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N Hydrogen Bonds (n + hydrogen_bond)
Selected AbstractsSyntheses and crystal structures of triorganotin (IV) derivatives with 2,2,-bipyridine-4,4,-dicarboxylic acidHETEROATOM CHEMISTRY, Issue 1 2009Ru-Fen Zhang Four organotin complexes with 2,2,-bipyridine-4,4,-dicarboxylic acid, H2dcbp: (Ph3n)2(dcbp) 1, [(PhCH2)3n]2(dcbp) , 2CH3OH 2, [(Me3Sn)2(dcbp)]n3, [(Bu3Sn)2(dcbp)]n4 have been synthesized. The complexes 1,4 were characterized by elemental, IR, 1H, 13C, 119n NMR, and X-ray crystallographic analyses. Crystal structures show that complex 1 is a monomer with one ligand coordinated to two triorganotin moieties, and a 1D infinite polymeric chain generates via intermolecular CH,,,N hydrogen bond; complex 2 is also a monomer and forms a 2D network by intermolecular O,H,,,O weak interaction; both of complexes 3 and 4 form 2D network structures where 2,2,-bipyridine-4,4,-dicarboxylate acts as a tetradentate ligand coordinated to trimethyltin and tri-n-butyltin ions, respectively. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:19,28, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20506 [source] Interpreting 2hJ(F,N), 1hJ(H,N) and 1J(F,H) in the hydrogen-bonded FH,collidine complex,MAGNETIC RESONANCE IN CHEMISTRY, Issue 12 2002Janet E. Del Bene Abstract Ab initio EOM-CCSD calculations were performed to determine 19F,1H, 19F,15N and 1H,15N spin,spin coupling constants in model complexes FH,NH3 and FH,pyridine as a function of the F,H and F,N distances. The absolute value of 1J(F,H) decreases and that of 1hJ(H,N) increases rapidly along the proton-transfer coordinate, even in the region of the proton-shared F,H,N hydrogen bond. In contrast, 2hJ(F,N) remains essentially constant in this region. These results are consistent with the recently reported experimental NMR spectra of FH,collidine which show that 1hJ(H,N) increases and 1J(F,H) decreases, while 2hJ(F,N) remains constant as the temperature of the solution decreases. They suggest that the FH,collidine complex is stabilized by a proton-shared hydrogen bond over the range of experimental temperatures investigated, being on the traditional side of quasi-symmetric at high temperatures, and on the ion-pair side at low temperatures. Copyright © 2002 John Wiley & Sons, Ltd. [source] X-ray crystallographic structures of enamine and amine Schiff bases of pyridoxal and its 1:1 hydrogen-bonded complexes with benzoic acid derivatives: evidence for coupled inter- and intramolecular proton transferACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2006Shasad Sharif Crystal structures of Schiff bases containing pyridoxal (PL), N -(pyridoxylidene)-tolylamine, C15H16N2O2 (I), N -(pyridoxylidene)-methylamine, C9H12N2O2 (III), and their 1:1 adduct with 2-nitrobenzoic acid, (I)+ C7H4NO (II), and 4-nitrobenzoic acid, (III)+ C7H4NO (IV), serve as models for the coenzyme pyridoxal-5,-phosphate (PLP) in its PLP-dependent enzymes. These models allow the study of the intramolecular OHN hydrogen bond of PL/PLP Schiff bases and the H-acceptor properties of their pyridine rings. The free base (I) forms hydrogen-bonded chains involving the hydroxyl side groups and the rings of adjacent molecules, whereas (III) forms related hydrogen-bonded cyclic dimers. The adducts (II)/(IV) consist of 1:1 hydrogen-bonded complexes, exhibiting strong intermolecular bonds between the carboxylic groups of the acids and the pyridine rings of (I)/(III). In conclusion, the proton in the intramolecular O,H,N hydrogen bond of (I)/(III) is located close to oxygen (enolamine form). The added acids protonate the pyridine ring in (II)/(IV), but only in the latter case does this protonation lead to a shift of the intramolecular proton towards the nitrogen (ketoimine form). All crystallographic structures were observed in the open form. In contrast, the formation of the pyridinium salt by dissolving (IV) leads to the cyclic aminal form. [source] 2-[(E)-(4-Chlorophenyl)methyleneamino]- N -(X -methylphenyl)-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide, where X = 2 and 3ACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2004The title compounds, both C23H21ClN2OS, are isomeric, with (I) and (II) being the N -3-methylphenyl and N -2-methylphenyl derivatives, respectively. The dihedral angle between the 4-chlorophenyl group and the thiophene ring in (II) [38.1,(1)°] is larger than that in (I) [7.1,(1)°], indicating steric repulsion between the chlorophenyl and o -toluidine groups in (II). In both compounds, an intramolecular N,H,N hydrogen bond forms a pseudo-six-membered ring, thus locking the molecular conformation. In the crystal structures, molecules are connected via N,H,O hydrogen bonds, forming chains along the b axis in (I) and along the c axis in (II). Intermolecular C,H,O/S and ,,, interactions are also observed in (II), but not in (I). [source] (R)-1-Phenylethylammonium 6-amino-5-nitropyrimidine-2,4(1H,3H)-dionate (R)-1-phenylethylamine hemisolvate: hydrogen-bonded sheets of ions with pendent solvent moleculesACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2003Christopher Glidewell In the title compound, 2C8H12N+·2C4H3N4O4,·C8H11N, the anions are linked by paired N,H,N hydrogen bonds [H,N = 2.07 and 2.11,Å, N,N = 2.942,(3) and 2.978,(3),Å and N,H,N = 173 and 170°] and by paired N,H,O hydrogen bonds [H,O = 1.98 and 2.05,Å, N,O = 2.855,(3) and 2.917,(3),Å, and N,H,O = 173 and 167°] into chains of rings. These chains are linked into sheets by further N,H,O hydrogen bonds in which all of the donors are provided by the cations [H,O = 1.83,2.17,Å, N,O = 2.747,(3),2.965,(3),Å and N,H,O = 141,168°]. The neutral amine molecule is pendent from the sheet and is linked to it by a single N,H,N hydrogen bond [H,N = 2.00,Å, N,N = 2.901,(3),Å and N,H,N = 175°]. [source] Acetone-4-methylthiosemicarbazone at 220,KACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2000Simon Parsons In the title compound, C5H11N3S, the trans conformation is stabilized by a weak intramolecular N,H,N hydrogen bond. Unusually, one N,H bond is not involved in any hydrogen-bond interactions and instead the molecules form a one-dimensional polymer via N,H,S intermolecular hydrogen bonds. [source] C[triple-bond]C,H,N hydrogen bonding in 3-methylthio-4-propargylthioquinolineACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2000Stanis, aw Boryczka The title compound, C13H11NS2, contains a C[triple-bond]C,H,N hydrogen bond to a pyridine-type N atom, with a C,N distance of 3.305,(4),Å and an H,N distance of 2.28,Å. This is one of the shortest C,H,N hydrogen bonds known. [source] Progress in the Understanding of Drug,Receptor Interactions, Part,2: Experimental and Theoretical Electrostatic Moments and Interaction Energies of an Angiotensin II Receptor Antagonist (C30H30N6O3S)CHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2007Raffaella Soave Dr. Abstract A combined experimental and theoretical charge density study of an angiotensin II receptor antagonist (1) is presented focusing on electrostatic properties such as atomic charges, molecular electric moments up to the fourth rank and energies of the intermolecular interactions, to gain an insight into the physical nature of the drug,receptor interaction. Electrostatic properties were derived from both the experimental electron density (multipole refinement of X-ray data collected at T=17,K) and the ab initio wavefunction (single molecule and fully periodic calculations at the DFT level). The relevance of S,,,O and S,,,N intramolecular interactions on the activity of 1 is highlighted by using both the crystal and gas-phase geometries and their electrostatic nature is documented by means of QTAIM atomic charges. The derived electrostatic properties are consistent with a nearly spherical electron density distribution, characterised by an intermingling of electropositive and -negative zones rather than by a unique electrophilic region opposed to a nucleophilic area. This makes the first molecular moment scarcely significant and ill-determined, whereas the second moment is large, significant and highly reliable. A comparison between experimental and theoretical components of the third electric moment shows a few discrepancies, whereas the agreement for the fourth electric moment is excellent. The most favourable intermolecular bond is show to be an NH,,,N hydrogen bond with an energy of about 50,kJ,mol,1. Key pharmacophoric features responsible for attractive electrostatic interactions include CH,,,X hydrogen bonds. It is shown that methyl and methylene groups, known to be essential for the biological activity of the drug, provide a significant energetic contribution to the total binding energy. Dispersive interactions are important at the thiophene and at both the phenyl fragments. The experimental estimates of the electrostatic contribution to the intermolecular interaction energies of six molecular pairs, obtained by a new model proposed by Spackman, predict the correct relative electrostatic energies with no exceptions. [source] Interaction of Zinc Oxide Clusters with Molecules Related to the Sulfur Vulcanization of Polyolefins ("Rubber")CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2006Ralf Steudel Prof. Dr. Abstract The vulcanization of rubber by sulfur is a large-scale industrial process that is only poorly understood, especially the role of zinc oxide, which is added as an activator. We used the highly symmetrical cluster Zn4O4 (Td) as a model species to study the thermodynamics of the initial interaction of various vulcanization-related molecules with ZnO by DFT methods, mostly at the B3LYP/6-31+G* level. The interaction energy of Lewis bases with Zn4O4 increases in the following order: CO Abinitio structure determination of m -toluidine by powder X-ray diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2004Mwaffak Rukiah The powder X-ray diffraction pattern of the crystalline phase of m -toluidine has been recorded with a sensitive curved detector (CPS120) at 150,K. The structure has been solved by real-space methods (simulated annealing) followed by Rietveld refinements with phenyl rings as rigid bodies and with soft constraints on bond lengths for peripheral atoms. The cell is monoclinic with space group P21/c and Z = 8. Equivalent molecules form chains along c. The crystalline cohesion is achieved by N,H,N hydrogen bonds between neighbouring chains of non-equivalent molecules and by van der Waals interactions of neighbouring chains of equivalent molecules. The hydrogen-bonding network has been confirmed by lattice-energy minimization. Anisotropic strain effects of the cell have been calculated. The directions of the minimal strains correspond to the directions of the hydrogen bonds. An explanation of the difficulty to crystallize the metastable phase is given. [source] Nine N -aryl-2-chloronicotinamides: supramolecular structures in one, two and three dimensionsACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2006Silvia 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] Oligosiloxanediols as building blocks for supramolecular chemistry: hydrogen-bonded adducts with amines form supramolecular structures in zero, one and two dimensionsACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2000Brian O'Leary The structure of 1,1,3,3,5,5-hexaphenyltrisiloxane-1,5-diol,pyrazine (4/1), (C36H32O4Si3)4·C4H4N2 (1), contains finite centrosymmetric aggregates; the diol units form dimers, by means of O,H,O hydrogen bonds, and pairs of such dimers are linked to the pyrazine by means of O,H,N hydrogen bonds. In 1,1,3,3,5,5-hexaphenyltrisiloxane-1,5-diol,pyridine (2/3), (C36H32O4Si3)2·(C5H5N)3 (2), the diol units are linked into centrosymmetric pairs by means of disordered O,H,O hydrogen bonds: two of the three pyridine molecules are linked to the diol dimer by means of ordered O,H,N hydrogen bonds, while the third pyridine unit, which is disordered across a centre of inversion, links the diol dimers into a C33(9) chain by means of O,H,N and C,H,O hydrogen bonds. In 1,1,3,3-tetraphenyldisiloxane-1,3-diol,hexamethylenetetramine (1/1), (C24H22O3Si2)·C6H12N4 (3), the diol acts as a double donor and the hexamethylenetetramine acts as a double acceptor in ordered O,H,N hydrogen bonds and the structure consists of C22(10) chains of alternating diol and amine units. In 1,1,3,3-tetraphenyldisiloxane-1,3-diol,2,2,-bipyridyl (1/1), C24H22O3Si2·C10H8N2 (4), there are two independent diol molecules, both lying across centres of inversion and therefore both containing linear Si,O,Si groups: each diol acts as a double donor of hydrogen bonds and the unique 2,2,-bipyridyl molecule acts as a double acceptor, thus forming C22(11) chains of alternating diol and amine units. The structural motif in 1,1,3,3-tetraphenyldisiloxane-1,3-diol,pyrazine (2/1), (C24H22O3Si2)2·C4H4N2 (5), is a chain-of-rings: pairs of diol molecules are linked by O,H,O hydrogen bonds into centrosymmetric R22(12) dimers and these dimers are linked into C22(13) chains by means of O,H,N hydrogen bonds to the pyrazine units. 1,1,3,3-Tetraphenyldisiloxane-1,3-diol,pyridine (1/1), C24H22O3Si2·C5H5N (6), and 1,1,3,3-tetraphenyldisiloxane-1,3-diol,pyrimidine (1/1), C24H22O3Si2·C4H4N2 (7), are isomorphous: in each compound the amine unit is disordered across a centre of inversion. The diol molecules form C(6) chains, by means of disordered O,H,O hydrogen bonds, and these chains are linked into two-dimensional nets built from R66(26) rings, by a combination of O,H,N and C,H,O hydrogen bonds. [source] Three ethyl 5-amino-1-aryl-1H -imidazole-4-carboxylates: hydrogen-bonded supramolecular structures in one, two and three dimensionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2007Marilia S. Costa The molecules of ethyl 5-amino-1-(4-cyanophenyl)-1H -imidazole-4-carboxylate, C13H12N4O2, are linked into a chain of alternating R22(10) and R44(34) rings by a combination of N,H,N and C,H,N hydrogen bonds. In ethyl 5-amino-1-(4-chlorophenyl)-1H -imidazole-4-carboxylate, C12H12ClN3O2, where the ethyl group is disordered over two sets of sites, a combination of N,H,O, N,H,N, C,H,N and C,H,,(arene) hydrogen bonds links the molecules into complex sheets. Two intermolecular hydrogen bonds, one each of N,H,N and C,H,O types, link the molecules of ethyl 5-amino-1-(2,6-difluorophenyl)-1H -imidazole-4-carboxylate, C12H11F2N3O2, into a continuous three-dimensional framework structure. [source] Four 2-aryl-8,8-dimethyl-6,7,8,9-tetrahydropyrazolo[2,3- a]quinazolin-6-ones: isolated molecules, hydrogen-bonded dimers, and ,-stacked chains of hydrogen-bonded dimersACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2006Silvia Cruz In each of the three compounds 2-(4-chlorophenyl)-5,8,8-trimethyl-6,7,8,9-tetrahydropyrazolo[2,3- a]quinazolin-6-one, C19H18ClN3O, (I), 2-(4-methoxyphenyl)-5,8,8-trimethyl-6,7,8,9-tetrahydropyrazolo[2,3- a]quinazolin-6-one, C20H21N3O2, (II), and 8,8-dimethyl-2-(4-methylphenyl)-6,7,8,9-tetrahydropyrazolo[2,3- a]quinazolin-6-one monohydrate, C19H19N3O·H2O, (IV), the non-aromatic carbocyclic ring adopts a half-chair conformation, while in 2-(4-chlorophenyl)-8,8-dimethyl-5-phenyl-6,7,8,9-tetrahydropyrazolo[2,3- a]quinazolin-6-one, C24H20ClN3O, (III), the corresponding ring adopts a conformation intermediate between the envelope and screw,boat forms. The structure of (I) consists of isolated molecules, while that of (II) contains dimers formed by C,H,O hydrogen bonds. In (III), dimers formed by C,H,O hydrogen bonds are linked into chains by means of an aromatic ,,, stacking interaction, while in the monohydrate, (IV), the heterocyclic molecules and the water molecules are linked by O,H,O and O,H,N hydrogen bonds to form centrosymmetric four-component aggregates. [source] 2-Amino-5-trifluoromethyl-1,3,4-thiadiazole and a redetermination of 2-amino-1,3,4-thiadiazole, both at 120,K: chains of edge-fused R22(8) and R44(10) rings, and sheets of R22(8) and R66(20) ringsACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2006Nubia Boechat Molecules of 2-amino-5-trifluoromethyl-1,3,4-thiadiazole, C3H2F3N3S, are linked by two independent N,H,N hydrogen bonds into sheets of alternating R22(8) and R66(20) rings, while the molecules of the unsubstituted 2-amino-1,3,4-thiadiazole, C2H3N3S, are linked, again by two independent N,H,N hydrogen bonds, but into chains of edge-fused R22(8) and R44(10) rings. [source] The 1:1 adduct of hexamethylenetetramine (HMT) with racemic trans -1,2-cyclohexanedicarboxylic acid (CDA)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2004Ramaiyer Venkatraman Hexamethylenetetramine and rac - trans -1,2-cyclohexanedicarboxylic acid crystallize in a 1:1 ratio as a neutral molecular adduct, C6H12N4·C8H12O4. Two dicarboxylic acid molecules and two tetramine molecules form a hydrogen-bonded ring, in the shape of a rhombus, which lies on a crystallographic twofold axis bisecting the two diacid molecules. The O,H,N hydrogen bonds have lengths 2.6808,(19) and 2.6518,(19),Å, and, in each ring, both acid molecules have the same handedness. [source] 2-Amino-4-(1-naphthyl)-5-oxo-5,6,7,8-tetrahydro-4H -chromene-3-carbonitrile and 2-amino-7,7-dimethyl-4-(1-naphthyl)-5-oxo-5,6,7,8-tetrahydro-4H -chromene-3-carbonitrileACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2004Vladimir N. Nesterov Syntheses and X-ray structural investigations have been carried out for the two title compounds, C20H16N2O2, (IIIa), and C22H20N2O2, (IIIb). In (IIIa), the heterocyclic ring adopts a sofa conformation, while in (IIIb), the ring has a flattened boat conformation. In both molecules, the fused cyclohexenone ring adopts a sofa conformation. The dihedral angles between these two flat fragments are 3.5,(2) and 17.5,(2)° in (IIIa) and (IIIb), respectively. The dihedral angles between the pseudo-axial naphthalene substituents and the planes of the pyran rings are 90.9,(1) and 96.7,(1)°, respectively. In the crystal structure of (IIIa), intermolecular N,H,N and N,H,O hydrogen bonds link the molecules into infinite tapes along the b axis, while molecules of (IIIb) form centrosymmetric dimers via N,H,N hydrogen bonds, with only one H atom of the NH2 donor group taking part in hydrogen bonding. [source] N,N,-Bis(2-pyridyl)benzene-1,2-diamineACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2004Maria Gdaniec Hindered rotation about the partial double C,N bonds between the amine and pyridine moieties in the title molecule, C16H14N4, results in two different conformations of the N -aryl-2-aminopyridine units. One, assuming an E conformation, is involved in a pair of N,H,N hydrogen bonds that generate a centrosymmetric (8) motif. The second, adopting a Z conformation, is not engaged in any hydrogen bonding and is flattened, the dihedral angle between the benzene and pyridine rings being 12.07,(7)°. This conformation is stabilized by an intramolecular C,H,N interaction [C,N,= 2.9126,(19),Å, H,N,=,2.31,Å and C,H,N,=,120°]. [source] Two hydrates of 6-methoxypurineACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2004Natalya Fridman 6-Methoxypurine crystallizes from N,N -methylformamide as the hemihydrate, C6H6N4O·0.5H2O, and from water as the trihydrate, C6H6N4O·3H2O. Both forms crystallize in the triclinic crystal system. Upon heating the trihydrate, molecules of water are liberated successively; the hemihydrate is formed at 383,K. In the hemihydrate, the H atom on the imidazole N atom is disordered between the two N atoms. The water molecule in the hemihydrate and the H atoms of a water molecule in the trihydrate are also disordered. In the hemihydrate, the organic moieties are connected by N,H,N hydrogen bonds, while they are connected via water molecules in the trihydrate. [source] Two dimorphs of 5-methylsulfanyl-1H -tetrazoleACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2004Natalya Fridman 5-Methylsulfanyl-1H -tetrazole, C2H4N4S, crystallizes in dimorphic forms; the ,-form crystallizes at room temperature in the monoclinic crystal system, space group P21/m, and the ,-form crystallizes by sublimation at 423,K in the orthorhombic crystal system, space group Pbcm. In both forms, the molecules occupy crystallographic mirror planes and are connected to one another via N,H,N hydrogen bonds, the amino H atoms being disordered. The two forms differ from one another in their packing; there are polar layers in the ,-form and non-polar layers in the ,-form. [source] (R)-1-Phenylethylammonium 6-amino-5-nitropyrimidine-2,4(1H,3H)-dionate (R)-1-phenylethylamine hemisolvate: hydrogen-bonded sheets of ions with pendent solvent moleculesACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2003Christopher Glidewell In the title compound, 2C8H12N+·2C4H3N4O4,·C8H11N, the anions are linked by paired N,H,N hydrogen bonds [H,N = 2.07 and 2.11,Å, N,N = 2.942,(3) and 2.978,(3),Å and N,H,N = 173 and 170°] and by paired N,H,O hydrogen bonds [H,O = 1.98 and 2.05,Å, N,O = 2.855,(3) and 2.917,(3),Å, and N,H,O = 173 and 167°] into chains of rings. These chains are linked into sheets by further N,H,O hydrogen bonds in which all of the donors are provided by the cations [H,O = 1.83,2.17,Å, N,O = 2.747,(3),2.965,(3),Å and N,H,O = 141,168°]. The neutral amine molecule is pendent from the sheet and is linked to it by a single N,H,N hydrogen bond [H,N = 2.00,Å, N,N = 2.901,(3),Å and N,H,N = 175°]. [source] 3-Amino-4,-methyl-5-ethylbiphenyl-2,4-dicarbonitrile and 3-amino-4,-(N,N -diethylamino)-5-ethylbiphenyl-2,4-dicarbonitrileACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2001A. Subbiah Pandi In the title compounds, C17H15N3 and C20H22N4, the methyl derivative crystallizes with two molecules in the asymmetric unit, while the N,N -diethylamino derivative crystallizes with one molecule per asymmetric unit. The biphenyl twist angle for both molecular structures is approximately 45°. The molecular packing is stabilized by N,H,N hydrogen bonds. [source] Two 1-substituted 4-nitroimidazolesACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2001Maciej Kubicki Crystalline 4-nitro-1-phenylimidazole, C9H7N3O2, (I), and 4,-nitro-1-phenyl-4,1,-biiimidazole, C12H9N5O2, (II), contain C,H,O and C,H,N hydrogen bonds, connecting the molecules into infinite chains. The aromatic fragments in both compounds are nearly planar. The dihedral angles between the benzene and imidazole rings are 26.78,(5)° in (I) and 29.36,(8)° in (II). [source] 4,5-Diazafluoren-9-olACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2000Chao Tu The title compound, C11H8N2O, has two crystallographically independent molecules in the crystal. Each molecule is basically planar except for the O atom. The two N atoms in the molecule show different behaviour as hydrogen-bonding acceptors. One of them is involved in intermolecular O,H,N hydrogen bonds which stabilize the crystal packing. [source] 2,3-Dihydro-3-methyl-2-nitrimino-1,3-thiazoleACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2000Janusz Kyzio The title compound {alternatively, 3-methyl-2-[oxido(oxo)hydrazono]-2,3-dihydro-1,3-thiazole}, C4H5N3O2S, was obtained by methylation of N -(2-thiazolyl)nitramine. The molecule lies on a mirror plane and the thiazole ring is planar, regular in shape and aromatic. The S atom participates in the aromatic sextet via an electron pair on the 3pz orbital. In the crystal, the molecules are arranged in parallel layers, bound to each other by weak C,H,O and C,H,N hydrogen bonds and by S,O dipolar interactions, with an interlayer separation of 3.23,Å. [source] 2,4,4-Trimethyl-2-phenyl-3-pentanone oximeACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2000Rudy L. Luck The title compound, C14H21NO, has two molecules in the asymmetric unit. Each molecule forms hydrogen-bonded dimers about inversion centers via O,H,N hydrogen bonds between oxime groups. The N,O distances in the oxime groups are 1.4160,(15) and 1.4131,(14),Å. [source] C[triple-bond]C,H,N hydrogen bonding in 3-methylthio-4-propargylthioquinolineACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2000Stanis, aw Boryczka The title compound, C13H11NS2, contains a C[triple-bond]C,H,N hydrogen bond to a pyridine-type N atom, with a C,N distance of 3.305,(4),Å and an H,N distance of 2.28,Å. This is one of the shortest C,H,N hydrogen bonds known. [source]
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