O Hydrogen Bonds (o + hydrogen_bond)

Distribution by Scientific Domains
Distribution within Chemistry


Selected Abstracts


9-Fluoro-18-hydroxy-[3.3]metacyclophane: Synthesis and Estimation of a C,F···H,O Hydrogen Bond

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2004
Hiroyuki Takemura
Abstract A cyclophane composed of fluorobenzene and phenol units was synthesized in order to observe the C,F···H,O hydrogen bond. In the crystal structure, 20% of the molecule clearly shows the intramolecular hydrogen bond and the other 80% is free from hydrogen bonding. On the other hand, a distinct low-field shift of the phenolic OH proton was observed in the 1H NMR spectrum compared to that of the F-free analog. Furthermore, O,H···F through-space coupling was observed. From the results of the crystallographic analysis, IR, and NMR spectra, the C,F···H,O hydrogen bond energy of this system was estimated to be 0.84,3.7 kJ·mol,1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]


Crystal structures and isotope effect on Na5H3(SeO4)4·2H2O and Na5D3(SeO4)4·2D2O crystals

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2010
T. Fukami
Abstract Differential scanning calorimetry (DSC) and X-ray diffraction measurements have been performed on pentasodium trihydrogen tetraselenate dihydrate Na5H3(SeO4)4·2H2O and deuterated Na5D3(SeO4)4·2D2O crystals. Any distinct anomaly around 428 K in the DSC curves for both crystals is suggested to be caused by a chemical reaction of thermal decomposition with hydrolysis at high temperature. The space group symmetry (triclinic P) and the structure parameters are determined at room temperature. The hydrogen atom in the centrosymmetric O-H(D)-O hydrogen bond of both crystals is found to be equally distributed at two equivalent sites in the bond. The expansions of two O-H-O hydrogen bonds by the substitution of deuterium are observed to be 0.016(6) and 0.011(4) Ć. The geometric isotope effect on hydrogen bonds is confirmed to be existed in Na5H3(SeO4)4·2H2O. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


9-Fluoro-18-hydroxy-[3.3]metacyclophane: Synthesis and Estimation of a C,F···H,O Hydrogen Bond

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2004
Hiroyuki Takemura
Abstract A cyclophane composed of fluorobenzene and phenol units was synthesized in order to observe the C,F···H,O hydrogen bond. In the crystal structure, 20% of the molecule clearly shows the intramolecular hydrogen bond and the other 80% is free from hydrogen bonding. On the other hand, a distinct low-field shift of the phenolic OH proton was observed in the 1H NMR spectrum compared to that of the F-free analog. Furthermore, O,H···F through-space coupling was observed. From the results of the crystallographic analysis, IR, and NMR spectra, the C,F···H,O hydrogen bond energy of this system was estimated to be 0.84,3.7 kJ·mol,1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]


Theoretical study of CH,O hydrogen bond in proton transfer reaction of glycine

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2006
P. Selvarengan
Abstract Density functional theory (DFT) calculations are used to study the strength of the CH,O H-bond in the proton transfer reaction of glycine. Comparison has been made between four proton transfer reactions (ZW1, ZW2, ZW3, SCRFZW) in glycine. The structural parameters of the zwitterionic, transition, and neutral states of glycine are strongly perturbed when the proton transfer takes place. It has been found that the interaction of water molecule at the side chain of glycine is high in the transition state, whereas it is low in the zwitterionic and neutral states. This strongest multiple hydrogen bond interaction in the transition state reduces the barrier for the proton transfer reaction. The natural bond orbital analysis have also been carried out for the ZW2 reaction path, it has been concluded that the amount of charge transfer between the neighboring atoms will decide the strength of H-bond. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]


Structural, spectroscopic, and theoretical studies of a very short OHO hydrogen bond in bis(4-(N -methylpiperidinium)-butyrate) hydrobromide

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2009
bieta Bartoszak-Adamska
Abstract The molecular structure of bis(4-(N -methylpiperidinium)-butyrate) hydrobromide, (MPBu)2HBr, has been characterized by single crystal X-ray diffraction, infrared and NMR spectroscopies, and by DFT calculations. The crystals of the title compound at 140,K are monoclinic, space group C2/c, with a,=,11.7118(4), b,=,7.8737(2), c,=,23.9240(8),Ć3,, ,,=,90.431(3)°, V,=,2206.1(1),Ć3, and Z,=,4. Two 4-(N -methylpiperidinium)-butyrate moieties are joined by a very short and centrosymmetric O.H.O hydrogen bond of 2.436(2),Ć3,. The piperidine ring adopts a chair conformation with the methyl group in the equatorial and the bulky (CH2)3COO substituent in the axial position. The broad absorption band below 1500,cm,1 in the FTIR spectrum confirms the existence of a very short O,H,O hydrogen bond. The 1H and 13C NMR spectra are interpreted on the basis of 2D experiments and the calculated GIAO/B3LYP/6-31G(d,p) magnetic isotropic shielding tensors. In the optimized structure of the complex, a 4-(N -methylpiperidinium)-butyrate zwitterion interacts with a 4-(N -methylpiperidinium)-butyric acid cation forming an O,. HO hydrogen bond of 2.580,Ć3,. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Isomeric N -(iodophenyl)nitrobenzamides form different three-dimensional framework structures

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2006
James L. Wardell
The isomeric N -(iodophenyl)nitrobenzamides, C13H9IN2O3, all form different three-dimensional framework structures. Molecules of N -(2-iodophenyl)-3-nitrobenzamide (II) are linked by a combination of N,H,O and C,H,O hydrogen bonds and a two-centre iodo,carbonyl interaction. The supramolecular structure of N -(2-iodophenyl)-4-nitrobenzamide (III) is built from one N,H,O and two C,H,O hydrogen bonds, but short I,O contacts are absent from the structure. In N -(3-iodophenyl)-2-nitrobenzamide (IV), which crystallizes with Z, = 2 in space group P21, the structure contains two N,H,O hydrogen bonds, four C,H,O hydrogen bonds, two two-centre iodo,nitro interactions and an aromatic ,,, stacking interaction. The structure of N -(3-iodophenyl)-3-nitrobenzamide (V) contains one N,H,O hydrogen bond and three C,H,O hydrogen bonds, together with a two-centre iodo,nitro interaction and an aromatic ,,, stacking interaction, while in N -(3-iodophenyl)-4-nitrobenzamide (VI), the combination of one N,H,O hydrogen bond and two C,H,O hydrogen bonds is augmented not only by a two-centre iodo,nitro interaction and an aromatic ,,, stacking interaction, but also by a dipolar carbonyl,carbonyl interaction. In the supramolecular structure of N -(4-iodophenyl)-4-nitrobenzamide (IX), which crystallizes with Z, = 2 in space group , there are two N,H,O hydrogen bonds, four C,H,O hydrogen bonds and two three-centre iodo,nitro interactions. [source]


Nine N -aryl-2-chloronicotinamides: supramolecular structures in one, two and three dimensions

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2006
Silvia Cuffini
Structures are reported here for eight further substituted N -aryl-2-chloronicotinamides, 2-ClC5H3NCONHC6H4X -4,. When X = H, compound (I) (C12H9ClN2O), the molecules are linked into sheets by N,H,N, C,H,,(pyridyl) and C,H,,(arene) hydrogen bonds. For X = CH3, compound (II) (C13H11ClN2O, triclinic with Z, = 2), the molecules are linked into sheets by N,H,O, C,H,O and C,H,,(arene) hydrogen bonds. Compound (III), where X = F, crystallizes as a monohydrate (C12H8ClFN2O·H2O) and sheets are formed by N,H,O, O,H,O and O,H,N hydrogen bonds and aromatic ,,, stacking interactions. Crystals of compound (IV), where X = Cl (C12H8Cl2N2O, monoclinic P21 with Z, = 4) exhibit inversion twinning: the molecules are linked by N,H,O hydrogen bonds into four independent chains, linked in pairs by C,H,,(arene) hydrogen bonds. When X = Br, compound (V) (C12H8BrClN2O), the molecules are linked into sheets by N,H,O and C,H,N hydrogen bonds, while in compound (VI), where X = I (C12H8ClIN2O), the molecules are linked into a three-dimensional framework by N,H,O and C,H,,(arene) hydrogen bonds and an iodo,N(pyridyl) interaction. For X = CH3O, compound (VII) (C13H11ClN2O2), the molecules are linked into chains by a single N,H,O hydrogen bond. Compound (VIII) (C13H8ClN3O, triclinic with Z, = 2), where X = CN, forms a complex three-dimensional framework by N,H,N, C,H,N and C,H,O hydrogen bonds and two independent aromatic ,,, stacking interactions. [source]


Polymorphs and pseudopolymorphs of N,N,-dithiobisphthalimide

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2002
Dorcas M. M. Farrell
N,N,-Dithiobisphthalimide, C16H8N2O4S2 (I), forms a wide range of polymorphs and solvates (pseudopolymorphs). When (I) is crystallized from methanol it yields a solvent-free polymorph (4), in Pna21 with Z, = 1, in which the molecules are linked into chains by a single C,H,O hydrogen bond: crystallization from either acetonitrile or dimethylformamide produces a monoclinic polymorph (5), in P21/c with Z, = 2, also solvent-free, in which the molecules are linked into molecular ladders. Nitromethane forms a monosolvate, C16H8N2O4S2·CH3NO2 (6), in P21/c with Z, = 1, in which the solvent molecules are linked to the molecules of (I) not only via a conventional C,H,O hydrogen bond but also via a polarized multicentre interaction involving all three C,H bonds of the solvent molecule. Chlorobenzene forms a precise hemisolvate, C16H8N2O4S2·0.5C6H5Cl (7), in P with Z, = 1, while ethylbenzene forms an approximate hemisolvate 2C16H8N2O4S2·0.913C6H5C2H5·0.087H2O (8), in P21/c with eight molecules of (I) per unit cell. In both solvates the molecules of (I) are linked, in (7) by ,,, stacking interactions augmented by weak C,H,O hydrogen bonds and in (8) by stronger C,H,O hydrogen bonds: the solvent molecules lie in isolated cavities, disordered across inversion centres in (7) and fully ordered in general positions in (8). Crystallization of (I) either from tetrahydrofuran or from wet tert -butanol yields isomorphous solvates (9) and (10), respectively, in C2/c with Z, = 0.5, in which molecules of (I) lie across twofold rotation axes and are linked by ,,, stacking interactions and very weak C,H,O hydrogen bonds, forming a framework enclosing continuous channels: highly disordered solvent molecules lie within these channels. p -Xylene and toluene form isomorphous hemisolvates (11) and (12) with unit cells metrically very similar to those of (9) and (10), but in P21/n with Z, = 1: in these two solvates the molecules of (I) are linked into a framework by very short C,H,O hydrogen bonds; the solvent molecules lie within continuous channels, but they are localized across inversion centres so that the toluene is disordered across an inversion centre. [source]


Amino-substituted O6 -benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2002
Antonio Quesada
The structures of eight 2,4,6-trisubstituted-5-nitrosopyrimidines (one of which crystallizes in two polymorphs) have been determined, including seven O6 -benzyl derivatives which are potential, or proven, in vitro inhibitors of the human DNA-repair protein O6 -alkylguanine-DNA-transferase. In the derivatives having an amino substituent at the 4-position, an intramolecular N,H,O hydrogen bond with the nitroso O as an acceptor leads to an overall molecular shape similar to that of substituted purines. There is a marked propensity for these nitroso compounds to crystallize with Z, = 2. The structure of an analogue with no nitroso group is also reported for comparative purposes. Compounds containing the N -alkyl substituents ,NHCH2COOEt, ,NHCH2CH2COOEt and ,NHCH(CH2Ph)COOEt, derived from amino acid esters, exhibit a rich variety of conformational behaviour, and in all of the nitroso compounds the bond lengths provide strong evidence for a highly polarized electronic structure. Associated with this polarization is extensive charge-assisted hydrogen bonding between the molecules, leading to supramolecular aggregation in the form of finite (zero-dimensional) aggregates, chains, molecular ladders, sheets and frameworks. [source]


Hydrated salts of 3,5-dihydroxybenzoic acid with organic diamines: hydrogen-bonded supramolecular structures in two and three dimensions

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2001
Colin J. Burchell
The trigonally trisubstituted acid 3,5-dihydroxybenzoic acid forms hydrated salt-type adducts with organic diamines. In 1,4-diazabicyclo[2.2.2]octane,3,5-dihydroxybenzoic acid,water (1/1/1) (1), where Z, = 2 in P21/c, the constitution is [HN(CH2CH2)3N]+·[(HO)2C6H3COO],·H2O: the anions and the water molecules are linked by six O,H,O hydrogen bonds to form two-dimensional sheets and each cation is linked to a single sheet by one O,H,N and one N,H,O hydrogen bond. Piperazine,3,5-dihydroxybenzoic acid,water (1/2/4) (2) and 1,2-diaminoethane,3,5-dihydroxybenzoic acid,water (1/2/2) (3) are also both salts with constitutions [H2N(CH2CH2)2NH2]2+·2[(HO)2C6H3COO],·4H2O and [H3NCH2CH2NH3]2+·2[(HO)2C6H3COO],·2H2O, respectively. Both (2) and (3) have supramolecular structures which are three-dimensional: in (2) the anions and the water molecules are linked by six O,H,O hydrogen bonds to form a three-dimensional framework enclosing large centrosymmetric voids, which contain the cations that are linked to the framework by two N,H,O hydrogen bonds; in (3) the construction of the three-dimensional framework requires the participation of cations, anions and water molecules, which are linked together by four O,H,O and three N,H,O hydrogen bonds. [source]


Migration of the proton in the strong O,H,O hydrogen bond in urea,phosphoric acid (1/1)

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2001
Chick C. Wilson
The structure of urea,phosphoric acid is reported at a large number of temperatures in the range 150,335,K from neutron diffraction data collected using a novel multiple single-crystal data collection method. The work focuses on the behaviour of the H atom involved in the short strong O,H,O hydrogen bond in this material. The position of this atom is shown to vary significantly, by around 0.035 ,Ć, as a function of temperature, becoming effectively centred at the highest temperatures studied. This result, only accessible due to the accurate determination of H-atom parameters by neutron diffraction, has implications for the potential governing the hydrogen bond. [source]


Structural characterization of protonated benzeneseleninic acid, the dihydroxyselenonium ion

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2000
Henning Osholm Sűrensen
The structure of the dihydroxyphenylselenonium ion (CHOSe) has been determined in its benzenesulfonate (CHOSe) and p -toluenesulfonate (CHOS) salts. Whereas the former salt is disordered, the latter less dense salt is well defined. This difference in crystallization behaviour is attributed to a C,H,O hydrogen bond involving the methyl group of the p -toluenesulfonate ion. The two salts display very similar hydrogen-bond arrangements and differ only with respect to the stacking of the phenyl groups. The dihydroxyselenonium ion is a strong acid with a pK value of ,0.9 determined from the variation of the 77Se chemical shift. A comparison with the two deprotonated species reveals a systematic increase in the Se,O bond lengths and the pyramidal configuration around Se with the number of protons attached. [source]


N -Cyclo­hexyl-2-[5-(4-pyridyl)-4-(p -tolyl)-4H -1,2,4-triazol-3-yl­sulfanyl]­acetamide dihydrate

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2006
Muharrem Dinçer
In the title compound, C22H25N5OS·2H2O, the mol­ecules are stacked in columns running along the b axis. In this arrangemant, the mol­ecules are linked to each other by a combination of one two-centre N,H,O hydrogen bond and four two-centre O,H,O hydrogen bonds containing two types of ring motif, viz.R44(10) and R33(11). In the crystal structure, centrosymmetric ,,, inter­actions between the triazole rings, with a distance of 3.691,(2),Ć between the ring centroids, also affect the packing of the mol­ecules. [source]


2,4-Dinitro­phenyl­hydrazine, redetermined at 120,K: a three-dimensional framework built from N,H,O, N,H,(O)2, N,H,,(arene) and C,H,O hydrogen bonds

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2006
James L. Wardell
In the title compound, C6H6N4O4, the bond distances indicate significant bond fixation, consistent with charge-separated polar forms. The mol­ecules are almost planar and there is an intra­molecular N,H,O hydrogen bond. The mol­ecules are linked into a complex three-dimensional framework structure by a combination of N,H,O, N,H,(O)2, N,H,,(arene) and C,H,O hydrogen bonds. [source]


X-ray studies of crystalline complexes involving amino acids and peptides.

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2006
XLIII.
The asymmetric unit of the dl -lysine complex of adipic acid [bis­(dl -lysinium) adipate], 2C6H15N2O2+·C6H8O42,, contains a zwitterionic singly charged lysinium cation and half a doubly charged adipate anion (the complete anion has inversion symmetry). That of the l -lysine complex (lysinium hydrogen adipate), C6H15N2O2+·C6H9O4,, consists of a lysinium cation and a singly charged hydrogen adipate anion. In both structures, the lysinium cations organize into layers inter­connected by adipate or hydrogen adipate anions. However, the arrangement of the mol­ecular ions in the layer is profoundly different in the dl - and l -lysine complexes. The hydrogen adipate anions in the l -lysine complex form linear arrays in which adjacent ions are inter­connected by a symmetric O,H,O hydrogen bond. [source]


2-Nitro­phenoxy­acetanilide: a chain of rings generated by C,H,O hydrogen bonds

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2004
Christopher Glidewell
In mol­ecules of the title compound, C14H12N2O4, the conformation is dominated by an intramolecular N,H,O hydrogen bond in which one of the nitro O atoms is the acceptor. The mol­ecules are linked by paired C,H,O hydrogen bonds [H,O = 2.41,Ć, C,O = 3.2990,(17),Ć and C,H,O = 156°] into centrosymmetric (14) dimers; these dimers are linked weakly into chains of alternating (14) and (40) rings by a second C,H,O hydrogen bond [H,O = 2.55,Ć, C,O = 3.5006,(15),Ć and C,H,O = 162°]. [source]


2-Nitroso-1,3-diphenyl-1,2,3,4-tetrahydrobenzo[b][1,6]naphthyridine

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2003
B. Sivakumar
The title compound, C24H19N3O, crystallizes in the centrosymmetric space group P21/a with one mol­ecule in the asymmetric unit. The tetra­hydro­pyridine ring has a boat conformation. The dihedral angle between the fused pyridine rings is 16.2,(1)°. The equatorial and axial orientations of the two phenyl groups with respect to the tetra­hydro­pyridine ring are confirmed. The nitroso group is coplanar with the attached C,N,C group. The interplanar angle formed between the fused tetra­hydro­pyridine and benzene planes is 13.4,(1)°. The crystal packing is stabilized by an intermolecular C,H,O hydrogen bond, which forms a C(9) graph-set chain running along the [001] direction. [source]


(12,17-Diethoxy­carbonyl-2,3,6,­7,11,­18-hexa­methyl­corrphy­cenato-­,4N)iodoiron(III) chloro­form solvate

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2001
Yoshiki Ohgo
The title complex, (diethyl 3,4,8,15,19,20-hexa­methyl-21,22,23,24-tetraazopenta­cyclo­[16.2.1.12,5.17,11.114,17]­tetracosa-1(20),2(22),3,5,7,9,11,13(24),14,16,18-undecaene-9,14-dicarb­oxyl­ate-,4N)­iodo­iron(III) chloro­form solvate, [Fe(C32H32­N4O4)I]·­CHCl3, shows an almost planar arrangement of the corrphycene moiety with a slightly distorted trapezoid pyramidal core; the FeIII atom is 0.416,(1),Ć from the plane of the C20N4 system. The Fe,N distances are 2.049,(3), 2.044,(3), 2.079,(3) and 2.075,(3),Ć. The solvated chloro­form forms a C,H,O hydrogen bond [C,O 3.107,(10),Ć] to an adjacent carbonyl O atom. This is the first X-ray structure analysis of a corrphycenatoiron(III) derivative. [source]


1,4,4-Tri­methyl-9-phenyl-8-oxa-9-aza­bi­cyclo­[3.2.2]­non-6-en-2-one

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2000
Silvia Russi
The structure of the adduct of eucarvone with nitro­so­benzene, C16H19NO2, is reported. The [3.2.2] bicyclic system corresponds to two seven-membered rings in boat and distorted chair conformations and a six-membered ring that adopts a distorted boat conformation. No conjugation is observed between the phenyl group and the N,O system. The packing is directed mainly by a C,O hydrogen bond, C,H,O-(1,,,x, ,y, z) and by intermolecular C,H,, interactions. [source]


[1a(1a,,5,,9a,)]-1,1a,4,5,7,8,9,9a-Octahydro-3-hydroxy-1,1,2,5-tetramethyl-7-methylene-6H -cyclopropa[3,4]cyclo­hept[1,2- e]inden-6-one

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2000
N. T. Do Valle
Interest in the title structure, C20H24O2, lies in the novel cis ring junction between the three- and seven-membered rings. This stereochemical arrangement causes the methylene moiety and the cycloheptane ring to be twisted out of the plane of the aromatic ring. The cyclopropane ring is also twisted out of the plane of the aromatic system. The molecules are linked by an O,H,O hydrogen bond [O,O 2.741,(3),Ć]. [source]


Low temperature powder diffraction and DFT solid state computational study of hydrogen bonding in NH4VO3

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2009
. Smr
Abstract The crystal structure of NH4VO3 was refined by the geometry optimization done by total energy minimization in solid state using DFT/plane waves approach. The lattice parameters were derived by the Le Bail technique from the low temperature X-ray (40-293 K) and synchrotron (100-293 K) powder diffraction data. The structure is formed by the infinite chains of irregular VO4 tetrahedra running approximately parallel to the c -axis, which are interlinked by the ammonium ions placed between them. The ammonium ions link to the [VO4], chains through one linear, one bifurcated and two trifurcated N-H,O hydrogen bonds. Considering their stability there are six distinct N-H,O hydrogen bonds: two strong with the N-H,O bond angles close to the straight, two medium with the bond angles of 123° and 148° and two very bent (105° and 107°) and hence weak hydrogen bonds. There is a reasonable agreement between the energies of the stretching ,(NH) modes estimated using the optimised N,O contact distances and those obtained experimentally. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Crystal structure of 2-(2'-hydroxyphenyl)-6-tributylstannyl-4-(3H )-quinazolinone and 2-(2'-hydroxyphenyl)-6-iodo-4-(3H)-quinazolinone

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2006
Ketai Wang
Abstract The structures of the title compounds C26H37N2O2Sn (I) and C14H9IN2O2 (II) were determined by single-crystal X-ray diffraction technique. Compound I crystallizes in the triclinic space group P1 with a = 9.560(3) Ć, b = 16.899(6) Ć, c = 17.872(5) Ć, , = 65.957(7)°, , = 83.603(5)°, , ( = 75.242(5)°, V = 2549.8(13) Ć3, Z = 4, and D =1.374 g/cm3. The compound consists of a quinazolinone ring with phenol and tributylstannyl moieties. Compound II crystallizes in the monoclinic space group P21/c with a = 7.6454(12) Ć, b = 5.9270(9) Ć, c = 27.975(4) Ć; , = 90°, , = 95.081(3)°, , = 90°, V = 1262.7(3) Ć3, Z = 4, and D = 1.915 g/cm3. The compound consists of a quinazolinone ring with phenol and iodine substituents. For both I and II, the short intramolecular O,H,N and two long intermolecular N,H,O hydrogen bonds are highly effective in holding the molecular system in a stable state. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Synthesis, spectroscopic studies and ab-initio structure determination from X-ray powder diffraction of bis-(N-3-acetophenylsalicylaldiminato)copper(II)

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2005
S. Banerjee
Abstract The synthesis, spectroscopic studies and crystal structure determination from X-ray powder diffraction have been carried out for bis-(N-3-acetophenylsalicylaldiminato)copper(II). The structure is triclinic, space group P1 with unit cell dimensions a = 11.817(1) Ć, b = 12.087(1) Ć, c = 9.210(1) Ć, , = 102.62(1)°, , = 111.16(1)°, , = 86.15(1)°, V = 1197.0(2)Ć3, Z = 2. The structure has been solved by Monte Carlo simulated annealing approach and refined by GSAS package. The final Rp value was 8.68%. The coordination geometry around the copper atom in the complex is intermediate between square-planar and tetrahedral with two salicylaldimine ligands in trans arrangement. Intermolecular C,H,O hydrogen bonds between molecules related by translation generate infinite chains along [010] direction. The molecular chains are linked via additional C,H,O hydrogen bonds to form a three-dimensional supramolecular network. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Crystal and molecular structures of atropisomeric N -aryl-1,2,3,4-tetrahydro-3,3-dimethyl-2,4-quinolinediones

HETEROATOM CHEMISTRY, Issue 3 2008
Mario Cetina
The crystal structures of N -aryl-1,2,3,4-tetrahydro-3,3-dimethyl-2,4-quinolinediones bearing methoxy- (1), methyl- (2), and chloro- (3) substituents in 2,-position of the phenyl ring have been determined by X-ray crystal structure analysis. The heterocyclic ring in 1,3 adopts an envelope conformation, with the smallest ring puckering in the ortho-chloro derivative 3. The N -aryl ring is almost perpendicular with respect to the quinoline-2,4-dione ring. The corresponding dihedral angle values are 83.2(1)°, 80.0(9)°, and 83.4(2)° in 1, 2 and 3, respectively. The hydrogen bond of CH,,,O type joins the molecules of the ortho-methoxy derivative 1 into dimers. The supramolecular structure also contains two CH,,,, interactions that link the hydrogen-bonded dimers into sheets. In ortho-methyl derivative 2, one CH,,,, interaction generates infinite chains, whereas two CH,,,O hydrogen bonds and three CH,,,, interactions in the ortho-chloro derivative 3 form three-dimensional framework. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:325,331, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20436 [source]


Theoretical study of the substituent effect on the intramolecular hydrogen bonds in di(4-hydroxycoumarin) derivatives

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 6 2006
Tzvetan Mihaylov
Abstract Geometry optimization of ortho -, meta -, and para -pyridyl-substituted di(4-hydroxycoumarin) [di(4-HC)] was performed with the density functional theory (DFT) [B3LYP/6-31G(d)] method. Two asymmetrical intramolecular OH,O hydrogen bonds (HBs) stabilized the structures. The calculated single HB energies varied from ,62.56 to ,47.53 kJ mol,1 and pointed to a relative strong hydrogen bond in the systems studied. The 2- and 6-pyridyl substituents produced the largest geometrical changes in di(4-hydroxycoumarin) fragment. The highest total HB energy was found for 2-pyridyl-substituted and the lowest one for 6-pyridyl-substituted di(4-hydroxycoumarin). The HB energy variations were confirmed with rotational barrier method calculations. Both steric and electrostatic factors were found to be responsible for the HB asymmetry in the compounds studied. According to the molecular electrostatic potential (MEP) calculations the most preferred reactive site for electrophilic attack of pyridyl-substituted di(4-hydroxycoumarin)s are the pyridine nitrogen and the carbonyl oxygens, followed by the hydroxyl oxygens. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]


Theoretical study of adsorption of methyl tert -butyl ether on broken clay minerals surfaces

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2005
A. Michalkova
Abstract The interactions between methyl tert -butyl ether (MTBE) and differently defected tetrahedral and octahedral fragments of clay minerals containing Si4+, Al3+, and Mg2+ central cations have been studied at the B3LYP and MP2 levels of theory in conjunction with the 6-31G(d) basis set. MTBE interacts with defect clay structures due to the formation of multiple CH,O and OH,O hydrogen bonds. Interactions of MTBE with systems containing different types of defected mineral fragments were found to vary. Systems containing the same type of defected mineral fragment with different central cation interact almost the same way with MTBE. The formation of hydrogen bonds leads to changes in the geometrical parameters and to the polarization of MTBE. The values of the interaction energies depend on the charge of the mineral fragment. They amount to 5 kcal/mol,35 kcal/mol. MTBE interacts more preferably with octahedral fragments than with tetrahedral fragments that contain an Al3+ central cation. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source]


Three isomeric 1-(2-chloronicotinoyl)-2-(nitro­phenyl)hydrazines, including three polymorphs of 1-(2-chloronicotinoyl)-2-(2-nitrophenyl)hydrazine: hydrogen-bonded supramolecular structures in two and three dimensions

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2007
Solange M. S. V. Wardell
1-(2-Chloronicotinoyl)-2-(2-nitrophenyl)hydrazine, C12H9Cl­N4O3, crystallizes in three polymorphic forms, two monoclinic forms in space groups Cc (Ia) and P21 (Ib), and an orthorhombic form in space group Pbcn (Ic). In the Cc polymorph (Ia) the molecules are linked into sheets by combinations of one N,H,O and two C,H,O hydrogen bonds, while in the P21 polymorph (Ib) the molecules are linked into sheets by combinations of three hydrogen bonds, one each of N,H,O, C,H,N and C,H,O types. In the orthorhombic polymorph (Ic) the molecules are linked into a complex three-dimensional framework structure by a combination of one N,H,O, one N,H,N and three C,H,O hydrogen bonds, and an aromatic ,,, stacking interaction. In the isomeric compound 1-(2-chloronicotinoyl)-2-(3-nitrophenyl)hydrazine (II) the molecules are again linked into a three-dimensional framework, this time by a combination of three hydrogen bonds, one each of N,H,O, N,H,N and C,H,O types, weakly augmented by a ,,, stacking interaction. The molecules of 1-(2-chloronicotinoyl)-2-(4-nitrophenyl)hydrazine (III) are linked into sheets by a combination of three hydrogen bonds, one each of N,H,O, N,H,N and C,H,O types. [source]


High-pressure neutron diffraction study of l -serine-I and l -serine-II, and the structure of l -serine-III at 8.1,GPa

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2006
Stephen A. Moggach
The hydrostatic compression of l -serine- d7 has been studied to 8.1,GPa by neutron powder diffraction. Over the course of this pressure range the compound undergoes two phase transitions, the first between 4.6 and 5.2,GPa, yielding l -serine-II, and the second between 7.3 and 8.1,GPa, yielding l -serine-III. All three polymorphs are orthorhombic, P212121, and feature chains of serine molecules connected via head-to-tail ND,O hydrogen bonds formed between ammonium and carboxylate groups. The chains are linked into a ribbon by a second set of ND,O hydrogen bonds. The hydroxyl moieties are distributed along the outer edges of the ribbon and in phase I they connect the ribbons into a layer by chains of OD,OD hydrogen bonds. The layers are connected together by a third set of ND,O hydrogen bonds, forming rings with substantial voids at their centres. In the transition from phase I to II these voids begin to close up, but at the cost of breaking the OD,OD chains. The OD,OD hydrogen bonds are replaced by shorter OD,O hydrogen bonds to carboxylate groups. At 7.3,GPa the O,O distance in the OD,O hydrogen bonds measures only 2.516,(17),Ć, which is short, and we propose that the phase transition to phase III that occurs between 7.3 and 8.1,GPa relieves the strain that has built up in this region of the structure. The hydroxyl D atom now bifurcates between the OD,O contact that had been present in phase II and a new OD,O contact formed to a carboxylate in another layer. Hirshfeld surface fingerprint plots show that D,D interactions become more numerous, while hydrogen bonds actually begin to lengthen in the transition from phase II to III. [source]


Isomeric N -(iodophenyl)nitrobenzamides form different three-dimensional framework structures

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2006
James L. Wardell
The isomeric N -(iodophenyl)nitrobenzamides, C13H9IN2O3, all form different three-dimensional framework structures. Molecules of N -(2-iodophenyl)-3-nitrobenzamide (II) are linked by a combination of N,H,O and C,H,O hydrogen bonds and a two-centre iodo,carbonyl interaction. The supramolecular structure of N -(2-iodophenyl)-4-nitrobenzamide (III) is built from one N,H,O and two C,H,O hydrogen bonds, but short I,O contacts are absent from the structure. In N -(3-iodophenyl)-2-nitrobenzamide (IV), which crystallizes with Z, = 2 in space group P21, the structure contains two N,H,O hydrogen bonds, four C,H,O hydrogen bonds, two two-centre iodo,nitro interactions and an aromatic ,,, stacking interaction. The structure of N -(3-iodophenyl)-3-nitrobenzamide (V) contains one N,H,O hydrogen bond and three C,H,O hydrogen bonds, together with a two-centre iodo,nitro interaction and an aromatic ,,, stacking interaction, while in N -(3-iodophenyl)-4-nitrobenzamide (VI), the combination of one N,H,O hydrogen bond and two C,H,O hydrogen bonds is augmented not only by a two-centre iodo,nitro interaction and an aromatic ,,, stacking interaction, but also by a dipolar carbonyl,carbonyl interaction. In the supramolecular structure of N -(4-iodophenyl)-4-nitrobenzamide (IX), which crystallizes with Z, = 2 in space group , there are two N,H,O hydrogen bonds, four C,H,O hydrogen bonds and two three-centre iodo,nitro interactions. [source]


Nine N -aryl-2-chloronicotinamides: supramolecular structures in one, two and three dimensions

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2006
Silvia Cuffini
Structures are reported here for eight further substituted N -aryl-2-chloronicotinamides, 2-ClC5H3NCONHC6H4X -4,. When X = H, compound (I) (C12H9ClN2O), the molecules are linked into sheets by N,H,N, C,H,,(pyridyl) and C,H,,(arene) hydrogen bonds. For X = CH3, compound (II) (C13H11ClN2O, triclinic with Z, = 2), the molecules are linked into sheets by N,H,O, C,H,O and C,H,,(arene) hydrogen bonds. Compound (III), where X = F, crystallizes as a monohydrate (C12H8ClFN2O·H2O) and sheets are formed by N,H,O, O,H,O and O,H,N hydrogen bonds and aromatic ,,, stacking interactions. Crystals of compound (IV), where X = Cl (C12H8Cl2N2O, monoclinic P21 with Z, = 4) exhibit inversion twinning: the molecules are linked by N,H,O hydrogen bonds into four independent chains, linked in pairs by C,H,,(arene) hydrogen bonds. When X = Br, compound (V) (C12H8BrClN2O), the molecules are linked into sheets by N,H,O and C,H,N hydrogen bonds, while in compound (VI), where X = I (C12H8ClIN2O), the molecules are linked into a three-dimensional framework by N,H,O and C,H,,(arene) hydrogen bonds and an iodo,N(pyridyl) interaction. For X = CH3O, compound (VII) (C13H11ClN2O2), the molecules are linked into chains by a single N,H,O hydrogen bond. Compound (VIII) (C13H8ClN3O, triclinic with Z, = 2), where X = CN, forms a complex three-dimensional framework by N,H,N, C,H,N and C,H,O hydrogen bonds and two independent aromatic ,,, stacking interactions. [source]