Hydrothermal Synthesis and Crystal Structure of the First Ammonium Indium(III) Phosphate NH4In(OH)PO4 with Spiral Chains of InO4(OH)2

Abstract

An ammonium indium hydrogen phosphate, NH4In(OH)PO4, was synthesized under mild hydrothermal conditions, and the crystal structure was characterized by single-crystal X-ray diffraction method. The compound crystallizes with the RbIn(OH)PO4 type with the following data: Mr=244.84, tetragonal, tP104, P43212 (No.96), a=9.416(2) Å, c=11.159(3) Å, V=989.9(3) Å3, Z=8, Dx=3.288 g cm−3, λ=0.71073 Å, μ=50.34 cm−1, F(000)=928, T=293 K, R1=0.0606, wR2=0.1472 for 91 variables and 1813 contributing unique reflections. The structure is characterized by chiral InO4(OH)2 chains along the c axis formed by sharing OH corners. The chains are isolated by PO4 tetrahedra leading to a three-dimensional framework structure with channels occupied by NH4+ ions. The framework structure is similar to that of KIn(OH)PO4 and γ-NaTiOPO4. The hydrogen bonds formed by NH4+ with the polyhedral oxygen atoms play an important role in the anisotropic changes of the lattice with respect to its alkali metal analogues. The topological construction of the title structure can be considered as an augmented 4,6-net with larger porosity.