Synthesis and structure of Mu-4, the new layered aluminophosphate [(C 2H 5) 2NH 2] 4[Al 8P 10O 40H 2]·[H 2O] 2.5

Abstract

The title compound (named Mu-4) is a new layered aluminophosphate with a unusual A1/P ratio for this kind of materials. Mu-4 was obtained from a quasi non-aqueous mixture involving mainly diethylformamide (DEF) as solvent, in addition to limited amounts of water. DEF is decomposed during the synthesis and the resulting protonated diethylamine is occluded in the as-synthesized material. The crystal structure was determined by single crystal X-ray diffraction. The symmetry is triclinic, a=8.632(4) Å, b=9.267(7) Å, c= 17.461(10) Å, α=86.66(5)°, β=82.20(4)° and γ=89.28(5)°, space group P-1. The structure consists of anionic double sheets essentially built from double 4-ring (D4R) units. The inorganic layers are in strong interaction with water and the protonated amine which is located in the interlayer spacing. Another type of diethylamine protrudes into the 8-membered rings (8-MR) present in the layers. The characterization of this new aluminophosphate by 13C, 27Al and 31P solid state NMR spectroscopy is also reported.