Crystal structure of ammonium indium di(hydrogenmonophosphate), (NH4)In[PO3(OH)

Abstract

H6InNO8P2, monoclinic, P121/c1 (No. 14), a = 9.6004(4) A, b = 8.2820(4) A, c = 9.6693(3) A, = 116.205(4)°, V = 689.8 A 3 , Z =4 ,Rgt(F) = 0.040, wRref(F 2 ) = 0.104, T = 295 K. Source of material (NH4)In[P2O6(OH)2] was synthesized under mild hydrothermal conditions. The reactions were carried out with mixtures of InCl3, LiCl·H2O, NaBO2·4H2O and (NH4)H2PO4 with the molar ratio of 1:4:9:6 in aqueous solution. The mixture was sealed in 20 ml glass tube. The pH value of the solution was about 0.2. 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. The starting materials are all of analytical grade and used without further purification. Discussion There was only one ammonium-indium phosphate [1] and one ammonium-indium borophospahte [2] reported up to now and the title compound is another indium phosphate with ammonium cation obtained as a by-product of new borophosphate, NaIn[BP2O8(OH)] [3]. The title compound has a new structure type which is characterized by isolated InO6 octahedra sharing common O-corners with six isolated PO3(OH) tetrahedra to form a three-dimensional network structure. Every PO3(OH) tetrahedron shares common O-corners with three InO6 octahedra besides the terminal OH group. In the structure, there are eight-membered rings formed by four InO6 octahedra and four hydrogenphosphate tetrahedra. Ammonium groups are distributed within the open elliptical channels running along the a axis. In InO6 octahedron the In—O bond distances range from 2.107 A to 2.168 A. Bond lengths and angles of hydrogenphosphate PO3(OH) tetrahedra are similar to other phosphates.