Synthesis and Structure Determination of a New Organically Templated Scandium Fluorophosphate Framework and Its Indium Analogue

Abstract

Two new isostructural scandium and indium phosphate frameworks, (C6H14N2)M4F2(PO4)4·4H2O (M = Sc, In), have been synthesized from hydrothermal conditions using an organic amine, 1,4-diazabicyclo[2.2.2]octane (DABCO), as a template. Their structures have been determined by single-crystal X-ray diffraction and supported by solid-state magic-angle spinning (MAS) NMR spectroscopy. They crystallize in the P21/n space group with a = 10.283(2) A, b = 12.698(2) A, c = 17.864(3) A, and β = 102.761(3)° and a = 10.280(2) A, b = 12.700(2) A, c = 17.860(4) A, and β = 102.47(3)° for Sc- and In-compounds, respectively. They are built from corner-sharing M octahedra and P tetrahedra which form eight- and six-membered channels along the b-axis. The channels are occupied by organic templates and water molecules. All PO4 groups share four corners with M polyhedra, resulting in a fully connected framework. The local environments around P, F, and Sc atoms in the Sc-compound were carefully examined by 31P MAS, 19F MAS, 45Sc MA...