COMPOSITE MICROPOROUS COMPOUNDS - PART I - SYNTHESIS AND STRUCTURE DETERMINATION OF 2 NEW VANADIUM ALKYLDIPHOSPHONATES (MIL-2 AND MIL-3) WITH 3-DIMENSIONAL OPEN FRAMEWORKS

Two vanadium diphosphonates were hydrothermally synthesized in a dilut e medium. ((VVO)-V-IV)(2)((VO)-O-IV(H2O))(4) {O3P-CH2-PO3}(4)(NH4)(4)( H2O)(4)(MIL-2) crystallizes in the orthorhombic system (space group P mmn (no. 59)) with lattice parameters of a = 13.512(7) Angstrom, b = 1 6.194(8) Angstrom, c = 4.677(2) Angstrom, V = 1023.4(9) Angstrom(3) an d Z = 1. Its structure, built up from corner-shared (VO5)-O-IV square pyramids, (VO5)-O-IV(H2O) octahedra and PO3CH2PO3 tetrahedral units, i s characterized by the presence of 14-membered tunnels inserting ammon ium cations and water molecules. ((VO)-O-V(H2O))((VO)-O-IV)O{O3P-(CH2) (2)-PO3} (NH4) (MIL-3) crystallizes in the P-1 (no. 2) triclinic space group with lattice parameters of a = 7.4548(3) Angstrom, b = 8.0825(3 ) Angstrom, c = 10.1660(4) Angstrom, alpha = 75.244(1)degrees, beta = 68.883(1)degrees, gamma = 80.648(1)degrees, V = 550.85(6) Angstrom(3) and Z = 2, Its structure is built up from chains of (VO6)-O-IV octahed ra and tetrahedral groups related by (VO4)-O-V(H2O) square pyramids. T he dehydration and the stability of both compounds are followed by the rmodiffractometric measurements. (C) 1998 Elsevier Science B.V. All ri ghts reserved.