共查询到20条相似文献,搜索用时 15 毫秒
1.
Andrei V. Afonin Dmitry V. Pavlov Alexander I. Albanov Ol'ga A. Tarasova Nina A. Nedolya 《Magnetic resonance in chemistry : MRC》2013,51(7):414-423
In the 1H NMR spectra of the 1‐vinylpyrroles with amino‐ and alkylsulfanyl groups in 5 and 2 positions, an extraordinarily large difference between resonance positions of the HA and HB terminal methylene protons of the vinyl group is discovered. Also, the one‐bond 1J(Cβ,HB) coupling constant is surprisingly greater than the 1J(Cβ,HA) coupling constant in pyrroles under investigation, while in all known cases, there was a reverse relationship between these coupling constants. These spectral anomalies are substantiated by quantum chemical calculations. The calculations show that the amine nitrogen lone pair is removed from the conjugation with the π‐system of the pyrrole ring so that it is directed toward the HB hydrogen. These factors are favorable to the emergence of the intramolecular C–HB???N hydrogen bonding in the s‐cis(N) conformation. On the other hand, the spatial proximity of the sulfur to the HB hydrogen provides an opportunity of the intramolecular C–HB???S hydrogen bonding in the s‐cis(S) conformation. Presence of the hydrogen bond critical points as well as ring critical point for corresponding chelate ring revealed by a quantum theory of atoms in molecules (QTAIM) approach confirms the existence of the weak intramolecular C–H???N and C–H???S hydrogen bonding. Therefore, an unusual high‐frequency shift of the HB signal and the increase in the 1J(Cβ,HB) coupling constant can be explained by the effects of hydrogen bonding. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
2.
Bikshandarkoil R. Srinivasan Ashish R. Naik Christian Näther Wolfgang Bensch Prof. Dr. 《无机化学与普通化学杂志》2007,633(4):582-588
The reaction of ammonium tetrathiometalate (NH4)2[MS4] (M = W or Mo) with the R(+) or S(?) forms of the organic amine α‐methylbenzylamine [PhCH(CH3)NH2] results in the formation of the corresponding non‐centrosymmetric bis(α‐methylbenzylammonium) tetrathiometalate complexes [PhCH(CH3)NH3]2[MS4] (R‐ammonium M = W 1 ; R‐ammonium M = Mo 2 ; S‐ammonium M = W 3 , S‐ammonium M = Mo 4 ) which were characterized by elemental analysis, IR, Raman, UV‐Vis and CD spectra, X‐ray powder diffractometry and single crystal X‐ray crystallography. Compounds 1 ‐ 4 crystallize in the chiral space group P21 and constitute the first examples of structurally characterized chiral organic ammonium group VI tetrathiometalates. The structures of 1 ‐ 4 consist of two crystallographically independent chiral organic ammonium cations and a tetrahedral tetrathiometalate dianion. The N‐H···S and C‐H···S interactions between the anions and cations organise them such that the organic ammonium ions always point towards the S atoms of [MS4]2?. 相似文献
3.
Guo‐Cheng Liu Yu‐Fei Wang Ai‐Xiang Tian Xiu‐Li Wang Jing‐Jing Cao Song Yang Hong‐Yan Lin 《无机化学与普通化学杂志》2013,639(1):148-157
Three new 2D/3D supramolecular architectures derived from Cu‐organic subunits and Keggin anions, [CuII2(biz)8(HPMoVI10MoV2O40)(H2O)2] · 2H2O ( 1 ), [CuI4(biz)8(SiW12O40)] · 2H2O ( 2 ) and [CuI2(dmbiz)4(Hdmbiz)2(SiW12O40)] ( 3 ) (biz = benzimidazole, dmbiz = 5, 6‐dimethyl benzimidazole), were obtained under hydrothermal conditions. Single crystal X‐ray diffraction analysis reveals that compound 1 has two kinds of [CuII(biz)2]2+ cations, which are further extended by Keggin anions into a 2D (4, 8)‐connected supramolecular network by hydrogen bonding interactions. In compound 2 , four types of [CuI(biz)2]+ subunits link the [SiW12O40]4– anions to form a 3D (2, 6)‐connected supramolecular structure. Compound 3 shows a 3D supramolecular network with a NaCl‐type topology constructed by [CuI(dmbiz)2]+ subunits, anions, and discrete [Hdmbiz]+ cations. Moreover, the electrochemical and photocatalytic properties of compounds 1 and 2 were investigated. 相似文献
4.
《Magnetic resonance in chemistry : MRC》2003,41(8):557-566
A complete analysis of the 1H and 13C spectra of the representative series of heteroaryl vinyl ethers and sulfides and heteroaryl styryl sulfides was carried out. The electronic and spatial structures of these compounds are discussed. It was shown that the C—H· · ·N intramolecular interactions in the investigated molecules influence significantly the spectral parameters and the conformational equilibrium. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
5.
Eric Bosch 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(10):748-752
Weak interactions between organic molecules are important in solid‐state structures where the sum of the weaker interactions support the overall three‐dimensional crystal structure. The sp‐C—H…N hydrogen‐bonding interaction is strong enough to promote the deliberate cocrystallization of a series of diynes with a series of dipyridines. It is also possible that a similar series of cocrystals could be formed between molecules containing a terminal alkyne and molecules which contain carbonyl O atoms as the potential hydrogen‐bond acceptor. I now report the crystal structure of two cocrystals that support this hypothesis. The 1:1 cocrystal of 1,4‐diethynylbenzene with 1,3‐diacetylbenzene, C10H6·C10H10O2, (1), and the 1:1 cocrystal of 1,4‐diethynylbenzene with benzene‐1,4‐dicarbaldehyde, C10H6·C8H6O2, (2), are presented. In both cocrystals, a strong nonconventional ethynyl–carbonyl sp‐C—H…O hydrogen bond is observed between the components. In cocrystal (1), the C—H…O hydrogen‐bond angle is 171.8 (16)° and the H…O and C…O hydrogen‐bond distances are 2.200 (19) and 3.139 (2) Å, respectively. In cocrystal (2), the C—H…O hydrogen‐bond angle is 172.5 (16)° and the H…O and C…O hydrogen‐bond distances are 2.25 (2) and 3.203 (2) Å, respectively. 相似文献
6.
《Magnetic resonance in chemistry : MRC》2002,40(2):114-122
1H and 13C NMR spectroscopy of a series of 1‐vinyl‐2‐(2′‐heteroaryl)‐pyrroles were employed for the analysis of their electronic and spatial structure. The C—H···N intramolecular interaction between the α‐hydrogen of the vinyl group and the pyridine nitrogen, a kind of hydrogen bonding, was detected in 1‐vinyl‐2‐(2′‐pyridyl)pyrrole, which disappeared in its iodide methyl derivative. It was shown that this interaction is stronger than the C—H···O and C—H···S interactions in 1‐vinyl‐2‐(2′‐furyl)‐ and ‐2‐(2′‐thienyl)‐pyrroles. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
7.
Influence of substitution on the strength and nature of CH···N hydrogen bond in XCCH···NH3 complexes
The effect of substitution on the strength and nature of CH···N hydrogen bond in XCCH···NH3 (X = F, Cl, Br, OH, H, Me) and NCH···NH3 complexes were investigated by quantum chemical calculations. Ab initio calculations were performed using MP2 method with a wide range of basis sets. With tacking into account the BSSE and ZPVE, the values of BEs decrease. Replacement of the nonparticipatory hydrogen atom of HCCH by the electronegative atoms (F, Cl, and Br), lead to the BEs increases. The BE corresponding to the replacement of the nonparticipatory hydrogen atom of HCCH by the OH and CH3 groups decreases. A far greater enhancement of the interaction energy arises from replacement of HCCH by the more acidic HCN. The natural bond orbital analysis and the Bader's quantum theory of atoms in molecules were also used to elucidate the interaction characteristics of these complexes. The electrostatic nature of H‐bond interactions is predicted from QTAIM analysis. In addition, the relationship between the isotropic and anisotropic chemical shifts of the bridging hydrogen and binding energy of complexes as well as electron density at N···H BCPs were investigated. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
8.
《Magnetic resonance in chemistry : MRC》2002,40(9):595-598
Unusual behaviour was observed in the study of the 17O, 13C and 1H NMR and IR spectra of crowded (1‐adamantyl)alkyl ketones. As the size of the alkyl substituent is increased, abnormal upfield chemical shifts in the 13C NMR and downfield shifts in the 17O NMR of the carbonyl group, as well as downfield shifts in the 1H NMR of the adamantyl γ'‐protons, are found. In the IR spectrum, the νC?O stretching frequencies of the ketones with bulky substituents show considerable red shifts. Correlation of the NMR shifts with the number of γ‐carbon atoms of the alkyl substituents and comparison with the IR results indicated that there is an intramolecular through‐space CH···O interaction in crowded ketones. This was supported by the results of ab initio calculations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
9.
Andrei V. Afonin Igor A. Ushakov Alexander V. Vashchenko Dmitry E. Simonenko Andrei V. Ivanov Alexander M. Vasil'tsov Al'bina I. Mikhaleva Boris A. Trofimov 《Magnetic resonance in chemistry : MRC》2009,47(2):105-112
According to the 1H, 13C and 15N NMR spectroscopic data and DFT calculations, the E‐isomer of 1‐vinylpyrrole‐2‐carbaldehyde adopts preferable conformation with the anti‐orientation of the vinyl group relative to the carbaldehyde oxime group and with the syn‐arrangement of the carbaldehyde oxime group with reference to the pyrrole ring. This conformation is stabilized by the C? H···N intramolecular hydrogen bond between the α‐hydrogen of the vinyl group and the oxime group nitrogen, which causes a pronounced high‐frequency shift of the α‐hydrogen signal in 1H NMR (~0.5 ppm) and an increase in the corresponding one‐bond 13C–1H coupling constant (ca 4 Hz). In the Z‐isomer, the carbaldehyde oxime group turns to the anti‐position with respect to the pyrrole ring. The C? H···O intramolecular hydrogen bond between the H‐3 hydrogen of the pyrrole ring and the oxime group oxygen is realized in this case. Due to such hydrogen bonding, the H‐3 hydrogen resonance is shifted to a higher frequency by about 1 ppm and the one‐bond 13C–1H coupling constant for this proton increases by ~5 Hz. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
10.
《Journal of Molecular Structure》2004,690(1-3):69-75
The crystal and molecular structures of (r-2, c-4)-3-benzyl-2,4,5,5-tetraphenyl-1,3-thiazolidine are investigated showing the existence of C(sp2)–HS and C(sp2)–HN intramolecular contacts. The analysis of geometrical parameters shows that C–HS contacts may be treated as hydrogen bonds but C–HN do not fulfil the geometrical criteria of the existence of H-bonds. The B3LYP/6-311+G* single point calculations were performed to obtain wave functions applied later for ‘atoms in molecules’ (AIM) study. The analysis of bond critical points based on the Bader theory (AIM) supports the existence of intramolecular C–HS H-bonds. 相似文献
11.
Andrei V. Afonin Igor A. Ushakov Alexander V. Vashchenko Evgeniy V. Kondrashov Alexander Yu. Rulev 《Magnetic resonance in chemistry : MRC》2010,48(9):661-670
In the series of diaminoenones, large high‐frequency shifts of the 1H NMR of the N? H group in the cis‐position relative to the carbonyl group suggests strong N? H···O intramolecular hydrogen bonding comprising a six‐membered chelate ring. The N? H···O hydrogen bond causes an increase of the 1J(N,H) coupling constant by 2–4 Hz and high‐frequency shift of the 15N signal by 9–10 ppm despite of the lengthening of the relevant N? H bond. These experimental trends are substantiated by gauge‐independent atomic orbital and density functional theory calculations of the shielding and coupling constants in the 3,3‐bis(isopropylamino)‐1‐(aryl)prop‐2‐en‐1‐one (12) for conformations with the Z‐ and E‐orientations of the carbonyl group relative to the N? H group. The effects of the N? H···O hydrogen‐bond on the NMR parameters are analyzed with the atoms‐in‐molecules (AIM) and natural bond orbital (NBO) methods. The AIM method indicates a weakening of the N? H···O hydrogen bond as compared with that of 1,1‐di(pyrrol‐2‐yl)‐2‐formylethene (13) where N? H···O hydrogen bridge establishes a seven‐membered chelate ring, and the corresponding 1J(N,H) coupling constant decreases. The NBO method reveals that the LP(O) →σ*N? H hyperconjugative interaction is weakened on going from the six‐membered chelate ring to the seven‐membered one due to a more bent hydrogen bond in the former case. A dominating effect of the N? H bond rehybridization, owing to an electrostatic term in the hydrogen bonding, seems to provide an increase of the 1J(N,H) value as a consequence of the N? H···O hydrogen bonding in the studied diaminoenones. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
12.
Zhi Min Jin Yuan Jiang Pan Xiao Feng Li Mao Lin Hu Liang Shen 《Journal of Molecular Structure》2003,660(1-3):67-72
A unique coordinated molecular capsule compound is synthesized and characterized by X-ray diffraction. The compound crystallizes in cubic space group of Pa-3 with a=14.348(1), b=14.348(1), c=14.348(1) Å, V=2953.8(4) Å3, Z=8. The diazabicyclo[2.2.2]octane-1,4-diium is occluded in the cubic anionic coordinated framework of K+ and (ClO4)− in a dimension of 7.174(1) Å, and assumes ordered feature. All of hydrogen atoms take parts in trifurcated hydrogen bonds of N–HO and C–HO type, respectively, the later being reported for the first time. The IR spectrum of the title compound shows significant shift of CH2 vibrational bands, and are correlated with X-ray structural data. 相似文献
13.
Calculations of 1 JNH, 1h JNH and 2h JNN spin–spin coupling constants of 27 complexes presenting N–H·N hydrogen bonds have allowed to analyze these through hydrogen‐bond coupling as a function of the hybridization of both nitrogen atoms and the charge (+1, 0, ? 1) of the complex. The main conclusions are that the hybridization of N atom of the hydrogen bond donor is much more important than that of the hydrogen bond acceptor. Positive and negative charges (cationic and anionic complexes) exert opposite effects while the effect of the transition states ‘proton‐in‐the‐middle’ is considerable. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
14.
Roser Pons Cristina Ibez Ana B. Buades Antonio Franconetti Angel Garcia‐Raso Juan J. Fiol Angel Terrn Elies Molins Antonio Frontera 《应用有机金属化学》2019,33(6)
We report the synthesis and X‐ray characterization of the N6‐benzyl‐N6‐methyladenine ligand (L) and three metal complexes, namely [Zn(HL)Cl3]·H2O ( 1 ), [Cd(HL)2Cl4] ( 2 ) and [H2L]2[Cd3(μ‐L)2(μ‐Cl)4Cl6]·3H2O ( 3 ). Complex 1 consists of the 7H‐adenine tautomer protonated at N3 and coordinated to a tetrahedral Zn(II) metal centre through N9. The octahedral Cd(II) in complex 2 is N9‐coordinated to two N6‐benzyl‐N6‐methyladeninium ligands (7H‐tautomer protonated at N3) that occupy apical positions and four chlorido ligands form the basal plane. Compound 3 corresponds to a trinuclear Cd(II) complex, where the central Cd atom is six‐coordinated to two bridging μ‐L and four bridging μ‐Cl ligands. The other two Cd atoms are six‐coordinated to three terminal chlorido ligands, to two bridging μ‐Cl ligands and to the bridging μ‐L through N3. Essentially, the coordination patterns, degree of protonation and tautomeric forms of the nucleobase dominate the solid‐state architectures of 1 – 3 . Additionally, the hydrogen‐bonding interactions produced by the endocyclic N atoms and NH groups stabilize high‐dimensional‐order supramolecular assemblies. Moreover, energetically strong anion–π and lone pair (lp)–π interactions are important in constructing the final solid‐state architectures in 1 – 3 . We have studied the non‐covalent interactions energetically using density functional theory calculations and rationalized the interactions using molecular electrostatic potential surfaces and Bader's theory of atoms in molecules. We have particularly analysed cooperative lp–π and anion–π interactions in 1 and π+–π+ interactions in 3 . 相似文献
15.
The reaction of 4‐phenyl‐2‐aminothiazole or 2‐amino pyridine with α‐bromo acetic (–)‐menthyl ester ( 2c ) yields new N‐alkyl cycloimmonium bromides ( 1c , 3 ) with the chiral (–)‐menthyl substituent, which were isolated and fully characterized by 1H and 13C NMR spectroscopy for the first time. In addition, starting from 4‐phenyl‐2‐aminothiazole, two further N‐alkyl cycloimmonium bromides ( 1a , 1b ) were prepared. The molecular and crystal structures of all three thiazole derived N‐alkyl cycloimmonium bromides ( 1a – c ) were determined by single‐crystal X‐ray diffraction. In all cases the crystal structures are dominated by N–H ··· Br hydrogen bonds, which results in the formation of an extensive hydrogen bonded network in the crystal. Interestingly, in all structures S ··· Br– distances shorter than the sum of the van der Waals radii are observed. 相似文献
16.
A. V. Afonin D-S. D. Toryashinova E. Yu. Schmidt 《Journal of Molecular Structure》2004,680(1-3):127-135
The C–HX (X=N, O, S) intramolecular hydrogen bond between the α-hydrogen of the vinyl group and the corresponding heteroatom in the series of 1-vinyl-2-(2′-heteroaryl)pyrroles was examined by ab initio calculations at the B3LYP/6-311(d,p) level. It was shown that the C–HN hydrogen bond is stronger than the C–HO hydrogen bond and the latter is, in turn, stronger than the C–HS hydrogen bond. This conclusion is supported by calculations of 1H NMR chemical shieldings. 相似文献
17.
Sobia Mastoor Shaheen Faizi Rubeena Saleem Bina Shaheen Siddiqui 《Magnetic resonance in chemistry : MRC》2014,52(3):115-121
The 1H and 13C NMR spectral study of several biologically active derivatives of 8‐quinolinol have been made through extensive NMR studies including homodecoupling and 2D‐NMR experiments such as COSY‐45°, NOESY, and HeteroCOSY. Electron donating resonance and electron withdrawing inductive effect of several groups showed marked changes in chemical shifts of nuclei at the seventh positions of O‐substituted quinolinols (2–15). Although in N‐alkyl, 8‐alkoxyquinolinium halides (16–21), ring A rightly showed low frequency chemical shift values. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
18.
Andrei V. Afonin Igor A. Ushakov Dmitry V. Pavlov Andrei V. Ivanov Al'bina I. Mikhaleva 《Magnetic resonance in chemistry : MRC》2010,48(9):685-692
The 1H, 13C and 15N NMR studies have shown that the E and Z isomers of pyrrole‐2‐carbaldehyde oxime adopt preferable conformation with the syn orientation of the oxime group with respect to the pyrrole ring. The syn conformation of E and Z isomers of pyrrole‐2‐carbaldehyde oxime is stabilized by the N? H···N and N? H···O intramolecular hydrogen bonds, respectively. The N? H···N hydrogen bond in the E isomer causes the high‐frequency shift of the bridge proton signal by about 1 ppm and increase the 1J(N, H) coupling by ~3 Hz. The bridge proton shows further deshielding and higher increase of the 1J(N, H) coupling constant due to the strengthening of the N? H···O hydrogen bond in the Z isomer. The MP2 calculations indicate that the syn conformation of E and Z isomers is by ~3.5 kcal/mol energetically less favorable than the anti conformation. The calculations of 1H shielding and 1J(N, H) coupling in the syn and anti conformations allow the contribution to these constants from the N? H···N and N? H···O hydrogen bondings to be estimated. The NBO analysis suggests that the N? H···N hydrogen bond in the E isomer is a pure electrostatic interaction while the charge transfer from the oxygen lone pair to the antibonding orbital of the N? H bond through the N? H···O hydrogen bond occurs in the Z isomer. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
19.
Investigation of the resonance‐assisted hydrogen bond in model β‐diketones through localized molecular orbital analysis of the spin–spin coupling constants related to the O–H · · · O hydrogen bond
下载免费PDF全文
![点击此处可从《Magnetic resonance in chemistry : MRC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The resonance‐assisted hydrogen bond (HB) phenomenon has been studied theoretically by a localized molecular orbital (LMO) decomposition of the spin–spin coupling constants between atoms either involved or close to the O–H · · · O system of some β‐diketones and their saturated counterparts. The analysis, carried out at the level of the second‐order polarization propagator approximation, shows that the contributions in terms of LMO to the paramagnetic spin orbital and the spin dipolar Ramsey terms proof the importance of the delocalized π‐electron structure supporting the idea of the existence of the resonance‐assisted HB phenomenon phenomenon. The LMO contributions to the Fermi contact term indicate mainly the presence of the HB that may or not be linked to the π‐electrons. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
20.
The review concerns the results of systematic X-ray diffraction studies of the electron density distribution in the crystals
of compounds with strong intramolecular hydrogen bonds N-H...O, O-H...O, O-H...N, and N-H...S. The advantages of the topological
analysis of the electron density distribution function in the analysis of the nature and estimation of the H-bond energies
directly from experimental data are discussed.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 1–14, January, 2006. 相似文献