STRUCTURE OF AN ADDUCT BETWEEN DIAMMONIUM DIHYDROGENDIPHOSPHATE AND TELLURIC ACID - (NH4)2H2P2O7.TE(OH)6

Telluric acid-diammonium dihydrogendiphosphate (1/1), Te(OH)6.(NH4)2H2P2O7, M(r) = 441.677, monoclinic, P2(1)/n, a = 7.651 (2), b = 21.790 (10), c = 6.689 (2) angstrom, beta = 113.85 (3)-degrees, V = 1020 (1) angstrom 3, Z = 4, D(x) = 2.876 Mg m-3, lambda(Ag K-alpha) = 0.5608 angstrom, mu = 1.766 mm-1, F(000) = 864, T = 294 K, final R = 0.033 for 3602 reflections. The title compound is the second example of an adduct between telluric acid and a diphosphate. Thick layers containing infinite [H2P2O7]n chains and layers of Te(OH)6 octahedra alternate perpendicular to the b axis. The hydrogen-bond scheme which includes very short bonds inside the [H2P2O7]n chains is described. Crystal data for the isotypic Rb salt are given.