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1.
Volker Böhmer Diethard Stotz Klaus Beismann Walter Vogt 《Monatshefte für Chemie / Chemical Monthly》1984,115(1):65-77
The kinetics of the bromination of six differently substituted 2,6-bis(hydroxybenzyl)phenols having only one reactivepara position at the phenolic unit in the middle of the molecule were studied in acetic acid at 22°C. The reaction rate decreases if intramolecular hydrogen bonds between one or two hydroxy groups of the adjacent phenolic units and the hydroxy group of the reacting unit become possible, and it is especially low, if these hydrogen bonds are directed to the middle by bulky substituents inortho position. This must be explained by a smaller +M-effect of the hydroxy group of the reacting unit. A kinetic isotope effect is observed in deutero acetic acid, where the reaction rate is decreased by the same amount for compounds with and without intramolecular hydrogen bonds. 相似文献
2.
Delphine Firley Bernard Fraisse Fatima Zouhiri Anne Spasojevi‐de Bir Didier Desmaële Jean D'Angelo Nour Eddine Ghermani 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(3):o154-o157
Both 7‐carboxylato‐8‐hydroxy‐2‐methylquinolinium monohydrate, C11H9NO3·H2O, (I), and 7‐carboxy‐8‐hydroxy‐2‐methylquinolinium chloride monohydrate, C11H10NO3+·Cl−·H2O, (II), crystallize in the centrosymmetric P space group. Both compounds display an intramolecular O—H⋯O hydrogen bond involving the hydroxy group; this hydrogen bond is stronger in (I) due to its zwitterionic character [O⋯O = 2.4449 (11) Å in (I) and 2.5881 (12) Å in (II)]. In both crystal structures, the HN+ group participates in the stabilization of the structure via intermolecular hydrogen bonds with water molecules [N⋯O = 2.7450 (12) Å in (I) and 2.8025 (14) Å in (II)]. In compound (II), a hydrogen‐bond network connects the Cl− anion to the carboxylic acid group [Cl⋯O = 2.9641 (11) Å] and to two water molecules [Cl⋯O = 3.1485 (10) and 3.2744 (10) Å]. 相似文献
3.
The molecular structure, heats of formation, energetic properties, strain energy and thermal stability for a series of substituted difurazano[3,4-b:3′,4′-e]piperazines and their analogues were studied using density functional theory. The results show that it is a useful way to increase the heat of formation values of energetic compounds by incorporating a five- or six-membered aromatic heterocycle to construct a fused ring system. The calculated detonation properties reveal that introducing one heterocycle to construct a fused ring structure greatly enhances their detonation properties. The substitution of the –NF2, –NO2 or –NHNO2 group is very useful for enhancing the detonation performance for the substituted derivatives. According to molecular structure and natural bond orbital analysis, the introduction of the –NO2, –NF2 or –NHNO2 group decreases the stability of the substituted derivative. There is a weak N–NO2 bond conjugation in the NO2-substituted derivatives. An analysis of the bond dissociation energies for several relatively weak bonds suggests that all the unsubstituted derivatives have good thermal stability, but the substitution of –NO2 or –NF2 remarkably decreases their stability. Considering the detonation performance and thermal stability, eight compounds may be considered as the potential candidates of high-energy density materials with less sensitivity. 相似文献
4.
Oxidation of some 2-(N,N-dimethylaminomethyl)ferrocenylalkylcarbinols by MnO2 is totally diastereoselective: only one diastereomer is oxidized. A study was performed to highlight the influential factors of this phenomenon. Several ferrocenyl alcohols have been studied. First, two diastereomers of the ferrocenyl amino alcohol bearing a deuterium as an R group have been synthesized and oxidized. The good reactivity of both diastereomers displayed the importance of the size of the alkyl group, which needs to be bulkier than a deuterium. The synthesis and the oxidation of endo- and exo-α-hydroxy [4](1,2)ferrocenophane enabled the elimination of the hypothesis involving the spatial position of the hydroxy group, while the two diastereomers were oxidized. The replacement of the dimethylamino group by a methoxy or a methyl, the oxidation of these compounds, and the study of the preferential conformation of each diastereomer showed clearly the influence of an intramolecular hydrogen bond. So,the diastereoselectivity was shown to depend on the steric bulk of the alkyl group and on the presence of a strong intramolecular hydrogen bond between the hydroxy group and the nitrogen. 相似文献
5.
Paul D. Ahn Roger Bishop Donald C. Craig Marcia L. Scudder 《Journal of inclusion phenomena and macrocyclic chemistry》1995,23(4):313-327
The 1,5-dichloro-(1) and 1,5-dibromo-(2) naphthalene-2,6-diols form isostructural lattices incorporating ...O–H...O–H...O–H... hydrogen bonding surrounding 21 screw axes. Each phenolic hydroxy group participates in one donor and one acceptor hydrogen bond. When crystallised from dioxane, both compounds form new 1:1 co-crystalline materials whose lattices are closely related but not isostructural. All inter-phenolic hydrogen bonding is now absent with each hydroxy group acting instead as a donor to a dioxane oxygen atom. In consequence, the hydrogen bonded layer structures of pure1 or2 are now replaced by hydrogen bonded chain arrangements. All four crystal structures are analysed and compared in crystal engineering terms through discussion of the various types of other weak intermolecular attractions involved in their lattice constructions.
Supplementary Data relating to this article are deposited with the British Library as supplementary publication No. SUP 82202 (19 pages). 相似文献
6.
Heteronuclear NMR spectroscopic investigations of hydrogen bonding in 2‐(benzo[d]thiazole‐2′‐yl)‐N‐alkylanilines
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T. K. Venkatachalam G. K. Pierens P. V. Bernhardt D. C. Reutens 《Magnetic resonance in chemistry : MRC》2015,53(6):448-453
The 2‐(benzo[d]thiazole‐2′‐yl)‐N‐alkylanilines have previously revealed the presence of a strong intramolecular hydrogen bond. This in turn gives rise to a more complicated multiplet for the protons attached to the carbon adjacent to the amino group. This intramolecular hydrogen bond was investigated by a deuterium exchange experiment using heteronuclear NMR spectroscopy (1H, 13C, 15 N and 2H). We observed changes in the multiplet structure and chemical shifts providing further evidence that the deuterium replaces the hydrogen in the intramolecular hydrogen bond. A time course study of the D2O exchange confirmed the presence of a strong hydrogen bond. The comparison of the structures obtained by X‐ray crystallography showed a very small difference in planarity between the two‐substituted and four‐substituted amino compounds. In both the cases, the phenyl ring is not absolutely coplanar with the thiazole unit. The existence of this intramolecular hydrogen bond in 2‐(benzo[d]thiazole‐2′‐yl)‐N‐alkylanilines was further confirmed by single crystal X‐ray crystallography. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
7.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(7):782-788
A number of cinnamamide derivatives possess anticonvulsant activity due to the presence of a number of important pharmacophore elements in their structures. In order to study the correlations between anticonvulsant activity and molecular structure, the crystal structures of three new cinnamamide derivatives with proven anticonvulsant activity were determined by X‐ray diffraction, namely (R,S)‐(2E)‐N‐(2‐hydroxybutyl)‐3‐phenylprop‐2‐enamide–water (3/1), C13H17NO2·0.33H2O, ( 1 ), (2E)‐N‐(1‐hydroxy‐2‐methylpropan‐2‐yl)‐3‐phenylprop‐2‐enamide, C13H17NO2, ( 2 ), and (R,S)‐(2E)‐N‐(1‐hydroxy‐3‐methyl‐butan‐2‐yl)‐3‐phenylprop‐2‐enamide, C14H19NO2, ( 3 ). Compound ( 1 ) crystallizes in the space group P with three molecules in the asymmetric unit, whereas compounds ( 2 ) and ( 3 ) crystallize in the space group P21/c with one and two molecules, respectively, in their asymmetric units. The carbonyl group of ( 2 ) is engaged in an intramolecular hydrogen bond with the hydroxy group. This type of interaction is observed for the first time in these kinds of derivatives. A disorder of the substituent at the N atom occurs in the crystal structures of ( 2 ) and ( 3 ). The crystal packing of all three structures is dominated by a network of O—H…O and N—H…O hydrogen bonds, and leads to the formation of chains and/or rings. Furthermore, the crystal structures are stabilized by numerous C—H…O contacts. We analyzed the molecular structures and intermolecular interactions in order to propose a pharmacophore model for cinnamamide derivatives. 相似文献
8.
Kate J. Akerman Orde Q. Munro 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(3):258-262
The Schiff base enaminones (3Z)‐4‐(5‐ethylsulfonyl‐2‐hydroxyanilino)pent‐3‐en‐2‐one, C13H17NO4S, (I), and (3Z)‐4‐(5‐tert‐butyl‐2‐hydroxyanilino)pent‐3‐en‐2‐one, C15H21NO2, (II), were studied by X‐ray crystallography and density functional theory (DFT). Although the keto tautomer of these compounds is dominant, the O=C—C=C—N bond lengths are consistent with some electron delocalization and partial enol character. Both (I) and (II) are nonplanar, with the amino–phenol group canted relative to the rest of the molecule; the twist about the N(enamine)—C(aryl) bond leads to dihedral angles of 40.5 (2) and −116.7 (1)° for (I) and (II), respectively. Compound (I) has a bifurcated intramolecular hydrogen bond between the N—H group and the flanking carbonyl and hydroxy O atoms, as well as an intermolecular hydrogen bond, leading to an infinite one‐dimensional hydrogen‐bonded chain. Compound (II) has one intramolecular hydrogen bond and one intermolecular C=O...H—O hydrogen bond, and consequently also forms a one‐dimensional hydrogen‐bonded chain. The DFT‐calculated structures [in vacuo, B3LYP/6‐311G(d,p) level] for the keto tautomers compare favourably with the X‐ray crystal structures of (I) and (II), confirming the dominance of the keto tautomer. The simulations indicate that the keto tautomers are 20.55 and 18.86 kJ mol−1 lower in energy than the enol tautomers for (I) and (II), respectively. 相似文献
9.
Mustafa OdabasÛoglu igdem Albayrak Orhan Büyükgüngr Peter Lnnecke 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(11):o616-o619
The title compounds, 2‐{[tris(hydroxymethyl)methyl]aminomethylene}cyclohexa‐3,5‐dien‐1(2H)‐one, C11H15NO4, (I), 6‐hydroxy‐2‐{[tris(hydroxymethyl)methyl]aminomethylene}cyclohexa‐3,5‐dien‐1(2H)‐one, C11H15NO5, (II), and 6‐methoxy‐2‐{[tris(hydroxymethyl)methyl]aminomethylene}cyclohexa‐3,5‐dien‐1(2H)‐one, C12H17NO5, (III), adopt the keto–amine tautomeric form, with the formal hydroxy H atom located on the N atom, and the NH group and oxo O atom display a strong intramolecular N—H⋯O hydrogen bond. The N—H⋯O hydrogen‐bonded rings are almost planar and coupled with the cyclohexadiene rings. The carbonyl O atoms accept two other H atoms from the alcohol groups of adjacent molecules in (I), and one from the alcohol and one from the phenol group in (II), but from only one alcohol H atom in (III). 相似文献
10.
Maria C. Blanco Alirio Palma Ali Bahsas Michael B. Hursthouse Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(9):o479-o482
4,4′‐(Phenylmethylene)bis(6‐allyl‐3‐chloro‐2‐methylaniline), C27H28Cl2N2, (I), and 4,4′‐(2‐thienylmethylene)bis(6‐allyl‐3‐chloro‐2‐methylaniline), C25H26Cl2N2S, (II), adopt similar molecular conformations, although the thienyl group in (II) exhibits orientational disorder over two sets of sites with occupancies of 0.614 (3) and 0.386 (3). The amino groups in both compounds are pyramidal. A single N—H...N hydrogen bond links the molecules of (I) into cyclic centrosymmetric dimers. Molecules of (II) are linked by an ordered C—H...π(arene) hydrogen bond to form cyclic centrosymmetric dimers, and these dimers are linked into statistically interrupted chains by a second C—H...π(arene) hydrogen bond involving a donor in the minor component of the disordered thienyl unit. 相似文献
11.
Ligia R. Gomes John Nicolson Low Fernanda Borges Fernando Cagide 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(8):927-933
The title compound, C17H13NO4, crystallizes in two polymorphic forms, each with two molecules in the asymmetric unit and in the monoclinic space group P21/c. All of the molecules have intramolecular hydrogen bonds involving the amide group. The amide N atoms act as donors to the carbonyl group of the pyrone and also to the methoxy group of the benzene ring. The carbonyl O atom of the amide group acts as an acceptor of the β and β′ C atoms belonging to the aromatic rings. These intramolecular hydrogen bonds have a profound effect on the molecular conformation. In one polymorph, the molecules in the asymmetric unit are linked to form dimers by weak C—H...O interactions. In the other, the molecules in the asymmetric unit are linked by a single weak C—H...O hydrogen bond. Two of these units are linked to form centrosymmetric tetramers by a second weak C—H...O interaction. Further interactions of this type link the molecules into chains, so forming a three‐dimensional network. These interactions in both polymorphs are supplemented by π–π interactions between the chromone rings and between the chromone and methoxyphenyl rings. 相似文献
12.
E. J. Gao S. H. Liu M. Zhang L. Lin R. S. Wang T. D. Sun Y. Wang Z. Wen 《Russian Journal of Coordination Chemistry》2011,37(4):257-261
A new coordination polymer [Pb(2,2′-Bipy)(NO3)2(H2O)] n has been successfully synthesized and characterized (where 2,2′-Bipy = 2,2′-bipyridine). The crystal structure of the polymer was determined by single-crystal X-ray diffraction, crystallizing in the monoclinic crystal system, space group P21/n with unit cell parameters: a = 7.1673(5), b = 9.8706(6), c = 19.1825(12) Å; β = 90.0780(10)°; V = 1357.08(15) Å3, and Z = 16. The Pb atom was six-coordinated with N(1) and N(2) from 2,2′-Bipy, O(2), O(3), and O(6) in nitrate; O(1) from coordinated water, forming a slightly distorted octahedral geometry. The structure units aggregate together to give birth to the infinite 1D chains via bridged nitrate, and 2D networks and three-dimensional frameworks were obtained through hydrogen bonding and π-π-stacking interaction among aromatic rings, respectively. 相似文献
13.
Dr. Min‐Xia Yao Qi Zheng Kang Qian Prof. Dr. You Song Prof. Dr. Song Gao Prof. Dr. Jing‐Lin Zuo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(1):294-303
By using the node‐and‐spacer approach in suitable solvents, four new heterotrimetallic 1D chain‐like compounds (that is, containing 3d–3d′–4f metal ions), {[Ni(L)Ln(NO3)2(H2O)Fe(Tp*)(CN)3] ? 2 CH3CN ? CH3OH}n (H2L=N,N′‐bis(3‐methoxysalicylidene)‐1,3‐diaminopropane, Tp*=hydridotris(3,5‐dimethylpyrazol‐1‐yl)borate; Ln=Gd ( 1 ), Dy ( 2 ), Tb ( 3 ), Nd ( 4 )), have been synthesized and structurally characterized. All of these compounds are made up of a neutral cyanide‐ and phenolate‐bridged heterotrimetallic chain, with a {? Fe? C?N? Ni(? O? Ln)? N?C? }n repeat unit. Within these chains, each [(Tp*)Fe(CN)3]? entity binds to the NiII ion of the [Ni(L)Ln(NO3)2(H2O)]+ motif through two of its three cyanide groups in a cis mode, whereas each [Ni(L)Ln(NO3)2(H2O)]+ unit is linked to two [(Tp*)Fe(CN)3]? ions through the NiII ion in a trans mode. In the [Ni(L)Ln(NO3)2(H2O)]+ unit, the NiII and LnIII ions are bridged to one other through two phenolic oxygen atoms of the ligand (L). Compounds 1 – 4 are rare examples of 1D cyanide‐ and phenolate‐bridged 3d–3d′–4f helical chain compounds. As expected, strong ferromagnetic interactions are observed between neighboring FeIII and NiII ions through a cyanide bridge and between neighboring NiII and LnIII (except for NdIII) ions through two phenolate bridges. Further magnetic studies show that all of these compounds exhibit single‐chain magnetic behavior. Compound 2 exhibits the highest effective energy barrier (58.2 K) for the reversal of magnetization in 3d/4d/5d–4f heterotrimetallic single‐chain magnets. 相似文献
14.
Anderson A. B. C. Júnior Gustavo S. G. De Carvalho Lippy F. Marques Charlane C. Corrêa Adilson D. Da Silva Flvia C. Machado 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(8):934-936
The title compound, C14H11NO4, exists in the solid phase in the zwitterionic form, 2‐{[(4‐carboxy‐3‐hydroxyphenyl)iminiumyl]methyl}phenolate, with the H atom from the phenol group on the 2‐hydroxybenzylidene ring transferred to the imine N atom, resulting in a strong intramolecular N—H...O hydrogen bond between the iminium H atom and the phenolate O atom, forming a six‐membered hydrogen‐bonded ring. In addition, there is an intramolecular O—H...O hydrogen bond between the carboxylic acid group and the adjacent hydroxy group of the other ring, and an intermolecular C—H...O contact involving the phenol group and the C—H group adjacent to the imine bond, connecting the molecules into a two‐dimensional network in the (10) plane. π–π stacking interactions result in a three‐dimensional network. This study is important because it provides crystallographic evidence, supported by IR data, for the iminium zwitterionic form of Schiff bases.<!?tpb=12pt> 相似文献
15.
Zhi‐Hui Zhang Xue Tan Sheng‐Chun Chen 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(9):o457-o459
Reaction of 5,5′‐methylenedisalicylic acid (5,5′‐H4mdsa) with 4,4′‐bipyridine (4,4′‐bipy) and manganese(II) acetate under hydrothermal conditions led to the unexpected 2:3 binary cocrystal 4,4′‐methylenediphenol–4,4′‐bipyridine (2/3), C13H12O2·1.5C10H8N2 or (4,4′‐H2dhdp)(4,4′‐bipy)1.5, which is formed with a concomitant decarboxylation. The asymmetric unit contains one and a half 4,4′‐bipy molecules, one of which straddles a centre of inversion, and one 4,4′‐H2dhdp molecule. O—H...N interactions between the hydroxy and pyridyl groups lead to a discrete ribbon motif with an unusual 2:3 stoichiometric ratio of strong hydrogen‐bonding donors and acceptors. One of the pyridyl N‐atom donors is not involved in hydrogen‐bond formation. Additional weak C—H...O interactions between 4,4′‐bipy and 4,4′‐H2dhdp molecules complete a two‐dimensional bilayer supramolecular structure. 相似文献
16.
Sean R. Parkin Edward J. Behrman 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(8):o324-o328
Crystals of 5‐hydroxy‐6‐methyl‐2‐pyridone, (I), grown from a variety of solvents, are invariably trigonal (space group R); these are 5‐hydroxy‐6‐methyl‐2‐pyridone acetone 0.1667‐solvate, C6H7NO2·0.1667C3H6O, (Ia), and 6‐methyl‐5‐hydroxy‐2‐pyridone propan‐2‐ol 0.1667‐solvate, C6H7NO2·0.1667C3H8O, (Ib), and the forms from methanol, (Ic), water, (Id), benzonitrile, (Ie), and benzyl alcohol, (If). They incorporate channels running the length of the c axis that contain extensively disordered solvent molecules. A solvent‐free sublimed powder of 5‐hydroxy‐6‐methyl‐2‐pyridone microcrystals is essentially isostructural. Inversion‐related host molecules interact via pairs of N—H...O hydrogen bonds to form R22(8) dimers. Six of these dimers form large R126(42) puckered rings, in which the O atom of each N—H...O hydrogen bond is also the acceptor in an O—H...O hydrogen bond that involves the 5‐hydroxy group. The large R126(42) rings straddle the axes and form stacked columns viaπ–π interactions between inversion‐related molecules of (I) [mean interplanar spacing = 3.254 Å and ring centroid–centroid distance = 3.688 (2) Å]. The channels are lined by methyl groups, which all point inwards to the centre of the channels. 相似文献
17.
Rüdiger W. Seidel Iris M. Oppel 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(6):m199-m201
The title compound, [Pd2(C4H13N3)2(C14H16N2)](NO3)4, comprises discrete tetracationic dumbbell‐type dinuclear complex molecules and noncoordinating nitrate anions. Two Pd(dien)2+ moieties (dien is diethylenetriamine) are joined by the rigid linear exo‐bidentate bridging 2,2′,6,6′‐tetramethyl‐4,4′‐bipyridine ligand to form the dinuclear complex, which lies across a centre of inversion in the space group P21/n, so that the rings in the 2,2′,6,6′‐tetramethyl‐4,4′‐bipyridine bridging ligand are parallel. In the crystal, the primary and secondary amino groups of the dien ligand act as hydrogen‐bond donors towards the nitrate anions to form a three‐dimensional hydrogen‐bond network. 相似文献
18.
Haozhe Yang Simone Budow‐Busse Henning Eickmeier Hans Reuter Frank Seela 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(12):1116-1120
The title compound {systematic name: 4‐amino‐5‐cyclopropyl‐7‐(2‐deoxy‐β‐D‐erythro‐pentofuranosyl)‐7H‐pyrrolo[2,3‐d]pyrimidine}, C14H18N4O3, exhibits an anti glycosylic bond conformation, with the torsion angle χ = −108.7 (2)°. The furanose group shows a twisted C1′‐exo sugar pucker (S‐type), with P = 120.0 (2)° and τm = 40.4 (1)°. The orientation of the exocyclic C4′—C5′ bond is ‐ap (trans), with the torsion angle γ = −167.1 (2)°. The cyclopropyl substituent points away from the nucleobase (anti orientation). Within the three‐dimensional extended crystal structure, the individual molecules are stacked and arranged into layers, which are highly ordered and stabilized by hydrogen bonding. The O atom of the exocyclic 5′‐hydroxy group of the sugar residue acts as an acceptor, forming a bifurcated hydrogen bond to the amino groups of two different neighbouring molecules. By this means, four neighbouring molecules form a rhomboidal arrangement of two bifurcated hydrogen bonds involving two amino groups and two O5′ atoms of the sugar residues. 相似文献
19.
Kanji Kubo Emi Yamamoto Akira Mori 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):611-613
The title compounds, 4‐hydroxy‐5‐oxo‐1,3,6‐cycloheptatriene‐1‐carbonitrile, C8H5NO2, (I), and 2‐hydroxy‐5‐nitro‐2,4,6‐cycloheptatrien‐1‐one, C7H5NO4, (II), have intra‐ and intermolecular hydrogen bonds. The structure of (II) contains two crystallographically independent molecules, (IIa) and (IIb). An intermolecular π–π interaction and an intermolecular NO2?π–π interaction are present in (I) and (II), respectively. 相似文献
20.
Density functional calculations at the B3LYP level with 6‐311G** and aug‐cc‐pVDZ basis sets were performed to predict the heats of formation (HOFs) for two pyrazine derivatives and eight pyridine derivatives. In the isodesmic reactions designed for the computation of heats of formation (HOFs), pyrazine and pyridine were chosen as reference compounds. The N‐oxidations for the ring nitrogen of pyrazine and pyridine derivatives decrease the HOF values when N‐oxide oxygen is neighboring with amino groups, but increase when it neighbors with nitro groups. Thermal stability was evaluated via bond dissociation energies (BDE) at the UB3LYP/6‐311G** level. As a whole, the homolysis of C–NO2 bonds is the main step for bond dissociation of the title compounds. The BDE values of title compounds are influenced by intramolecular hydrogen bonds. The hydrogen bond effects associated with the length of the H···O bonds were analyzed by the electron density at the critical points and natural bond orbital. 相似文献