Mass spectrometric determination of the electron affinity of C<Subscript>60</Subscript>(CF<Subscript>3</Subscript>)<Subscript>10</Subscript> and C<Subscript>60</Subscript>(CF<Subscript>3</Subscript>)<Subscript>12</Subscript> molecules

Knudsen cell mass spectrometry was used to study ion-molecular electron exchange reactions between some trifluoromethyl derivatives of C₆₀ fullerene. Electron affinity values were experimentally determined for C₆₀(CF₃)₁₀ and the S ₆ isomer of C₆₀(CF₃)₁₂ and compared with the results of calculations and the data in the literature.     

The thermodynamic properties of the [(Me<Subscript>3</Subscript>Si)<Subscript>7</Subscript>C<Subscript>60</Subscript>]<Subscript>2</Subscript> fullerene complex

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.     

Triple-decker complexes with a central borole ligand C<Subscript>4</Subscript>H<Subscript>4</Subscript>BR

The review summarizes the results of the recent author’s research on the synthesis of triple-decker complexes with bridging borole ligand. Electrophilic stacking of sandwich compounds with [(ring)M] ⁿ⁺ (n = 1, (ring)M = (C₅R₅)Ru, (C₄Me₄)Co; n = 2, (ring)M = Cp*Co, Cp*Rh, etc.) cationic fragments were used as a general method of synthesis of the complexes. The influence of the substituent at the boron atom on the course of stacking reactions is discussed. The spectral, structural, and electrochemical properties of the complexes synthesized are also considered. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 1–7, January, 2008.     

An <Emphasis Type="Italic">ab initio </Emphasis> Quantum-Chemical Study of C<Subscript>6</Subscript>H<Subscript>5</Subscript>S(O)CH<Subscript>3</Subscript> and C<Subscript>6</Subscript>H<Subscript>5</Subscript>S(O)CF<Subscript>3</Subscript>

The potential functions of internal rotation around the C -S bond in the C₆H₅S(O)CH₃ and C₆H₅S(O)CF₃ molecules were obtained by ab initio MP2(full)/6-31+G* calculations. The stationary points were identified by solving the vibrational problems. The structures in which the plane of the C -S-C bonds is approximately perpendicular to the benzene ring plane correspond to the energy minimum. The barriers to rotation around the C -S bond, corrected for the zero-point vibration energy, are 21.29 [C₆H₅S(O)CH₃] and 28.98 [C₆H₅S(O)CF₃] kJ mol⁻¹. The bond angles (deg) are as follows: 95.7 (CSC), 107.1 (C SO), 106.3 (C SO) in C₆H₅S(O)CH₃; 93.5 (CSC), 108.2 (C SO), 105.2 (C SO) in C₆H₅S(O)CF₃. The bond lengths are as follows (Å): 1.520 (S=O), 1.804 (C -S), 1.810 (C -S) in C₆H₅S(O)CH₃; 1.507 (S=O), 1.799 (C -S), 1.870 (C -S) in C₆H₅S(O)CF₃. According to the results of NBO calculations, the formally double S=O bond consists of a strongly polarized covalent σ bond (S→O) and an almost ionic bond. An increase in the S=O bond multiplicity relative to a single bond is mainly due to hyperconjugation by the mechanism n(O)→σ*(C -S) and n(O)→σ*(C -S) and, to a lesser extent, by interaction of the oxygen lone electron pairs with the Rydberg orbitals of the S atoms, characterized by a large contribution of the d component.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 96–104.Original Russian Text Copyright © 2005 by Bzhezovskii, Il’chenko, Chura, Gorb, Yagupol’skii.     

Time-Resolved Fourier Transform Emission Spectroscopy of CF<Subscript>3</Subscript>Br and CF<Subscript>3</Subscript>CFHCF<Subscript>3</Subscript> in a Pulsed Electrical Discharge

The environmentally important decomposition of halogenated species CF₃Br and CF₃CHFCF₃ in helium discharge plasma was investigated by time-resolved high-resolution Fourier transform infrared emission spectroscopy. Contrary to classical pyrolysis, a deeper fragmentation of precursors up to atoms and lower molecular species was observed. Excited molecular products CF, CF₂ and CF₄ achieved the maximal concentration in the afterglow. The high concentration of all these species is in agreement with a kinetic model based on radical chemistry. The non-detectable concentration of CF₃ can be connected to its high reactivity and the formation of more stable products, CF₄ and CF₂, by addition or release of a fluorine atom, respectively. Other products included HF, HBr, CO and cyano compounds that were produced by secondary reactions with traces of water vapor, atmospheric oxygen and nitrogen present in original industrial samples as impurities.     

Synthesis of cationic complexes [(C<Subscript>4</Subscript>Me<Subscript>4</Subscript>)CoL]<Superscript>+</Superscript> (L is naphthalene,phenanthrene, and anthracene)

Cationic arene complexes [Cb*Co(naphthalene)]⁺ (2, Cb* = C₄Me₄) and [Cb*Co(phenanthrene)]⁺ were synthesized by the reactions of [Cb*Co(MeCN)₃]⁺ with arenes. The [Cb*Co(anthracene)]⁺ complex was synthesized by the abstraction of the iodide ion from [Cb*CoI]₂ by TIBF₄ in the presence of anthracene. Complex 2 exchanges the naphthalene ligand for other arenes at room temperature. 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. 1861–1863, September, 2007.     

(Tetramethylcyclobutadiene)cobalt complexes 7. Mono- and dinuclear arene complexes containing the [(C<Subscript>4</Subscript>Me<Subscript>4</Subscript>)Co]<Superscript>+</Superscript> fragment

The mononuclear arene complexes [Cb*Co(arene)]⁺ (3a–g; Cb* = C₄Me₄; arene is biphenyl (a), diphenylmethane (b), 1,2-diphenylethane (c), diphenyl ether (d), p-terphenyl (e), 1,2-dimesitylethane (f), or 1,3-dimesitylpropane (g)) were synthesized by the reactions of arenes either with the benzene complex [Cb*Co(C₆H₆)]⁺ (1) under visible light irradiation or with the acetonitrile derivative [Cb*Co(MeCN)₃]⁺ (2) in refluxing THF. The reactions of 2 with 1,2-diphenyle-thane, 1,3-dimesitylpropane, and p-terphenyl in a ratio of 2: 1 afforded the dinuclear complexes [Cb*Co(μ-η:η-arene)CoCb*]²⁺ (4c,e,g). The stability of the dinuclear arene complexes was estimated by DFT calculations. The structures of the complexes [3a]PF₆ and [3e]PF₆ ere established by X-ray diffraction. For Part 6, see Ref. 1. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 535–539, March, 2008.     

Prediction of new A<Subscript>3+</Subscript>B<Subscript>3+</Subscript>C<Subscript>2+</Subscript>O<Subscript>4</Subscript> compounds

Hitherto unprepared ABCO₄ compounds (where A and B stand for tervalent metals (r _A ≥ r _B) and C stands for a divalent metal) are predicted. Criteria are found to predict the possibility for these compounds to crystallize in some type of structure (K₂NiF₄, CaFe₂O₄, YbFe₂O₄, or spinel) at room temperature and atmospheric pressure. The prediction is based only on the properties of elements and simple oxides. A special software system for computer-aided analysis of information is used for calculations involving pattern recognition based on use case.     

Quantum-chemical study of organoxenon molecules Xe(CF<Subscript>3</Subscript>)<Subscript>2</Subscript> and FXeCF<Subscript>3</Subscript>

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.     

Benzene Adsorption on C<Subscript>24</Subscript>, Si@C<Subscript>24</Subscript>, Si-Doped C<Subscript>24</Subscript>, and C<Subscript>20</Subscript> Fullerenes

The absorption feasibility of benzene molecule in the C₂₄, Si@C₂₄, Si-doped C₂₄, and C₂₀ fullerenes has been studied based on calculated electronic properties of these fullerenes using Density functional Theory (DFT). It is found that energy of benzene adsorption on C₂₄, Si@C₂₄, and Si-doped C₂₄ fullerenes were in range of –2.93 and –51.19 kJ/mol with little changes in their electronic structure. The results demonstrated that the C₂₄, Si@C₂₄, and Si-doped C₂₄ fullerenes cannot be employed as a chemical adsorbent or sensor for benzene. Silicon doping cannot significantly modify both the electronic properties and benzene adsorption energy of C₂₄ fullerene. On the other hand, C₂₀ fullerene exhibits a high sensitivity, so that the energy gap of the fullerene is changed almost 89.19% after the adsorption process. We concluded that the C₂₀ fullerene can be employed as a reliable material for benzene detection.     

Thermokinetics on the reaction of formation of Dy[(C<Subscript>5</Subscript>H<Subscript>8</Subscript>NS<Subscript>2</Subscript>)<Subscript>3</Subscript>(C<Subscript>12</Subscript>H<Subscript>8</Subscript>N<Subscript>2</Subscript>)]

The enthalpy change of formation of the reaction of hydrous dysprosium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen?H₂O) in absolute ethanol at 298.15 K has been determined as (-16.12 ± 0.05) kJ?mol^-1 by a microcalormeter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59 ± 0.29) kJ?mol^t-1 by a thermochemistry cycle. The values of the enthalpy change of formation both in liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction.     

Enthalpy of sublimation and vapor pressure for the <Emphasis Type="Italic">S</Emphasis><Subscript>6</Subscript> isomer of C<Subscript>60</Subscript>(CF<Subscript>3</Subscript>)<Subscript>12</Subscript>

High-temperature mass spectrometry was used to determine the saturation vapor pressure and the enthalpy and entropy of sublimation of the C₆₀(CF₃)₁₂ trifluoromethylfullerene.     

Magnetic properties of a dinuclear complex (2,3-Me<Subscript>2</Subscript>C<Subscript>5</Subscript>H<Subscript>3</Subscript>N)<Subscript>2</Subscript>Fe<Subscript>2</Subscript>(μ-OOCCMe<Subscript>3</Subscript>)<Subscript>4</Subscript> with “China lantern” structure

Magnetic characteristics of the dinuclear complex (2,3-Me₂C₅H₃N)₂Fe₂(μ-OOCCMe₃)₄ (1) were studied in the temperature interval 2–300 K. The magnetic behavior of complex 1 was interpreted in terms of the orbital-dependent exchange theory with allowance for the temperature dependence of the populations of the split ⁵T_2g ground-state components of the Fe^II ions. The calculated values of the orbital-dependent exchange parameters are in good agreement with the results reported for dinuclear carboxylates of other 3d-transition metals and suggest the existence of strong ferromagnetism in some types of heterodinuclear carboxylates.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2035–2039, October, 2004.     

New Hybrid Material: (C<Subscript>3</Subscript>H<Subscript>6</Subscript>N<Subscript>3</Subscript>)<Subscript>4</Subscript>Bi<Subscript>2</Subscript>Cl<Subscript>10</Subscript>. Synthesis,Structural Study and Spectroscopic Behavior

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) ų 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.     

Electron interactions in the (η<Superscript>2</Superscript>-C<Subscript>60</Subscript>)Pd[P(Ph<Subscript>2</Subscript>)C<Subscript>5</Subscript>H<Subscript>4</Subscript>]<Subscript>2</Subscript>Fe complex

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.     

Synthesis of sodium tungstate from the system Na<Subscript>2</Subscript>C<Subscript>2</Subscript>O<Subscript>4</Subscript>-NaNO<Subscript>3</Subscript>-WO<Subscript>3</Subscript>

The physicochemical basis of the heterogeneous reaction between the components of the system (sodium oxalate)-(sodium nitrate)-(tungsten(VI) oxide) has been studied. The reaction of WO₃ with sodium oxalate-nitrate mixtures occurs at a lower temperature and at a higher rate than the reaction with pure sodium carbonate. A high-yield process for the synthesis of high-purity sodium tungstate has been developed on the basis of this study.     

Effect of Temperature on Thermophysical Properties of Ethanol + Aliphatic Alcohols (C<Subscript>4</Subscript>–C<Subscript>5</Subscript>) Mixtures

Summary. Speeds of sound, densities, and refractive indices of the binary mixtures containing ethanol+(2-methyl-1-propanol, 2-methyl-1-butanol, 1-pentanol, or 3-methyl-1-butanol) were measured at 288.15 ≤ T/K ≤ 323.15 and atmospheric condition in the whole compositional range. The effect of temperature was analyzed by several chemical terms.     

1,4-dithiane radical cations in the CF<Subscript>3</Subscript>CCl<Subscript>3</Subscript> matrix: Photoisomerization mechanism

It has been established that the photoinduced process observed in EPR and in optical absorption spectra for 1,4-dithiane radical cations in the CF₃CCl₃ matrix at 77 K can be ascribed to a “boat”—“twist boat” conformational transition.     

Measurement of the rate constants of the reactions of the chlorine atom with C<Subscript>3</Subscript>F<Subscript>7</Subscript>I and CF<Subscript>3</Subscript>I using the resonance fluorescence of chlorine atoms

The rate constants of the reactions of the chlorine atom with C₃F₇I (k ₁) and CF₃I (k ₂) have been measured using the resonance fluorescence of chlorine atoms in a flow reactor at 295 K: k ₁ = (5.2 ± 0.3) × 10⁻¹² cm³ molecule⁻¹ s⁻¹ and k ₂ = (7.4 ± 0.6) × 10⁻¹³ cm³ molecule⁻¹ s⁻¹. No iodine atoms have been detected in the reaction products.