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1	Author	Snezhana Bakalova	Requires cookie*
	Title	S
	Abstract	o lv e n t E f fe c ts o n th e F lu o re s c e n c e P r o p e r tie s o f M e th y ld ih y d ro q u in o lin o n e s The absorption and fluorescence spectra and the fluorescence quantum yields of two methyl-2,3-dihydro-4(lH)-quinolinones in various solvents are reported. In some solvents deuteration-induced fluorescence enhancement has been observed. The solvent effects in aprotic solvents are consistent with the general type of solvent interaction. For protic solvents, solute-solvent complexation in the excited state is suggested.
	Reference	Z. Naturforsch. 46a, 823—827 (1991); received May 24 1991
	Published	1991
	Keywords	Fluorescence, Dihydroquinolinones, Hydrogen bond
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	TEI-XML for	default:Reihe_A/46/ZNA-1991-46a-0823.pdf
	Identifier	ZNA-1991-46a-0823
	Volume	46

2	Author	Matthias Frey, PeterG. Jones	Requires cookie*
	Title	Secondary Bonding Interactions in Some Halopyridinium and Dihalopyridinium Halides
	Abstract	The packing motifs of 2-and 3-chloropyridinium chloride can be interpreted in terms of classical hydrogen bonds N+-H -C 1~ and non-classical C-H--C1" interactions, with halo-gen-halogen contacts playing a subordinate role. In the corresponding bromine derivatives, Br--Br interactions are much more important. Of the dihalo derivatives, 3,5-dichloropyridinium chloride crystallises with classical linear hydrogen bonds of the form N+-H -C1_ , but its chlorine-chlorine interactions are at best weak; the corresponding bromine derivative displays aggregates of bromine atoms and three-centre hydrogen bonds N+-H (-B r")2 .
	Reference	Z. Naturforsch. 56b, 889—896 (2001); received May 15 2001
	Published	2001
	Keywords	Pyridinium, Halides, Hydrogen Bonds
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	TEI-XML for	default:Reihe_B/56/ZNB-2001-56b-0889.pdf
	Identifier	ZNB-2001-56b-0889
	Volume	56

3	Author	M. Grottel, A. Kozak, Z. Pająk	Requires cookie*
	Title	*H and 19 F NMR Study of Cation and Anion Motions in Guanidinium Hexafluorozirconate
	Abstract	Proton and fluorine NMR second moments and spin-lattice relaxation times of polycrystalline guanidinium hexafluorozirconate and its deuterated analogue were studied in laboratory (60 MHz) and rotating (H, = 20 G) frames over a wide range of temperature. An analysis of the experimental results enabled us to reveal a dynamical inequivalence of two crystallographically independent cations and an unexpected high mobility of nonspherical anion dimers. A comparison of the ions dynamics in 2:1 complex studied with the guanidinium 1:1 and 3:1 complexes has shown a significant contribution of the hydrogen bonds to the potential barriers hindering the anion reorien-tations. At low temperatures a proton motion in the hydrogen bond and at 400 K a solid-solid phase transition have been discerned.
	Reference	Z. Naturforsch. 51a, 991—996 (1996); received May 14 1996
	Published	1996
	Keywords	NMR, Ion Motions, Hydrogen Bonds, Phase Transitions
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	TEI-XML for	default:Reihe_A/51/ZNA-1996-51a-0991.pdf
	Identifier	ZNA-1996-51a-0991
	Volume	51

4	Author	Nobuo Nakamura, Hirotsugo Masui, Takahiro Ueda	Requires cookie*
	Title	Effect of Intermolecular Hydrogen Bonding on the Nuclear Quadrupole Interaction in Imidazole and its Derivatives as Studied by ab initio Molecular Orbital Calculations
	Abstract	Ab initio Hartree-Fock molecular orbital calculations were applied to the crystalline imidazole and its derivatives in order to examine systematically the effect of possible N-H---N type hydrogen bond-ing on the nuclear quadrupole interaction parameters in these materials. The nitrogen quadrupole coupling constant (QCC) and the asymmetry parameter (r?) of the electric field gradient (EFG) were found to depend strongly on the size of the molecular clusters, from single molecule, to dimer, trimer and to the infinite molecular chain, i.e., crystalline state, implying that the intermolecular N-H -N hydrogen bond affects significantly the electronic structure of imidazole molecule. A certain correla-tion between the QCC of l4 N and the N-H bond distance R was also found and interpreted on the basis of the molecular orbital theory. However, we found that the value of the calculated EFG at the hy-drogen position of the N-H group, or the corresponding QCC value of 2 H, increases drastically as /C* when R is shorter than about 0.1 nm, due probably to the inapplicability of the Gaussian basis sets to the very short chemical bond as revealed in the actual imidazole derivatives. We suggested that the ob-served N-H distances in imidazole derivatives should be re-examined.
	Reference	Z. Naturforsch. 55a, 315—322 (2000); received August 26 1999
	Published	2000
	Keywords	Hydrogen Bond, Nuclear Quadrupole Interaction, Molecular Orbital, Imidazole
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	TEI-XML for	default:Reihe_A/55/ZNA-2000-55a-0315.pdf
	Identifier	ZNA-2000-55a-0315
	Volume	55

5	Author	Taka-Aki Nihei, Shin'. Ichi, Ishimaru, Ryuichi Ikeda	Requires cookie*
	Title	C1 NQR Studies of Hydrogen Transfer in Crystalline /7-Chlorobenzoic Acid
	Abstract	35 C1 NQR frequencies and spin-lattice relaxation times 7, Q were measured inp-ClC 6 H 4 C0 2 H(PCB A) and p-ClQF^CC^DtPCBA-d,) at 77-333 K. T lQ in PCB A gave a shallow minimum of 8.0 ms at ca. 110 K, which could be explained by a double proton transfer mechanism in the carboxylic acid dimer referring to *H NMR data giving a T 1H minimum at almost the same temperature. PCBA-d, showed temperature dependent NQR frequencies quite analogous to those in PCBA, whereas their r 1Q behavi-our was quite different in its minimum value and its temperature as well as temperature gradient. These results were explained by suppressed deuteron tunnelling and the Ubbelohde effect.
	Reference	Z. Naturforsch. 55a, 355—358 (2000); received August 27 1999
	Published	2000
	Keywords	CI NQR, Hydrogen-Bond, Hydrogen-transfer, Tunneling
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	TEI-XML for	default:Reihe_A/55/ZNA-2000-55a-0355.pdf
	Identifier	ZNA-2000-55a-0355
	Volume	55

6	Author	Masao Hashimoto, Akiko Shono, Yoshiyuki Mido, Haruo Niki, Hiroshi Hentona, Koichi Mano	Requires cookie*
	Title	Narrowing of the 3 5 CI NQR Lines of Trichloroacetamide Caused by Its Ferroelectric Phase Transition
	Abstract	Dielectric measurements on single crystals and DSC of the title compound (monoclinic, space group P2 X) revealed a ferroelectric transition at ca. 355 K (AH xs 0.5 kJ mol"Powder x-ray diffraction indicated that the high temperature phase is also monoclinic and the change in volume at the transition is very small. A displacement of hydrogen atoms is considered as responsible for the appearance of ferroelectricity. The 35 C1 NQR signals at ca. 77 K were considerably broad, but a drastic narrowing took place after the compound had once experienced the phase transition. A tentative assignment of the NQR spectrum was made from a calculation of the NQR frequencies based on the CNDO/2 method. Another phase transition was evidenced by a small drift of the DSC curve and a slight anomaly of the dielectric behavior around 358 K. The present *H NMR experi-ments gave no indication of the onset of torsional motion of the NH 2 group reported to occur at ca. 210 K.
	Reference	Z. Naturforsch. 45a, 327—333 (1990); received August 26 1989 in revised form November 1 1989
	Published	1990
	Keywords	NQR, Phase transition, Ferroelectricity, Hydrogen bond, Disordered structure
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	TEI-XML for	default:Reihe_A/45/ZNA-1990-45a-0327.pdf
	Identifier	ZNA-1990-45a-0327
	Volume	45

7	Author	R. Alf Steudel, Angela Albertsen, M. Onika Kustos, Joachim Pickardt	Requires cookie*
	Title	X-Ray Structural Analysis and Vibrational Spectra of Sodium Cysteine-S-sulfonate, +H3N C H (C 0 0 )CH 2S 20 3Na -3 /2 H 20 [1]
	Abstract	The title com pound crystallizes orthorhombically (space group C 222,) with a = 797.0, b = 870.3 and c = 2739.0 pm. The anions are zwitterions which are heavily involved in intra-and intermolecular NH --O and OH -O hydrogen bonding. The two types o f sodium cations are coordinated by six oxygen atoms each o f which belongs to either S 0 3 groups (N a 2) or water molecules and S 0 3 groups (N a l). A second type o f water molecules is not coordinated to the cations. The SS bond length is 208.2 pm. Infrared and Raman spectra o f the title com pound are reported and tentatively assigned. The SS stretching vibration is observed at 409 cm -1.
	Reference	Z. Naturforsch. 48b, 555—560 (1993); received July 23 1992
	Published	1993
	Keywords	Cysteine, S-Sulfonate, Structure, Spectra, Hydrogen Bonds
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	TEI-XML for	default:Reihe_B/48/ZNB-1993-48b-0555.pdf
	Identifier	ZNB-1993-48b-0555
	Volume	48

8	Author	Norbert Kuhn3, Joanna Fahl3, Roland Boeseb, Gerald Henkelc	Requires cookie*
	Title	Zur Reaktion von 2,3-Dihydroimidazol-2-ylidenen mit Pentafluorpyridin: Carbene als Reaktionspartner in der nucleophilen aromatischen Substitution [1] On the Reaction of 2,3-Dihydroimidazol-2-ylidenes with Pentafluoropyridine: Carbenes as Reactants in Nucleophilic Aromatic Substitution [1]
	Abstract	The 2,3-dihydro-l,3,4,5-tetraalkylimidazol-2-ylidenes 3 (R = Me, i'so-Pr) react immediately with pentafluoropyridine to form the 2-tetrafluoropyridylimidazolium salts 4 in good yields. In contrast with the tetramethyl derivative 4a, alkyl fluoride is eliminated from the isopropyl salt 4b to give 1 -isopropyl-4,5-dimethyl-2-tetrafluoropyridylimidazole, which dimerises via hydrogen bridges in the solid state (7). The X-ray structures of l,3-diisopropyl-4,5-dimethyl-2-tetrafluoropyridylimidazolium chloride (5) and 7 are reported.
	Reference	Z. Naturforsch. 53b, 881—886 (1998); eingegangen am 9. April 1998
	Published	1998
	Keywords	Carbenes, Imidazoles, Pyridines, Nucleophilic Aromatic Substitution, Hydrogen Bonds
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	TEI-XML for	default:Reihe_B/53/ZNB-1998-53b-0881.pdf
	Identifier	ZNB-1998-53b-0881
	Volume	53

9	Author	BirteA. Hrens, PeterG. Jones, Sonderdruckanforderungen An, ProfP G Dr, Jo	Requires cookie*
	Title	P olysulfonylam ine, C X X II
	Abstract	[1] N ich t-kon ven tion elle W asserstoff brücken in B is[diphenylphosphino-(diphenylphosphinselenid)m ethan]-gold(I)-di(m ethansulfonyl)am id Polysulfonylamines, CXXII. Non-Conventional Hydrogen Bonds in Bis[diphenylphosphino(diphenylphos-phinselenide)methane]gold(I) Di(methanesulfonyl)amide In the crystal structure of (dppmSe)2Au+ N (S 0 2C H 3)2-(dppm = Ph2PCH2PPh2) chains are formed from non-conventional hydrogen bonds of the type C -H --0 . Within these chains two bi furcated hydrogen bond systems are present, each involving one methylene hydrogen (H ---0 2.51, 2.65 A) and one phenyl hydrogen (H — O 2.31, 2.35 A) as donors.
	Reference	Z. Naturforsch. 54b, 1474—1477 (1999); eingegangen am 16. Juli 1999
	Published	1999
	Keywords	Gold(I), Hydrogen Bonds, X-Ray Data
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	TEI-XML for	default:Reihe_B/54/ZNB-1999-54b-1474_n.pdf
	Identifier	ZNB-1999-54b-1474_n
	Volume	54

10	Author	Maciej Kubicki3, Teresa Borowiak3, WieslawZ. Antkowiakb	Requires cookie*
	Title	Hydrogen Bonds in "Carboxyoximes": the Case of Bomane Derivatives
	Abstract	The tendency of forming mixed carboxyl-to-oxime hydrogen bonds was tested on the series of bomane derivatives: one with the acid function only (bomane-2-erajfo-carboxylic acid), one with the oxime function (2,2'-diethylthiobomane-3-oxime), and one with both oxime and carboxylic functions (bomane-2-oxime-3-endo-carboxylic acid). The crystal structures of these compounds were determined by means of X-ray diffraction. In bomane-2-^n^/o-carboxylic acid and 2,2'-diethylthiobom ane-3-oxime 'homogenic' hydrogen bonds were found, and these hydrogen bonds close eight-and six-membered rings, respectively. By contrast, in bomane-2-oxime-3-era/o-carboxylic acid 'heterogenic' hydrogen bonds between carboxylic and oxime bonds were found. This carboxylic-oxime, or 'carboxyoxime' system is almost always present in compounds which have both oxime and carboxylic groups; therefore it can be regarded as an element of supramolecular structures (synthon). The presence of such synthons can break the tendency of carboxylic acids and oximes towards crystallizing in centrosymmetric structures.
	Reference	Z. Naturforsch. 55b, 677—684 (2000); received March 16 2000
	Published	2000
	Keywords	Bom ane Derivatives, Hydrogen Bonds, Supramolecular Synthons
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	TEI-XML for	default:Reihe_B/55/ZNB-2000-55b-0677.pdf
	Identifier	ZNB-2000-55b-0677
	Volume	55

11	Author	M. S. De Giam, M. G. Iam Biagi, D.M S Esquivel	Requires cookie*
	Title	Hydrogen Bond Indices and Tertiary Structure of Yeast tRNAPhe
	Abstract	The rigidity and stability of the tertiary structure of yeast tR N A Phe is related to a bond index obtained in an IEHT (iterative extended Hückel theory) calculation. The index permits a quantitative estimate of the electron density along the hydrogen bond, having thus an appealing physical meaning. The results indicate that Hoogsteen-type bonds have, as expected, greater electronic population than Watson-Crick type ones. Other non-Watson-Crick pairs, the wobble pair and G\|5—C48, exhibit high values of the index for the N H ... O bond. In the triples, the electron density of the hydrogen bridges does not weaken (compared with the one of the pairs involved). Contour density maps are shown and dipolar moments of pairs and triples are qualitatively discussed.
	Reference	Z. Naturforsch. 38c, 621 (1983); received March 29 1983
	Published	1983
	Keywords	tRNAPhe, Tertiary Structure, Hydrogen Bond, Bond Index, Non-Watson-Crick Pairs
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	TEI-XML for	default:Reihe_C/38/ZNC-1983-38c-0621.pdf
	Identifier	ZNC-1983-38c-0621
	Volume	38

12	Author	Masao Hashimoto, Takahiro Isono, Haruo Niki, Takuya Higa	Requires cookie*
	Title	Fade-Out of 35 C1 NQR in Chloral n-Butylhemiacetal
	Abstract	Continuous wave and pulsed NQR, dielectric absorption and infrared (IR) measurements were carried out to investigate the origin of the peculiar temperature dependence of the S/N ratio of the 35 C1 NQR in the title compound. The dielectric and IR experiments evidenced a thermally activated jumping motion of the H atom participating in O-H O H-bonds. As T x and T 2 below 120 K were much longer than T 2 * of about 10 us, the line broadening in this temperature region was attributed to static lattice defects. A random freezing of the jumping motion may be the origin of the defects. In the range 120-170 K, S/N was extremely low and T 2 was less than 10 \|is, probably having a minimum in between. The short T 2 is considered to be responsible for the low S/N. A minimum of S/N at about 240 K is attributed to a 7\ minimum (less than 10 (is) at that temperature.
	Reference	Z. Naturforsch. 45a, 472—476 (1990); received August 26 1989 in revised form December 1 1989
	Published	1990
	Keywords	NQR, Relaxation times, Hydrogen bond, Dielectric absorption, Disordered structure
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	TEI-XML for	default:Reihe_A/45/ZNA-1990-45a-0472.pdf
	Identifier	ZNA-1990-45a-0472
	Volume	45

13	Author	Takashige Shimizu, Tetsuo Asaji, Daiyu Nakamura, Ryuichi Ikeda	Requires cookie*
	Title	Uniaxial Reorientation of Octahedral Complex Anions Excited in Triethylammonium Hexachlorostannate (IV) Crystals
	Abstract	The temperature dependence of the 35 C1 NQR spin-latticew relaxation time T1Q has been deter-mined for the three resonance lines observed in [(C2H5)3NH]2SnCl6. The higher frequency lines fade out around 150 K upon heating, whereas the lowest line shows up to room temperature no anomaly, although these three lines are assigned to chlorines belonging to the same complex anion. The T1Q values of the higher two lines decrease exponentially around the fade-out temperature, where T iq of the lowest line shows no such behavior. These results are explained by the onset of uniaxial reorientations of the octahedral complex ions by 90° about the Cl-Sn-Cl axis containing the lowest frequency chlorines. The activation energy (£J of this reorientation (22-24 kJ moP 1) is the lowest so far reportd for [SnCl6] 2-ions. £a about the other axes is 67 kJ mop 1 , indicating a remarkable anisotropic reorientation.
	Reference	Z. Naturforsch. 47a, 283—287 (1992); received July 19 1991
	Published	1992
	Keywords	Spin-Lattice Relaxation, NQR, NMR, Reorientational Motion, Hydrogen Bond
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	TEI-XML for	default:Reihe_A/47/ZNA-1992-47a-0283.pdf
	Identifier	ZNA-1992-47a-0283
	Volume	47

14	Author	Yoshio Kume, Maki Tokoro, Tetsuo Asaji, Ryuichi Ikeda, Daiyu Nakamura	Requires cookie*
	Title	Reorientational Motion of Hydrogen Bonded Octahedral Complex Anions in Hydrazinium Hexachlorostannate(IV), (N 2 H 5 ) 2 SnCl 6 , as Studied by 35 C1 NQR Spin-Lattice Relaxation Measurements
	Abstract	The temperature dependences of NQR frequencies and spin-lattice relaxation times, T1Q, of 35 C1 in (N2H5)2SnCl6 were measured. Four NQR signals distributed in a fairly wide frequency range were observed, the lowest-frequency line exhibiting an anomalous positive temperature coefficient. The highest-frequency line showed a steep temperature dependence. These results could be interpreted by considering the intermolecular interaction between CI and -NH2 in N2H^. Below ca. 250 K, T1Q of the upper three signals exhibited a gradual decrease upon heating, explainable by lattice vibra-tions, while a shallow Tig minimum, ascribable to the modulation of electric quadrupole interaction, was observed at ca. 11ÖK for the lowest-frequency signal. The reorientation of [SnCl6] 2 ~ was elucidated to be highly anisotropic, in that it reorients about one of the CI-Sn-Cl axes much more frequently than about the other two axes. The activation energies were determined to be 62 and 94 kj mol -1 for the respective reorientations.
	Reference	Z. Naturforsch. 47a, 288—292 (1992); received July 17 1991
	Published	1992
	Keywords	Key word: Spin-Lattice Relaxation, NQR, NMR, Reorientational Motion, Hydrogen Bond
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	TEI-XML for	default:Reihe_A/47/ZNA-1992-47a-0288.pdf
	Identifier	ZNA-1992-47a-0288
	Volume	47

15	Author	Takeshi Kyan, Hamagawa, Takahiro Isono, Masao Hashimoto	Requires cookie*
	Title	Hiroshi
	Abstract	The crystal structure of cyclohexylhemiacetal (cycHx-CH) was determined at 296 K: monoclinic, space group P2 Jc, a =1028.7 (9), b = 609.5 (1), c = 1811.9 (4) pm, and ß = 99.79 (3)°, Z -4, R = 0.0552. The three 5s Cl NQR lines in cycHx-CH, T., T2, and T2*, were measured by a pulsed method at 80-300 K. Below 200 K Tf 1 obeyed the T law well, indicating that the spin lattice relaxation is governed by lattice vibrations. The reorientation of CC13 seems to be responsible for the sharp T: drop observed above 250 K. Shoulders in the T { vs. 1/T curves indicate the presence of Ti minima at about 240 K. A fluctuation of the EFG due to a dynamic disorder of hydrogen atoms in the OH groups is assumed to explain the T x minima.
	Reference	Z. Naturforsch. 47a, 299 (1992); received July 25 1991
	Published	1992
	Keywords	Chlorine NQR, Spin-lattice relaxation, Hydrogen bond, Crystal structure
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	TEI-XML for	default:Reihe_A/47/ZNA-1992-47a-0299.pdf
	Identifier	ZNA-1992-47a-0299
	Volume	47

16	Author	Ivar Olovsson, Halina Ptasiewicz-Bak, GarryJ. Mclntyre	Requires cookie*
	Title	Superposition and Polarization Effects on the Electron Density of Lone Pairs
	Abstract	There appears to be conflicting experimental evidence on the redistribution of the electron density in the lone-pair and other regions of a molecule due to the interaction with its nearest neighbours. In some experimental as well as theoretical deformation density maps a decrease in the lone-pair density has been reported, whereas in other cases an increase has been found. It appears that two major, counteracting factors are responsible for these differences (apart from experimental errors in the diffraction studies and limited accuracy in the theoretical calculations): an increase in the lone-pair density is expected due to the polarizing influence of the neighbours, whereas simple superposition of the isolated monomer deformation densities will lead to an apparent decrease due to the overlap with the negative contours of the neighbouring atom. Depending on which of these factors is the dominant one, an increase or decrease may thus be observed. These points are illustrated by recent results on nickel sulfate hexahydrate and some other hydrogen-bonded compounds. The electron density based on the fitted deformation functions of all atoms in the structure is compared with the individual densities calculated from deformation functions of the separate monomers. In this way the effects of simple superposition of the individual densities have been studied, and a partitioning of the electrostatic and polarization contributions to the hydrogen bonds and other relatively weak bonds to the oxygen lone-pairs attempted.
	Reference	Z. Naturforsch. 48a, 3—11 (1993); received January 30 1992
	Published	1993
	Keywords	Electron density, Superposition effects, Polarization effects, Lone pairs, Hydrogen bonds
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	TEI-XML for	default:Reihe_A/48/ZNA-1993-48a-0003.pdf
	Identifier	ZNA-1993-48a-0003
	Volume	48

17	Author	Masao Hashimoto, Shuji Matsumoto, Masakazu Kunitomo, Haruo Niki, Hirotaka Odahara, Katsuji Tamaki	Requires cookie*
	Title	35C1 NQR Relaxation and Hydrogen Bond in Some Chloral Hemiacetals
	Abstract	The crystal structure of chloral ethylhemiacetal has been determined at 291 K: monoclinic, space group C f -P 2 lt Z = 2, a = 854.5(1), b = 594.0(3), c = 853.3(1) pm, ß = 108.30(2)°, R = 0.0962. A sharp decrease of the spin lattice relaxation time 7i found for the 35C1 N Q R o f the CC13 groups in chloral methyl-, ethyl-and n-heptylhemiacetals is attributed to the onset of reorientation of the group over a potential barrier o f ca. 39, 37, and 32 kJ/m ol, respectively. An unusual vs. 1/T curve with a 7i minimum superimposed on the sharp decrease of 7\ due to the reorientation was observed for each of the three Cl N Q R lines of nH p-C H . This phenom enon is tentatively ascribed to a fluctuation of EFG caused by jum ping m otion o f the hydrogen atom s in the OH groups.
	Reference	Z. Naturforsch. 49a, 279 (1994); received August 16 1993
	Published	1994
	Keywords	Crystal structure, Hydrogen bond, Chlorine N Q R, Spin lattice relaxation
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0279.pdf
	Identifier	ZNA-1994-49a-0279
	Volume	49

18	Author	J.M M Cordeiro	Requires cookie*
	Title	Effective Pair Potentials and Structure of Water
	Abstract	Classical Monte Carlo calculations have been performed in order to investigate the ability of the TIP4P, SPC, and SPCE water models to reproduce the structural features of liquid water. The simula-tions were carried out in the NPT ensemble at 4 thermodynamic conditions. The results are compared with recent neutron diffraction data. Essentially, the three models capture equally well the thermody-namic and structural features of water. Although they were parametrized to reproduce the water prop-erties at ambient conditions, the agreement with the experimental pair correlation functions was even better at supercritical conditions. This is because the effective pair potentials have some difficulty to re-produce cooperative interactions, like hydrogen bonds. These interactions are less effective at super-critical conditions, where the liquid behaves roughly like a gas
	Reference	Z. Naturforsch. 54a, 311—316 (1999); received December 16 1998
	Published	1999
	Keywords	Monte Carle Simulation, Non-polarizable Water Models, Radial Distribution Functions, Hydrogen-bonds
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	TEI-XML for	default:Reihe_A/54/ZNA-1999-54a-0311.pdf
	Identifier	ZNA-1999-54a-0311
	Volume	54

19	Author	T.Stanley Cameron, JamesD. Healy, RobertA. Shaw, Michael Woods	Requires cookie*
	Title
	Abstract	The structure of the title compound was determined by X-ray crystallography. The compound is a cyclic dimer with short N--O and N---S contacts.
	Reference	(Z. Naturforsch. 31b, 1421—1422 [1976]; received July 19 1976)
	Published	1976
	Keywords	X-ray, Crystal Structure, Phosphorus Acid-Base Cyclic Dimer, Hydrogen-Bond
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	TEI-XML for	default:Reihe_B/31/ZNB-1976-31b-1421_n.pdf
	Identifier	ZNB-1976-31b-1421_n
	Volume	31

20	Author	SvenM. Jessen, H. Orst Küppers, DeanC. Luehrs	Requires cookie*
	Title	Hydrogen Bonding in Acid Li-, Ni-, Tetrabutylammonium, and Ammonium Salts of Benzene-1,2,4,5-tetracarboxylic Acid (Pyromellitic Acid)
	Abstract	Four acid salts o f pyromellitic acid (benzene-1,2,4,5-tetracarboxylic acid) have been syn thesized and studied by X-ray diffraction and IR spectroscopy. (1) Dilithium dihydrogen py-romellitate pentahydrate, Li2[C6H 2(COO)4H 2] • 5 H zO; monoclinic, P 2 1/m, a = 6.214(2), b = 19.647(7), c = 6.592(2)Ä , ß = 115.90(2)°, Z = 2, R = 0.068, Rw = 0.067. (2) Hexaaquanickel dihydrogen pyromellitate, [N i(H 20) 6][C6H 2(C 0 0) 4H2]; monoclinic, P2/m, a = 6.528(1), b = 9.927(2), c = 6.472(1)Ä , ß = 115.57(1)°, Z = 1, R = 0.044, /?w = 0.039. (3) Tetrabutylammoni um trihydrogen pyromellitate, [(C4H 9)4N][C6H-,(COO)4H 3]; monoclinic, P 2 ,/c, a = 9.719(4), b = 18.823(8), c = 15.795(5) Ä, ß = 107.42(3)°, Z = 4, R = 0.059, Rw = 0.039. (4) Diam m onium dihydrogen pyromellitate, [N H 4],[C6H ,(CO O)4H2]; monoclinic, P 2 l/c\ a = 4.7665(6), b = 11.681(3), c = 10.149(2) Ä, ß = 102'. 19(2)°, Z = 2, R = 0.045, Rw = 0.039. Com pounds 1, 2, and 3 show very short intramolecular hydrogen bonds between adjacent carboxylic groups (O -O distances 2.384(6), 2.386(5), 2 . 3 8 7 (3) respectively). Com pound 4 forms intermolecular hy drogen bonds (O -O distance 2.642(2) A). The different hydrogen bonding modes are also evi dent in the IR spectra.
	Reference	Z. Naturforsch. 47b, 1141—1153 (1992); received October 1 1991 /March 27 1992
	Published	1992
	Keywords	Pyromellitates, Hydrogen Bonds, Crystal Structure, Acid Pyromellitates, IR Spectra
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	TEI-XML for	default:Reihe_B/47/ZNB-1992-47b-1141.pdf
	Identifier	ZNB-1992-47b-1141
	Volume	47

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