Synthesis and Structure of Acetonitrile Solvates of Copper(II) Monofluoroacetate and Silver(I) Trifluoroacetate, [Cu2(CH2FCOO)4· 2CH3CN](CH3CN) and Ag3(CF3COO)3(CH3CN)2

Compounds [Cu₂(CH₂FCOO)₄· 2CH₃CN](CH₃CN) (I) and Ag₃(CF₃COO)₃(CH₃CN)₂(II) were synthesized and studied by X-ray structural analysis. Crystals Iare monoclinic, space group C2/c, a= 27.854(6), b= 8.286(2), c= 19.428(4) Å, = 106.82(3)°, V= 4292(2) ų, Z= 8, R ₁= 0.0426; crystals IIare triclinic, space group , a= 8.676(2), b= 9.819(2), c= 11.961(2) Å, = 95.27(3), = 109.59(3)°, = 104.60(3)°, V= 911.4(3) ų, Z= 2, R ₁= 0.0252. Structure Iis composed of the structural units (lanterns) typical of copper(II) carboxylates. The presence of an additional acetonitrile molecule noncoordinated by the copper atoms makes it possible to consider compound Ias a lattice clathrate. Structure IIhas no analogs among the silver carboxylates. It simultaneously contains silver atoms with coordination numbers varying from 2 to 4.     

Theoretical studies of the reactions of Cl atoms with CF3CH2OCH n F(3−n) (n = 1, 2, 3)

This paper presents the theoretical studies of the reactions of Cl atoms with CF₃CH₂OCH₃, CF₃CH₂OCH₂F and CF₃CH₂OCHF₂ using an ab initio direct dynamics theory. The geometries and vibrational frequencies of the reactants, complexes, transition states and products are calculated at the MP2/6-31+(d,p) level. The minimum energy path is also calculated at same level. The MC-QCISD method is carried out for further refining the energetic information. The rate constants are evaluated with the canonical variational transition state theory (CVT) and CVT with small curvature tunneling contributions in the temperature range 200–1,500 K. The results are in good agreement with experimental values.     

Theoretical studies on the reactions OH + CH3COCCl2 X (X = F, Cl, Br)

Theoretical investigations are carried out on the title reactions by means of the direct dynamics method. The optimized geometries, frequencies and minimum energy path are obtained at the MP2/6-31 + G(d,p) level, and energetic information is further refined at the MC-QCISD (single-point) level. The rate constants for both reactions are calculated by the improved canonical variational transition state theory with the small-curvature tunneling correction in a wide temperature range 200–3,000 K. The theoretical rate constant is in good agreement with the available experimental data. Furthermore, the effects of different halogen substitution on the rate constants are also discussed.     

Geometric shielding corrections for calculation of electron scattering by CO2, C2H2, CHCl3, CH2Cl2, CH3Cl,CHF3, CH2F2 and CH3F at 30–5000 eV

Taking into account the changes of the geometric shielding effect in a molecule as the incident electron energy varies, an empirical fraction, which depends on the energy of the incident electrons, the target's molecular dimension and the atomic and electronic numbers in the molecule, is presented. Using this empirical fraction, a new formulation of the additivity rule is proposed. Using the new additivity rule, the total cross sections of electron scattering by CO₂, C₂H₂, CHCl₃, CH₂Cl₂, CH₃Cl, CHF₃, CH₂F₂ and CH₃F are calculated at the Hartree–Fork level at 30–5000 eV. The quantitative total cross sections are compared with those obtained by experiments and other theories, and good agreement is obtained over a wide energy range, especially above 100 eV.     

Chlorination of charged buckyballs: reactions of C60x+ cations (x = 1–3) with Cl2, CCl4, CDCl3, CH2Cl2, and CH3Cl

The chlorination of singly and multiply charged C₆₀ cations has been investigated with the selected-ion flow tube technique. Observations are reported for the reactions of C₆₀^·+, C₆₀²⁺ and C₆₀^·3+ with Cl₂, CCl₄, CDCl₃, CH₂Cl₂ and CH₃Cl at room temperature (295 ± 2 K) in helium at a total pressure of 0.35 ± 0.02 Torr. C₆₀^·+ and C₆₀²⁺ were observed not to chlorinate, or react in any other way, with these five molecules. Chlorine also did not react with C₆₀^·3+, but bimolecular chloride transfer and electron transfer reactions, reactions that result in charge reduction/charge separation, were observed to occur with CCl₄, CDCl₃, CH₂Cl₂ and CH₃Cl. Chloride transfer was the predominant channel seen with CCl₄, CDCl₃ and CH₂Cl₂ while electron transfer dominates the reaction with CH₃Cl. These results are consistent with trends in chloride affinity and ionization energy. The reluctant chlorination of the first two charge states of C₆₀ is attributed to the energy required to distort the carbon cage upon bond formation, while the observed chloride transfer to C₆₀^·3+ is attributed to the greater electrostatic interactions with this ion.     

Accurate ab initio potential energy surface, thermochemistry, and dynamics of the Cl(2P, 2P(3/2) + CH4 → HCl + CH3 and H + CH3Cl reactions

We report a high-quality, ab initio, full-dimensional global potential energy surface (PES) for the Cl((2)P, (2)P(3/2)) + CH(4) reaction, which describes both the abstraction (HCl + CH(3)) and substitution (H + CH(3)Cl) channels. The analytical PES is a least-squares fit, using a basis of permutationally invariant polynomials, to roughly 16,000 ab initio energy points, obtained by an efficient composite method, including counterpoise and spin-orbit corrections for the entrance channel. This composite method is shown to provide accuracy almost equal to all-electron CCSD(T)/aug-cc-pCVQZ results, but at much lower computational cost. Details of the PES, as well as additional high-level benchmark characterization of structures and energetics are reported. The PES has classical barrier heights of 2650 and 15,060 cm(-1) (relative to Cl((2)P(3/2)) + CH(4)(eq)), respectively, for the abstraction and substitution reactions, in good agreement with the corresponding new computed benchmark values, 2670 and 14,720 cm(-1). The PES also accurately describes the potential wells in the entrance and exit channels for the abstraction reaction. Quasiclassical trajectory calculations using the PES show that (a) the inclusion of the spin-orbit corrections in the PES decreases the cross sections by a factor of 1.5-2.5 at low collision energies (E(coll)); (b) at E(coll) ≈ 13,000 cm(-1) the substitution channel opens and the H/HCl ratio increases rapidly with E(coll); (c) the maximum impact parameter (b(max)) for the abstraction reaction is ~6 bohr; whereas b(max) is only ~2 bohr for the substitution; (d) the HCl and CH(3) products are mainly in the vibrational ground state even at very high E(coll); and (e) the HCl rotational distributions are cold, in excellent agreement with experiment at E(coll) = 1280 cm(-1).     

Electronic state dependence of the ion-molecule reaction CH(3)CN(+) + CH(3)CN → CH(4)CN(+) + CH(2)CN: threshold electron-secondary ion coincidence (TESICO) and direct ab initio molecular dynamics study

The ion-molecule reaction, CH(3)CN(+) + CH(3)CN → CH(3)CNH(+) + CH(2)CN, has been investigated using the threshold electron-secondary ion coincidence (TESICO) technique. Relative reaction cross sections for two microscopic reaction mechanisms, i.e., proton transfer (PT) from the acetonitrile ion CH(3)CN(+) to neutral acetonitrile CH(3)CN and hydrogen atom abstraction (HA) by CH(3)CN(+) from CH(3)CN, have been determined for two low-lying electronic states, (2)E and (2)A(1) of the CH(3)CN(+) primary ion. The cross section for PT of the (2)A(1) state was smaller than that of the (2)E state, whereas that of HA are almost the same in the two states. Ab initio calculations showed that the dissociation of the C-H(+) bond of CH(3)CN(+) is easier in the (2)E state than that in the (2)A(1) state. The direct ab initio molecular dynamics (MD) calculations showed that two mechanisms, direct proton transfer and complex formation, contribute the reaction dynamics.     

Pulse radiolysis study of energy transfer processes in Xe–M mixtures (M=CH2F2,CHF3,CHF2Cl,CHFCl2 and CF3Cl)

The time-resolved spectroscopy measurements were used to study the kinetics of energy transfer process in the pulse radiolysis of xenon- fluoro- and chlorofluoromethanes mixtures. The main channel, at xenon pressure above 40 Torr, seems to be of third order, while at lower xenon pressures the second order process was the main one.     

Chlorine reaction with platinum triamine [Pt(N,N-DimeTm)PyCl3]Cl (N,N-DimeTm = (CH3)2N(CH2)3NH2). Crystal structure of [Pt(N,N-DimeTm)Cl2], [Pt(N,N-DimeTm(Py)Cl3]Cl · H2O and [Pt{(CH3)2N(CH2)2C(O)NH}(Py)Cl3]

Treatment of platinum(II) diamine [Pt(N,N-DimeTm)Cl₂] (I) with pyridine gave tetramine [Pt(N,N-DimeTm)Py₂]Cl₂ (II); by oxidation with chlorine this was converted to Pt(IV) triamine, [Pt“(N,N-DimeTm(Py)Cl₃]Cl (III) with a six-membered chelate ring. According to X-ray diffraction data, the reaction of complex II with chlorine is accompanied by removal of the pyridine molecule from the trans-position to the NH₂ group of N,N-dimethyltrimethylenediamine. The reaction of complex III with chlorine at 20°C afforded a mixture of compounds (IV) and the complex [Pt“(CH₃)₂N(CH₂)₂C(O)NH”(Py)Cl₃] (V) with an amidate six-membered metal ring, dimethylpropioamide, which was also isolated upon refluxing a mixture of IV in an aqueous solution. The UV/Vis and IR spectra of the obtained complexes were studied, and X-ray diffraction analysis of I, III, and V was performed. The crystals of I are triclinic, space group P $ \bar 1 $ ; a = 7.6526(4) Å, b = 11.5571(6) Å, c = 12.4432(7) Å, α = 113.85(1)°, β = 96.54(2)°, γ = 106.78(2)°; Z = 4; R _hkl = 0.051. The crystals of III are monoclinic, space group C2/c; a = 36.715(2) Å, b = 7.8179(4) Å, c = 29.721(16) Å, β = 127.80(1)°; Z = 16; R _hkl = 0.036. The crystals of V are monoclinic, space group P2₁/n; a = 7.0398(6) Å, b = 27.458(2) Å, c = 7.687(6) Å, β = 106.270(1)°; Z = 4; R _hkl = 0.052.     

The Cl−NH3, Cl−H2O,F−NH3 and F−H2O clusters and their photoelectron spectra

The geometries of the Cl^–NH₃, Cl^–H₂O, F^–NH₃ and F^–H₂O clusters are optimized using the coupled cluster method. The four lowest ionization potentials are then calculated, leading to the ground and low excited states of the neutral species. The first three IPs describe ionization from the externalp state of the halogen atom, whereas the fourth corresponds to ionization from the NH₃ or H₂O moiety, leading to charge transfer complexes. These complexes were recently observed in the photoelectron spectrum of Cl^–NH₃, in full accord with our calculations.Supported in part by the U.S.-Israel Binational Science Foundation     

用分子束研究.F(^2P)与CH3F和CH3Cl的化学反应

近年来, 我们在研究含氟烯烃和烷烃的红外激光诱导氧化和氯化反应的基础上, 深入研究了红外激光诱导卤代烷烃的脱卤化氢并生成: CF2卡宾和:CFCF3卡宾的反应[1-4]以往的研究往往是根据反应产物推论反应机理, 认为在反应过程中存在着卡宾中间体,但在实验中未能直接检测到. Kakimoto[5,6]曾报道过在流动体系中测到了.F+CH3F和.F+CH3Cl反应中:CHF和:CHCl的激光荧光激发谱, 但没有讨论卡宾形成的机理.Hirota[7]在讨论.F+CH3F反应时, 认为:CHF可能由攫氢过程产生而对于.F+CH3Cl反应同时生成:CHF和:CHCl未做说明. 本实验中用扩散分子束代替了流动反应体系, 从而大大减少了产物和反应物气体分子间的猝灭过程, 获得了信噪比大而清晰的图谱, 由此确证了:CHF和:CHCl的存在, 说明了.F+CH3Cl反应中自由基攫氢过程和偶合反应过程共存的反应历程. 这一结论对红外激光诱导一碳卤代宾化学反应机理研究有重要参考意义.     

Photoelectron Spectroscopy and Structures of X−⋅⋅⋅CH2O (X=F,Cl, Br,I) Complexes

A combined experimental and theoretical approach has been used to investigate X⁻⋅⋅⋅CH₂O (X=F, Cl, Br, I) complexes in the gas phase. Photoelectron spectroscopy, in tandem with time-of-flight mass spectrometry, has been used to determine electron binding energies for the Cl⁻⋅⋅⋅CH₂O, Br⁻⋅⋅⋅CH₂O, and I⁻⋅⋅⋅CH₂O species. Additionally, high-level CCSD(T) calculations found a C_2v minimum for these three anion complexes, with predicted electron detachment energies in excellent agreement with the experimental photoelectron spectra. F⁻⋅⋅⋅CH₂O was also studied theoretically, with a C_s hydrogen-bonded complex found to be the global minimum. Calculations extended to neutral X⋅⋅⋅CH₂O complexes, with the results of potential interest to atmospheric CH₂O chemistry.     

Electronic structure and conformation properties of halogen-substituted acetyl acrylic anhydrides, CX3C(O)OC(O)CH═CH2 (X = H, F, or Cl)

Acetyl acrylic anhydride (CH(3)C(O)OC(O)CHCH(2)) and its halogen-substituted derivatives (CF(3)C(O)OC(O)CHCH(2) and CCl(3)C(O)OC(O)CHCH(2)) were prepared by the heterogeneous reaction of gaseous CH(2)═CHC(O)Cl with CX(3)C(O)OAg (X = H, F, or Cl). The molecular conformations and electronic structure of these three compounds were investigated by HeI photoelectron spectroscopy, photoionization mass spectroscopy, FT-IR, and theoretical calculations. They were theoretically predicted to prefer the [ss-c] conformation, with each C═O bond syn with respect to the opposite O-C bond and the C═C bond in cis orientation to the adjacent C═O bond. The experimental first vertical ionization potential for CH(3)C(O)OC(O)CHCH(2), CF(3)C(O)OC(O)CHCH(2), and CCl(3)C(O)OC(O)CHCH(2) was determined to be 10.91, 11.42, and 11.07 eV, respectively. In this study, the rule of the conformation properties of anhydride XC(O)OC(O)Y was improved by analyzing the different conformations of anhydrides with various substitutes.     

Prediction and characterization of HCCH···AuX (X = OH, F, Cl, Br, CH3, CCH, CN, and NC) complexes: a π Au-bond

In this article, we performed quantum chemical calculations to study the π Au-bond in the HCCH···AuX (X = OH, F, Cl, Br, CH(3), CCH, CN, and NC) system. For comparison, we also investigated the HCCH···Au(+) and H(2)CCH(2)···AuF complexes. The equilibrium geometries and infrared spectra at the MP2 level were reported. The interaction energies were calculated at the MP2 and coupled-cluster single double triple levels. The natural bond orbital results support the Dewar-Chatt-Duncanson model. Moreover, we focused on the influence of X atom on the geometries, interaction energies, and orbital interactions as well as the comparison between HCCH···AuF and H(2)CCH(2)···AuF complexes. Although the π Au-bond in these complexes is electrostatic in nature, the weight of covalent nature is also important.     

Does alpha-fluorination affect the structural trans-influence and kinetic trans-effect of an alkyl ligand? Molecular structures of Pd(TMEDA)(CH(3))(R(F)) and a kinetic study of the trans to cis isomerization of Pt(TMEDA)(CH(3))(2)I(R(F)) [R(F) = CF(2)CF(3), CFHCF(3), CH(2)CF(3)

Reaction of Pd(TMEDA)(CH(3))(2) [TMEDA = tetramethylethylenediamine] with fluoroalkyl iodides R(F)I affords a series of square planar Pd(II) complexes Pd(TMEDA)(CH(3))(R(F)) [R(F) = CF(2)CF(3) (9), CFHCF(3) (10), CH(2)CF(3) (11)], presumably by oxidative addition followed by reductive elimination of CH(3)I. The solid-state structures of each compound have been determined by single crystal X-ray diffraction studies, allowing the effect of increasing alpha-fluorination on the structural trans-influence of alkyl ligands to be examined. In these compounds there is no significant difference observed in the trans-influence of the three fluorinated alkyl ligands toward the trans-N atom, although a significant cis-influence on the neighboring methyl ligand is apparent. Oxidative addition of the same series of fluoroalkyl ligands to the corresponding Pt(TMEDA)(CH(3))(2) affords octahedral Pt(IV) complexes trans-Pt(TMEDA)(CH(3))(2)(R(F))I [R(F) = CF(2)CF(3) (12), CFHCF(3) (13), CH(2)CF(3) (14)] as the kinetic products. In each case, subsequent isomerization to the corresponding all cis-isomers is observed; in the case of 13, the stereocenter at the alpha-carbon results in two diastereomeric cis-isomers, which are formed at different rates. The molecular structures of 13 and its more stable all cis-isomer 16b have been crystallographically determined. Kinetic studies of the trans-cis isomerization reactions show the mechanism to involve a polar transition state, presumably involving iodide dissociation, followed by rearrangement of the cation, and iodide recombination. High dielectric solvents increase the rate, but solvent coordinating ability has no effect. Dissolved salts (LiI, LiOTf) show normal accelerative salt effects, with no inhibition in the case of added iodide, consistent with the formation of an intimate ion pair intermediate. The kinetic parameters show that the trans-effects of fluoroalkyl ligands in these compounds follow the order expected from the relative sigma-donor properties of the ligands, with CF(2)CF(3) < CFHCF(3) < CH(2)CF(3).     

Unimolecular reactions in the CF3CH2Cl ↔ CF2ClCH2F system: isomerization by interchange of Cl and F atoms

The recombination of CF(2)Cl and CH(2)F radicals was used to prepare CF(2)ClCH(2)F* molecules with 93 ± 2 kcal mol(-1) of vibrational energy in a room temperature bath gas. The observed unimolecular reactions in order of relative importance were: (1) 1,2-ClH elimination to give CF(2)═CHF, (2) isomerization to CF(3)CH(2)Cl by the interchange of F and Cl atoms and (3) 1,2-FH elimination to give E- and Z-CFCl═CHF. Since the isomerization reaction is 12 kcal mol(-1) exothermic, the CF(3)CH(2)Cl* molecules have 105 kcal mol(-1) of internal energy and they can eliminate HF to give CF(2)═CHCl, decompose by rupture of the C-Cl bond, or isomerize back to CF(2)ClCH(2)F. These data, which provide experimental rate constants, are combined with previously published results for chemically activated CF(3)CH(2)Cl* formed by the recombination of CF(3) and CH(2)Cl radicals to provide a comprehensive view of the CF(3)CH(2)Cl* ? CF(2)ClCH(2)F* unimolecular reaction system. The experimental rate constants are matched to calculated statistical rate constants to assign threshold energies for the observed reactions. The models for the molecules and transition states needed for the rate constant calculations were obtained from electronic structures calculated from density functional theory. The previously proposed explanation for the formation of CF(2)═CHF in thermal and infrared multiphoton excitation studies of CF(3)CH(2)Cl, which was 2,2-HCl elimination from CF(3)CH(2)Cl followed by migration of the F atom in CF(3)CH, should be replaced by the Cl/F interchange reaction followed by a conventional 1,2-ClH elimination from CF(2)ClCH(2)F. The unimolecular reactions are augmented by free-radical chemistry initiated by reactions of Cl and F atoms in the thermal decomposition of CF(3)CH(2)Cl and CF(2)ClCH(2)F.     

Coupled cluster,MP2, and DFT study of structures,stabilities, vibrations,and bonding properties of XXeOH (X = F,Cl, Br,and I)

The optimized geometries, molecular properties, and stabilities of new noble gas molecules, XXeOH (X = F, Cl, Br, and I), were studied using CCSD, MP2, CAM-B3LYP, and WB97XD methods and large basis sets. All XXeOH molecules showed equilibrium structures with Cs symmetry. The results also showed that some bonds in XXeOH could be presented as a typical ionic bond. An alteration in ion-pair character was observed for IXeOH, showing two OH ^? and IXe ⁺ parts, while in other molecules, they could be presented as XeOH ⁺ and X ^? . Two decomposition routes were proposed for these molecules that showed high exothermic reactions. However, despite their low thermodynamic stabilities, their decomposition rate constants were small and all molecules (except BrXeOH) had high kinetic stabilities, indicating the possibility for identification and characterization of these molecules. However, in addition to the calculation of their vibrational frequencies, NBO atomic charges, and hybridizations, the bonding properties of XXeOH molecules were studied by AIM calculations (to calculate electron densities, bond elipticities, and Laplacian of electron densities) and second-order intramolecular perturbation energies using NBO calculations. Moreover, the ease of formations and relative stabilities of XXeOH molecules were compared using heats of formations, Gibbs free energies of formations and isodesmic reactions. These calculations showed that the stability of XXeOH molecules was decreased from F to I.     

Structure of a new binuclear complex of tungsten [W2S4Cl2(dppe)2]·2CH3CN

Journal of Structural Chemistry - In the reaction of (Et4N)2[W2S4Cl4] with 1,2-bis(diphenylphosphino)ethane in acetonitrile a new binuclear complex of tungsten(V) [W2S4Cl2(dppe)2]·2CH3CN is...     

Characterization of [Re2Cl3(μ-dppm)2(NCCH3)2][Cl] and [Re2Cl3(μ-dppm)2(NCC6H5)2][Cl]·2CH2Cl2 by X-ray Crystallographic and Two-Dimensional NMR Spectroscopic Techniques

The complex Re₂Cl₆(P-n-Bu₃)₂ prepared in situ reacts with CH₃CN to form a blue-green solution. Addition of the chelating phosphine bis(diphenylphosphino)methane (dppm) results in the formation of the complex [Re₂Cl₃(-dppm)₂(NCCH₃)₂][Cl] (1) upon heating. The two acetonitrile molecules adopt a trans geometry on the rhenium center with the axially coordinated chlorine. The analogous trans benzonitrile species [Re₂Cl₃(-dppm)₂(NCC₆H₅)₂][Cl]·2CH₂Cl₂ (2) is synthesized under the same reaction conditions. The coupling constants of the AABB ³¹P{¹H} NMR spectra of the compounds were elucidated from ³¹P–³¹P homonuclear J-resolved NMR experiments. Additional characterization methods include ³¹P{¹H} NMR spectroscopy, UV-vis spectroscopy, and X-ray crystallography.     

Synthesis and structure of gold complexes [Ph3PR]+[Au(CN)2I2-trans]−, R = Et,CH2Ph,Ph

Russian Chemical Bulletin - Gold complexes [Ph3PR]+[Au(CN)2I2-trans]?, where R = Et (1), CH2Ph (2), Ph (3), were synthesized by the reaction of potassium dicyanodiiodoaurate with...