The crystal structure of the microporous solid MAPO-39 (ATN) refined from single crystal diffraction data

MAPO-39 is a crystalline magnesiumaluminophosphate with an idealized framework composition Al 7 MgHP 8 O 32 and a crystal structure corresponding to zeolite framework topology ATN, FW = 974.0, tetragonal, space group I4/m, a = 13.2088(2) A, c = 5.2771(2) A, V= 920.71(6) A 3 , Z = 1, D x = 1.754 Mg m -3 , μ (MoK α ) = 0.65 mm -1 , λ (MoK α ) = 0.71069 A, μ (CuK α ) = 6.30 mm -1 , λ (CuK α ) = 1.5418 A, F(000) = 479. The intensities of 9733 reflections were measured on a single crystal X-ray diffractometer with MoK α radiation, and 3253 reflections with CuK α radiation. Both data sets were combined and 1304 averaged unique intensities obtained, refinement on |F|, R = 0.093, R w = 0.024, including all unobserved and weak F hkl . A previously published structural model of MAPO-39 with wide 1-dimensional pores outlined by 8-rings in space group I4 and based on X-ray powder diffraction data has been essentially confirmed for MAPO-39. It did not prove possible to locate precisely the template molecules in the wide pores of MAPO-39, most probably because these molecules are highly disordered. The narrower channels outlined by saddle-shaped 8-rings are small enough to be locally plugged by inverted phosphate and aluminate tetrahedra which stick out into the 1-dimensional pore. The magnesium atoms in MAPO-39 replace statistically part of the aluminium atoms in the framework. The net of primary bonds P-O and Al-O of MAPO-39 corresponds to Net 8' predicted by Wells (Three-dimensional nets and polyhedra, New York, Wiley, 1977, p. 134) as a possible tetrahedral framework. It is the tetragonal equivalent of the hexagonal cancrinite net.