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1.
Quantum-chemical calculations of the geometry and energies of nine possible isomers of 12-vertex cobaltacarborane CpCoC2B9H11 (1) were carried out by the DFT method (PBEPBE/DGDZVP/DGA1). Thermodynamic stability of the isomers increases with increasing
distance between the carbon atoms in the cage and is virtually independent of the position of the CpCo vertex. The relative
stabilities of the 1,2,3-(17.57 kcal mol−1), 1,2,4-(3.72 kcal mol−1), and 1,2,9-isomers of 1 (0 kcal mol−1) are similar to the corresponding values for the ortho (17.61 kcal mol−1), meta (3.21 kcal mol−1), and para isomers (0 kcal mol−1) of carborane C2B10H12. The results of the present study confirm a close similarity of the CpCo and BH fragments in metallacarborane chemistry.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1557–1559, July, 2005. 相似文献
2.
Stephen D. Williams Timothy J. Johnson Thomas P. Gibbons Christopher L. Kitchens 《Theoretical chemistry accounts》2007,117(2):283-290
The accuracy of various computational methods (Hartree–Fock, MP2, CCSD, CAS-SCF, and several types of DFT) for predicting
relative intensities in Raman spectra for C6H6, C6D6, and C6F6 was compared. The predicted relative intensities for ν1 and ν2 were compared with relative intensities measured by an FT-Raman spectrometer. While none of these methods excelled at this
prediction, Hartree–Fock with a large basis set was most successful for C6H6 and C6D6, while PW91PW91 was the most successful for C6F6. 相似文献
3.
I. V. Kalinovskaya A. N. Zadorozhnaya V. E. Karasev 《Russian Journal of General Chemistry》2011,81(9):1778-1781
The intensively luminescing mixed-ligand europium compounds were synthesized of the composition Eu(C10H11F7O2)3D, where C10H11F7O2 is heptafluorodimethyloctanedione, D is either 1,10-phenanthroline (C12H8N2), triphenylphosphine oxide (C18H15PO), hexamethylphosphoramide (C6H18N3PO), benzotriazole (C6H5N3), or phenylguanidine [(C6H5NH)2 =NH]. The luminescent properties of europium compounds in the crystalline state and in a polymer matrix of high-pressure
polyethylene (HPPE) and polyvinyl chloride (PVC) and kinetics of the luminescence intensity decay under UV radiation were
studied. The most photo-resistant in HDPE and PVC was found to be Eu(C10H11F7O2)3Ph3PO. 相似文献
4.
Jian-Long Xia Wei-Cheng Xiong Gang Chen Guang-Ao Yu Shan Jin Sheng-Hua Liu 《Transition Metal Chemistry》2009,34(4):389-393
Abstract Formal [2 + 2 + 2] addition reaction of [Cp*Ru(H2O)(NBD)][BF4] (NBD = norbornadiene) with 4,4′-Diethynylbiphenyl generates [C9H9-η6-C6H4(RuCp*)–C6H4(RuCp*)-η6-C9H9][BF4]2. The reaction of [Cp*Ru(H2O)(NBD)][BF4] with 1,4-diphenylbutadiyne generates the unusual [2 + 2 + 2] additional organic compound Ph–C≡C–C9H8–Ph in addition to the organometallic compound [Cp*Ru(η6-C6H5–C≡C–C≡C–Ph)][BF4]. [C9H9-η6-C6H4(RuCp*)–C6H4(RuCp*)-η6-C9H9][BPh4]2 is generated after the reaction of compound [C9H9-η6-C6H4(RuCp*)–C6H4(RuCp*)-η6-C9H9][BF4]2 with Na[BPh4]. The structure of this compound was confirmed by X-ray diffraction. A possible approach to form Ph–C≡C–C9H8–Ph and [Cp*Ru(η6-C6H5–C≡C–C≡C–Ph)][BF4] is suggested.
Graphical Abstract Formal [2 + 2 + 2] addition reaction of [Cp*Ru(H2O)(NBD)]BF4 (NBD = norbornadiene) with 4,4′-Diethynylbiphenyl generates [C9H9-η6-C6H4(RuCp*)–C6H4(RuCp*)-η6-C9H9][BF4]2. The reaction of [Cp*Ru(H2O)(NBD)][BF4] with 1,4-diphenylbutadiyne simply generates unusual [2 + 2 + 2] additional organic compound Ph–C≡C–C9H8–Ph in addition to the organometallic compound [Cp*Ru(η6-C6H5–C≡C–C≡C–Ph)][BF4]. [C9H9-η6-C6H4(RuCp*)–C6H4(RuCp*)-η6-C9H9][BPh4]2 is generated after the reaction of compound [C9H9-η6-C6H4(RuCp*)–C6H4(RuCp*)-η6-C9H9][BF4]2 with Na[BPh4]. The structure of this compound was confirmed by X-ray diffraction. And the possible approach to form Ph–C≡C–C9H8–Ph and [Cp*Ru(η6-C6H5–C≡C–C≡C–Ph)][BF4] was suggested.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Direct on-line studies of a C2HCl3/He/O2 microwave discharge plasma made possible the evolution and detection of many unfamiliar ionic species. Numerous ionic chlorocarbons,
chlorohydrocarbons, oxygenated chlorohydrocarbons, oxygenated hydrocarbon radicals, and simple hydrocarbon species were identified
mass spectrometrically as by-products: C
m
Cl
n
(m = 1–4, 6, 8; n = 1–8), C
m
H
n
Cl
x
(m = 1–4, 6, 7, 10; n, x = 1–6), C
m
H
n
Cl
x
O
y
(m = 1–5, 12; n = 1–7; x = 1, 2, 4, 6; y = 1–3),
C
n
H2n−1O (n = 2, 3), C
m
H
n
(m = 2, 4, 6, 8; n = 2, 4), and so on. The studies clearly showed the presence of various unfamiliar positive ionic O-containing species such
as C2ClO2, CCl3CO, C2H2Cl4O2, and C4H2Cl6O3. It is apparent that positive-ion reactions play a significant role in producing many ionic species in the chemistry of C2HCl3 plasmas. 相似文献
6.
Matthias Weil Franz Werner Frank Kubel 《Monatshefte für Chemie / Chemical Monthly》2002,133(3):267-275
Summary. Single crystals of MgAl2F8(H2O)2 have been obtained under hydrothermal conditions (250°C, 14 d) from a starting mixture of AlF3 and MgAlF5(H2O)2 in a 5% (w/w) HF solution. The crystal structure has been determined and refined from single crystal data (Fmmm (#69), Z = 4, a = 7.2691(7), b = 7.0954(16), c = 12.452(2) ?, 281 structure factors, 27 parameters, R(F
2 > 2σ (F
2)) = 0.0282, wR(F
2 all) = 0.0885). The obtained crystals were systematically twinned according to (010/100/001) as twinning matrix, reflecting
the pseudo-tetragonal metric. The crystal structure is composed of perowskite-type layers built of corner sharing AlF6 octahedra with an overall composition of AlF4
− which are connected via common fluorine atoms of [MgF4/2(H2O)2/1] octahedra. Group-subgroup relations of MgAl2F8(H2O)2 to WO3(H2O)0.33 and to other M(II)M(III)2 F8(H2O)2 structures are briefly discussed. Above 570°C, MgAl2F8(H2O)2 decomposes under elimination of water into α-AlF3, β-AlF3, and MgF2.
Received October 29, 2001. Accepted (revised) December 6, 2001 相似文献
7.
Marcin Środa 《Journal of Thermal Analysis and Calorimetry》2009,97(1):239-243
Glasses have been synthesized in the system SiO2–Al2O3–Na2O–AlF3–LaF3–Er2O3. A base glass (in mol% 67SiO2–9Al2O3–20Na2O–Al2F6–3La2F6) was modified by 0.5, 0.75, 1, 1.25, 1.5, 2 and 5 mol% Er2O3, respectively. Glasses were prepared by conventional fusion method from 20 g batches. The glass transition temperature (T
g), the jump-like changes of the specific heat (ΔC
p) accompanying the glass transition and the enthalpy of crystallization (ΔH) were calculated. DTA measurements clearly reveal that the increase of the Er2O3 content in the glass changes the effects of crystallization and diminishes the thermal stability of the glassy network. In
the same time the changes in the transition temperature are observed. The formation of NaLaF4 and Na1.45La9.31(SiO4)6(F0.9O1.1) as a main phase was confirmed. The diminishing of the thermal stability was connected with erbium which incorporated into
Na1.45La9.31(SiO4)6(F0.9O1.1) structure. 相似文献
8.
L. G. Bulusheva A. V. Okotrub V. V. Bashilov V. I. Sokolov 《Russian Chemical Bulletin》2005,54(12):2730-2734
The electronic structure of the (η2-C60)Pd[P(Ph2)C5H4]2Fe complex was calculated by the “hybrid” B3LYP method. Comparison of the experimental X-ray emission C-Kα spectrum and theoretical
spectrum of the compound demonstrated that the electron interactions between the C60 core, palladium atom, and organometallic fragment are described correctly in the framework of the quantum chemical method
used. The electronic structure of the organometallic fullerene complex can be presented as a set of blocks of orbitals corresponding
to different types of chemical bond.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2640–2644, December, 2005. 相似文献
9.
The hydrogen-bonded structures of the CH3OH complexes with CF4, C2F2, OC, Ne, and He are designated as the starting points for geometry optimizations without and with counterpoise (CP) correction
at MP2 level of theory with the basis sets 6-31+G*, 6-31++G**, and 6-311++G**, respectively. Tight convergence criteria are
applied throughout all geometry optimizations in order to reduce the computational errors. According to the optimizations
without CP correction, a blue-shifted O–H···Y (where Y = F, O, Ne, or He) hydrogen bond exists in all these five complexes.
The magnitudes of blue shifts of ν(O–H) of the former four complexes with respect to that of CH3OH are reduced greatly when the polarization and diffuse functions of the hydrogen atoms are added (results from 6-31+G* versus
those from 6-31++G**). However, for the complexes CH3OH–CF4 and CH3OH–C2F2, our optimizations using the CP corrections did not find the hydrogen-bonded structure to be a stationary point. The energy
minimum of both the complexes corresponds to a non-hydrogen-bonded structure. 相似文献
10.
R. G. Bulgakov Yu. G. Ponomareva Z. S. Muslimov F. G. Valyamova R. A. Sadykov R. F. Tuktarov 《Russian Chemical Bulletin》2007,56(2):211-219
Fullerenyl radicals (FR) RC60
· and chemiluminescence (CL) are generated in the presence of O2 in C60—R3Al (R = Et, Bui) solutions in toluene (T = 298 K). The FR are formed due to the addition of the R· radical, which is an intermediate of R3Al autooxidation, to C60. Mass spectroscopy and HPLC were used to identify EtnC60Hm (n, m = 1–6), EtpC60 (p = 2–6), and dimer EtC60C60Et as stable products of FR transformations. As found by ESR, the EtC60
· radical (g = 2.0037) is also generated by photolysis of solutions obtained after interaction in the (C60— R3Al)—O2 system. In the presence of dioxygen, the FR is not oxidized but yields complexes with O2, which appear as broadening of the ESR signals. Chemiluminescence arising in the (C60—R3Al)—O2 system is much brighter (I
max = 1.86·108 photon s−1 mL−1) than the known background CL (I
max = 6.0·106 photon s−1 mL−1) for the autooxidation of R3Al and is localized in a longer-wavelength spectral region (λmax = 617 and 664 nm). This CL is generated as a result of energy transfer from the primary emitter 3CH3CHO* to the products of FR transformation: RnC60Hm, RpC60, and EtC60C60Et.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 205–213, February, 2007. 相似文献
11.
E. Vessally M. Nikoorazm A. Esmaili H. Ghoudarzi Afshar 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(4):631-635
Thermal internal energy gaps, ΔE
s−t; enthalpy gaps, ΔH
s−t; Gibbs free energy gaps, ΔD
s−t, between singlet (s) and triplet (t) states of R2C4H2M (M = C, Si, and Ge) were calculated at B3LYP/6-311++G** level of theory. The ΔG
s−t of R2C4H2C was increased in the order (in kcal/mol): R = −CH3 (−10.51) > −H (−9.59) > i-Pr (−9.51) > t-Bu (−8.98). While, the ΔG
s−t of R2C4H2Si and R2C4H2Ge were increased in the order (in kcal/mol): −CH3 (17.01) > i-Pr (15.30) > −H (15.26) > t-Bu (14.35) and -H (22.79) > −CH3 (22.69) > i-Pr (21.66) > t-Bu (21.01), respectively. 相似文献
12.
N. I. Gruzinskaya A. S. Pimenova P. A. Khavrel’ L. N. Sidorov E. Kemnitz S. I. Troyanov 《Russian Chemical Bulletin》2009,58(11):2276-2282
Fluorocyclohexa adducts C60(C4F8)
n
were synthesized by high-temperature reaction of fullerene C60 with 1,2-C2F4I2 or 1,4-C4F8I2 in sealed tubes. Their separation by HPLC allowed us to determine molecular structure (X-ray diffraction) of four new compounds
C6(C4F8)
n
(n = 2, 3, 4, and 6). Structures of isomers C60(C4F8)
n
were discussed in terms of a concept of consecutive addition of C4F8 groups to the fullerene cage. 相似文献
13.
B3LYP/6-31G(d) hybrid HF/DFT and BLYP/6-31G(d, p) DFT calculations were carried out to determine the structural and electronic
properties of the endohedral complex of C60 with Tetrahedral N4 (Td N4), N4@C60. It was demonstrated that N4 was seated in the center of the fullerene cage and the tetrahedral structure of N4 is remained in the cage. The formation of this complex is endothermic with inclusion energy of 37.92 kcal/mol. N4 endohedral doping perturbs the molecular orbitals of C60 not so much, the calculated HOMO–LUMO gaps, the electron affinity (EA) and the ionizational potential (IP) of N4@C60 are similar to that of C60. 相似文献
14.
Nopsiri Chaiyo Rangson Muanghlua Surasak Niemcharoen Banjong Boonchom Panpailin Seeharaj Naratip Vittayakorn 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1023-1029
The thermal transformation of Na2C2O4 was studied in N2 atmosphere using thermo gravimetric (TG) analysis and differential thermal analysis (DTA). Na2C2O4 and its decomposed product were characterized using a scanning electron microscope (SEM) and the X-ray diffraction technique
(XRD). The non-isothermal kinetic of the decomposition was studied by the mean of Ozawa and Kissinger–Akahira–Sunose (KAS)
methods. The activation energies (E
α) of Na2C2O4 decomposition were found to be consistent. Decreasing E
α at increased decomposition temperature indicated the multi-step nature of the process. The possible conversion function estimated
through the Liqing–Donghua method was ‘cylindrical symmetry (R2 or F1/2)’ of the phase boundary mechanism. Thermodynamic functions (ΔH*, ΔG* and ΔS*), calculated by the Activated complex theory and kinetic parameters, indicated that the decomposition step is a high energy
pathway and revealed a very hard mechanism. 相似文献
15.
D. A. Loginov M. M. Vinogradov Z. A. Starikova P. V. Petrovskii A. R. Kudinov 《Russian Chemical Bulletin》2007,56(11):2162-2165
The visible light irradiation of the [(η5-C6H7)Fe(η-C6H6)]+ cation (1) in acetonitrile resulted in the substitution of the benzene ligand to form the labile acetonitrile species [(η5-C6H7)Fe(MeCN)3]+ (2). The reaction of 1 with ButNC in MeCN produced the stable isonitrile complex [(η5-C6H7)Fe(ButNC)3]+ (3). The photochemical reaction of cation 1 with pentaphosphaferrocene Cp*Fe(η-cyclo-P5) afforded the triple-decker cation with the bridging pentaphospholyl ligand, [(η5-C6H7)Fe(μ-η:η-cyclo-P5)FeCp*]+ (4). The latter complex was also synthesized by the reaction of cation 2 with Cp*Fe(η-cyclo-P5). The structure of the complex [3]PF6 was established by X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 2007. 相似文献
16.
The complex impedance method in the temperature range of 291–660 K was used to study conductivity of oxofluoride BiO0.1F2.8 belonging to the tysonite structural type (LaF3). Bismuth oxofluoride was synthesized using a solid-phase method at 770–870 K for 1–2 h in an argon atmosphere. Heterovalent
substitution of fluoride ions F− by oxygen ions O2− in the anionic BiF3 matrix sublattice results in high ionic conductivity (∼0.1 S/cm at 660 K) of BiO0.1F2.8 ceramic samples. 相似文献
17.
The reactions of [RuCl2(PPh3)3] with 8-hydroxy-2-methyl-quinoline-7-carboxylic acid was examined, and a novel ruthenium(II) complex—[Ru(PPh3)2(C5H8NO)2]—was obtained. The compound was studied by IR, UV–vis spectroscopy, and X-ray crystallography. The molecular orbital diagram
of the complex was calculated with the density functional theory (DFT) method. The spin-allowed singlet–singlet electronic
transitions of the compound were calculated using the time-dependent DFT method, and the UV–vis spectrum of the compound was
discussed, on this basis. The luminescence property of the [Ru(PPh3)2(C5H8NO)2]was examined. 相似文献
18.
Density functional theory (DFT) methods have been applied to study the properties of series of N5
+ salts. The thermal stabilities of the crystals are evaluated based on the reaction enthalpy (ΔH) and free energy change (∆G) of the salts when they dissociate into neutral products. The energy outputs of salts in explosion indicate that all N5
+ salts yield large energy except for N5SbF6 and N5Sb2F11. Considering the released energy and thermal stability, (N5)2SnF6, N5PF6, N5BF4, and N5SO3F may be potential candidates of very energetic explosives. 相似文献
19.
Charges on the atoms and structural parameters of the Xe(CF3)2, FXeCF3, and XeF2 molecules were calculated by the MP2(full)/MIDI(d6)&6-311G(d
6) quantum-chemical methods. The calculated energy of Xe(CF3)2 is greater by 113 kcal/mol than the overall energy of C2F6 and Xe, and the energy of FXeCF3 is greater by 108 kcal/mol than the overall energy of CF4 and Xe, the barrier to the decomposition being estimated at 40 kcal/mol. Both Xe(CF3)2 and FXeCF3 molecules are stable with respect to spontaneous decomposition with elimination of difluorocarbene.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 12, 2004, pp. 1808–1810.Original Russian Text Copyright © 2004 by Semenov, Sigolaev. 相似文献
20.
Yu. M. Shul’ga A. F. Shestakov V. M. Martynenko S. A. Baskakov N. Yu. Trifonov E. M. Anokhin A. V. Maksimychev 《Russian Chemical Bulletin》2011,60(6):1112-1117
Methane-intercalated fullerite (CH4)0.56C60 was obtained by low-temperature precipitation from solution. Methane transition from the gas phase to the octahedral void
of fullerite is accompanied by a bathochromic shift of normal vibrational frequencies (by 19 and 8 cm−1 for ν3 and ν4, respectively). The methane 13C signal in the proton decoupling 13C NMR spectrum is observed as a singlet at δ−0.42. According to quantum chemical calculations using density functional theory,
location of methane in the octahedral void of fullerite (C60)6 leads to a decrease in the total energy of fullerite by 4 kcal mol−1. 相似文献