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The study of the IR spectral data for metallated acetonitrile (counter ions Li+, Na+, K+ in solvents tetrahydrofuran, THF, and hexamethylphosphotriamide, HMPT) and its D3? and 15N- derivatives together with and normal coordinate calculations showed that the mesomeric ion H2CCN has a favoured planar structure and the carbon-metal bond has a pronounced ionic character. 相似文献
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The IR spectra of the products of electrochemical and chemical (alkali metals, naphthalene anion-radical) reduction of substituted α,βdiaryl-acrylonitriles (32 compounds) were studied. It was found that the anion-radicals initially formed dimerize into the corresponding dimeric dianions. Correlation of v(CN) (dimeric dianions) with v(CN) (sodium methoxide adducts, ref 26), as well as with the σ? constants of the substituents in the α-aromatic rings were found. The effects of the β-substituents, counter ions and solvents on v(CN) of the dimeric dianions are discussed. 相似文献
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Ahmad S. Shawali H. M. Hassaneen M. Sami H. M. Fahham 《Journal of heterocyclic chemistry》1976,13(5):1137-1140
Ethyl cyanoacetate reacts with the hydrazidic halides IV-VI in presence of sodium ethoxide in ethanol at room temperature to give the pyrazole derivatives VIII-X respectively. Similar treatment of IV-VIII with cyanoacetanilide gives the substituted pyrazoles XI-XIV respectively. The results show that IV to VIII, unlike I, follow one and the same sequence in their reactions with cyanoacetic acid derivatives. The structure assignments of the products VIII-XIV were based on elemental analysis and spectral evidence. 相似文献
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《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1991,47(12):1775-1779
Triphenyltin IV polybasic acid derivatives have been synthesized, and structures suggested on the basis of their IR spectra. Tetrahedral oxoanions behave as polydentate ligands giving infinite type structures. The cleavage of these infinite type structures occurs when the derivatives react with strong Lewis bases giving discrete structure adducts. A particular type of coordination of the selenite (tetradentate) has been established. 相似文献
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《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1994,50(12):2105-2115
The IR spectra of a series of 6 phenylnitroethenes (PNE) and 6 phenylnitropropenes (PNP) were assigned, based on a normal coordinates calculation performed on styrene and styrene-d8. Some frequencies were sensitive to the electronic properties of the substituents, and others to the substitution on Cβ. AM1 minimum energy conformations and rotational barriers around the ClCα bond were calculated. According to these calculations, PNE are planar and PNP display an angle of 45° between the ethylenic and aromatic planes. AM1 underestimates the height of the electronic barriers, which is however modulated by the electron donor properties of the substituent on the ring. A correlation between the calculated electronic barrier and the CC ethylenic stretching frequency was observed. 相似文献
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V. G. Voronin M. I. Shemeryankina A. I. Ermakov S. B. Goncharenko Yu. N. Portnov 《Chemistry of Heterocyclic Compounds》1977,13(10):1137-1139
On the basis of data from the IR spectra of 4-thiobarbituric acid derivatives, and their deutero analogs, and similarly constructed model compounds, it was established that the investigated substances exist in the thione lactam form and form two types of associates through intermolecular hydrogen bonds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1416–1419, October, 1977. 相似文献
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S. Ghersetti G. Maccagnani A. Mangini F. Montanari 《Journal of heterocyclic chemistry》1969,6(6):859-868
The infrared and ultraviolet spectra of many pyridine N-oxide derivatives have been studied. Ultraviolet spectra show a strong solvent effect in going from aprotic to hydroxylic solvents due to strong hydrogen bonding. Values of δ H° for several systems CH3OH/XPyNO in tetra-chloroethylene solution were evaluated by infrared techniques and a linear correlation δ H° vs. δ v OH has been found. Features of the infrared and ultraviolet characteristic absorption bands were also investigated. 相似文献
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Khan MS Khan ZH 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(4):777-790
The geometries of hydroxy derivatives of 1,4-naphthoquinone (NQ), viz., 2-hydroxy-1,4-naphthoquinone (2HNQ), 5-hydroxy-1,4-naphthoquinone (5HNQ), and 5,8-dihydroxy-1,4-naphthoquinone (DHNQ), have been optimized using the semiempirical and ab initio theoretical methods. Semiempirical methods used for the optimization are Austin Model 1 (AM1) and Zerner's Intermediate Neglect of Differential Overlap/1(ZINDO/1). For ab initio calculations the 6-31G* basis set is used. The electronic spectra of 1,4-naphthoquinone and its hydroxy derivatives are calculated using the semiempirical Zerner's Intermediate Neglect of Differential Overlap/Spectroscopy (ZINDO/S) method employing the geometries optimized at AM1, ZINDO/1 and ab initio levels and compared with their electronic absorption spectra measured by us. For hydroxy substituted systems, such calculations for spectral assignments are made for the first time. It is found that though the predictions of the three theoretical methods for the geometries are similar, the predictions of the ZINDO/S method using the ZINDO/1 optimized geometries, are better for the transition wavelengths in the visible region of the hydroxy substituted naphthoquinones, especially for 5HNQ and DHNQ. 相似文献
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The cyclopropyl carbanions C3H4X– (X=H (I), F (II), Cl (III), CF3 (IV), COCH3 (V), CN (VI), NO2 (VII), which are formed by the removal of a proton at the position, were calculated by the semiempirical MINDO/3 and MNDO methods with full optimization of the geometry. The MINDO/3 method, in agreement with the results from nonempirical methods and experimental data, leads to a nonplanar configuration at the anionic center; the angle between the CX bond and the CCC plane was 58–62°. In all probability the conclusion about a planar structure for all the investigated carbanions except (II), which emerges from the MNDO calculations, is unreliable. By calculation of the change of energies in the isodesmic reactions C3H5
– + C3H5X C3H4X– + C3H6 it was found that substitution of hydrogen by the polar substituent X stabilizes the carbanion. On the basis of an analysis of the changes in the length of the cyclic and extracyclic bonds in the transition from the neutral molecule to the carbanion it was established that the introduction of substituents N02, COCH3, and CN into the carbanion gives rise to predominant donation of electron density along the system through the ring to the substituent while the introduction of a halogen leads to transfer of electron density from the substituent to the anionic center.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 5, pp. 590–594, September–October, 1985. 相似文献
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《Journal of Molecular Structure》1986,139(3-4):179-195
The structure and properties of ascorbic acid (AA) radicals are considered by using semiempirical MINDO/3 and MNDO methods. It is found that the most stable radical is the AA
anion, in accordance with ESR measurements. This radical is thermodynamically more stable than the parent molecule. The origin of the enhanced stability of AA
is elucidated by using a particular form of the energy-partitioning technique. The pronounced reactivity of AA
, on the other hand, can be rationalized by the unpaired spin and the high orbital energy of the singly-occupied MO. These features are probably responsible for the radical-trap behavior of AA
. The properties of AA
, certainly make an appreciable contribution to the biochemical versatility of ascorbic acid. Finally, it should be mentioned that side chains of AA and AA
are very flexible which increases their chelating abilities. 相似文献
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《Spectrochimica Acta》1966,22(2):173-186
The infrared spectrum from 33–4000 cm−1, and the Raman spectrum with polarizations, have been obtained for butatriene, H2CCCCH2. The molecule is definitely planar (symmetry D2h), and not twisted like allene (D2d). Vibrational assignments have been made with reasonable assurance to most of the fundamental. The CC stretching vibrations provide a textbook example of the interaction of three nearly identical closely-coupled oscillators.Several of the perpendicular infrared bands have a rich and resolvable fine structure, and that for the 854 cm−1 band was analyzed. Combining the result with Stoicheff's value for B̃0, 0·1314 cm−1, gives A0 = 4·786 ± 0·01 cm−1. By assuming rCH = 1·085 Å, the HCH angle is calculated to be 119·0 ± 0·5°. If IC = IA + IB, then B0 = 0·133 ± 0·01 and C0 = 0·130 ± 0·01 cm−1. 相似文献
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Infrared spectra and structures of carbanions—XI: Estimation of σ+ constants of anionic substituents
σ+ constants of H2Cxxx- (?11.2), HNxxx- (?7.6), C2H5OOC-HCxxx- (?5.0), NC-HCxxx- (?5.4) and some other anionic substituents were estimated on the basis of νCN of the corresponding benzonitrile anions and by using the correlations for benzonitriles, in polar aprotic solvents. 相似文献