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1.
Degradation of (C60)
n
polymer and the C120 and C120O dimers at different temperatures was studied by IR and ESR spectroscopy. The formation of C60 was revealed. The polymer stability was found to be higher than the stability of the dimers. Peculiar features of the IR spectra of three-dimensional hyper-crosslinked polymers obtained by liquid-phase polymerization of C60 are discussed. 相似文献
2.
The diacetylenic adducts, Fe2(CO)6{-EC(H) = C(C CMe)E} (E = E, E E; E, E = S, Se, Te) (1–8) have been obtained from the room temperature stirring of Fe2(CO)6(-EE) with HC CC CMe in methanol solvent containing sodium acetate. Compounds 1–8 have been characterized by IR and multinuclear NMR (1H, 13C, 77Se, and l25Te) spectroscopy. Trends in the chemical shifts of 77Se and 125Te NMR spectra of Fe2(CO)6{-EC(H) = C(C CMe)E} with a variation of EE are discussed. 相似文献
3.
Summary For visual analysis of the density reorganization and distortion, the one-dimensional cut (x, y
0,z
0) and the two-dimensional cut (x, y, z
0) of the three-dimensional electron density difference function (x, y, z) are frequently employed. However, these cut functions do not satisfy any sum rules in contrast to the original difference function (x, y, z). To avoid this difficulty, the use of the marginal electron density functions
x
(x) and
xy
(x, y) and their difference functions
x
(x) and
xy
(x, y) is proposed. The marginal densities are condensation of the three-dimensional density onto a particular plane or line of our interest, and they satisfy the sum rule (i.e., the conservation of the number of electrons) exactly. Some basic properties of the marginal electron density are clarified for typical diatomic molecular orbitals. An illustrative application is given for the bonding and antibonding processes in the H2 system. 相似文献
4.
O. G. Shakirova Yu. G. Shvedenkov D. Yu. Naumov N. F. Beizel' L. A. Sheludyakova L. S. Dovlitova V. V. Malakhov L. G. Lavrenova 《Journal of Structural Chemistry》2002,43(4):601-607
Solid phases FexNi1-x(Htrz)3(NO3)2 · H2O (0.4 x 0.8$) and Ni(Htrz)3(NO3)2 · H2O were synthesized and studied. The phases were studied by means of magnetochemistry, powder Xray difraction analysis, and electronic and IR spectroscopy. The heterometallic phases are described by the stoichiographic method of differentiating dissolution (DD). The values of x were determined by two methods — atomic absorption and DD. Magnetochemical data showed that the solid phases exhibit a hightemperature 1A1 5T2 0.5 x 0.8 and disappears at x = 0.4. The spin transition is accompanied by thermochromism (color changed from pink to white at 0.6 x 1 and from pink to light lilac at x = 0.5). A decrease in x leads to a decrease in the temperature of the forward (under heating Tc ) and reverse (under cooling Tc ) transitions, a decrease in hysteresis value ( Tc), and a smearing of the spin transition. 相似文献
5.
Ab initio SCF-MO-LCAO calculations have been performed with a 7s3p/3s GTO basis set for the CH3O--lactam + OH– reaction which is related to the mode of action of -lactam antibiotics. The comparison of the present results with the previous ones for -lactam + OH– and 3-cephem + OH– shows that the CH3O substitution has a negligible effect on the amidic bond breaking of -lactam, so that this group probably influences other steps of the antibiotic reactivity of cephaloporins. 相似文献
6.
The reaction of phenylacetylene with CO and n-butanol in toluene (363 K) catalyzed by the Pd(dba)2/m(CF3COOH)/n(Ph3P) system (dba is dibenzylideneacetone; 2 m 8; 10 n 30) is studied. The initial rate of the main product (butyl 2-phenylpropenoate) buildup is found to depend on the pressure of CO and the concentrations of reactants and system components. The state of the catalyst under reaction conditions is studied in situby IR spectroscopy. A kinetic model is developed based on the experimental results. This model corresponds to the mechanism that resembles the hydride mechanism in the type of main intermediates in the catalytic cycle. 相似文献
7.
Lei Liu Wen-Guang Li Qing-Xiang Guo 《Journal of inclusion phenomena and macrocyclic chemistry》1999,34(4):413-419
A multiple regression model was generated, which can satisfactorily estimate the association constants (K
a
) for the inclusion complexation of -cyclodextrin with mono- and 1,4-disubstituted benzenes. It was found that lnK K
a
was correlated with the substituent molar refraction (R
m
), hydrophobic constant () and Hammett constant ) of the guest compounds with a correlation coefficient of 0.95. The main driving forces for -cyclodextrin complexation was concluded to consist of van der Waals forces and hydrophobic interactions, while the influence of electronic effects was small. 相似文献
8.
Toshikatsu Koga 《Theoretical chemistry accounts》1989,75(6):417-424
Based on momentum- and position-space analyses of the moment operators for two-electron atoms, it is shown that there exists a family of two-electron wave functions which satisfy a proportionality relation, r/
1
v
/r
12
v
=p/
1
v
/p
12
v
=2–v/2, between the one and two-electron moments in position and momentum spaces, where v is an arbitrary number for which the moments are well-defined. 相似文献
9.
Conclusions When heated in the presence of a catalytic amount of BF3 etherate,-trifluoromethyl--diethylamino--fluoroacrylic acid N, N-dimethylamide is reversibly isomerized to-trifluoromethyl--dimethylamino--fluoroacrylic acid N, N-diethylamide. The methyl esters of-trifluoromethyl--diethylammo--fluoroacrylic acid and-trifluoromethyl--phenoxy--fluoroacrylic acid N,N-dimethylamide are not isomerized under the same conditions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No.1, pp.137–141, January, 1976. 相似文献
10.
R. I. Soltanov E. A. Paukshtis E. N. Yurchenko 《Reaction Kinetics and Catalysis Letters》1985,28(1):139-144
Influence of the strength and concentration of non protic centers on the catalytic activity of metal-zeolite catalysts in isomerization of n-butane has been studied. A relationship between the specific activity and the center strength is suggested.
-. , .相似文献
11.
Summary The following chromium(III) complexes of 4-aminobenzophenone have been prepared and investigated by infrared and electronic spectra and magnetic susceptibility measurements: CrCl3L, CrCl3L2 (pink and brown), CrCl3L3, CrCl3L6, CrBr3L2, CrBr3L3, CrBr3L4, CrBr3L6, CrBr3L7 and CrBr3L8. The CrBr3 complexes were each isolated in a yellow and a red form. In the red CrBr3 and in the yellow CrBr3L2 the ligand is bonded through the amine nitrogen. The CrCl3 complexes are probably molecular complexes. 相似文献
12.
V. A. Razdobarov V. A. Sadykov S. A. Veniaminov N. N. Bulgakov O. N. Kovalenko Yu. D. Pankratiev V. V. Popovskii G. N. Kryukova S. F. Tikhov 《Reaction Kinetics and Catalysis Letters》1988,37(1):109-114
The differentiation of surface oxygen forms of Co3O4 by energy, reactivity and centers of adsorption has been carried out.
Co3O4 , .相似文献
13.
Fe(III) hydrolysis and fluoride complexation behavior was examined in 0.68 molal sodium perchlorate at 25°C. Our assessment of the complexation of Fe(III) by fluoride ions produced the following results: logF1 = 5.155, logF2 = 9.107, logF3 = 11.96, logF4 = 13.75, where logFn = 5.155=[FeF
n
(3-n)+
][Fe3+]–1[F–]–n. The stepwise fluoride complexation constants,FK
n+1, obtained in our work (where logF
K
n+1 =logFn) indicate that K
n+1/K
n
=0.072±0.01. Formation constants for equilibria, Fe3++nH2OFe(OH)
n
(3–n)+
+nH+, expressed in the form
n
*
[Fe(OH)
n
(3-n)+
][H+]n
,[Fe
3+]-1, were estimated as
1
*
= –2.754, and
2
*
–7. Our study indicates that the results of previous hydrolysis investigations include very large overestimates of Fe(OH)
2
+
formation constants. 相似文献
14.
N. G. Chernorukov Yu. N. Mikhailov A. V. Knyazev A. S. Kanishcheva E. V. Zamkovaya 《Russian Journal of Coordination Chemistry》2005,31(5):364-367
A procedure for the synthesis of uranyltricarbonatetetrarubidium Rb4UO2(CO3)3 was developed. Its crystal structure was determined by X-ray diffraction analysis: space group C2/c; a=10.778(5) , b=9.381(2) , c=12.509(3) . =94.42(3)°, Z=4; 1178 independent reflections, R=0.0662.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 387–390.Original Russian Text Copyright © 2005 by Chernorukov, Mikhailov, Knyazev, Kanishcheva, Zamkovaya. 相似文献
15.
V. N. Mitkin 《Journal of Structural Chemistry》2003,44(1):82-115
The paper reviews published data on the structure and composition of two large classes of inorganic polymer fluorocarbon materials (IP FCMs), including hightemperature (HT) and lowtemperature (LT) modifications of graphite fluorides and fluorographitelike compounds CF
x
(x = 0.5 – 1.12$) and CF1+y (y = 0.08 – 1.33$) and intercalated fluorographite compounds (IFGCs) based on C
x
F (x < 2) matrices. According to Xray diffraction data, C1s and F1s Xray photoelectron spectroscopy (XPS), 13C and 19F NMR, CK
and FK
Xray spectroscopy, and IR and Raman spectroscopy, as well as MNDO calculations, the structure of monolayers and the properties of IP FCMs of C2F – CF1+y composition depend on the combination of C(sp
3) – F fragments bonded to the sp
2 fragments of the starting carbon matrices. The structure of hightemperature CF1+y is specified by the presence of structurally isolated external and internal C(sp
3)F2 groups located on the boundaries of C(sp
3) – F skeleton monolayers and in the holes of their nanostructures, respectively. The enthalpy of formation of HT FCMs does not depend on the type of starting carbon material and is linearly proportional to the F/C atomic ratio; C(sp
3)F and C(sp
3)F2 groups are chemically indistinguishable in HT FCMs. Six models for the structure of C2F and C4F monolayers in LT FCMs are considered. The best agreement with spectroscopy and MNDO data is obtained using modified Yudanov–Gornostaev's model for C2F, in which alternating rows of graphitelike sp
2 carbon fragments coexist with rows of bonded perfluorocyclohexane sp
3 cells. For lowtemperature C24F–C2F, electric conductivity and C1s and F1s XPS data are generalized and composition–property diagrams are constructed. In this case, the conductivity, C1s and F1s XPS, and the interplanar distances in monolayers are explained using the concept of planarity of C
x
F monolayers and the ensuing ideas of semiionic and semicovalent C=F bonds. For C4F · yA–C2F · zA compositions, 13C and 19F NMR data, C1s and F1s XPS, and IR data are accounted for by the predominant sp
3 nature of the structureforming C=F bonds. 相似文献
16.
D. McNaughton 《Structural chemistry》1992,3(4):245-252
The infrared spectrum of dichloroacetylene, prepared by the pyrolysis of dichloromaleic anhydride at 1000°C, has been recorded at both low and high resolution. In the low resolution spectrum a number of combination bands not previously observed have been assigned, the infrared active fundamentals have been reassigned, and a center wavenumber value has been determined for the Raman activev
1 fundamental. The high resolution spectra of a number of fundamental bands, summation bands, and one difference band for the isotopomers,35CICC35CI and35CICC37CI, have been assigned, while a more limited number of bands has been assigned for the species37CICC37CI and35CI13CC35CI. The resultant rotational and vibration-rotation constants have been used to obtainr
o,r
e,r
s, and partial rs structural parameters. The most reliable bond lengths are obtained from the partialr
s treatment and are 164.105(53) pm for the C-CI bond and 119.203(79) pm for the CC bond. 相似文献
17.
The doping of MnO2 with small quantities of Bi2O3 results in an increase of the surface oxygen bond energy. Accordingly, the values of the specific catalytic activity and selectivity to nitrous oxide are lower for the doped catalyst than for pure MnO2. The mechanism of low temperature ammonia oxidation is the same on both catalysts.
Bi2O3 MnO2 . , , MnO2. .相似文献
18.
A comparative analysis of the relative reactivities of N-arylimides of endo-and exobicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic acids for the addition reactions of hexachlorocyclopentadiene and bromine has been carried out. According to different correlations the transition states of these two processes are shown to be similar.
N- - - [2,2,1] -5--2,3- . .相似文献
19.
The hydrogen sorption of carbon-supported platinum catalysts, studied by the potentiodynamic method, differs significantly from that of unsupported platinum. The difference depends on the preparation method and on the nature of the support. Possible explanations are suggested as (i) some kind of interaction between metal and support atoms during impregnation, (ii) high dispersity (amorphous structure) and (iii) hydrogen spillover onto the carbon support.
Pt/C, . . (I) , (II) ( ), (III) .相似文献
20.
Vinod K. Ahluwalia Manjula Khanna Rishi P. Singh 《Monatshefte für Chemie / Chemical Monthly》1982,113(2):197-200
Obtusinin (1) has been synthesised by the reaction of 6-methoxy-7-(3-methylbut-2-enyloxy)-2H-1-benzopyran-2-one (3) with OsO4. Synthesis of 7-(3-hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-one (2) has been achieved by the regiospecific oxidation of3 with SeO2 followed by reduction of the formed aldehyde with KBH4.
Synthese von Obtusinin und 7-(3-Hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-on
Zusammenfassung Obtusinin (1) wurde über 6-Methoxy-7-(3-methylbut-2-enyloxy)-2H-1-benzopyran-2-on (3) mit OsO4 synthetisiert. Die Darstellung von 7-(3-Hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-on (2) wurde mittels regioselektiver Oxidation von3 mit SeO2, gefolgt von Reduktion des gebildeten Aldehyds mit KBH4, bewerkstelligt.相似文献