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1.
Hydrogen (H-) bonding ability of most stable keto and enol tautomers of formo- and thioformohydroxamic acids has been investigated by optimizing their 1:1 aggregates with MeSH and MeSeH as model molecules for sulfur and selenium containing amino acid side chains. Although enol is the most stable conformer of thioformohydroxamic acid, yet the most stable aggregate in both hydroxamic acids (HAs) being formed with keto conformer suggests that H-bonding can influence specific conformational dominance. In the aggregates, HAs preferably act as H-bond donor and S/Se of MeSH and MeSeH act as H-bond acceptor. The S···H and Se···H H-bonds although disfavored by electrostatics yet are favored by significant charge transfer. H-bonding preference and strength of interaction of HAs with MeSH and MeSeH is remarkably similar but markedly different from MeOH. AIM and NBO analysis have been employed to understand the role of electron delocalization, bond polarizations, charge transfer etc. as contributors to stabilization energy. 相似文献
2.
Hasan Karabıyık Hande Petek Nazan Ocak İskeleli Çiğdem Albayrak 《Structural chemistry》2009,20(5):903-910
The molecular and crystal structure of (E)-2-Acetyl-4-(2-bromophenyldiazenyl)phenol (1) and (E)-2-Methyl-4-(o-tolyldiazenyl)phenol (2) were characterized and determined by single crystal X-ray diffraction method besides spectroscopic means. The periodic organization
of 1 is stabilized by C–H···O type weak H-bond and Br···O type weak halogen bonding and thus, a two dimensional puckered network
is established almost parallel to () the plane. Molecules of 2 are linked into C(7) chains generated by translation along the [1 0 1] direction with the aid of O–H···N type H-bonds, and these chains are
strengthened by C–H···π interactions involving o-tolylphenol ring. Quantum chemical studies at B3LYP/6-311 ++G(d,p) level reveal that potential barrier of the compounds around
Ar–N torsions is of double minimum character unless it is defected by the presence of o-substituent groups in the vicinity of the azo bridge. The results from crystallographic and quantum chemical studies suggest
that azo benzene compounds may adapt non-planar geometry apart from the most stable planar conformation, which is located
on the secondary minima of double potential barrier regarding rotational motion around Ar–N bonds. 相似文献
3.
Agnieszka Czylkowska Danuta Czakis-Sulikowska Rafał Kruszyński Mirosława Markiewicz 《Structural chemistry》2010,21(2):415-423
A novel mixed-ligand complexes of Er(III), Yb(III) and Lu(III) with title ligands were prepared and characterized by chemical
and elemental analysis and IR spectroscopy, conductivity (in methanol, dimethyloformamide and dimethylsulphoxide). The thermal
properties of complexes in the solid state were studied. The mode of metal–ligand coordination was discussed. The title compounds
are isomorphic and isostructural in solid state. All atoms in studied compounds lie in general positions but occurrence of
inversion on the midpoint of the bond linking two pyridine rings leads to existence in asymmetric unit one complex molecule
and half of outer coordination sphere 4-bpy molecule. All chelating carboxylate groups are symmetrically bonded to the metal
cations. The molecules of studied compounds are connected to the three dimensional network via O–H···O and O–H···N intermolecular
hydrogen bonds. In the structures also exist C–H···O, C–H···Cl weak hydrogen bonds and π····π stacking interactions. 相似文献
4.
R. S. Rathore K. Sathiyanarayanan N. S. Karthikeyan P. G. Aravindan 《Structural chemistry》2010,21(5):909-914
Derivatives of azabicyclo[3.3.1]nonanone tend to prefer for weak interactions in the crystal over strong N–H···O hydrogen
bonds. The main stabilizing forces in the investigated azatricyclo[7.3.1.02,7]trideca-trienone derivatives are C–H···O, N–H···π and C–H···π interactions, leading to interesting structural patterns. The
azabicyclo[3.3.1]nonanone ring adopts chair-envelope conformation having exo-C2,C4-aromatic substituents. Amino NH is in trigonal
pyramidal configuration. The interesting stereochemistry of azabicyclo[3.3.1]nonanone, driving exceptional preference for
weaker interactions over strong hydrogen bonds serves a useful example toward engineering and design strategy, and structure
prediction methodologies. 相似文献
5.
FANG-JUN HUO CAI-XIA YIN PIN YANG 《Journal of inclusion phenomena and macrocyclic chemistry》2006,56(1-2):193-196
The [2]pseudorotaxane of cucurbit[6]uril (Q6) with 1,6-bis(imidazol-1-yl)hexane dihydrobromide was synthesized and its crystal structure was described. The structure of [2]pseudorotaxane was mainly stablized by host–guest C–H···O interactions. Self-assembly of the [2]pseudorotaxane produces infinite one-dimensional chains with intermolecular N–H···O, C–H···O, and π···π interactions; thus, a linear non-covalent pseudopolyrotaxane is formed. 相似文献
6.
The (CH3OH)
n
(n = 2–8) clusters formed via hydrogen bond (H-bonds) interactions have been studied systemically by density functional theory
(DFT). The relevant geometries, energies, and IR characteristics of the intermolecular OH···O H-bonds have been investigated.
The quantum theory of atoms in molecule (QTAIM) and natural bond orbital (NBO) analysis have also been applied to understand
the nature of the hydrogen bonding interactions in clusters. The results show that both the strength of H-bonds and the deformation
are important factors for the stability of (CH3OH)
n
clusters. The weakest H-bond was found in the dimer. The strengths of H-bonds in clusters increase from n = 2 to 8, moreover, the strengths of H-bonds in (CH3OH)
n
(n = 4–8) clusters are remarkably stronger than those in (CH3OH)
n
(n = 2, 3) clusters. The small differences of the strengths of H-bonds among (CH3OH)
n
(n = 6–8) clusters indicate that a partial covalent character is attributed to the H-bonds in these clusters. The linear relationships
between the electron density of BCP (ρb) and the H···O bond length of H-bonds as well as the second-perturbation energies E(2) have also been investigated and used to study the nature of H-bonds, respectively. 相似文献
7.
Xing Chen Wen-Tao Yin Qian Huang Hong-Rong Zuo Jia-Rong Zhou Lin-Liang Yu Chun-Lin Ni Xue-Lei Hu 《Transition Metal Chemistry》2010,35(2):143-149
Two new salts, [BzTPP]2[Cu(mnt)2] (1) and [4NO2BzTPP]2[Cu(mnt)2] (2) (BzTPP+ = benzyltriphenylphosphonium and mnt2− = maleonitriledithiolate) have been prepared and characterized by elemental analyses, UV, IR, molar conductivity and single-crystal
X-ray diffraction. The single-crystal structure analysis shows that 1 crystallizes in the monoclinic space group P21/n, while 2 crystallizes in the triclinic space group P−1. The effects of weak intramolecular interactions such as C–H···O, C–H···S, C–H···N, C–H···Cu hydrogen bonds and p···π, π···π stacking interactions in the solids generate a 3D network structure. It is noted that the change in the molecular
topology of the counteraction when the 4-substituted group in the benzyl ring is changed from H to NO2 results in differences in the crystal system, space group, weak interactions and the stacking mode of the cations and anions
of 1 and 2. The magnetic susceptibilities of these salts measured in the temperature range 2.0 to 300 K show weak ferromagnetic coupling
features with θ = 2.05 × 10−2 K for 1 and 5.13 × 10−3 K for 2. 相似文献
8.
The experimental electron density of a chromone derivative was determined from a multipole refinement of 100 K X-ray synchrotron
data and complemented by theoretical calculations with experimental and optimized geometry. Atomic and topological properties
were obtained using the Quantum Theory of Atoms in Molecules approach. The examination of topological parameters unambiguously
showed π-delocalization within the H-bonded ring. The application of source function analysis confirmed the intramolecular
N–H···O hydrogen bond to be a resonance-assisted hydrogen bond. The topological study confirmed the covalent nature of N–H···O
interaction and the electrostatic nature of weak C–H···O interactions. 相似文献
9.
Cyril Rajnák Ján Titi? Roman Bo?a Ján Moncol’ Zdeňka Padělková 《Monatshefte für Chemie / Chemical Monthly》2011,36(4):789-795
Abstract
A mononuclear complex [CoL2Cl2]·3.5H2O (L = 2-[(2,2-diphenylethylimino)methyl]pyridine-1-oxide) has been synthesized and characterized by X-ray structure analysis. The crystal structure confirms the formation of an interesting porous framework with channel diameters of about 8 ? through weak C–H···π and C–H···Cl interactions. The magnetic properties of this complex have also been studied, and the susceptibility and magnetization data were analyzed in terms of the spin Hamiltonian formalism. They confirm substantial zero-field splitting, D/hc = 75 cm−1. 相似文献10.
Yu-Ping Sun Xiao-Hui Ren Hai-Jun Wang Yan-Yan Shan Li-Juan Xing 《Structural chemistry》2009,20(2):213-220
Theoretical studies on hydrogen-bonded complexes between amino acids (glycine, alanine, and leucine) and urea in gas phase have been carried out using density functional theory (DFT) and ab initio methods at the B3LYP/6-311++g** and MP2/6-311++g** theory levels. The structures, binding energy, Chelpg (charges from electrostatic potentials using a grid-based method) charge distribution, and bond characteristics of the mentioned complexes were calculated. Urea is a good H-bond donor and an excellent receptor for highly electronegative atoms like O and N, through the formation of two or more hydrogen bonds. The NH2 and COOH groups of amino acids can form several different types of H-bonds with urea molecular, as well as CαH and alkyl side chains. The calculated high binding energy also suggests multiple H-bonds formed in one complex. The OH···O contact is the strongest hydrogen bond interaction with H···O separation around 1.65 Å and its relevant angle close to 176°. The closely linear amide H-bonds NH···O and OH···N strongly stabilize the amino acid–urea complex with H···O separation between 1.89 and 2.38 Å. The weaker CH···O/N H-bonds are also discussed as significant interaction in biological systems involving amino acids. 相似文献
11.
Oleg V. Shishkin Irina V. Omelchenko Andrei L. Kalyuzhny Boris V. Paponov 《Structural chemistry》2010,21(5):1005-1011
Results of X-ray diffraction study and quantum-chemical calculations revealed that molecular conformation of thioindirubin
molecule creates suitable conditions for formation of intramolecular C–H···O and S···O interactions. Analysis of molecular
electrostatic potential (MEP) demonstrates existence of two areas of positive MEP (σ-holes) in the outermost part of the sulfur
atom on the continuation of the lines of the C–S bonds. One of these σ-holes is oriented toward region of negative MEP around
the oxygen atom of carbonyl group. Such situation corresponds to formation of σ-hole or chalcogen bond. Existence of both
types of bonding interactions is confirmed by topological analysis of electron density distribution using “Atoms in Molecules”
(AIM) theory. Energies of the C–H···O hydrogen bond and the S···O σ-hole bond derived from AIM and NBO theories are very close. 相似文献
12.
Qian Huang Wei-qiang Chen Xing Chen Xiao-bin Liu Jia-rong Zhou Hong-rong Zuo Lin-liang Yu Chun-lin Ni 《Transition Metal Chemistry》2009,34(7):765-771
Two new hybrid organic–inorganic salts, [BzDMAP]2[Cu(mnt)2](1) and [NO2BzDMAP]2[Cu(mnt)2] (2) ([BzDMAP]+ = 1-benzyl-4′-dimethylaminopyridinium, [NO2BzDMAP]+ = 1-(4′-nitrobenzyl)-4′-dimethylaminopyridinium, and mnt2− = maleonitriledithiolate) have been characterized structurally and magnetically. The [BzDMAP]+ or [NO2BzDMAP]+ cations (C) and the [Cu(mnt)2]2− anions (A) in 1 and 2 stack into a 1D alternating CC-A-CC-A-CC column. The Cu···N, π···π, C–H···N, C–H···O, and C–H···S weak interactions play
important roles in the molecular stacking and generate a 2D or 3D structure of 1 and 2. The magnetic susceptibilities of these salts measured in the temperature range 2.0–300 K show weak antiferromagnetic coupling
features with θ = −2.370 K for 1 and −0.222 K for 2. 相似文献
13.
Abstract
Four complexes of 3,3-diphenylpropanoate (L) and 4,4′-bipyridine as auxiliary bridging ligands were synthesized and characterized, namely [Zn(L)2(4bpy)(EtOH)2]∞ (1), [Co(L)2(4bpy)(EtOH)2]∞ (2), [Ni(L)2(4bpy)(EtOH)2]∞ (3), and [Cu(L)2(4bpy)(H2O)]∞ (4) (4bpy = 4,4′-bipyridine). X-ray single-crystal diffraction analyses show that complexes 1–4 all take one-dimensional (1D) fishbone-like structures incorporating bridging 4bpy ligands. The complexes show different supramolecular frameworks interlinked via intermolecular hydrogen bonds, π···π stacking, and/or C–H···π supramolecular interactions. Complex 3 only has a simple one-dimensional fishbone-like chain, whereas complexes 1 and 2 show two-dimensional supramolecular structures by interchain C–H···O hydrogen bonds. Complex 4 is assembled into two-dimensional layers and then an overall three-dimensional framework by a combination of interchain O–H···O hydrogen bonds and C–H···π supramolecular interactions. The luminescent properties of the ligands and their complexes were investigated. 相似文献14.
Katayoun Marjani Mohsen Mousavi Omid Arazi Akram Ashouri Samira Bourghani Mohammad Rajabi 《Monatshefte für Chemie / Chemical Monthly》2009,33(3):1331-1336
Abstract
Sodium-hydroxide-catalyzed condensation of di-p-methyl- and di-p-methoxybenzil with acetone derivatives was investigated in methanol. Di- and trisubstituted products were obtained as cyclopentenones, while tetraaryl-substituted systems were isolated as cyclopentadienones. The structures of the products were identified by elemental analysis, infrared (IR), nuclear magnetic resonance (1H NMR), and mass spectroscopy. The solid-state structure of 4-hydroxy-3,4-bis(4-methoxyphenyl)-5,5-dimethyl-2-cyclopenten-1-one was further studied by single-crystal X-ray diffraction analysis. The title compound crystallizes in an orthorhombic space group and intermolecular O–H···O and C–H···O hydrogen bonds stabilize the crystal lattice. 相似文献15.
Crystal structures of a series of p-halogenated 6,6-diphenylfulvenes 2–5 are reported and comparatively discussed including the known structure of the non-halogenate parent compound 1. The molecular structures show twisted conformations of the plane aryl and fulvene subunits against each other, rather unaffected
by the different halogen substituents. The packing structures exclusively involve C–H···X (X = F, Cl, π) contacts while Hal···Hal
and π-stacking interactions do not occur. 相似文献
16.
The complexes formed via hydrogen bonding interactions between cysteine and propanoic acid have been studied at the density
three-parameter hybrid functional DFT-B3LYP/6-311++G(d,p) level regarding their geometries, energies, vibrational frequencies,
and topological features of the electron density. The quantum theory of atoms in molecules (QTAIM) and natural bond orbital
(NBO) analysis was employed to elucidate the interaction characteristics in cysteine–propanoic acid (Cys–Prop) complexes.
More than 10 kinds of hydrogen bonds (H-bonds) including intra- and inter-molecular H-bonds have been found in Cys–Prop complexes.
The results show that both the strength of H-bonds and the deformation are important factors for the stability of Cys–Prop
complexes. The strongest H-bonds (O2HA···O1B and O2HA···O1B) exist in the most stable Cys–Prop complex. The stronger H-bonds formed between hydroxyl and O (or N) atom usually stronger
than those involve C (or S) atom. Relationships between the electron density (ρ) of BCP and H-bond length as well as the Fock matrix element (F
ij) has also been investigated and used to study the nature of H-bonds. Moreover, the results show that the change of the bond
length linearly correlates with the corresponding frequency shift. 相似文献
17.
Chun-Sen Liu E. Carolina Sañudo Li-Fen Yan Ze Chang Jun-Jie Wang Tong-Liang Hu 《Transition Metal Chemistry》2009,34(1):51-60
Abstract To explore the influence of the anthracene ring skeleton, with a large conjugated π-system, on the structures and properties
of its complexes, two MnII complexes with anthracene-9-carboxylate ligand were synthesized and structurally characterized: {[Mn(L)2(H2O)2](H2O)}∞ (1) and [Mn2(L)4(phen)2(μ-H2O)](CH3OH) (2) (L = anthracene-9-carboxylate and phen = 1,10-phenanthroline). Complex (1) has a one-dimensional (1D) chain structure that is further assembled to form a two-dimensional (2D) sheet, and then an overall
three-dimensional (3D) network by π···π stacking and/or C–H···π interactions. Complex (2) makes a dinuclear structure by incorporating the chelating phen ligand, which is further interlinked via inter-molecular
π···π stacking and C–H···π interactions to generate a higher-dimensional supramolecular network along the different crystallographic
directions. The results reveal that the bulky anthracene ring skeleton in L, by virtue of intra- and/or inter-molecular π···π
stacking and C–H···π interactions, plays an important role in the formation of complexes (1) and (2). The magnetic properties of (1) and (2) were further investigated. As expected, the very long inter-metallic separations result in weak magnetic coupling, with
the corresponding coupling constant values of J = −10 cm−1 for (1) and J = −2.46 cm−1 for (2).
Graphical abstract The constructions of two new MnII complexes comprising 1D chain (1) and dinuclear subunit (2) structures have been successfully achieved by using a bulky anthracene-9-carboxylic acid (HL), together with incorporating
the chelating 1,10-phenanthroline as a co-ligand for (2). The result reveals that the bulky anthracene ring skeleton of HL, by virtue of intra- and/or inter-molecular π···π stacking
and C–H···π interactions, plays an important role in the formation of the supramolecular architectures of (1) and (2). Moreover, magnetic properties of the complexes have been investigated.
相似文献
18.
Hasan Karabıyık Hande Petek Nazan Ocak İskeleli Çiğdem Albayrak 《Structural chemistry》2009,20(6):1055-1065
The molecular and crystal structure of (Z)-6-((4-bromophenylamino)methylene)-2,3-dihydroxycyclohexa-2,4-dienone were determined by single crystal X-ray diffraction
and spectroscopic methods. Molecules of the compound can be regarded as a resonance hybrid of cis-keto tautomer and zwitterionic form. Pairs of molecules of the compound generate pseudocyclic centrosymmetric R22 (10) R_{2}^{2} (10) supramolecular synthons with the aid of O–H···O type intermolecular H-bonds. Stacking of R22 (10) R_{2}^{2} (10) synthons along b-axis is stabilized by π···π interactions. Changes in both covalent topology and molecular geometry of the compound accompanying
proton transfer were monitored by a relaxed PES scan with respect to hydroxyl bond length used as redundant internal coordinate.
Quantum chemical studies at 6-311 + G(d,p) level reveal that bond lengths which are indicative to tautomerization process
cannot reach their expected values even if proton transfer occurs in gas phase and pseudo-aromatic chelate ring formation
has primary effect on the stabilization of NH tautomer. Resonance-assisted intramolecular H-bond affects the electronic state
of its neighboring aromatic fragments. 相似文献
19.
Wen-Kui Dong Jun-Feng Tong Yin-Xia Sun Jian-Chao Wu Jian Yao Shang-Sheng Gong 《Transition Metal Chemistry》2010,35(4):419-426
Two new mono- and dinuclear Cu(II) complexes, namely [CuL1]·0.5H2O (1) and [(Cu2(L2)2)(DMF)]·0.5DMF (2) (H2L1 = 1,2-bis{[(Z)-(3-methyl-5-oxo-1-phenyl-1H-pyrazolidin-4(4H)-yl)(phenyl)]methylene-aminooxy}ethane; H2L2 = 1,3-bis{[(Z)-(3-methyl-5-oxo-1-phenyl-1H-pyrazolidin-4(4H)-yl)(phenyl)] methyleneaminooxy}propane), have been synthesized and characterized by X-ray crystallography. The unit cell
of complex 1 contains two crystallographically independent but chemically identical [CuL1] molecules and one crystalline water molecule, showing a slightly distorted square-planar coordination geometry and forming
a wave-like pattern running along the a-axis via hydrogen bonding and π···π stacking interactions. Complex 2 has a dinuclear structure, comprising two Cu(II) atoms, two completely deprotonated phenolate bisoxime (L2)2− moieties (in the form of enol), and both coordinated and hemi-crystalline DMF molecules. Complex 2 has square-planar and square-pyramidal geometries around the two copper centers, whose basic coordination planes are almost
perpendicular and form an infinite three-dimensional supramolecular network structure involving intermolecular C–H···N, C–H···O,
and C–H···π(Ph) hydrogen bonding and π···π stacking interactions of neighboring pyrazole rings. 相似文献
20.
Abstract The molecular and crystal structure of a 1:1 co-crystal of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)–chloranilic acid, (1), has been determined by X-ray diffraction at the monoclinic space group P21/c with cell parameters of a = 8.422(6), b = 7.343(4), c = 16.112(7) ?, β = 104.988(8)°, V = 962.5(10) ?3 and Z = 2. In the crystal structure, two components connect via the intermolecular O–H···N hydrogen bonds [2.804(4) ?] and S···O
heteroatom interaction [2.945(3) ?] with R
2
2(7) couplings to form a unique and infinite one-dimensional supramolecular tape structure. The calculations of (1) at the HF/6-31G(d), MP2/6-31G(d), and B3LYP/6-31G(d) levels can almost reproduce X-ray geometry. In addition, the distances
of the intermolecular O–H···N and S···O interactions by MP2/6-31G(d) and B3LYP/6-31G(d) levels agree well with those in the
crystal. The calculated binding energies corrected BSSE and ZPE are −4.487 (HF), −7.473 (MP2), and −5.640 (B3LYP) kcal/mol.
The results suggest that the complex (1) is very stable and the dispersion interaction is significantly important for the attractive intermolecular interaction in
(1). The NBO analysis has revealed that the n(N) → σ*(O–H) interaction gives the strongest stabilization to the system and the major interaction for the intermolecular
S···O contact is n(O) → σ*(S–N).
Index Abstract In the crystal structure of the title compound, the molecules are linked by intermolecular O–H···N hydrogen bonds and short
S···O heteroatom interactions with R
2
2(7) couplings to construct a unique and infinite one-dimensional supramolecular tape structure.
相似文献