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1.
The reaction of 2,2,2-trichlorobenzo[d]-1,3,2-dioxaphosphole-5-carbonylchloride with phenylacetylene in benzene (80 °C) afforded 2-(2-chloro-2-phenylethenyl)-2,2-dichlorobenzo[d]-1,3,2-dioxaphosphole-5-carbonylchloride (yield >95%) as a result of the electrophilic cis-addition of the phosphorus(v) derivative at the triple bond of acetylene with retention of coordination of the P atom. Hydrolysis
of this compound affords predominantly 2-hydroxy-5-(hydroxycarbonyl)phenyl (2-chloro-2-phenylethenyl)phosphonate.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 377–379, February, 2006. 相似文献
2.
V. V. Kuznetsov 《Russian Journal of General Chemistry》2010,80(12):2491-2494
Computer simulation of the routes of conformational isomerization of 1,3,2-dioxathiane and its Soxides by nonempirical quantum-chemical method RHF/6-31G(d) revealed the main and local minima and transition states of this
process. It was shown that the barrier of ring inversion is reduced in going from 1,3,2-dioxathiane to its oxides. The established
ΔG
0 (300 K) value of S=O group in cyclic sulfite (−15.0 kJ mol−1) is in good agreement with the experimental data. 相似文献
3.
A. Yu. Zhukov T. A. Fink I. I. Stoikov I. S. Antipin 《Russian Chemical Bulletin》2009,58(5):1007-1014
The ability of new synthetic receptors, i.e., p-tert-butylthiacalix[4]arenes tetrasubstituted at the lower rim and containing secondary amide groups to form complexes with a
number of spherical (F−, Cl−, Br−, I−), Y-shaped (MeCOO−), trigonal (NO3
−), and tetrahedral (H2POO4
−) anions has been studied. It was shown that the nature of substituents on the nitrogen atom of the amide groups and configuration
of the macrocycle affect the stability constant values of the forming complexes. 相似文献
4.
Hasan Marai Ewa Kita Emilia Kiersikowska Sylwia Kuchta Anna Bajek Tomasz Drewa 《Transition Metal Chemistry》2012,37(4):337-344
Three chromium(III) complexes with asparagine (Asn) and histidine (His) of the [Cr(ox)2(Aa)]2− type, where Aa = N,O–Asn, N,O–His or N,N′–His, were obtained and characterized in solution. The complexes with N,O–Aa undergo acid-catalysed aquation to give a free amino acid and cis-[Cr(ox)2(H2O)2]−, whereas the complex with N,N′–His undergoes parallel reaction paths: (1) isomerization to the N,O–His complex and (2) liberation of an oxalate ligand. Kinetics of the N,O–Aa complexes in HClO4 media were studied spectrophotometrically under pseudo-first-order conditions. The absorbance changes were attributed to
the chelate ring opening at the Cr–N bond. The linear dependence of rate constants on [H+] was established, and a mechanism for the chelate ring cleavage was postulated. The existence of a metastable intermediate
with O-monodentate Aa ligand was proved experimentally. Effect of [Cr(ox)2(Aa)]2− on 3T3 fibroblasts proliferation was studied. The tests revealed low cytotoxicity of the complexes. Complexes with Ala, His
and Cys are good candidates for biochromium sources. 相似文献
5.
K. I. Pashkevich V. I. Filyakova V. G. Ratner O. G. Khomutov 《Russian Chemical Bulletin》1998,47(7):1239-1247
Efficient procedures for the regioselective synthesis of fluoroalkyl-containing threefive-, six-, and seven-membered heterocycles
as well as of related fused compounds, namely, α,β-epoxyketones, α,β-aziridinylketones, pyrazoles, pyrazolines, isoxazolines,
1,2-dithiolenes, amino- and mercaptopyrimidines, Δ3,5-2-thioxo-1,3,2-thiazaphosphorines, Δ3,5-2-thioxo-1,3,2-oxazaphosphorines, 2,3-dihydro-1,4-diazepines, azirino[1,2-a]quinoxalines, benzo[b]-and naphtho[2,3-b]-1,4-diazepines, and triazolopyridazines, which have been developed by the authors and coworkers, are summarized. The α-
and β-functionalized fluoroalkylcontaining carbonyl compounds (β-diketones, β-ketoesters, their salts, regioisomeric β-aminovinyl
ketones, β-aminovinylthiones, β-hydroxyketones, α,β-enones, and their halogen derivatives) were used as synthons in the processes
of formation of the above-mentioned heterocycles.
Dedicated to the memory of Academician I. Ya. Postovskii on his 100th birthday.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1279–1286, July, 1998. 相似文献
6.
M. Z. Kassaee M. R. Momeni F. A. Shakib M. Ghambarian S. M. Musavi 《Structural chemistry》2009,20(3):517-524
Biologically important bicyclic species, including 6H-, 6H-6-aza-, and 6-oxabenzocycloheptatrienes (in which the benzene moiety is fused meta with respect to the tetrahedral constituents: –CH2–, –NH–, and –O–, respectively), show strong shifts of tautomerizations in favor of the corresponding tricyclic benzonorcaradienes
(with ΔH values of −11.49, −14.55, and −19.20 kcal mol−1, respectively), at B3LYP/6-311++G**//B3LYP/6-31G*, and MP2/6-311++G**//MP2/6-31G* levels, and at 298 K. In contrast, such
shifts are strongly disfavored by the isomeric bicyclic species in which the benzene moieties are fused ortho or para with respect to –CH2–, –NH–, and –O–, respectively. Hence for species with ortho benzene rings including 5H-, 5H-5-aza- and 5-oxabenzocycloheptatrienes, tautomerization ΔH values are 30.76, 31.89, and 25.27 kcal mol−1, respectively, while for species with para fused benzene moieties including 7H-, 7H-7-aza-, and 7-oxabenzocycloheptatrienes, tautomerization ΔH values are 24.12, 26.00, and 19.55 kcal mol−1, respectively. NICS calculations are successfully used to rationalize these results. The calculated energy barriers for inversion
of the seven-membered rings of bicyclic species predict a dynamic nature for all the structures except for the virtually planar
6H-6-aza- and 6-oxabenzocycloheptatrienes. Finally, our theoretical data are compared to the experimental results where available.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
7.
The boron rings containing planar octacoordinate transition metals, D
8h
FeB8
2−, CoB8
− and CoB8
3+, C
2v
FeB8, D
2h
CoB8
+ and CoB8, are optimized with all real vibrational frequencies at the B3LYP/6–311+G* level of the theory. The D
8h
FeB8
2− and CoB8
− isomers are global minima, while D
8h
CoB8
3+ is only local minimum. The electronic structure character of these systems is revealed by natural bond orbital (NBO) analysis,
showing that the boron rings containing planar octacoordinate transition metals have stability and aromaticity with six π
electrons. The aromaticity is confirmed by nucleus independent chemical shifts (NICS) calculations.
Supported by the specialized research fund for the doctoral program of higher education (20060007030) 相似文献
8.
The temperature dependences of the equilibrium constants of two chain reversible reactions in quinonediimine (quinonemonoimine)—2,5-dichlorohydroquinone
systems in chlorobenzene were studied. The enthalpy of equilibrium of the reversible reaction of quinonediimine with 4-hydroxydiphenylamine
was estimated from these data (ΔH = − 14.4±1.6 kJ mol−1) and a more accurate value of the N-H bond dissociation energy in the 4-anilinodiphenylaminyl radical was determined (D
NH = 278.6±3.0 kJ mol−1). A chain mechanism was proposed for the reaction between quinonediimine and 2,5-dichlorohydroquinone, and the chain length
was estimated (ν = 300 units) at room temperature. Processing of published data on the rate constant of the reaction of styrylperoxy
radicals with 2,5-dichlorohydroquinone in the framework of the intersecting parabolas method gave the O-H bond dissociation
energy in 2,5-dichlorohydroquinone: D
OH = 362.4±0.9 kJ mol−1. Taking into account these data, the O-H bond dissociation energy in the 2,5-dichlorosemiquinone radical was found: D
OH = 253.6±1.9 kJ mol−1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1661–1666, October, 2006. 相似文献
9.
N,N-dimethyl-3-oxa-glutaramic acid was purified and characterized by 1H-NMR, Fourier transform infrared spectroscopy (FT-IR) and elemental analysis. The thermal decomposition of the title compound
was studied by means of thermogravimetry differential thermogravimetry (TG-DTG) and FT-IR. The kinetic parameters of its second-stage
decomposition reaction were calculated and the decomposition mechanism was discussed. The kinetic model function in a differential
form, apparent activation energy and pre-exponential constant of the reaction are 3/2 [(1−α)1/3−1]−1, 203.75 kJ·mol−1 and 1017.95s−1, respectively. The values of ΔS
≠, ΔH
≠ and ΔG
≠ of the reaction are 94.28 J·mol−1·K−1, 203.75 kJ·mol−1 and 155.75 kJ·mol−1, respectively.
Supported by the National Natural Science Foundation of China (Grant No. 20106009) 相似文献
10.
Yu. N. Belokoń Yu. N. Bubnov T. D. Churkina A. A. Chesnokov K. A. Kochetkov N. Yu. Kuznetsov V. N. Khrustalev N. I. Raevskii 《Russian Chemical Bulletin》1997,46(5):982-989
The stereochemistry of addition of Br2 toE-andZ-(R)-N-cinnamoyl-4-phenyloxazolidin-2-ones was studied. It was established that both theE-andZ-isomers give only two out of four possible diastereoisomers in the presence of Lewis acids (BPr3 or AlBr3). The absolute configurations of the diastereoisomers [(2S', 3R') and (2R', 3S') of the side chain] were established by X-ray structural analysis. The stereochemistry observed is a consequence of the stepwise
bromination and the absence of bridging bromine atoms along the reaction coordinate. In the case of theZ-isomer, the diastereoselectivity of the reaction was high, whereas it is low in the case of theE-isomer. It was suggested that at the first stage of addition of Br2 at the C=C bond, the attack of the Br+ cation occurs at the α position, and the second stage of transfer of Br− occurs with the participation of boron or aluminum complexes in the intermediate state of the bromination reaction. This
hypothesis as well as the results of calculations of the initial conformations of the substrates provide an explanation of
the regularities observed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1022–1028, May, 1997. 相似文献
11.
pH potentiometric and spectrophotometric investigations on the complex formation equilibria of CuII with iminodiacetate (ida2−) and heterocyclic N-bases, viz. imidazole and benzimidazole (B), in aqueous solution in binary and ternary systems using
different molar ratios of the reactants indicated the formation of complexes of the types, Cu(ida), Cu(ida)(OH)−, (ida)Cu(OH)Cu(ida)−, Cu(B)2+, Cu(H-1B)+, Cu(ida)(H−1B)−, (ida)Cu(B)Cu(ida) and (ida)Cu(H−1B)Cu(ida)−. Formation constants of the complexes at 25 ±1° at a fixed ionic strength,I = 0.1 mol dm−3 (NaNO3) in aqueous solution were evaluated and the complex formation equilibria were elucidated with the aid of speciation curves.
Departure of the experimental values of the reproportionation constants(ΔlogK
cu) of ternary Cu(ida)(H−1B)− complexes from the statistically expected values, despite their formation in appreciable amounts at equilibrium, were assigned
tofac(f)-mer(m) equilibria of the ida2− ligand coordinated to CuII, as the N-heterocyclic donors, (H−1B)−, coordinatetrans- to the N-(ida2−) atom in the binary Cu(ida)
f
complex to form the ternary Cu(ida)
m
(H−1B)− complexes 相似文献
12.
V. G. Avakyan L. E. Gusel’nikov S. L. Gusel’nikov V. F. Sidorkin 《Russian Chemical Bulletin》2005,54(9):2013-2022
The effect of the nature of substituents at sp2-hybridized silicon atom in the R2Si=CH2 (R = SiH3, H, Me, OH, Cl, F) molecules on the structure and energy characteristics of complexes of these molecules with ammonia, trimethylamine,
and tetrahydrofuran was studied by the ab initio (MP4/6-311G(d)//MP2/6-31G(d)+ZPE) method. As the electronegativity, χ, of the substituent R increases, the coordination bond
energies, D(Si← N(O)), increase from 4.7 to 25.9 kcal mol−1 for the complexes of R2Si=CH2 with NH3, from 10.6 to 37.1 kcal mol−1 for the complexes with Me3N, and from 5.0 to 22.2 kcal mol−1 for the complexes with THF. The n-donor ability changes as follows: THF ≤ NH3 < Me3N. The calculated barrier to hindered internal rotation about the silicon—carbon double bond was used as a measure of the
Si=C π-bond energy. As χ increases, the rotational barriers decrease from 18.9 to 5.2 kcal mol−1 for the complexes with NH3 and from 16.9 to 5.7 kcal mol−1 for the complexes with Me3N. The lowering of rotational barriers occurs in parallel to the decrease in D
π(Si=C) we have established earlier for free silenes. On the average, the D
π(Si=C) energy decreases by ∼25 kcal mol−1 for NH3· R2Si=CH2 and Me3N·R2Si=CH2. The D(Si←N) values for the R2Si=CH2· 2Me3N complexes are 11.4 (R = H) and 24.3 kcal mol−1 (R = F). sp2-Hybridized silicon atom can form transannular coordination bonds in 1,1-bis[N-(dimethylamino)acetimidato]silene (6). The open form (I) of molecule 6 is 35.1 and 43.5 kcal mol−1 less stable than the cyclic (II, one transannular Si←N bond) and bicyclic (III, two transannular Si←N bonds) forms of this molecule, respectively. The D(Si←N) energy for structure III was estimated at 21.8 kcal mol−1.
Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1952–1961, September, 2005. 相似文献
13.
M. A. Pudovik S. A. Terent'eva I. A. Litvinov O. N. Kataeva V. A. Naumov A. N. Pudovik 《Russian Chemical Bulletin》1993,42(10):1706-1709
The reaction of 2-diethylamino-3-diethylaminomethyl-1,3,2-benzoxazaphospholine with functionally substituted alcohols and
phenols occurs with the cleavage of exocyclic P-N bond followed by N→P migration of the diethylaminomethyl group and formation
of imidophosphonate dimers. A similar reaction with polyhydroxy compounds (diethylene glycol, glycerol) results in symmetrical
and asymmetrical spirophosphoranes.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1781–1784, October, 1993. 相似文献
14.
Annia Galano J. Raúl Alvarez-Idaboy Annik Vivier-Bunge 《Theoretical chemistry accounts》2007,118(3):597-606
Eight cyclopropane derivatives (Δ − R) have been modeled, with R = −H, −CH3, −NH2, −C ≡ CH, −C ≡ CCH3, −OH, −F and −C ≡ N. All geometries have been fully optimized at the MP2/ AUG-cc-pVTZ level of calculations. Natural bond
orbital analyses reveal extra p character (spλ, λ > 3) in the C-C bonds of the cyclopropyl rings. The banana-like σ
CC
bonds in the rings are described in detail. Alkene-like complexes between Δ − R molecules and hydrogen fluoride are identified. These weakly bonded complexes are formed through unconventional hydrogen
bond interactions between the hydrogen atom in the HF molecule and the carbon–carbon bonds in the cyclopropane ring. A topological
analysis of the electronic charge density and its Laplacian has been used to characterize the interactions. The possible relevance
of such complexes in the modeling of substrate–receptor interactions in some anti-AIDS drugs is discussed.
Contribution to the Serafin Fraga Memorial Issue. 相似文献
15.
V. I. Minkin M. S. Korobov R. Ya. Olekhnovich G. S. Borodkin L. E. Nivorozhkin 《Russian Chemical Bulletin》1995,44(11):2168-2171
Kinetics and reaction mechanisms governing inversion of the tetrahedral configuration at the metal center in the series ofbis-chelate Zn(II) complexes of 3,2-, 1,2-, and 2,1-oxy(mercapto)naphthaldimines, respectively4–6, have been studied with the use of dynamic1H NMR spectroscopy. A polytopal rearrangement of the diagonal twist type has been found to be an energetically preferable pathway of the inversion reaction for complexes4 and5 with a ZnN2O2 coordination site, whereas the inversion reaction for complexes with a ZnN2S2 coordination site occurs by an intramolecular dissociation-recombination pathway that involves cleavage of a Zn-N coordination bond. In the case of complexes6, the inversion reaction is governed mainly by intramolecular degenerate ligand exchange reactions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11. pp. 2261–2265, November, 1995.This work was supported by the Russian Foundation for Basic Research (project No. 93-03-18692) and the International Science Foundation (grant No. RNJ 000). 相似文献
16.
Comparative quantum chemical calculations of structural parameters, chemical shifts of 11B NMR spectra, and atomic charges in 10-vertex boron hydride anions [1-CB9H10]− and [1-B10H9N2]− were performed using the restricted Hartree-Fock method with the 6-31++G(D,P) basis set.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1853–1855, September, 2007. 相似文献
17.
Base hydrolysis of [Cr(ox)2(quin)]3− (where quin2− is N,O-bonded 2,3-pyridinedicarboxylic acid dianion) causes successive ligand dissociation and leads to a formation of a
mixture of oligomeric chromium(III) species, known as chromates(III). The reaction proceeds through [Cr(ox)(quin)(OH)2]3− and [Cr(quin)(OH)4]3− formation. Dissociation of oxalato ligands is preceded by the opening of the Cr-quin chelate-ring at the Cr–N bond. The kinetics
of the chelate-ring opening and the first oxalate dissociation were studied spectrophotometrically, within the lower energy
d–d band region at 0.4–1.0 M NaOH. The pseudo-first-order rate constants (k
obs0 and k
obs1) were calculated using SPECFIT software for an A → B → C reaction pattern. Additionally, kinetics of base hydrolysis of [Cr(ox)(quin)(OH)2]3− and cis-[Cr(ox)2(OH)2]3− were studied. The determined pseudo-first-order rate constants were independent of [OH−]. A mechanism is postulated that the reactive intermediate with the one-end bonded quin ligand, [Cr(ox)2(O-quin)(OH)]4−, formed in the first reaction stage, subsequently undergoes oxalates substitution. Kinetic parameters for the chelate-ring
opening and the first oxalate dissociation were determined. 相似文献
18.
Yue Zhang Natsumi Watanabe Yuuko Miyawaki Yutaka Mune Kenta Fujii Yasuhiro Umebayashi Shin-ichi Ishiguro 《Journal of solution chemistry》2005,34(12):1429-1443
Aprotic N,N-dimethylpropionamide (DMPA) and N,N,N′,N′-tetramethylurea (TMU) are both strong donor solvents and coordinate to metal ions through the carbonyl oxygen atom. These
solvents show a different conformational aspect in the bulk phase, i.e., DMPA exists as either a planar cis or a nonplanar staggered conformer, while TMU exists in a single planar cis conformer. It has been established that the manganese(II) ion is solvated by five molecules in both solvents. Interestingly,
although the planar cis conformer of DMPA is more favorable than the nonplanar staggered one in the bulk phase, the reverse is the case in the coordination
sphere of the metal ion, i.e., a conformational change occurs upon solvation. To reveal the thermodynamic aspect of this conformational change, the complexation
of Mn(II) with bromide ions in DMPA and TMU has been studied by titration calorimetry at 298 K. It was found that the Mn(II)
ion forms mono-, di- and tri-bromo complexes in both solvents, and their formation constants, enthalpies and entropies were
obtained. The Δ H∘1 value for MnBr+ strongly depends on the solvent, i.e., it is positive (19.4 kJ-mol−1) in DMPA and negative (−8.7 kJ-mol−1) in TMU, whereas the Δ H^∘2 and Δ H∘3 values for the stepwise formation of MnBr2 and MnBr3− are both small and negative. The enthalpy of transfer ΔtH∘ from DMPA to TMU, which is evaluated on the basis of the extrathermodynamic TATB assumption, is 25.5 kJ-mol−1 for Mn2+ and −3.6 kJ-mol−1 for MnBr+. These values indicate that the difference between the formation enthalpy of MnBr+ in the two solvents, Δ H^∘1 (DMPA) – Δ H∘1 (TMU), is mainly ascribed to the value of ΔtH∘(Mn2+). It is found that the metal ion is also five-coordinated in the monobromo complex, MnBr(DMPA)4+ . The enthalpy for the conformational change of DMPA from its planar cis to the nonplanar staggered form is evaluated to be −11 and −5.5 kJ-mol−1 for Mn(DMPA)52 + and MnBr(DMPA)4+, respectively. Note that these values are significantly smaller than the corresponding value (5.0 kJ-mol−1) in the bulk phase. We thus conclude that, although steric hindrance among solvent molecules is reduced by replacing one
DMPA of Mn(DMPA)52 + with the relatively small bromide ion, DMPA molecules are still sterically hindered in the MnBr(DMPA)4+ complex. 相似文献
19.
I. A. Poroshina N. P. Kotsupalo L. T. Menzheres V. P. Isupov 《Journal of Structural Chemistry》1994,35(5):709-719
Crystallochemical features of anion (Cl−, Br−, I−, NO
3
−
, CO
3
2−
, SO
4
2−
) varieties of the aluminum and lithium hydroxide were studied by using the aluminum and lithium binary hydroxide (LiOH·2Al(OH)3·2H2O) model in space group P63cm with the tetrahedral coordination of lithium. Atomic coordinates corresponding to the lowered lattice symmetry were refined.
Institute of Solid State Chemistry and Processing of Mineral Raw Materials, Siberian Branch, Russian Academy of Sciences.
Novosibirsk State Pedagogical University. Translated fromZhurnal Struktumoi Khimii, Vol. 35, No. 5, pp. 158–170, September–October, 1994.
Translated by T. Yudanova 相似文献
20.
Shangfen Gao Guangqun Tan Hongyan Yuan Dan Xiao Martin M. F. Choi 《Mikrochimica acta》2006,153(3-4):159-162
A simple and green analytical procedure based on chlorophyll a is presented for the determination of Hg2+ ion. Chlorophyll a was extracted and purified from the leaves of pea and is employed as a reagent for analysis of Hg2+ ion. It displays remarkable fluorescence emission at 674 nm when excited at 412 nm. The emission intensity decreased significantly
on exposure to various concentrations of Hg2+ ion. This forms the basis for the determination of Hg2+ ion. The proposed method was evaluated for sensitivity and selectivity. The linear concentration range was found to be 2.0–10 μM
with r2 = 0.997 and the limit of detection for Hg2+ ion was 1.3 μM. Ions including Pb2+, Cd2+, Ag+, Zn2+, Co2+, Ni2+, Cu2+, Mg2+, Mn2+, Ru3+, Er3+, K+, Na+, NH4+, Cl−, NO3−, CH3COO− and SO42− did not interfere with the measurement of Hg2+ ion even at 500-fold excess. Since chlorophyll a is widely available in the leaves of most plants, and the extraction and purification process is simple, this technique can
provide an alternative, sensitive and economical way to determine Hg2+ ion. 相似文献