, IR, DTA/TGA. and the calculation of the electric charge balance show the presence of ammonium ions and protons. Both ammonium ions and hydroniums are located within the free loop of helical ribbons, and close to the inner wall of the helical channels (1)(infinity)[BP2O8](3-)}, respectively, balancing charge and stabilizing helical ribbons.