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1.
The temperature dependence of the heat capacity C p o of the [(Me3Si)7C60]2 fullerene complex was measured for the first time using precision adiabatic vacuum calorimetry over the temperature range 6.7–340 K and high-accuracy differential scanning calorimetry at 320–635 K. For the most part, the error in the C p o values was about ±0.5%. An irreversible endothermic effect caused by the splitting of the dimeric bond between fullerene fragments and the thermal decomposition of the complex was observed at 448–570 K. The thermodynamic characteristics of this transformation were calculated and analyzed. Multifractal analysis of the low-temperature (T < 50 K) heat capacity was performed, and conclusions were drawn concerning the character of the heterodynamicity of the structure. The experimental data obtained were used to calculate the standard thermodynamic functions C p o (T), H o (T) ? H o (0), S o (T) ? S o (0), and G o (T) ? H o (0) over the temperature range from T → 0 to 445 K and estimate the standard entropy of formation of the compound from simple substances at 298.15 K. The standard thermodynamic properties of [(Me3Si)7C60]2 are compared with those of the (C60)2 dimer, the [(η6-Ph2)2Cr]+[C60]?? fulleride, and the initial C60 fullerene.  相似文献   

2.
(U)PBE0/cc-pVDZ method is used to study the structure of C60Cl30, C60(OH)30 molecules and Fe@C60(OH)30 endocomplex. The triplet state of the endocomplex is shown to be the lowest in energy among its four states corresponding to different spin multiplicities and positions of Fe nucleus within the fullerene cavity. This state is characterized by bonding between the iron atom and one of two benzenoid cycles of the carbon cage, six internuclear Fe–C distances (208 pm), and 1s22s22p63s23p63d7.24s0.14p0.3 electron configuration of iron with spin population of 2.36.  相似文献   

3.
Gas-phase electron diffraction and HF/6-31G*, HF/6-31G**, and B3LYP/6-31G* ab initio calculations were used to find that in the gas phase at 242°C the calix[4]arene [-(C6H3OH)-CH2-]4 molecule possesses a C4 conformation. Geometric parameters of the molecule were determined, and the energies of C-H?O hydrogen bonds (7.3 kcal mol?1) were estimated by the AM1 method.  相似文献   

4.
The molecular structure of the isomer 4348 (C 2v ) of fullerene C66, which does not obey the rule of isolated pentagons, is analyzed. Data on the distribution of single, double, and delocalized bonds in this molecule were obtained for the first time. Quantum-chemical (DFT) calculations showed that the hypothetical C66 molecule was a biradical, which was the reason for its instability. In metallofullerene Sc2@C66, the main changes in bond lengths and electron density transfer from scandium atoms to the carbon shell of fullerene occurred in pentalene substructures and conjugated π bond chains.  相似文献   

5.
A rotating-bomb calorimeter was used to measure the energy of combustion of crystalline fullerene chloride C60Cl30 · 0.09Cl2, Δc U° = (?24474 ± 135 kJ/mol). The result was used to calculate the standard enthalpy of formation, Δf H° (C60Cl30, cr) = 135 ± 135 kJ/mol, and the C-Cl bond energy, 195 ± 5 kJ/mol. The C-X (X = F, F, Cl, and Br) bond energies in fullerene C60 derivatives and other organic compounds are compared.  相似文献   

6.
This study investigates the interaction between C20 and the cis-PtCl2(NH3)2 complex using MPW1PW91 quantum chemical calculations in gas and solution phases. Two interaction modes between C20 and the cis-PtCl2(NH3)2 complex are considered: I-isomer (η2-C20) and II-isomer (η1-C20). It also determines the effects of the solvent polarity on the dipole moment, electronic spatial extent (ESE), structural parameters, and frontier orbital energies of two possible isomers of the C20cis-PtCl2(NH3)2 complex. The bonding interaction between C20 and the cis-PtCl2(NH3)2 complex was examined through energy decomposition analysis (EDA). The metal–ligand bonds are evaluated using the percentage composition of the specific groups of frontier orbitals. The quantum theory of atoms in molecules (QTAIM) analysis is applied to assess the Pt–C bonds within the complex. Finally, the Pt–C spin-spin coupling constants are calculated using the gauge independent atomic orbital (GIAO) method.  相似文献   

7.
The structure of (C3H6N3)4Bi2Cl10 was determined by single crystal X-ray diffraction at room temperature. It crystallizes in the orthorhombic space group Pcmn, with a = 9.430 (1) Å, b = 17.426 (3) Å, c = 19.883(5) Å, V = 3267.3 (11) Å3 and Z = 4. The structure consists of discrete binuclear [Bi2Cl10]4– anions and 3-aminopyrazolium cations. The crystal packing is governed by weak N–H···Cl hydrogen bonds, π–π and electrostatic Cl···Cl interactions. Infrared spectrum is used to gain more information on the title compound. An assignment of the observed vibration modes is reported. The crystal morphology is studied using the BFDH laws. The calculated HOMO and LUMO energies show that charge transfer occur within organic and inorganic molecules. The optical absorption of the zero-dimensional hybrid was also investigated.  相似文献   

8.
The present research work reports the study on crystal structure, vibrational spectroscopy and thermal analysis of organic-inorganic hybrid compound (C6H5(CH2)2NH3)2CdCl4. Single crystals of bis(phenethylammonium)tetrachlorocadmate (C6H5(CH2)2NH3)2CdCl4 (PEA–Cd) were obtained by diffusion at room temperature. This compound crystallizes in the orthorhombic space group C2cb with unit cell parameters a = 7.4444(2) Å, b = 38.8965(3) Å, c = 7.3737(2) Å and Z = 4. Single crystal structure has been solved and refined to R = 0.036 and wR = 0.092. The structure consists of an extended [CdCl4]2– network and two [C6H5(CH2)2NH3]+ cations to form a two-dimensional perovskite system. The infrared (IR) spectrum of the title compound was recorded at room temperature. Differential scanning calorimetry (DSC) was used to investigate the phase transition; this compound exhibits a reversible single solid-solid phase transition.  相似文献   

9.
The values of ΔH°298, S°298, H°298H°0, T, ΔH fus, and C p(T), as well as the temperature dependences of the Gibbs energy function, are calculated for Bi8O11 oxide by proven computational methods.  相似文献   

10.
Quantum-mechanical calculations with the FEFF8 code were used to study the electronic energy structure of 200-atomic clusters of As2S3, AsSI, AgAsS2, and TiS2 semiconductor compounds. The calculated local partial densities of electronic states are compared with the sulfur K and L X-ray emission spectra and sulfur K absorption spectra for fine powders of these compounds. Good agreement between theory and experiment has been obtained.  相似文献   

11.
More than twenty M6Al38 isomers and several M12Al32 isomers of carbon- and silicon-substituted aluminum clusters with six and twelve dopant atoms of general formula MnAl44–n(M = C and Si, n = 6 and 12) have been studied by the density functional theory method. Calculations predict that, in the lowest-lying M6Al38, isomer, all substitutions of C atoms for Al are localized in one outer surface layer of the aluminum cage. In the course of optimization, the C atoms with a negative charge of about 1e are incorporated into positions of the intermediate layer to transform it into a 12-atom face composed of three adjacent vertex-sharing six-membered rings with short C–Al bonds. In the favorable isomer of M6Al38, the dopants are scattered as individual Si atoms located in both outer layers or in the subsurface space between the outer layers and the inner core of the cluster. Optimization of low-lying isomers with twelve starting substitutions of C and Si for Al in both outer layers has localized two preferable C12Al32 isomers. One of them contains three covalently bonded diatomic C2 anions, which are combined through bridging aluminum atoms in the three-dimensional [C6Al7] cluster inside the severely distorted outer cage. In the second, most favorable, isomer, the dopants are distributed as isolated C anions; together with the bridging Al atoms, they form the [M12Al32] inner cage with an unusual dumbbell-like structure. For M12Al32, the aluminum cage undergoes moderate distortions. The silicon atoms remain in the outer layers and form five-membered ring subclusters [Si5] and [Si2Al3] bound to the neighboring intermediate layers through elongated and weakened Si–Al bonds. Evaluation of the energies of the model exchange reactions Al44 + M6 → M6Al38 + Al6 and Al44 + 2M6 → M12Al32 + 2Al6 shows that for M= C both reaction are exothermic, whereas for M = Si the former reaction is nearly isothermal and the second reaction is endothermic and requires significant energy inputs. The differences between the equilibrium structures and the relative positions on the energy scale of the isomers of the C6Al38–Si6Al38 and C12Al38–Si12Al38 clusters are examined.  相似文献   

12.
The Sm2S3-Sm2O3 phase diagram was studied by physicochemical methods of analysis from 800 K up to melting. Two oxysulfides are formed in the system: Sm10S14O with tetragonal crystal structure (space group I41/acd; unit cell parameters: a = 1.4860 nm, c = 1.9740 nm; microhardness: H = 4700 MPa; solid decomposition temperature: 1500 K) and Sm2O2S with hexagonal structure (space group P-3m1; a = 0.3893 nm, c = 0.6717 nm; H = 4500 MPa; congruent melting temperature: 2370 K). Within the extent of the Sm2O2S-based solid solution (61–70 mol % Sm2O3) at 1070 K, a singular point appears at the compound composition on property-composition curves. The eutectic coordinates: 23 mol % Sm2O3 and 1850 K; 80 mol % Sm2O3 and 2290 K.  相似文献   

13.
The possibility of enhancing the ignition and combustion of the CH4/air/O3 and C2H2/air/O3 mixtures by exciting the asymmetric vibrations of the O3 molecule with CO2 laser radiation is considered. Even the admixture of small amounts of O3 (2.5–5.0 vol %) into the hydrocarbon/air mixtures intensifies ignition and shortens the induction period. The excitation of the O3 molecules with 9.7-μm radiation speeds up the chain process and further reduces the induction period and the ignition temperature. The induction period can be shortened by a factor of 10–100 even at low radiation energies absorbed by the gas (E S = 10?3-10?2 J/cm3).  相似文献   

14.
The concentration dependences of densities of fullerene C70 solutions in benzene, toluene, and p-xylene were determined pycnometrically.  相似文献   

15.
3′H-Cyclopropa[1,9](C60-Ih)[5,6]fullerene-3′-carboxylic acid can be synthesized in a good yield by cyclopropanation of fullerene C60 with 2-(dimethyl-λ4-sulfanylidene)acetates provided that the ester residue is readily hydrolyzable in acid medium.  相似文献   

16.
Properties of CF x /Li and CF x /Na cells were examined while using galvanostatic charging/discharging, electrochemical impedance spectroscopy and scanning electron microscopy (SEM). The capacity during the first cycle was as high as ca. 1000 mAh g?1. Such an electrode is suitable for primary CF x /Li and CF x /Na batteries. SEM images of CF x cathode showed that during discharging it was transformed into amorphous carbon and LiF or NaF crystals (of diameter of ca. 5–20 μm). These systems (C?+?LiF or C?+?NaF) cannot be reversibly converted back into CF x /Li or CF x /Na, respectively. Exchange current densities are between 10?7 Acm?2 and 10?9 Acm?2 when working with LiPF6 and NaPF6 electrolytes (1.12?×?10?7 Acm?2 and 6.82?×?10?9 Acm?2, respectively). Those values are low and indicate that the charge transfer process may be the rate-determining step. Activation energies for the charge transfer process were 57 and 72 kJ mol?1 for CF x /LiPF6 and CF x /NaPF6 systems, respectively. Higher activation energy barrier for the CF/Na+?+?e??→?C?+?NaF reaction results in lower observed exchange current density in comparison to the system with lithium ions.  相似文献   

17.
Single crystals of two new mercury thiohalides of the composition Hg3S2Cl2? xBrx(x = 0.5) have been grown from gas phase and studied by X-ray crystallography. Structure refinement for monoclinic (I) and cubic (II) phases (I: a = 16.841(2) Å, b = 9.128(2) Å, c = 9.435(4) Å; β = 90.080(10)°, V = 1450.3(7) Å3, space group C2/m, Z = 8, R = 0.0528; II: a = 18.006(2) Å, V = 5837.8(11) Å3, space group \(Pm\bar 3n\), Z = 32, R = 0.0503) clearly shows that they are polymorphs of the same composition Hg3S2Cl1.5Br0.5. The monoclinic modification I is similar to the synthetic phases γ-Hg3S2Cl2, β-Hg3S2Br2, Hg3Se2Br2 and to the analogue of radtkeite mineral, Hg3S2ClI. The modification II is isostructural to the synthetic β-Hg3S2Cl2. In both structures, each S atom coordinates three Hg atoms with the formation of pyramidal SHg3 units (Hg-S 2.37–2.48 Å; HgSHg 93.1–97.5 ). The SHg3 units are linked through Hg vertices into corrugated layers [Hg12S8]∞∞ (I) and isolated cubic groups [Hg12S8] (II). Similarly to other mercury chalcohalides, the crystal structures are basically determined by the halogen atoms which form a cubic sublattice incorporating the Hg-S moieties.  相似文献   

18.
The crystal structure of As-schwatzite Cu6(Cu5.26Hg0.75)(As2.83Sb1.17)S13 (Aktash deposit, Altai mountains) is refined. Tetrahedrally shaped dark-gray single crystals of the mineral belong to the cubic crystal system: I4¯3m space group, a = 10.2890(1) Å, V = 1089.2(1) Å3, d = 4.99 g/cm3, Z = 2 for the composition Cu11.26Hg0.75As2.83Sb1.17S13, R = 0.0177. The structure is based on the sphalerite-like framework comprising identically oriented (Cu,Hg)S4 tetrahedra ((Cu,Hg)-S 2.3452(8) Å) and (As,Sb)S3 pyramids ((As,Sb)-S 2.311(1) Å) sharing their vertices. The centers of [Cu6] octahedra in the (000) and (1/2 1/2 1/2) positions coinciding with the centers of the “cluster” anionic vacancies [□]4 are occupied by the so-called “thirteenth” sulfur atom. Quantum chemical calculations of the electron density are carried out for the [As4S13Cu6]6 fragment. The calculation results confirm the presence of strain in the [As4S13Cu6]6 moiety, which exists due to the support of the surrounding symmetric framework including the external sulfur atoms of the fragment. The possibility of inclusion of mercury into the framework, which is much richer in arsenic than in antimony, is demonstrated. High stability of the framework determines significant compression of the S-centered [SCu6] octahedron in its interstices, bringing together copper atoms to 3.145(1) Å and shortening the Cu-S distances to 2.224(1) Å  相似文献   

19.
The radial distribution of hydrogen on C20(cage) and C19Si(cage), and C19B(cage) fullerene structures is investigated at different temperatures (273 K, 293 K, 320 K, and 400 K) for the pressure range between 1 MPa and 30 MPa using the (N,V,T) Monte Carlo simulation. The gravimetric storage capacity and radial distribution function parameters show that, under the identical temperature and pressure conditions, the magnitude of the hydrogen radial distribution on the C19B surface is larger than that on C19Si and C20. The calculated maximum of the gravimetric storage capacity for C19B at 273 K and 30 MPa is 7.6%.  相似文献   

20.
The crystal and molecular structure of doubly protonated tetraazamacrocyclic complex of gold(III) [Au(C14H24N4)][H3O](ClO4)4 has been determined. The crystals are monoclinic: a = 11.158(2) Å, b = 8.243(1) Å, c = 14.756(2) Å; β = 98.65(1)°, V = 1341.8(3) Å3, Z = 2, ρ(calc) = 1.134 g/cm3, space group P21/n. The structure is built of almost flat centrosymmetrical Au(C14H24N4)]3+ and [H3O]+ cations and [ClO4]? anions. The gold atom is coordinated with four nitrogen atoms of the ligand forming a flat square. The coordinated ligand is protonated at its γ-carbon atoms of the two six-membered chelate rings. The Au-N bond lengths are almost identical (the mean value is 1.994 Å). The six-membered rings of the complex contain C=N diimine bonds. The [H3O]+ oxonium ion has H-bonds with the oxygen atoms of perchlorate ions.  相似文献   

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