Crystal structure of diammonium indium (monophosphate-monohydrogenmonophosphate), (NH4)2ln[(PO4)(HPO4)

Abstract

H9InN2O8P2, orthorhombic, Fdd2 (No. 43), a = 17.459(4) A, b = 9.200(2) A, c = 9.720(2) A, V = 1561.3 A, Z = 8, Rgt(F) = 0.061, wRref(F) = 0.148, T = 295 K. Source of material (NH4)2In[(PO4)(HPO4)] was synthesized under mild hydrothermal conditions. The reactions were carried out with mixtures of InCl3, H3BO3 and (NH4)H2PO4 with the molar ratio of 1:6 : 8 in aqueous solution. The mixture was sealed in 20 ml glass tubes. The filling of the solution were about 30% of the glass tubes. The glass tubes were placed in an oven with subsequent heating at 413 K for 7 days. All starting materials were of analytical grade and used without further purification. Discussion There were only two ammonium-indium phosphates [1,2] and one ammonium-indium borophospahte [3] reported up to now and the title compound is another indium phosphate with ammonium cation. The title compound has a new structure type which is characterized by isolated InO6 octahedra sharing common O-corners with six isolated PO4 tetrahedra to form a three dimensional network structure. Each PO4 tetrahedron shares common O-corners with three InO6 octahedra. According to the present model, the hydrogen atom bridges symmetrically two PO4 tetrahedra. However, the H atom is presumably disordered, splitting in two positions, and in an ordered model the O3PO···H–OPO3 groups would exist. The structure can also be considered as a packing of layers perpendicular to the a-axis. Each layer is constructed by fusing eight-membered rings formed by four InO6 octahedra and four phosphate (or hydrogenphosphate) tetrahedra. The alternating layers are shifted by 1/4 of a period along both band c-axis with respect to their neighboring layers. This construction results to two sets of channels runing along the [011] and [011] directions. The channels have a nearly rectangular cross section and are formed by two five-membered U-shaped half-rings in an up-and-down fashion. The ammonium groups are distributed within the channels. The In—O bond distances within the InO6 octahedron range from 2.093 A to 2.171 A. Bond lengths and angles in the phosphate PO4 tetrahedra are similar to those in other phosphates. Z. Kristallogr. NCS 217 (2002)309-310 309 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless prism, size 0.07 × 0.07 × 0.10 mm Wavelength: Mo K radiation (0.71073 A) : 34.61 cm−1 Diffractometer, scan mode: Enraf Nonius CAD4, /2 2 max: 67.74° N(hkl)measured, N(hkl)unique: 834, 834 Criterion for Iobs, N(hkl)gt: Iobs > 2 (Iobs), 644 N(param)refined: 57 Programs: SIR92 [4], SHELXL-97 [5], DIAMOND [6] Table 1. Data collection and handling. O(1) 16b 0.2476(7) 0.423(1) 0.496(1) 0.013(2) O(2) 16b 0.2476(7) 0.594(1) 0.689(1) 0.009(2) O(3) 16b 0.1205(5) 0.518(1) 0.583(1) 0.013(2) O(4) 16b 0.1962(6) 0.340(1) 0.726(1) 0.015(2) N(1) 16b 0.1439(9) 0.824(2) 0.499(2) 0.024(3) H(1) 8a 1/4 1/4 0.7135 0.05 H(2) 16b 0.1879 0.8895 0.5567 0.05 H(3) 16b 0.1486 0.8201 0.4136 0.05 H(4) 16b 0.0885 0.8504 0.5257 0.05 H(5) 16b 0.1694 0.7424 0.5515 0.05 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso