Novel Pillared Layer Structure of the Organically Templated Indium Phosphate [In₈(HPO₄)₁₄(H₂O)₆](H₂O)₅(H₃O)(C₃N₂H₅)₃

An imidazole encapsulating indium phosphate with an In:P ratio of 4:7 and a new pillared layer structure has been synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction, ³¹P CPMAS NMR, and thermogravimetric analysis. [Crystal data:  [In₈(HPO₄)₁₄(H₂O)₆](H₂O)₅(H₃O)(C₃N₂H₅)₃, M_r = 2686.72, trigonal, space group P−3c1 (No. 165), a =13.859(2) Å, c =19.186(8) Å, V = 3193(4) ų, Z = 2, R = 3.6%, R_w = 3.7% (1650 observed data with I > 3σ(I))]. The structure consists of layers assembled from InO₆ and InO₅(OH₂) octahedra and PO₃(OH) tetrahedra which are pillared through additional InO₆ octahedra to produce a three-dimensional framework. The framework contains a two-dimensional array of channels in which imidazolium cations, hydroxonium ions, and water molecules reside. Within the channels are 16-membered rings of alternating In and P polyhedra which have dimensions ∼8.6 × 9.7 Å.