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1.
The reaction of N-benzoylphosphoramidic dichloride with amines afforded some new N-benzoylphos-phoric triamides with formula C6H5C(O)NHP(O)(X)2, X=NH–CH(CH3)2 (1), NH–CH2–CH(CH3)2 (2), NH–CH2–CH(OCH3)2 (3), N(CH3)[CH2CH(OCH3)2] (4) and N(CH3)(C6H11) (5) that were characterized by 1H,13C,31P NMR, IR spectroscopy and elemental analysis. The structures have been determined for compounds 4 and 5 by X-ray crystallography. These compounds contain one amidic hydrogen atom and form centrosymmetric dimmers via intermolecular
–P–O⋯H–N–hydrogen bonds besides weak C–H⋯O hydrogen bonds that lead to three-dimensional polymeric clusters in the crystalline
lattice. 相似文献
2.
A. G. Nozad S. Meftah M. H. Ghasemi M. Aghazadeh 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(13):2270-2277
DFT calculations of electric field gradient (EFG) tensors at the sites of 14N, 17O, and 2H nuclei are carried out to characterize the hydrogen bond (HB) interactions in the sulfapyridine crystal structure. One-molecule
(monomer) and hydrogen-bonded hexameric cluster models of sulfapyridine are constructed according to available X-ray coordinates
where the proton positions are optimized. Then, EFG tensors are calculated for both monomer and target molecule in the hexameric
cluster of sulfapyridine to show the effect of HB interactions on the tensors. The calculated EFG tensors are converted to
the experimentally measurable nuclear quadrupole resonance (NQR) parameters: quadrupole coupling constant (C
Q
) and asymmetry parameter (η
Q
). The results reveal different contribution of various nuclei to N-H⋯N and N-H⋯O HB interactions in the cluster where the
N2 and O1 have major contributions. The computations are performed with B3LYP and B3PW91 functionals DFT method and 6-311+G*
and 6-311++G** standard basis sets using the Gaussian 98 package. 相似文献
3.
The method of momentum electron density for interatomic interactions has been applied to the two lowest σ states of the H
2
+
system. For attractive (1sσg) and repulsive (2pσ
u
) interactions, the behaviour of momentum density and its effect on the stabilization energy of the system are examined quantitatively.
The concept of contraction and expansion of the momentum density is shown to form an important guiding principle in this approach.
The origin of covalent bonding is discussed based on the energy partitioning proposed previously. 相似文献
4.
I. A. Grigor'ev M. A. Voinov M. A. Fedotov 《Chemistry of Heterocyclic Compounds》2005,41(9):1134-1138
Derivatives of 3-imidazoline 3-oxide have been studied by 14N and 17O NMR methods. Regularities of the influence of substituents and of a hydrogen bond on chemical shifts have been made apparent.
The range of changes of the chemical shifts of the nitrogen and oxygen nuclei of the nitrone group has been determined. Both
in the 17O and in the 14N NMR spectra the signals of the amino derivatives are the highest field signals for the nitrone group, and the lowest field
signals are the signals of the cyano derivatives in the series of derivatives investigated. Depending on the substituent (from
amino to cyano group) the 17O chemical shifts varied over a range ∼155 ppm, but the interval of change of the 14N chemical shifts for the same substituents was ∼110 ppm.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1336–1341. September, 2005. 相似文献
5.
Hossein Reza Darabi Marjan Azimzadeh Arani Mohsen Tafazzoli Mina Ghiasi 《Monatshefte für Chemie / Chemical Monthly》2008,139(10):1185-1189
The existence of a short C–H ⋯ π (alkyl–alkyne) interaction in the structure of a strained and relatively rigid tolanophane
is expected to hinder the rotation about the C–C sp3 single bond. Variable-temperature NMR experiments (performed in three solvents, CDCl3, THF-d8, and acetone-d6) and ab initio density functional calculations were carried out to investigate its dynamic nature. An energy barrier of 48.6 kJ/mol is determined
at coalescence (210 K) with acetone-d6 which is in good agreement with calculation result (54 kJ/mol).
Correspondence: Hossein Reza Darabi, Chemistry and Chemical Engineering Research Center of Iran, Pajoohesh Blvd., km 17, Karaj
Hwy, 14968-13151 Tehran, Iran. 相似文献
6.
The mono- and bisligands complexes formed by rare earth cation (Sc, Y) with pentazolato anion or cyclo-P5− anion, the all-nitrogen counterparts of metallocenes or the all-phosphorus counterparts of metallocenes, have been studied
at hybrid basis sets level with the DFT method. The geometric parameters, binding energy and the charge distributions of these
complexes were characterized. And their stable orders were obtained. Monoligand complexes incline to become bisligands complexes
due to their destabilization. The charge transferring between ligand and metallic cation has affinity with the stability of
complex. The possibility of forming stable [M(η
5-E5)2] (M = Sc, Y, E = N, P) complexes is predicted and they are viable synthetic targets theoretically, especially Sc(η
5-N5)2. 相似文献
7.
A. V. Afonin C. Vizioli M. de Azua Ruiz R. H. Contreras 《Russian Chemical Bulletin》1996,45(6):1292-1295
Anab initio quantum-chemical calculation of the direct13C–1H spin-spin coupling constants in the CH4–H2O system was carried out and experimental data obtained for a series ofN-vinyl compounds were analyzed. The specific C-H ....X (X = O, N) intramolecular interactions result in increasing the direct13C–1H spin-spin coupling constant of the hydrogen involved in bonding and decreasing the direct13C-1H spin-spin coupling constant for the hydrogen atom that takes no part in the interaction.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1362–1365, Tune, 1996. 相似文献
8.
Molar excess volumes, V
ijk
E, and speeds of sound, U
ijk
, of o-toluidine (i) + benzene (j) + cyclohexane or n-hexane or n-heptane (k) ternary mixtures have been measured as a function of composition at 308.15 K. The observed speed of sound data have been
utilized to determine the excess isentropic compressibilities, (K
S
E)
ijk
, of the ternary (i+j+k) mixtures. The Moelywn-Huggins concept (Huggins in Polymer 12: 389–399, 1971) of connectivity between the surfaces of the binary mixture constituents has been extended to ternary mixtures (using the
concept of a connectivity parameter of third degree of molecules, 3
ξ, which in turn depends on its topology) to obtain an expression that describes well the measured V
ijk
E and (K
S
E)
ijk
data. The observed data have also been analyzed in terms of Flory’s theory. 相似文献
9.
The tripodal ligand N,N′,N″-tri(benzimidazolyl)-methane has been used to synthesize nickel(II) complexes along with an exogeneous
ligand, X(X = Cr−,NO
3
−
,ClO
4
−
, HCOO−, OAc− and CNS−). Electronic absorption spectra reveal that the present nickel(II) complexes have six coordinate tetragonal geometries. The
value of Racah parameter(B), crystal field splitting parameter (Dq) and term,β0 (which is a measure of covalency) have been calculated.1HNMR spectroscopy reveals a dominantσ-delocalization pattern in these complexes. 相似文献
10.
G. R. Dey 《Research on Chemical Intermediates》2007,33(7):599-611
Gamma radiolysis of oxygenated 1–10 mM azide solutions was carried out at various pH values. In oxygenated 10 mM azide solutions,
H2O2 and NO
2
−
were observed as radiolytic products while NH3 was not. The concentration of H2O2 reached its maximum level at a dose of 1 kGy, whereas NO
2
−
yield increased non-linearly beyond 2 kGy in this system. Both in aerated and oxygenated systems, G(NO
2
−
) and G(H2O2) were found to vary with N
3
−
concentration. The yield of NO
2
−
was found to be dependent on both dose rate and pH. On pulse radiolysis, NO
2
−
was found as a radiolytic product in aerated 1 mM azide solution at pH 6.8. In this system the intermediate generated exhibits
absorbance around 250 nm. The overall results obtained during the present study reveal that in presence of both reducing radical
(mainly e
aq
−
) and oxygen, N
3
−
produced an intermediate possibly NH2O
2
•
radical, which is the prime source for NO
2
−
generation. 相似文献
11.
The photoluminescence properties of xZnO–(100−x)SiO2 (x = 0, 5, 10, 20) containing 1% Eu2O3 prepared by a sol–gel method were systematically investigated. The results indicated that the relative proportion of f–f transitions to charge transfer (CT) absorption decreased with the increase of ZnO concentration. The intensity of 5D0–7FJ transitions of Eu3+ ions was enhanced with the increase of ZnO content due to local structure changes and decreased quantities of Eu3+ ions clusters. The results of fluorescence line narrow (FLN) spectra indicated that Eu3+ ions occupied one site in SiO2 glass and two sites in ZnO–SiO2 glasses. The second-order crystal field parameters were calculated. B20 and B22 for site 1 increased with excitation energy, while ones hardly changed for site 2. 相似文献
12.
Mircho Georgiev Tatiana Popova Zhorro S. Nickolov Nikolay Goutev Georgi Georgiev Hiroatsu Matsuura 《Central European Journal of Chemistry》2004,2(4):617-626
The hypothesis that the degree of hydration of poly(oxyethylene) (POE) in aqueous solution depends on the mole ratio of water
molecules to ether oxygen atoms in the molecule has been verified by studying the isotropic Raman spectra in the O−H stretching
region for four short-chain POEs (C 1E
n
C 1 withn=1−4). Excellent coincidence of the O−H stretching Raman band for all four POEs studied in the range of mole ratio H2O/O
ether
from 25 to 0.6 was observed, thus confirming the assumption stated above. A conclusion that all ether oxygen atoms in the
POE molecule participate in hydrogen bonding with water molecules has been made. 相似文献
13.
采用微波固相法制备了CaWO_4∶xEu~(3+),ySm~(3+),zLi~+红色荧光粉。测量样品的XRD图、激发谱、发射谱及发光衰减曲线,研究并分析了Eu~(3+)、Sm~(3+)、Li~+的掺杂浓度,对样品微结构、光致发光特性、能量传递及能级寿命的影响。结果表明,Eu~(3+)、Sm~(3+)、Li~+掺杂并未引起合成粉体改变晶相,仍为CaWO_4单一四方晶系结构。Eu~(3+)、Sm~(3+)共掺样品中,Sm~(3+)掺杂为3%时,Sm~(3+)对Eu~(3+)的能量传递最有效。Li~+掺杂起到了助熔剂和敏化剂的作用,使样品发光更强。在394 nm激发下,与CaWO_4∶3%Eu~(3+)样品比较,3%Eu~(3+)、3%Sm~(3+)共掺CaWO_4及3%Eu~(3+)、3%Sm~(3+)、1%Li~+共掺CaWO_4样品的发光分别增强2倍及2.4倍。同一激发波长下,单掺Eu~(3+)样品寿命最短,Sm~(3+)、Eu~(3+)共掺样品随Sm~(3+)浓度增加,寿命先减小后增加,且掺杂了Li~+的样品比不掺Li~+的样品~5D_0能级寿命有所增加。 相似文献
14.
The molecular structure of 23,24,25,26,27,29,30-heptamethyl-19,28-oxahexacyclo[15.13.18.017,18.013,14.08,9.05,10]tetracos-3-yl acetate III. Compound III C32H52O3 crystallizes in the monoclinic crystal system with the unit cell parameters a = 13.265(15) ?, b = 6.481(7) ?, c = 32.274(4) ?, β = 99.333(2)°, space group C2, Z = 4, d = 1.176 g/cm3.
Original Russian Text Copyright ? 2009 by N. I. Medvedeva, O. B. Flechter, and A. A. Korlyukov
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 399–401, March–April, 2009. 相似文献
15.
Bikshandarkoil R. Srinivasan Christian Näther Sunder N. Dhuri Wolfgang Bensch 《Monatshefte für Chemie / Chemical Monthly》2006,137(4):397-411
Summary. Four new organic ammonium tetrathiotungstates (N–Me–enH2)[WS4] (1), (N,N′-dm-1,3-pnH2)[WS4] (2), (1,4-bnH2)[WS4] (3), and (mipaH)2[WS4] (4), (N–Me–enH2 = N-methylethylenediammonium, N,N′-dm-1,3-pnH2 = N,N′-dimethyl-1,3-propanediammonium, 1,4-bnH2 = 1,4-butanediammonium, and mipaH = monoisopropylammonium) were synthesized by the base promoted cation exchange reaction and characterized by elemental analysis,
infrared, Raman, UV-Vis and 1H NMR spectroscopy as well as single crystal X-ray crystallography. The structures of 1–4 consist of [WS4]2− tetrahedra which are linked to the organic ammonium cations via N–H⋯S hydrogen bonding. The strength and number of the S⋯H
interactions affect the W–S bond lengths as evidenced by distinct short and long W–S bonds. The IR spectra exhibit splitting
of the W–S vibrations, which can be attributed to the distortion of the [WS4]2− tetrahedron. From a comparative study of several known tetrathiotungstates it is observed that a difference of more than
0.033 ? between the longest and shortest W–S bonds in a tetrathiotungstate will result in the splitting of the asymmetric
stretching vibration of the W–S bond. 相似文献
16.
A. A. Kamyshova A. Z. Kreindlin P. V. Petrovskii A. S. Peregudov Yu. A. Borisov A. A. Koridze 《Russian Chemical Bulletin》2005,54(12):2805-2812
The reaction of [Cp*2RuBr]+Br− with bromine in CH2Cl2 (CD2Cl2) in an inert atmosphere at room temperature produces the complexes [Cp*Ru(Br)C5Me4CH2Br]+Br3
− (syn conformer), [Cp*Ru(Br)C5Me3(CH2Br)2]+ (syn and anti conformers), and [Ru(Br)(C5Me4CH2Br)2]+ (syn conformer). All complexes were characterized by 1H and 13C NMR spectroscopy; the former complex, by elemental analysis. These complexes were also prepared by the reaction of [Cp*RuC5Me4CH2]+BF4
− with bromine in CH2Cl2.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2712–2718, December, 2005. 相似文献
17.
V. A. Maksakov V. P. Kirin S. V. Tkachev A. V. Golovin 《Russian Chemical Bulletin》1999,48(11):2158-2161
The migration of the double bond in the allylcarboxamide ligands of (μ-H)Os3(μ-O=CN RCH2CH=CH2) (CO)10 (R=H (1) or CH3 (2)), (μ-D)Os3(μ-O=CNDCH2CH=CH2) (CO)10, and (μ-H)Os3(μ-O=CNHCD2CH=CH2)(CO)10 clusters was studied by1H,2H, and13C NMR spectroscopy. Neither μ-D nor ND groups in the deuterated complexes are directly involved in prototropic processes of
allylic rearrangement. Initially, the deuterium atom of the CD2 group migrates to the ψ-carbon atom of the allyl fragment to form the −CD=CH-CH2D propenyl moiety, in which the deuterium and hydrogen atoms are gradually redistributed between the ψ-and β-carbon atoms.
The triosmium cluster complexes containing the bridging carboxamide ligands O=CNRR' catalyze the allylic rearrangement ofN-allylacetamide. Based on the data obtained, the probable scheme of the allylic rearrangements in clusters1 and2 was proposed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2182–2186, November, 1999. 相似文献
18.
B. I. Ugrak Yu. A. Manaev V. P. Perevalov S. A. Shevelev 《Russian Chemical Bulletin》1992,41(11):2012-2017
The15N NMR chemical shifts and15N-1H SSCCs are presented for substituted N-methylpyrazoles with substituents such as CH3, NO2, Br, Cl, NH2, O=CNH2, O=CPh, and COOH at the carbon atoms. The15N chemical shifts of the cyclic atoms of nitrogen and the nitro groups are discussed as well as the geminal and vicinal SSCCs of the ring nitrogen atoms with the hydrogen atoms of the CH and CH3 fragments.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117334 Moscow. D. I. Mendeleev Chemico-Technological Institute, Moscow, Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2554–2561, November, 1992. 相似文献
19.
The mechanism of the spin-forbidden reaction Ti+(4F, 3d24s1) + C2H4→TiC2H2
+ (2A2) + H2 on both doublet and quartet potential energy surfaces has been investigated at the B3LYP level of theory. Crossing points
between the potential energy surfaces and the possible spin inversion process are discussed by means of spin-orbit coupling
(SOC) calculations. The strength of the SOC between the low-lying quartet state and the doublet state is 59.3 cm−1 in the intermediate complex IM1-4B2. Thus, the changes of its spin multiplicity may occur from the quartet to the doublet surface to form IM1-2A1, leading to a sig-nificant decrease in the barrier height on the quartet PES. After the insertion intermediate IM2, two distinct
reaction paths on the doublet PES have been found, i.e., a stepwise path and a concerted path. The latter is found to be the
lowest energy path on the doublet PES to exothermic TiC2H2
+(2A2) + H2 products, with the active barrier of 4.52 kcal/mol. In other words, this reaction proceeds in the following way: Ti++C2H4→4IC→IM1-4B2→4,2ISC→IM1-2A1→[2TSins]→IM2→[2TSMCTS]→IM5→TiC2H2
+(2A2)+H2.
Supported by ‘Qinglan’ Talent Engineering Funds by Tianshui Normal University. 相似文献
20.
Lenoble V Garnier C Masion A Ziarelli F Garnier JM 《Analytical and bioanalytical chemistry》2008,390(2):749-757
This work allowed the characterization of the Cd-binding sites of two compounds taken as models for exudates, the main components
of soil organic matter (SOM). The studied compounds were exopolysaccharides (EPS), specifically exudates of roots (polygalacturonic
acid) and of soil bacteria (Phytagel). Potentiometric acid–base titrations were performed and fitting of the obtained results
indicated the presence of two main classes of acidic sites, defined by their pK
a values, for both EPS but of a different nature when comparing the two compounds. The two studied exopolysaccharides presented
different acidic/basic site ratios: 0.15 for Phytagel and 0.76 for polygalacturonic acid. Spectroscopic techniques (13C/113Cd NMR, FTIR) distinguished different Cd surroundings for each of the studied EPS, which is in agreement with the titration
results. Furthermore, these analyses indicated the presence of –COOH and –OH groups in various proportions for each exopolysaccharide,
which should be linked to their reactivity towards cadmium. Cadmium titrations (voltammetric measurements) also differentiated
different binding sites for each compound and allowed the determination of the strength of the Cd-binding site of the EPS.
Fitting of the results of such voltammetric measurements was performed using PROSECE (Programme d’Optimisation et de Speciation Chimique dans l’Environnement), a software coupling chemical speciation calculation and binding parameter optimization. The fitting, taking into account
the Cd2+/H+ competition towards exopolysaccharides, confirmed the acid-base titrations and spectroscopic analyses by revealing two classes
of binding sites: (i) one defined as a strong complexant regarding its Cd2+–EPS association (logK = 9–10.4) and with basic functionality regarding H+–EPS association (pK
a = 11.3–11.7), and (ii) one defined as a weak complexant (logK = 7.1–8.2) and with acidic functionality (pK
a = 3.7–4.0). Therefore the combination of spectroscopic analyses, voltammetry, and fitting allowed the precise characterization
of the binding sites of the studied exopolysaccharides, mimicking the main SOM components. Furthermore, the binding parameters
obtained by fitting can be used in biogeochemical models to better define the role of key SOM compounds like exudates of roots
and of soil bacteria on trace metal transport or assimilation. 相似文献