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21Author    Udo Kunze, Hussain Jawad, Wolfgang Hiller, Regina NaumerRequires cookie*
 Title    Phosphinsubstituierte Chelatliganden, XIV [1] Wasserstoff-Brückenbindung in THF-Addukten von Tetracarbonylchrom-und -molybdänkomplexen mit P,S-koordinierten Phosphinothioformamid-Liganden. Kristallstruktur von [(CO) 4 Cr(PPh 2 C(S)NHMe)] THF Phosphine-Substituted Chelate Ligands, XIV [1] Hydrogen Bonding in THF-Adducts of Tetracarbonylchromium and -molybdenum Complexes with P,S-Coordinated Phosphinothioformamide Ligands. Crystal Structure of [(CO) 4 Cr(PPh 2 C(S)NHMe)] * THF  
 Abstract    The tetracarbonyl chromium and molybdenum P,S-chelate complexes la, b and 2a, b are obtained by low-temperature photolysis of the metal hexacarbonyls with the neutral phos-phinothioformamide ligands, Ph 2 PC(S)NHR (R = Me (a), Ph (b)), as stoichiometric 1/1 THF adducts. A weak N-H---O(THF) hydrogen bond is deduced from the ; H NMR spectra which show a collapse of the N-methyl doublet in la (T c -18 °C) but not in 2a. Unusually small P-C(S) couplings are observed in the 13 C{'H} NMR spectra. The N-methyl chromium complex la crystal-lizes in the triclinic space group P1 (Z = 2) with the lattice constants a = 1076.6(3), b = 1235.8(3), c = 915.1(3) pm, a = 97.99(4)°, ß = 92.73(5)°, y = 87.63(5)°. The planar thioamide unit adopts the Z configuration and is linked to the tetrahydrofuran molecule by a hydrogen bond (N-H1-031 164°) with an 0---H contact distance of 191 pm. 
  Reference    Z. Naturforsch. 40b, 512—517 (1985); eingegangen am 23. November 1984 
  Published    1985 
  Keywords    Hydrogen Bonding, THF-Adducts, Phosphinothioformamide Complexes, Crystal Structure, Chromium Complex 
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 TEI-XML for    default:Reihe_B/40/ZNB-1985-40b-0512.pdf 
 Identifier    ZNB-1985-40b-0512 
 Volume    40 
22Author    Christian Robl, Stephanie HentschelRequires cookie*
 Title    Zur Kenntnis von Be[C2(C O O )2] * 4 H20 - Ein durch starke Wasserstoffbrückenbindungen stabilisiertes anorganisches Derivat der Acetylendicarbonsäure On Be[C2(COO)2]-4 H 20 -An Inorganic Derivative of Acetylenedicarboxylic Acid Stabilized by Strong Hydrogen Bonding  
 Abstract    Colorless orthorhombic single crystals o f Be[C2(COO)2] • 4 H 20 were grown in aqueous silica gel. Space group Cmcm, a = 1004.7(1), b = 675.0(1), c = 1262.4(2) pm, Rg = 0.0264. The crys­ tal structure consists o f Be(H20)^+ tetrahedra and planar [C2(COO)2]2' anions linked together by strong asymmetric hydrogen bonds. A layer-like arrangement extending parallel (010) made up by [C2(COO)2]2~ anions and hydrogen bound water m olecules o f the Be(H20)^ + tetra­ hedra is the primary structural feature o f Be[C,(COO)2] -4 H 20 . These layers are stacked and interlinked by coordinative bonds between Be^+ and H 20 to yield a rigid three-dimensional framework. Thermal decom position com m ences with endotherm ic loss o f water o f crystallisa­ tion at 160 °C followed by several steps o f exothermic degradation yielding finally a soot-like am orphous residue. 
  Reference    Z. Naturforsch. 45b, 1499—1502 (1990); eingegangen am 3. Mai 1990 
  Published    1990 
  Keywords    Beryllium Acetylenedicarboxylate, X -R ay Structure, Thermal Analysis, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/45/ZNB-1990-45b-1499.pdf 
 Identifier    ZNB-1990-45b-1499 
 Volume    45 
23Author    DietrichM. Ootz, Dieter StäbenRequires cookie*
 Title    Die Hydrate von terf-Butanol: Kristallstruktur von Me3COH * 2 H20 und Me3COH * 7 H20 [ 1 ]  
 Abstract    The system /er/-butanol-water has been confirmed by X-ray powder diffraction and single­ crystal structure analysis to contain two hydrates, a dihydrate and a higher hydrate. The com ­ position o f the latter, contradictory in the literature, could be resolved in favor o f the new one o f a heptahydrate. The dihydrate (m.p. 0.7 °C) is m onoclinic with space group P2, and Z = 2 formula units per unit cell o f dim ensions a = 6.017, b = 6.055, c = 10.377 A and ß -106.60° at -150 °C. The heptahydrate (m.p. -6 °C, dec.) is orthorhombic with space group Pnma, Z = 4, a -12.589, b = 15.251 and c = 6.645 A at -150 °C. Both hydrates contain characteristic layers o f hydrogen-bonded O atom s, which in the heptahydrate are further linked into a three-di-m ensional semi-clathrate structure. 
  Reference    Z. Naturforsch. 48b, 1325—1330 (1993); eingegangen am 17. Mai 1993 
  Published    1993 
  Keywords    te/7-Butanol Hydrates, Melting Diagram, Crystal Structure, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/48/ZNB-1993-48b-1325.pdf 
 Identifier    ZNB-1993-48b-1325 
 Volume    48 
24Author    Dietrich Mootz, Michael BornRequires cookie*
 Title    Niedere Hydrate von Aminen. Kristallstrukturen der Hemihydrate von Ethyl-und Diethylamin sowie des Hemi-und Monohydrats von 1-Butylamin [1] Lower Hydrates of Amines. Crystal Structures of the Hemihydrates of Ethyl-and Diethylamine and the Hemi-and M onohydrate of 1-Butylamine  
 Abstract    The melting diagrams of three systems alkylamine-water have been reexamined and the crystal structures of four lower hydrates determined for the first time. The hydrate EtNH2 -0.5 H20 , m.p. -72 °C, is triclinic with space^roup P 1 and Z = 4 formula units per unit cell of dimensions a = 5.104, b = 8.137, c = 9.394 Ä, a = 100.41, ß = 98.41 and y = 97.96° at -150°C. The O and N atoms are hydrogen-bonded into a two-dimensional array l[ON6/3] analogous to the layer of the Cdl2 structure type. The hydrate Et2NH • 0.5 H20 , m.p. -20 °C, is monoclinic with 12/a, Z = 8 , a -8.324, b = 15.090, c = 10.006 Ä and ß -103.34° at -100 °C. The O and N atoms are linked into a four-membered ring spiro chain ifON^] analogous to that in SiS2. The hydrate l-BuNH2 0.5H20 (m.p. -57 °C, monoclinic, P 2x/c, Z = 8,a = 14.994, b = 5.086, c = 16.15 A .,ß -103.45° at -81 °C) contains essentially the same hydrogen-bonded array as the hydrate EtNH,-0.5H20 (see above). l-BuNH2-H20 , the only monohydrate in­ vestigated besides the three hemihydrates (m.p. -60 °C, monoclinic, C 2/m, Z = 4, a = 9.68, b = 4.238, c = 15.58 A, ß = 94.9° at -81 °C), has also a two-dimensional H20/N H 2 partial structure, similar to a subset of the three-dimensional network of the adduct NH3 H20 of analogous composition. Z ur Bildung kristalliner Hydrate von einfachen Alkylaminen gibt es eine Reihe von z. T. schon recht frühen Untersuchungen mit allerdings nicht immer eindeutigen und widerspruchsfreien Ergebnissen. Die Bestimmung von Kristallstrukturen be­ schränkte sich bisher auf einige höhere Hydrate mit W assergehalten oberhalb denen von Pentahydra-ten. Solche wasserreichen Phasen wurden als Cla-thrathydrate oder Semiclathrate charakterisiert. Sie enthalten nämlich dreidimensional vernetzte W irtsstrukturen aus den W assermolekülen und in deren m ehr oder weniger gestörten polyedrischen H ohlräum en die fast immer auch noch H-brücken-aktiven (N -H — O und/oder O -H -N) Am in­ moleküle als Gastspezies [2]. Gegenstand der vorliegenden A rbeit sind nun erstmals K ristallstrukturen niederer Hydrate von * Sonderdruckanforderungen an Prof. Dr. D. Mootz. 
  Reference    Z. Naturforsch. 49b, 243—249 (1994); eingegangen am 27. Oktober 1993 
  Published    1994 
  Keywords    Amine Hydrates, Lower Hydrates, Melting Diagram, Crystal Structure, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/49/ZNB-1994-49b-0243.pdf 
 Identifier    ZNB-1994-49b-0243 
 Volume    49 
25Author    Stefan Horstmann, Wolfgang SchnickRequires cookie*
 Title    Synthese, Kristallstruktur und Eigenschaften von Tetraaminophosphoniumiodid [P(NH2)4]I Synthesis, Crystal Structure, and Properties of Tetraaminophosphonium Iodide [P(NH2)4]I  
 Abstract    The title compound has been prepared starting from phosphorothionic triamide SP(N H 2)3 by methylation of the sulfur atom and subsequent ammonolysis reaction in dry acetonitrile and dichloromethane, respectively, both at room temperature. Suitable single crystals are obtained from an acetonitrile solution in a temperature gradient between 70 °C and room temperature. The crystal structure o f [P(N H 2)4]I has been determined by single crystal X-ray methods (P 4!nbm\ a = 842.6(2), c = 486.7(2) pm, Z = 2). In the solid [P(NH2)4]+-and I~-ions are found with significant N -H -I -h y d r o g e n bonding interactions between anions and cations (H —I: 276.4 pm). The P -N -b o n d length in the cation (160.7(2) pm) represents the shortest P -N H 2 bond distance reported to date indicating a significant electrostatic strengthening. The condensation behaviour of [P(N H 2)4]I in solution and in the solid has been investigated. 
  Reference    Z. Naturforsch. 49b, 1381—1386 (1994); eingegangen am 5. Mai 1994 
  Published    1994 
  Keywords    Tetraaminophosphonium Salt, Synthesis, Crystal Structure, Hydrogen Bonding, Condensation Reactions 
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 TEI-XML for    default:Reihe_B/49/ZNB-1994-49b-1381.pdf 
 Identifier    ZNB-1994-49b-1381 
 Volume    49 
26Author    DietrichK. Breitinger, Roman BreiterRequires cookie*
 Abstract    ?ram-(NH4)2[R u (S 0 3)2(N H 3)4]-4 H 20 (1) (m onoclinic, P l x!n\ a = 629.8(3), b = 1000.6(2), c = 1345.7(5) pm, ß = 112.25(4)°, Z = 2; R = 0.021; R w = 0.017) is obtained as pale greenish-yellow crystals by reaction of /ra « s-[R u (S 0 3H)2(N H 3)4] (2) with aqueous ammonia, and crys­ tallization at +5 °C. The compound, when isolated, is stable at room temperature for only a few days even under inert gas, but persists under the mother liquor. In the centrosymmetric anion frö/?s-[Ru(S03)2(N H 3)4]2~ the bonds Ru-S = 230.5(1) pm are significantly longer than in the neutral complex 2 (227.6(1) pm), whereas the Ru-N bonds are the same in both com ­ plexes within experimental error (averages 214.1 and 214.0 pm). Hence, the mutual trans-influence of the sulfite ligands is weakened on protonation; the bonding of the co-ligands in c/s-position is not affected. The internal structure o f the sulfite ligand in 1 with long S-O bonds (average 151.2(5) pm) and small angles O-S-O (average 106.1(6)°) and the weakened Ru-S bond are a good match. The structure of 1 is held together by a complex network of hydrogen bonds, in which all potential hydrogen-bond donors (O H 2, N H 4+, N H 3) and accep­ tors (H 20 , S 0 3) are involved. The structural findings are reflected in the vibrational spectra. 
  Reference    Z. Naturforsch. 51b, 517 (1996); received August 25 1995 
  Published    1996 
  Keywords    Ruthenium(II) Sulfito Complex, Crystal Structure, m ws-Influence, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/51/ZNB-1996-51b-0517.pdf 
 Identifier    ZNB-1996-51b-0517 
 Volume    51 
27Author    Thomas Dahlems, Dietrich Mootz, Michaela SchillingRequires cookie*
 Title    Zweidimensionales Eis und H50 2+-Ionen. Zur Bildung und Struktur tiefschmelzender molekularer und ionischer Hemi-bis Hexahydrate halogenierter Essigsäuren CCl"F3."COOH (n = 1 bis 3) [1] Two-Dimensional Ice and H 50 2+ Ions. On Formation and Structure of Low-Melting Molecular and Ionic Hemi-through Hexahydrates of Haloacetic Acids CCl"F3."COOH (n = 1 to 3) [1]  
 Abstract    Hydrate formation o f haloacetic acids CCl"F3_"COOH (n = 1, 2, 3) has been studied by D TA and tem perature-dependent X-ray powder diffraction, and evidence obtained for five phases, all melting at temperatures below ambient. The hydrates have been confirmed and further characterized by their crystal structures at -1 5 0 °C. Three lower hydrates, CC12F C O O H 0.5H -> 0 (space group P2,/c and Z = 8 formula unites per unit cell), CC1F2C 0 0 H H 20 (P2,/c, Z = 4), and CC1F2C 0 0 H -4 H 20 (P I, Z = 2), have molecular structures with the acid and water m olecules hydrogen-bonded in two-dimensional arrays. The structures of the remaining hydrates, CCl2F C O O H -6H 20 and CC13C 0 0 H -6 H 20 (sim i­ lar, but not isotypic, both P 1 and Z = 2), are ionic, as (H s0 2+)(C X 3C 0 Ö) -4 H 20 , and three-dimensional. The neutral water molecules are hydrogen-bonded in ice-like layers rare in crystal chemistry. A lso, CCl2FCOOH is established only as the second acid o f which a lower hydrate is molecular and a higher one ionic. 
  Reference    Z. Naturforsch. 51b, 536 (1996); eingegangen am 16. Oktober 1995 
  Published    1996 
  Keywords    Crystal Structure, Haloacetic Acid Hydrate, Hydrogen Bonding, Melting Diagram 
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 TEI-XML for    default:Reihe_B/51/ZNB-1996-51b-0536.pdf 
 Identifier    ZNB-1996-51b-0536 
 Volume    51 
28Author    Antje Albert, D. Ietrich, M. OotzRequires cookie*
 Title    Formation and Crystal Structures of the Hydrates of 18-Crown-6 [1]  
 Abstract    The melting diagram of the system 18-crown-6/water has been set up and the existence of four binary hydrates confirmed. Crystal structures have been determined for three of these, in addition to that for the hexahydrate already published. The hydrates are monoclinic, a tetrahydrate (previously reported as a 4.5-hydrate) with space group P2|/c and Z = 2 formula units per unit cell, an octahydrate with I2/a and Z = 4, and a dodecahydrate with P2i/n and Z= 2. In each structure the crown ether molecule has the (pseudo) D.^ conformation common for many of its complexes, and is immediately hydrogen-bonded by a group of four water molecules in a similar, characteristic pattern. In the tetrahydrate, with one of the waters disordered, the total connectivity is that of a 1D chain, while the overall structures of the octa-and dodecahydrate are 3D networks. Four of the six independent water molecules in the dodecahydrate are linked with each other into a rare 2D ice-like layer. 
  Reference    Z. Naturforsch. 52b, 615—619 (1997); received January 15 1997 
  Published    1997 
  Keywords    Crown Ether, Crystal Structure, Hydrate, Hydrogen Bonding, Melting Diagram 
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 TEI-XML for    default:Reihe_B/52/ZNB-1997-52b-0615.pdf 
 Identifier    ZNB-1997-52b-0615 
 Volume    52 
29Author    Stephanie Janeda, Dietrich Mootz, HerrnRequires cookie*
 Title    Niedere Hydrate aliphatischer primärer Amine. Neue Untersuchungen zu Bildung und Struktur [1] Lower Hydrates of Aliphatic Primary Amines. New Studies of Formation and Structure [1]  
 Abstract    After earlier work in this laboratory on lower hydrates of amines, the melting diagram of the system 1 ,8-diaminooctane/water and six new crystal structures of hemi-and monohydrates of terminal primary n-alkylamines and diamines have been determined. In the hydrates 1 -PrNH2 • 0.5 H20 (space group C 2/m with Z = 4 formula units per unit cell), l-HexNH2 • 0.5 H20 (PI, Z = 2) and H2N(CH2)nNH2 • H20 with n = 4, 6, 8 (P 2x/c, Z = 4), the O and N atoms are hydrogen-bonded into a two-dimensional array analogous to the mutual coordination of cations and anions in the Cdl2 structure type: [ON6/3] ~ [CdI6/3]. In the hydrate H2N(CH2)2NH2 • H20 (C 2/c, Z = 4), the H20/N H 2 partial structure is three-dimensional but can be reduced, by neglecting the longest H bond, to an array which is again just two-dimensional and related now to the red Hgl2 structure type: [ON4y2] ~ [HgI4/2], In all the monohydrates, the arrays as defined are crosslinked by the alkylene cnains of the bifunctional amine molecules. 
  Reference    Z. Naturforsch. 53b, 1197—1202 (1998); eingegangen am 22. Mai 1998 
  Published    1998 
  Keywords    Amine Hydrates, Hydrates, Melting Diagram, Crystal Structure, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-1197.pdf 
 Identifier    ZNB-1998-53b-1197 
 Volume    53 
30Author    Di, Stephanie Janeda, Dietrich MootzRequires cookie*
 Title    Di-bis Pentahydrate von fünf Alkylendiaminen. Eine Fallstudie zu ein-und zweidimensionalen Wasserpolymeren in Festkörpern [1]-to Pentahydrates of Five Alkylenediamines. A Case Study of One-and Two-Dimensional Water Polymers in Solids [1]  
 Abstract    The crystal structures of five low-melting hydrates of »-alkane-a,u;-diamines, H2N(CH2)"NH2 • x H20 , for short C" ■ x W, have been determined. As a common feature, the water molecules are mutually linked by hydrogen bonds O-H -O to form low-dimensional polymers. These are a meandering chain in C2 • 2 W (space group I 2la, Z -4 formula units per unit cell), a zig zag chain in C6 • 2 W (P 2,/c, Z = 2), a ribbon of consecutively condensed five-membered rings in C3 • 3 W (P 2,/c, Z = 4) and a layer of condensed and spiro-linked rings of varying size each in C7 • 3 W (P i, Z = 4) and C4 • 5 W (C 21c, Z = 4). Further hydrogen bonding, between the water polymers and the bifunctional amine molecules, leads to overall connectivities which are three-dimensional in each structure. 
  Reference    (Z. Naturforsch. 54b, 103—108 [1999]; eingegangen am 7. September 1998) 
  Published    1999 
  Keywords    Amine Hydrates, Hydrates, Melting Diagram, Water Polymers, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-0103.pdf 
 Identifier    ZNB-1999-54b-0103 
 Volume    54 
31Author    M. Athias, O. SengeRequires cookie*
 Title    Fixation o f Neutral M olecules in the Binding Cavity of Nonplanar Porphyrins -A Third Dodeca- phenylporphyrin Modification with NH -Solvent Hydrogen Bonding  
 Abstract    Reprint requests to Priv.-Doz. Dr. M. O. Senge. Fax: 0 3 0 -8 3 8 -4 2 4 8 . E-mail: mosenge@chemie.fu-berlin.de A third crystalline modification of dodecaphe-nylporphyrin is described in which the pyrrole ni­ trogen atoms are hydrogen-bonded to two etha­ nol molecules. This is the first crystallographic proof for the accessibility of nitrogen atoms in saddle-distorted free base porphyrins for hy­ drogen bonding. N o such coordination is possible in either planar or ruffled porphyrins. Thus, the possibility exists to utilize conformationally dis­ torted porphyrins for the binding of neutral m ole­ cules. 
  Reference    Z. Naturforsch. 54b, 821 (1999); received March 2 1999 
  Published    1999 
  Keywords    Porphyrins, Steric Strain, Conformational Flexi­ bility, Crystal Structure, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-0821_n.pdf 
 Identifier    ZNB-1999-54b-0821_n 
 Volume    54 
32Author    Christoph Mockenhaupt, Ralf Eßmanna, HeinzDieter LutzRequires cookie*
 Title    [Ni(NH3 )6]S0 4 : Kristallstruktur und Infrarotspektren [Ni(NH3)6]S 0 4: Crystal Structure and Infrared Spectra  
 Abstract    The crystal structure of [Ni(NH3)6]S 0 4 has been determined by single-crystal X-ray dif­ fraction (P2,/c; Z = 4; a = 705.0(1), b = 1195.2(2), c = 1180.0(2) pm, ß = 96.14(3)°; 2271 reflections; R x = 3.94%). In the hitherto unknown structure type, both the [Ni(NH3)6]2+ and the S 0 42-ions form chains along [100], The six crystallographically different ammine ligands of the distorted [Ni(NH3)6]2+ octahedra are involved in hydrogen bonds to six crystallographically equivalent S 0 42-ions (site symmetry C |). The strength of the hydrogen bonds differs strongly (i'od ° f matrix isolated N H 2D molecules: 2378 -2494 cm -1 , N -O distances: 272 -340 pm). The temperature evolution of the IR bands reveals the decrease of the dynamic orientational disorder of the N H 3 molecules with decreasing temperature. 
  Reference    Z. Naturforsch. 54b, 843—848 (1999); eingegangen am 8. März 1999 
  Published    1999 
  Keywords    Hexammine Nickel Sulfate, Ammoniates, Crystal Structure, IR Data, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-0843.pdf 
 Identifier    ZNB-1999-54b-0843 
 Volume    54 
33Author    Michael Schur, Astrid Gruhl, Christian Näther, Inke Jeß, Wolfgang BenschRequires cookie*
 Title    (CH3NH3)2Sb2S4, a New Thioantimonate(III) with Building Groups Stabilized by Hydrogen Bonds  
 Abstract    (CH3NH3)2Sb2S4 has been isolated from the reaction of antimony with sulfur in the presence of manganese in an ethanolic solution of methylamine under solvothermal conditions. Two pyramidal SbS? units are linked via common S-S edges to give dimeric Sb2S42-anions, which are joined via secondary Sb --S contacts of 3.074(2) and 2.975(2) A forming infinite 1 [SbS2]-^n chains consisting of edge-linked xp-SbS4 trigonal bipyramids. The cis configuration o? the Sb2S42-anions in the title compound is observed for the first time. A specific hydrogen-bonding pattern between the amino-hydrogen and the sulfur atoms stabilizes this configuration and gives rise to anionic layers separated by the methyl groups. 
  Reference    Z. Naturforsch. 54b, 1524—1528 (1999); received July 21 1999 
  Published    1999 
  Keywords    Thioantimonates, Solvothermal Synthesis, Crystal Structure, Hydrogen Bonding, Polymerie Anions 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-1524.pdf 
 Identifier    ZNB-1999-54b-1524 
 Volume    54 
34Author    Hans-Helmut Paul, Helmut Sapper, Wolfgang LohmannRequires cookie*
 Title    H -N M R Investigations on the Hydrogen Bond Formation between the Tranquilizers Diazepam and Nitrazepam and Some Nucleobases  
 Abstract    The form ation of hydrogen bonds between the minor tranquilizers diazepam and nitrazepam and a few nucleobases was studied in deuterochloroform solution by means of proton m agnetic resonance spectroscopy. The therm odynam ic and spectroscopic data of the associations were evaluated on the basis of a dim er model, using the concentration dependent shifts of the protons involved in hydrogen bonds. The interactions of nitrazepam (Zl//0= —10 to —21 k j/m o l; AG°25 — 0 . 2 to —7.4 kj/m ol) were found to be stronger than those of diazepam (A H ° = — 1 0 to — 13 k j/m o l; A G ls = 6.0 to 6.4 k j/m o l). The various binding sites of the benzodiazepines for hydrogen bonds are discussed. 
  Reference    Z. Naturforsch. 33c, 870 (1978); received June 16/Septem ber 14 
  Published    1978 
  Keywords    1978 1, 4-Benzodiazepines, Hydrogen Bonding, Nucleobases, Dimer Model 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0870.pdf 
 Identifier    ZNC-1978-33c-0870 
 Volume    33 
35Author    Sophie Creuzet, TeresaM. Iranda, Jean-M Arc DucruetRequires cookie*
 Title    Comparison of Experimental and Calculated Hydrogen Bonding Properties of Some Urea and Triazine Inhibitors of Photosystem II  
 Abstract    Previous studies o f structure/activity relationships o f photosystem II inhibitors, including com parisons o f their inhibitory power in herbicide-resistant and susceptible chloroplasts, have led to predict the role o f hydrogen bonding, associated to hydrophobicity, in the binding onto the Qb site. The crystallographic structures o f bacterial reaction centers now allow these bonds to be identified. In order to be able to understand the binding o f various herbicides and the effects o f resistance mutations within the Q B site, a reliable estimation o f hydrogen bonding strengths is needed. We show here, by calculating interactions with model com pounds, con ­ trolled by physicochemical measurements, that the hydrogen bonding properties o f the C = X nucleophilic moiety present in most PS II inhibitors are different for triazines as compared to urea or amide derivatives. Semiempirical methods (AM 1) fail to reproduce the energies o f hy­ drogen bonds between a triazine ring nitrogen and a phenolic proton. An empirical method (SI BFA), designed to reproduce interaction energies, has been adapted with the aim o f calculat­ ing the binding energies o f various herbicides with models o f the Q B site. 
  Reference    Z. Naturforsch. 48c, 179 (1993); received November 12 1992 
  Published    1993 
  Keywords    Herbicide, Herbicide Resistance, Hydrogen Bonding, M olecular Calculation, Photosystem II 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0179.pdf 
 Identifier    ZNC-1993-48c-0179 
 Volume    48 
36Author    M. Weisser, W. WeyrichRequires cookie*
 Title    The Electronic Structure of Hydrogen Bonding in a-Oxalic Acid Dihydrate  
 Abstract    Compton spectra of a-oxalic acid dihydrate single-crystal slices and powder samples were mea-sured in a helium atmosphere using 59.537 keV 241 Am radiation. In the anisotropic case, the scattering vector was oriented parallel to the shortest hydrogen bond, in the direction of the C = O bond, parallel to the C — O bond and perpendicular to the (a, c)-plane. The comparison of theoretical reciprocal form factors, calculated with a local density-approximation (LDA) method for an a-(COOH) 2 • 2H 2 0 cluster in triple-zeta basis-set quality, with the experimental data has demon-strated that there is a considerable influence of intermolecular interactions on the electronic struc-ture. Further calculations including the intermolecular interactions of the first coordination sphere by symmetrical orthogonalisation of the LDA wave functions clearly improved the agreement of experiment and theory. A theoretical analysis of the reciprocal form factor B a (s) in the direction of the three different hydrogen bonds of a-oxalic acid dihydrate on the basis of the cluster calculations has shown that in the region above s = 1.9 Ä all these bonds are dominated by electrostatic attrac-tion and exchange repulsion of the donor and the acceptor system. 
  Reference    Z. Naturforsch. 48a, 315—324 (1993); received January 28 1993 
  Published    1993 
  Keywords    a-Oxalic acid dihydrate, Compton spectroscopy, Hydrogen bonding, Reciprocal form factor, Density functional calculations 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0315.pdf 
 Identifier    ZNA-1993-48a-0315 
 Volume    48 
37Author    G. Gowri, Tina Briere, Sudha Srinivas, Hwa-Suck Cho, T. P. Das, M. Frank, W. Kreische, K.V S Rama RaoRequires cookie*
 Title    Theory of Nuclear Quadrupole Interactions in Solid Fluoromethanes with Implanted l9 F* Nuclei. Coupling of HF* and Host Molecule  
 Abstract    The Quadrupole Coupling Constant e 2 qQ and Asymmetry Parameter rj of fluorine for fluorine-substitute methane compounds are calculated using the Hartree-Fock Roothaan procedure. Our results are compared with experimental data from measurements by the Time Differential Perturbed Angular Distribution (TDPAD) technique using excited 19 F* (spin 5/2) nuclei. The theoretical e 2 qQ's for the 19 F* nuclei in the fluoromethanes are in good agreement with experimental results. For CH 2 F 2 and CHC1F 2 molecules, where finite rj are expected from symmetry considerations, our results for ri are small, 0.12 and 0.05 respectively, in agreement with experimental observation. Besides the F* coupling constants associated with the C-F bonds in fluoromethanes, additional interesting NQI parameters, close to those in solid hydrogen fluoride, are observed in the TDPAD measurements. It is demonstrated through investigations of the total energies and electric field gradients that these additional NQI parameters for the fluoromethanes can be explained by a HF* molecule hydrogen-bonded through the hydrogen to a fluorine atom in the host molecular systems. This complexing of an ionic molecule to the host molecules in organic solids containing strongly electronegative atoms is expected to be a general feature in both implantation and conventional techniques. 
  Reference    Z. Naturforsch. 51a, 565—571 (1996); received March 8 1996 
  Published    1996 
  Keywords    Nuclear Quadrupole Interaction, 19 F* (nuclear excited state), Fluoromethane, Hartree-Fock Calculation, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0565.pdf 
 Identifier    ZNA-1996-51a-0565 
 Volume    51 
38Author    Dietrich Mootz, Angelika Merschenz-QuackRequires cookie*
 Title    Zur Kenntnis der höchsten Hydrate der Schwefelsäure: Bildung und Struktur von H2S 0 4*6,5 H20 und H2S 0 4-8 H20 [1] On the Highest Hydrates of Sulfuric Acid: Formation and Structure of H 2S 0 4 -6.5 H 20 and H 2S 0 4-8 H 20 [1]  
 Abstract    The phase diagram of the system sulfuric acid-water in the range 80—100 mol % H20 was reinvestigated by low-temperature DTA and X-ray powder diffraction. The results are compared with other studies in the literature. The crystal structures of the hydrates H2S 0 4 • 6.5 H20 , melting incongruently at —54 °C, and H2S 0 4-8 H 20 (metastable) were determined to be those of oxonium salts, (H50 2)(H 70 3)S 0 4-1.5 H20 and (H50 2)2S 0 4-4 H20 , respectively. 
  Reference    Z. Naturforsch. 42b, 1231 (1987); eingegangen am 1. Juni 1987 
  Published    1987 
  Keywords    System H2S 0 4—H20, Sulfuric Acid, Hydrate Structures, Hydrogen Bonding, Oxonium Salts 
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 TEI-XML for    default:Reihe_B/42/ZNB-1987-42b-1231.pdf 
 Identifier    ZNB-1987-42b-1231 
 Volume    42 
39Author    Dietrich Mootz, Dieter StäbenRequires cookie*
 Title    Clathrathydrate von Tetramethylammoniumhydroxid: Neue Phasen und Kristallstrukturen [1] C lathrate Hydrates of Tetramethylammonium Hydroxide: New Phases and Crystal Structures [1]  
 Abstract    The melting diagram o f the system tetramethylammonium hydroxide-water has been re­ investigated in the region o f 6 6 .6 7 -100 mol% H 20 , using D T A , DSC and temperature-depend-ent X-ray powder diffraction. This was done as correction and supplementation o f a previous study in the same laboratory (D. M ootz, R. Seidel, J. Incl. Phenom. 8 , 139 (1990)). The system is now considered to contain as many as eight stable hydrates, three o f them dimorphic with a low-temperature a and a high-temperature ß form. The com positions are Me4N 0 H -x H 20 with x = 2 (a and ß), 4, 4.6 (a and ß), 5 (a and ß), 6.67, 7.5, 8.75 and 10. A second 7.5-hydrate, called 7 .5 a in the previous study, is now regarded as metastable. -Structure determinations have been performed for the new phases with x = 4.6 (a), 6.67 and 8.75. The 4.6a-hydrate, transforming to 4.6ß at 32 °C, is cubic with space group Pa 3 and Z = 40 formula units per unit cell. The lattice constant is a = 21.493Ä at -1 6 0 °C. The 6.67-hydrate, melting with decom ­ position at 13 °C, is monoclinic with space group P 2 ,/w and Z = 6 . It was studied as the O-deuterated isotype with unit-cell dimensions a -11.874, b = 20.019, c = 8.272 Ä and ß = 103.84° at 3 °C. The 8.75-hydrate, melting with decom position at -3 °C, is cubic with space group 143 d, Z = 16 and a -18.38(2) Ä at -2 0 °C. The three structures, as most others o f the higher hydrates o f the system studied previously, are those o f polyhedral clathrate hydrates. For the hydrates 4 .6 a and 6.67 deviations o f the anionic, i.e. proton-deficient, new water structures from being fully four-connected are described in detail. The 8.75-hydrate is isostruc-tural with the hitherto unparalleled 9.75-hydrate o f /-butyl amine. -The phase identity and structure o f the 4.6/?-hydrate were recognized as those attributed to an erroneously assumed 5/?-phase in the previous study. 5 ß now denotes the room-temperature form o f the penta-hydrate, previously called 5 a. The present 5 a is another o f the new phases and the only one o f the system with its structure still undetermined. 
  Reference    Z. Naturforsch. 47b, 263—2 (1992); eingegangen am 8. Juli 1991 
  Published    1992 
  Keywords    Clathrate Hydrates, Crystal Structures, Hydrogen Bonding, M elting Diagram, Tetramethylammonium Hydroxide 
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 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-0263.pdf 
 Identifier    ZNB-1992-47b-0263 
 Volume    47 
40Author    C. Hristian, Robl, Stephanie HentschelRequires cookie*
 Title    Unendliche Y2(H2O)10[C6(COO)6]-Ketten in Y2[C6(COO)6] * 14H20  
 Abstract    Infinite Chains o f Y2(H2O)10[C6(COO)6] in Y 2[C6(COO)6] • 14H20 Colourless monoclinic single crystals of Y ^C ^C O O)^ • 14H20 were grown in aqueous silica gel (space group P 2 Jn, a = 847.5(1), b = 923.4(2), c = 1632.0(3) pm, ß = 100.33(1)°, Z = 2, 223 param eters, 1784 reflections, Rg = 0.0357). Y 3+ is coordinated by 5 water molecules and 3 oxygen atom s o f the mellitate anion in a dodecahedral fashion. Y 3+ and [C6(COO)6]6-ions are linked by coordinative bonds, yielding infinite chains o f com position Y 2(H 2O)10[C6(COO)6] extending parallel to [100], Hydrogen bonds connect adjacent chains. 
  Reference    Z. Naturforsch. 47b, 1561—15 (1992); eingegangen am 5. M ärz 1992 
  Published    1992 
  Keywords    Y ttrium Mellitate, X-Ray, Chain Structure, Hydrogen Bonding, Differential Thermal Analysis 
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 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-1561.pdf 
 Identifier    ZNB-1992-47b-1561 
 Volume    47