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Three-dimensional Frameworks (three-dimensional + frameworks)
Selected AbstractsThree-Dimensional Frameworks of Gallium Selenide Supertetrahedral Clusters.CHEMINFORM, Issue 21 2004Xianhui Bu Abstract For Abstract see ChemInform Abstract in Full Text. [source] Polymorphism and piezochromicity in the three-dimensional network-based phosphate RbCuPO4ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2010Paul F. Henry Rubidium copper phosphate, RbCuPO4, forms two room-temperature polymorphs that have been investigated with neutron powder diffraction. Polymorph (II) can be converted quantitatively into (I) by grinding the material or by pelletization, and the phase transition is accompanied by a significant colour change from very pale green to sky blue. Polymorph (II) can be obtained essentially free of (I) by quenching from 723,K. Each polymorph shows two unique Cu atoms: in (I) both sites are four-coordinate in a 2:1 ratio, whereas in (II) the atoms are four- and five-coordinate in a 1:1 ratio. In each case these sites are linked by phosphate tetrahedra to form three-dimensional frameworks based on the 42638- a four-connected net. The Rb atoms are hosted in the six- and eight-ring channels that are similar to those observed in zeolite ABW. The (II) , (I) phase transition is also accompanied by a volume reduction of 2.1% even though the average coordination of the Cu atoms also falls. The structures of the polymorphs are critically examined and compared with those of KNiPO4 and KCuPO4 in terms of hexagonal close packing containing ordered phosphate arrays. As a result of buckling of the six-ring layers, one-dimensional chains of dimerized copper polyhedra are identified in (II), chains that become trimers with mirror symmetry in (I). [source] Hydrated metal complexes of N -(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)glycinate: interplay of molecular, molecular,electronic and supramolecular structuresACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2001John N. Low The title anion, (C7H8N5O4),, L,, forms hydrated metal complexes with a range of metal ions M+ and M2+. Lithium and manganese(II) form finite molecular aggregates [Li(L)(H2O)3] (1) and [Mn(L)2(H2O)4].6H2O (4) in which the molecular aggregates are linked into three-dimensional frameworks by extensive hydrogen bonding. The sodium and potassium derivatives, [Na2(L)2(H2O)3] (2) and [K(L)(H2O)] (3) both form organic,inorganic hybrid sheets in which metal,oxygen ribbons are linked by strips containing only organic ligands: these sheets are linked by hydrogen bonds into three-dimensional frameworks. In (2) the metal,oxygen ribbon is built from pairs of edge-shared trigonal bipyramids linked by water molecules, while in (3) it consists of a continuous chain of vertex-sharing octahedra. The nitroso group in the anion acts as an ,1 ligand towards Na+ and as an ,2 ligand towards K+. In all cases the anion L, shows the same unusual pattern of interatomic distances as the neutral parent LH. [source] The triple pyrophosphate Cs3CaFe(P2O7)2ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Nataliya Yu. The complex phosphate tricaesium calcium iron bis(diphosphate), Cs3CaFe(P2O7)2, has been prepared by the flux method. Isolated [FeO5] and [CaO6] polyhedra are linked by two types of P2O7 groups into a three-dimensional framework. The latter is penetrated by hexagonal channels along the a axis where three Cs atoms are located. Calculations of caesium Voronoi,Dirichlet polyhedra give coordination schemes for the three Cs atoms as [8,+,3], [9,+,1] and [9,+,4]. The structure includes features of both two- and three-dimensional frameworks of caesium double pyrophosphates. [source] Two caesium vanadium hydrogenphosphates with tunnelled structures: Cs2V2O3(PO4)(HPO4) and Cs2[(VO)3(HPO4)4(H2O)]·H2OACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2010Romain Gautier Dicaesium divanadium trioxide phosphate hydrogenphosphate, Cs2V2O3(PO4)(HPO4), (I), and dicaesium tris[oxidovanadate(IV)] hydrogenphosphate dihydrate, Cs2[(VO)3(HPO4)4(H2O)]·H2O, (II), crystallize in the monoclinic system with all atoms in general positions. The structures of the two compounds are built up from VO6 octahedra and PO4 tetrahedra. In (I), infinite chains of corner-sharing VO6 octahedra are connected to V2O10 dimers by phosphate and hydrogenphosphate groups, while in (II) three vanadium octahedra share vertices leading to V3O15(H2O) trimers separated by hydrogenphosphate groups. Both structures show three-dimensional frameworks with tunnels in which Cs+ cations are located. [source] Three-dimensional hydrogen-bonded structures in the 1:1 proton-transfer compounds of l -tartaric acid with the associative-group monosubstituted pyridines 3-aminopyridine, 3-carboxypyridine (nicotinic acid) and 2-carboxypyridine (picolinic acid)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2010Graham Smith The 1:1 proton-transfer compounds of l -tartaric acid with 3-aminopyridine [3-aminopyridinium hydrogen (2R,3R) -tartrate dihydrate, C5H7N2+·C4H5O6,·2H2O, (I)], pyridine-3-carboxylic acid (nicotinic acid) [anhydrous 3-carboxypyridinium hydrogen (2R,3R)-tartrate, C6H6NO2+·C4H5O6,, (II)] and pyridine-2-carboxylic acid [2-carboxypyridinium hydrogen (2R,3R)-tartrate monohydrate, C6H6NO2+·C4H5O6,·H2O, (III)] have been determined. In (I) and (II), there is a direct pyridinium,carboxyl N+,H...O hydrogen-bonding interaction, four-centred in (II), giving conjoint cyclic R12(5) associations. In contrast, the N,H...O association in (III) is with a water O-atom acceptor, which provides links to separate tartrate anions through Ohydroxy acceptors. All three compounds have the head-to-tail C(7) hydrogen-bonded chain substructures commonly associated with 1:1 proton-transfer hydrogen tartrate salts. These chains are extended into two-dimensional sheets which, in hydrates (I) and (III) additionally involve the solvent water molecules. Three-dimensional hydrogen-bonded structures are generated via crosslinking through the associative functional groups of the substituted pyridinium cations. In the sheet struture of (I), both water molecules act as donors and acceptors in interactions with separate carboxyl and hydroxy O-atom acceptors of the primary tartrate chains, closing conjoint cyclic R44(8), R34(11) and R33(12) associations. Also, in (II) and (III) there are strong cation carboxyl,carboxyl O,H...O hydrogen bonds [O...O = 2.5387,(17),Å in (II) and 2.441,(3),Å in (III)], which in (II) form part of a cyclic R22(6) inter-sheet association. This series of heteroaromatic Lewis base,hydrogen l -tartrate salts provides further examples of molecular assembly facilitated by the presence of the classical two-dimensional hydrogen-bonded hydrogen tartrate or hydrogen tartrate,water sheet substructures which are expanded into three-dimensional frameworks via peripheral cation bifunctional substituent-group crosslinking interactions. [source] Compounds of glycine with metal sulfates and thiosulfates: glycine cobalt sulfate pentahydrate, glycine sodium thiosulfate dihydrate and glycine potassium thiosulfateACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2006Ladislav Bohatý In the crystal structures of the title compounds, hexaaquacobalt(II) tetraaquadiglycinatocobalt(II) bis(sulfate), [Co(H2O)6][Co(C2H5NO2)2(H2O)4](SO4)2, (I), poly[diaqua-,3 -glycinato-di-,4 -thiosulfato-tetrasodium(I)], [Na4(C2H5NO2)(S2O3)2(H2O)2]n, (II), and poly[,2 -glycinato-,4 -thiosulfato-dipotassium(I)], [K2(C2H5NO2)(S2O3)]n, (III), all atoms are located on general positions, except the Co atoms in (I), which are located on inversion centres. In (I), hydrogen bonds play an important role, while the alkali thiosulfate compounds are characterized by three-dimensional frameworks of polyhedra. Relations to other compounds of glycine and metal sulfates are commented on. [source] |