Hybrid open-frameworks:: synthesis and structures of four vanado-alkyldiphosphonates with occluded potassium cations

The ternary systems KVO3: H2O3P-(CH2)-PO3H2O:H2O (n = 1, 2, 3) were hydrothermally investigated. Four phases were obtained and their structures determined by single crystal X-ray diffraction. K-4((VO)-O-IV)(2)((VO)-O-IV(H2O))(4){O3P-CH2 -PO3}(4).8H(2)O or MIL-2K is orthorhombic (S.G. P mmn (n degrees 59)) with lattice parameters a = 13.7642(2) Angstrom, b = 15.6796(4) Angstrom, c = 4.6902(1) Angstrom, V = 1012.23(4) Angstrom(3), Z = 1. Its three-dimensional framework presents some 14-membered tunnels inserting potassium cations and water molecules. K((VO)-O-V(H2O))((VO)-O-IV)O{O3P-(CH2)-PO3} or MIL-3K is triclinic (S.G. P -1 (n degrees 2)) with lattice parameters a = 7.3807(2) Angstrom, b = 7.9984(3) Angstrom, c = 10.0641(3) Angstrom, alpha = 75.695(1), beta = 69.178(1)4 gamma = 80.769(1)degrees V = 536.37(3) Angstrom(3), Z= 2. MIL-3K exhibits a pillared structure showing inorganic layers covalently linked by the ethyl chains. Its dehydration is studied. The pillared structures of K((VO)-O-IV)(2)(OH) {O3P-(CH2)(3)-PO3}3H(2)O or MIL-7K(HT) and K((V2O3)-O-IV/V)(H2O){O3P-(CH2)(3)-PO3}. H2O or MIL-7K(LT) are closely related, differing only by the neighbouring and the oxidation state of one vanadium atom. Both structures are monoclinic (S.G. C 2/c (n degrees 15)) with lattices parameters a = 14.4939(1) Angstrom, b = 10.2595(2) Angstrom, c = 18.6782(2) Angstrom, beta = 98.991(1)degrees, V = 2743.32(6) Angstrom(3), Z = 8 and a = 14.6228(1) Angstrom, b = 10.2783(2) Angstrom, c = 18.2716(3) Angstrom, beta = 100.272(1)degrees, V = 2702.16(7) Angstrom(3), Z = 8 for MIL-7K(HT) and MIL-7K(LT), respectively. (C) 2000 Editions scientifiques et medicales Elsevier SAS. All rights reserved.