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H...O Hydrogen (h...o + hydrogen)

Distribution by Scientific Domains
Chemistry100%

Terms modified by H...O Hydrogen

  • h...o hydrogen bond
    		•

    Selected Abstracts

    Trans -cinnamic acid and coumarin-3-carboxylic acid: experimental charge-density studies to shed light on [2,+,2] cycloaddition reactions

    ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009
    Judith A. K. Howard
    As part of an ongoing series of experimental charge-density investigations into the intra- and intermolecular interactions present in compounds which undergo solid-state [2,+,2] cycloaddition reactions, the charge-density analyses of trans -cinnamic acid and coumarin-3-carboxylic acid are reported. Thus, high-resolution single-crystal X-ray diffraction data were recorded at 100,K for trans -cinnamic acid (sin,,/,max = 1.03,Å,1) and coumarin-3-carboxylic acid (sin,,/,max = 1.19,Å,1). In addition to the anticipated O,H...O hydrogen bonds weak C,H...O interactions were identified in both structures along with very weak intermolecular interactions between pairs of molecules that undergo solid-state [2,+,2] cycloaddition reactions upon irradiation. [source]

    Interactions between dimers of {1,1,-[o -phenylenebis(nitrilomethylidyne)]di-2-naphtholato-,4O,N,N,,O,}nickel(II)

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2009
    Anita Blagus
    In the title compound, [Ni(C28H18N2O2)], the NiII centre has a square-planar coordination geometry in which the Schiff base ligand acts as a cis - O,N,N,,O,-tetradentate ligand. The crystal structure is built up of centrosymmetric dimer units stacked into chains along the [010] direction. Adjacent chains associate via C,H...O hydrogen bonding only, leading to a two-dimensional sheet-like structure consisting of layers parallel to (10). The cofacial dimeric complex contains an Ni...Ni contact of 3.291,(4),Å. [source]

    Channel-forming solvates of 6-chloro-2,5-dihydroxypyridine and its solvent-free tautomer 6-chloro-5-hydroxy-2-pyridone

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009
    Sean R. Parkin
    On crystallization from CHCl3, CCl4, CH2ClCH2Cl and CHCl2CHCl2, 6-chloro-5-hydroxy-2-pyridone, C5H4ClNO2, (I), undergoes a tautomeric rearrangement to 6-chloro-2,5-dihydroxypyridine, (II). The resulting crystals, viz. 6-chloro-2,5-dihydroxypyridine chloroform 0.125-solvate, C5H4ClNO2·0.125CHCl3, (IIa), 6-chloro-2,5-dihydroxypyridine carbon tetrachloride 0.125-solvate, C5H4ClNO2.·0.125CCl4, (IIb), 6-chloro-2,5-dihydroxypyridine 1,2-dichloroethane solvate, C5H4ClNO2·C2H4Cl2, (IIc), and 6-chloro-2,5-dihydroxypyridine 1,1,2,2-tetrachloroethane solvate, C5H4ClNO2·C2H2Cl4, (IId), have I41/a symmetry, and incorporate extensively disordered solvent in channels that run the length of the c axis. Upon gentle heating to 378,K in vacuo, these crystals sublime to form solvent-free crystals with P21/n symmetry that are exclusively the pyridone tautomer, (I). In these sublimed pyridone crystals, inversion-related molecules form R22(8) dimers via pairs of N,H...O hydrogen bonds. The dimers are linked by O,H...O hydrogen bonds into R46(28) motifs, which join to form pleated sheets that stack along the a axis. In the channel-containing pyridine solvate crystals, viz. (IIa),(IId), two independent host molecules form an R22(8) dimer via a pair of O,H...N hydrogen bonds. One molecule is further linked by O,H...O hydrogen bonds to two 41 screw-related equivalents to form a helical motif parallel to the c axis. The other independent molecule is O,H...O hydrogen bonded to two related equivalents to form tetrameric R44(28) rings. The dimers are ,,, stacked with inversion-related dimers, which in turn stack the R44(28) rings along c to form continuous solvent-accessible channels. CHCl3, CCl4, CH2ClCH2Cl and CHCl2CHCl2 solvent molecules are able to occupy these channels but are disordered by virtue of the site symmetry within the channels. [source]

    The coordination polymers poly[,-4,4,-bipyridyl-di-,-formato-copper(II)] and catena -poly[[[diaqua(1-benzofuran-2,3-dicarboxylato)copper(II)]-,-1,2-di-4-pyridylethane] dihydrate]

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009
    Rajesh Koner
    The title compounds, [Cu(CHO2)2(C10H8N2)]n, (I), and {[Cu(C10H4O5)(C12H12N2)(H2O)2]·2H2O}n, (II), are composed of one-dimensional linear coordination polymers involving copper(II) ions and bidentate bipyridyl species. In (I), the polymeric chains are located on twofold rotation axes at (x, x, 0) and are arranged in layered zones centered at z = 0, , ½ and parallel to the ab plane of the tetragonal crystal. Weak coordination of the formate anions of one layer to the copper centers of neighboring layers imparts a three-dimensional connectivity to this structure. In (II), the polymeric chains propagate parallel to the a axis of the crystal. Noncoordinated water molecules link the chains through O,H...O hydrogen bonding in directions perpendicular to c, imparting to the entire structure three-dimensional connectivity. The metal ions adopt distorted octahedral and square-based pyramidal environments in (I) and (II), respectively. This study indicates that, under the given conditions, extended coordination involves CuII centers associating with the bipyridyl ligands rather than with the competing benzofurandicarboxylate entities. [source]