Equilibrium Structures and Isomerization Reactions of the Unsaturated Germylenoid H2C=GeLiF

The unsaturated germylenoid H2C=GeLiF has been studied by using DFT method at the B3LYP/6-311+G (d, p) level. Geometry optimization calculations indicate that H2C=GeLiF has three equilibrium configurations, in which the p-complex is the lowest in energy and the most stable structure. Two transition states for isomerization reactions of H2C=GeLiF are located and the energy barriers are calculated. For the most stable one, vibrational frequencies and infrared intensities have been predicted.     

Mechanism of Insertion Reactions between Silylenoid H2SiLiF and GeH3R (R =F,OH, NH2): a Theoretical Study

Theoretical investigations on the insertion reaction mechanisms of three- membered-ring silylenoid H2 Si Li F with GeH 3R(R = F, OH, NH2) have been systematically carried out by combined density functional theory(DFT) and ab initio quantum chemical calculations. The geometries of all stationary points for these reactions were optimized using the B3 LYP method and then the QCISD method was used to calculate the single-point energies. The calculated results indicate that, there are one precursor complex(Q), one transition state(TS), and one intermediate(IM) which connect the reactants and the products along the potential energy surface. The insertion reactions of three-membered-ring silylenoid with Ge H3 R proceed in a concerted manner, forming H2RSi-Ge H3 and Li F. The calculated potential energy barriers of the three reactions are 29.17, 30.90, and 54.07 k J/mol, and the reaction energies for the three reactions are –127.05, –116.91, and –103.31 k J/mol, respectively. The insertion reactions in solvents are similar to those in vacuum. Under the same situation, the insertion reactions should occur easily in the following order: GeH 3-F GeH 3-OH GeH 3-NH2. The elucidations of the mechanism of these insertion reactions provided a new mode of silicon-germanium bond formation.     

Thermodynamic and Kinetic Studies on the Sill ＋ XH3 （X=N, P） Reactions

Based on the quantum chemical study of the silylidyne insertion reaction with NH3 or PH3, the general statistical thermodynamics and Eyring transition state theory with Wigner correction are used to compute the changes of thermodynamic functions, equilibrium constants, A factors and rate constants of the two reactions in the temperature range 200-2000K. The results show that both of these reactions are thermodynamically dominant at low temperatures and kinetically favored at higher temperatures. The comparison between these two reactions shows that the Sill reaction with NH3 is more exothermic than Sill with PH3, while the rate constant of Sill reaction with NH3 is lower than that of Sill with PH3 at the same temperature.     

THE REFINEMENT OF CRYSTAL STRUCTURE OF BALIPHOLITE

Balipholite is a new mineral discovered in China. Its space group is C cca with the lattice parameters a=13.587(6), b=20.164(10), c=5.144(1). The structure was refined to an R value of 0.047 for 949 independent reflections with (|F_0|>3σ|F_0|). Balipholite has the simailar structure as that of the carpholite group but with large cations Ba occupying the caves of the structure. It is very interesting to point out that the additional anions F and OH occupy different crystallographic positions. Formula of balipolite can he written a BaMg_2LiAl_3(Si_2O_6)_2(OH)_4F_4.     

Computational studies of σ-type weak interactions between NCO/NCS radicals and XY(X = H,Cl;Y = F,Cl,and Br)

The triatomic radicals NCO and NCS are of interest in atmospheric chemistry,and both the ends of these radicals can potentially serve as electron donors during the formation of σ-type hydrogen/halogen bonds with electron acceptors XY(X = H,Cl;Y = F,Cl,and Br).The geometries of the weakly bonded systems NCO/NCS···XY were determined at the MP2/aug-cc-pVDZ level of calculation.The results obtained indicate that the geometries in which the hydrogen/halogen atom is bonded at the N atom are more stable than those where it is bonded at the O/S atom,and that it is the molecular electrostatic potential(MEP)-not the electronegativity-that determines the stability of the hydrogen/halogen bond.For the same electron donor(N or O/S) in the triatomic radical and the same X atom in XY,the bond strength decreases in the order Y = F > Cl > Br.In the hydrogen/halogen bond formation process for all of the complexes studied in this work,transfer of spin electron density from the electron donor to the electron acceptor is negligible,but spin density rearranges within the triatomic radicals,being transferred to the terminal atom not interacting with XY.     

全氟和多氟烷基磺酸的研究 X:在亲核取代反应中全氟烷基3-氧杂全氟烷基磺酸酯的唯一的硫-氧键断裂

Perfluoroalkyl 3-oxaperfluoralkanesulfonates XCF2OCF2CF2SO3CF2OCF2X (1) (X=CF2I (1a), CF2Cl (1b), HCF2 (1c), Cl2CF (1d)) reacted readily with various mucleophiles leading to S--O seission exclusively, thus 1 -- XCF2OCF2CF2SO2Y+XCF2OCF2COZ In the presence of a catalytic amount of halide (F-, Cl-, Br-, I-) and thiecyanate in diglyme 1 decomposed to give the corresponding sulfonly fluoride 2 (X=F) and acyl fluoride 3(Z=F). At room temperature 1 did not react with excess ethanol, but under refluxing for 12.5h, 1 was converted to 2 (Y=F) and 3 (Z=OEt). More powerful nucleophile ethoxide ion reacted readily with 1 at-60 - -50`C yielding Et2O and 3 (Z=OEt) but no 2 (Z=F). When the reaction was carried out at 80`C the yields of the products varied with the order of mixing of the reactants i.e. when 1 was added to excess ethoxide in ethanol, products are 3(Z=OEt), Et2O and 2(Y=F), but with ethoxide adding to 1 the yield of 2 (Y=F) was increased and that of ether decreased whereas the yield of 3 (Z=OEt) remained constant. Carboxylates (CF3CO2-, CH3CO2-) also caused S--O cleavage of 1 to give acetyl fluoride, 2 (y=F) and 3 (Z=F) as a result of decomposition of the intermediary mixed anhydride by the fluoride ion. In the same manner R2NH, C6H5NH2 reacted with 1 giving the products of S--O cleavage. In contrast to the nucleophilic reactions of α, α-di-H-perfluoroalkyl perfluoroalkanesulfonates (mainly C--O cleavage) it has been found that all nucleophies attack the sulfur atom of 1 exclusively. A possible interpretation is that the SN2 attack at sp3 carbon atom in highly fluorinated system is made impossible by the shielding effect of the two fluorine atoms in the alcoholic moiety and leaving the attack on the sulfur as the only alternative.     

Quasi-classical Trajectory Study of the Intramolecular Isotope Effect in the Reaction O（3p）＋H2/HD

Theoretical studies of the dynamics of the reactions O（3p）＋H2/HD（ν=0, j=0）→OH＋H have been performed with quasi-classical trajectory method （QCT） on an ab initio potential surface for the lowest triplet electronic state of H2O（aA＂）. The QCT-calculated integral cross sections are in good agreement with the earlier time-dependent quantum mechanics results. The state-resolved rotational distributions reveal that the product OH rotational distributions for O＋HD have a preference for populating highly internally excited states compared with the O＋H2 reaction. Distributions of differential cross sections show that directions of scattering are strongly dependent on the choice of quantum state. The polarization dependent generalized differential cross-sections and the distributions were calculated and a pronounced isotopic effect is revealed. The calculated results indicate that the product polarization is very sensitive to the mass factor.     

Synthesis,Crystal Structure,Fluorescent Property and DFT Calculations of a New Zn(Ⅱ) Complex Based on 3-(2-Pyridyl)-5-(4-pyridyl)-1H-1,2,4-triazole

A new coordination compound Zn(2,4?-bpt)2(H_2O)(1) based on the versatile ligand 2,4?-Hbpt(2,4?-Hbpt = 3-(2-pyridyl)-5-(4-pyridyl)-1H-1,2,4-triazole) was prepared by hydrothermal reactions. The structure of complex 1 has been characterized by X-ray single-crystal diffraction, elemental analysis, X-ray powder diffraction, IR spectrum analysis and thermogravimetric analysis. Single-crystal X-ray diffraction analysis indicates that the complex belongs to monoclinic system, space group C2/c with a = 23.877(3), b = 0.7483(9), c = 1.2492(2) ?, b = 92.681(2)°, V = 2230.6(4) ?3, Z = 4, Dc = 1.572 g/cm~3, m = 1.143 mm~(-1), Mr = 527.85 and F(000) = 1080. The final R = 0.0581 and w R = 0.0898 with I 2s(I). 1 is a 0D motif which is connected by hydrogen bonds to form a corrugated 1D pattern. In addition, 1 shows strong photoluminescent emissions in the solid state at room temperature which can be used as potential optical materials. Theoretical calculations based on density functional theory(DFT) were employed in order to explicate the stability and chemical reactivity of 2,4?-Hbpt with different conformations. The results indicated that conformation I is more stable and prior to coordination in the reactions.     

Dy(OTf)3 Catalyzed Reaction of Indole with Aldehydes and Ketones in Ionic Liquids

The use of environmentally benign reaction media is very important in view of today' s environmentally con scious attitude. In connect with this, room temperature ionic liquids that are air and moisture stable have received a good deal of attention in recent years as novel solvent systems for organic synthesis. A number of reactions such as Friedel-Crafts reactions, Diels-Alder cycloadditions, hydrogenations, and Heck reactions have employed ionic liquids as solvents. Among them, the Friedel-Crafts reaction[1] is of great synthetic significance in view of laboratory synthesis and industrial production. Recent studies showed that Friedel-Crafts reaction of indole with carbonyl compounds proceeded readily in aqueous media. [2] However, the aqueous reactions suffer from some common problems,such as tedious work-up, reuse of catalyst and so on.     

CFD modeling of reaction and mass transfer through a single pellet: Catalytic oxidative coupling of methane

In this study a mathematical model of a small scale single pellet for the oxidative coupling of methane(OCM)over titanite pervoskite is developed.The method is based on a computational fluid dynamics(CFD)code which known as Fluent may be adopted to model the reactions that take place inside the porous catalyst pellet.The steady state single pellet model is coupled with a kinetic model and the intra-pellet concentration profiles of species are provided.Subsequent to achieving this goal,a nonlinear reaction network consisting of nine catalytic reactions and one gas phase reaction as an external program is successfully implemented to CFD-code as a reaction term in solving the equations.This study is based on the experimental design which is conducted in a differential reactor with a Sn/BaTiO3 catalyst(7-8 mesh) at atmospheric pressure,GHSV of 12000 h-1,ratio of methane to oxygen of 2,and three different temperatures of 1023,1048 and 1073 K.The modeling results such as selectivity and conversion at the pellet exit are in good agreement with the experimental data.Therefore,it is suggested that to achieve high yield in OCM process the modeling of the single pellet should be considered as the heart of catalytic fixed bed reactor.     

Synthesis, Crystal Structure, UV-vis and EPR Studies of（ NH3CH2CH2NH2 ） 2.5 [ Mo0.5^（V）W0.5^（VI）O2 （ OC6H4O ） 2]

Cis-dioxo-metal complex ( NH3CH2CH2NH2 ) 2.5 [ Mo0.5^(V)W0.5^(VI)O2 ( OC6H4O ) 2] 1 was obtained by the reaction of tetra-butyl ammonium hexamolybdotungstate with 1, 2-dihydroxybenzene in the mixed solvent of CH3OH, CH3CN and ethylenediamine,and characterized by X-ray diffraction, UV-vis and EPR analysis. Compared with its analogous complexes (NH3CH2CH2NH2)3[Mo^(V)O2(OC6H40)2] 2 and (NH3CH2CH2NH2)2[W^(VI)O2(OC6H4O)2] 3, the results show that tungsten(VI) is less active in redox than molybdenum (VI) and that the change of the valence induced by substitution of W(VI) for Mo(V) in EMO2(OC6H40)2]n- does not influence the coordination geometry of the complex anion in which the metal center exhibits distorted octahedral coordination with cis-dioxo catechol. The responses to EPR of complexes 1 and 2 are active but complex 3 is silent,and the UV-vis spectra exhibited by the three complexes are obvious different because of the different electronic configuration between the central Mo(V) and W(VI) ions in the complexes.It is noteworthy that complexes 1 and 2 have the similar EPR signal to flavoenzyme, suggesting that the three complexes have the same coordination geometry feature with the co-factor of flavoenzyme.     

Boosting the Energy Density of Flexible Asymmetric Supercapacitor with Three Dimensional Fe2O3 Composite Brush Anode

Flexible asymmetric supercapacitor is fabricated with three dimensional(3D)Fe2O3/Ni(OH)2 composite brush anode and Ni(OH)2/MoO2 honeycomb cathode.Particularly for 3D composite brush anode,a layer of thin Fe2O3 film is firmly adhered on a 3D Ni brush current collector with the assist of Ni(OH)2,functioning as both adherence layer and pseudocapacitive active material.The unique 3D Ni brush current collector possesses large surface area and stretching architecture,which facilitate to achieve the composite anode with high gravimetric capacitance of 2158 F/g.In terms of cathode,Ni(OH)2 and MoO2 have a synergistic effect to improve the specific capacitance,and the resulting Ni(OH)2/MoO2 honeycomb cathode shows a very high gravimetric capacitance up to 3264 F/g.The asymmetric supercapacitor(ASC)has balanced cathode and anode,and exhibits an ultrahigh gravimetric capacitance of 1427 F/g and an energy density of 476 W·h/kg.The energy density of ASC is 3-4 times higher than those of other reported aqueous electrolyte-based supercapacitors and even comparable to that of commercial lithium ion batteries.The device also shows marginal capacitance degradation after 1000 cycles'bending test,demonstrating its potency in the application of flexible energy storage devices.     

The Reactivity of 2,4,6-Tirphenylpyridinium Ylids

Nitrogen ylids1,2 are reactive species which are not studied as vastly as phosphorus or sulfur ylids3. We have been studying the chemistry of pyridinium ylids and in a previous paper4, we reported the generation of ylid 2 via decarboxylation of pyridinium betaine 1 and then studied the reaction with certain electrophile. In this work, we wish to report other type of reactions that observed and the reactivity of 2. a: R = H b: R = CH312- CO2refluxScheme 13a: A = EtOH b: A = PhCHOc…     

Electrochemical Oxidation of Ammonia on Ir Anode in Potential Fixed Electrochemical Sensor

Ir catalyst possesses a good electrocatalytic activity and selectivity for the oxidation of NH3 and/or NH4OH at Ir anode in the potential fixed electrochemical sensor with the neutral solution. Owing to the same electrochemical behavior of NH3 and NH4OH in a NaClO4 solution, NH4OH can be used instead of NH3 for the experimental convenience. It was found that the potential of the oxidation peak of NH4OH at the Ir/GC electrode in NaClO4 solutions is at about 0.85 V, and the current density of the oxidation peak of NH4OH is linearly proportional to the concentration of NHaOH. The electrocatalytic oxidation of NH4OH is diffusion-controlled. Especially, Ir has no electrocatalytic activity for the CO oxidation, illustrating that CO does not interfere in the measurement of NH4OH and the potential fixed electrochemical NH3 sensor with the neutral solution, and the anodic Ir catalyst possesses a good selectivity. Therefore, Ir may have practical application in the potential fixed electrochemical NH3 sensor with the neutral solution.     

CRYSTAL STRUCTURE OF N, N'''' -BIS ( 2-METHOXY-1-NAPH-THYLMETHYL)-4,13-DIAZA-18-CROWN-6 POTASSIUM IODIDE

<正> Crystal of N , N'-bis(2-methoxy-l-naphthylmethyl)-4,13-diaza-18-crown-6 potassium iodide diethanol solvate[(C36H46N2O6)K]+I- · 2C2H5OH (Mr = 860. 47) is orthorhombic with space group Pcab, a = 17. 531(5), 6 = 21. 149(8), c = 23. 060(4)(?). F=8550. 00(?)3, Z = 8, F(000) = 3167. 64 and Dc=1. 337g/ cm3, μ = 8. 74cm-1, R = 0. 057. In the title complex, the donor atoms of the macro-ring are arranged in a twisted boat conformation. The potassium ion is octa-coordi-nated with four oxygen and two nitrogen atoms of the macro-ring and two oxygen atoms of the two side arms at the same side to form a distorted hexagonal bipyramid.     

DFT Investigation on the Insertion Reaction of an Isocyanide into the（Silyl）（silylene）molybdenum Si-C Bond

The chemistry of silylene-transition-metal complexes LnM(=SiR2)SiR3 is one of the attractive synthetic targets in organometallic chemistry for such complexes are key intermediates in many transition metal-catalyzed systems.In the present work,the novel insertion reactions of an isocyanide into the Cp*Mo(CO)2(=SiMe2)(SiMe3) Si-C bond were investigated extensively by using the DFT method.The effective core potentials(ECP) with a double-ζ valence basis set(LanL2DZ) were employed for Mo and Si and the standard 6-31G basis set for all other atoms.Polarization functions[22] were added for Si(ζd = 0.262),C(ζd = 0.8) and N(ζd = 0.8).The effect of solvent was evaluated with the standard PCM model.Our calculations show that the two-step channel is energetically favorable,and the solvation mode has minor influence on the relative energies.     

Photochemical behaviour of halophenols in aqueous solution

The mechanism of photolysis by direct absorption of chloro-, bromo-and fluorophenols (XPhOH with X=Cl, Br or F) is much more dependent on the position of the halogen than on its nature. In all cases, the first step is a heterolytic C-X scission with release of the halogenated acid HX. 3-XPhOH is almost specifically converted into resorcinol. The anionic form of 2-XPhOH is transformed with a rather high quantum yield into cyclopentadiene carboxylic acids. By nanosecond laser-flash photolysis the first transient detected is a ketene which is converted into fulvene-6, 6 diol and then into the cyclopentadiene carboxylic acids. The phototransformation is about 10 times less efficient from the neutral form and not so specific. The irradiation of 4-XPhOH leads to the formation of a carbene which is the first detected transient. According to the experimental conditions, this transient reacts with oxygen producing a benzoquinone-O-oxide and subsequentlyp-benzoquinone, with water leading to hydroquinone or with another molecule of halophenol producing a halogenodihydroxybiphenyl. It was also observed that 4-chlororesorcinol behaves as both 4-ClPhOH and 2-ClPhOH. Chlorohydroquinone does not react as monohalophenols, the main photoproducts are hydroquinone and chlorobenzoquinone. This reaction is consistent with a radical mechanism. The transformation of halophenols can be sensitized by phenol and in most cases by hydroquinone. The half-life of the triplet state of hydroquinone was evaluated at 0.9μs and the intersystem crossing yield at 0.39. The sensitization of 3-FPhOH was observed with phenol but not with hydroquinone leading to the conclusion that the energy level of its triplet state lies in the range 310–350 kJ mol⁻¹. It is lower than 310 kJ for the other halophenols studied here.     

The preparation, structure and spectra properties of dual μ3-oxo bridged tetranuclear complexes containing the [CrnFe4-nO2]8+ core(n=0,2,4)

The preparation and characterization of [CrnFe4-nO2(O2CMe)7(bipy)2]Cl (1, n=0; 2, n=2; 3, n=4, bipy=2,2'-bipyridine) are described. The three complexes (1, 2 and 3) are obtained by tipyridine-mediated conversion of trinuclear [CrnFe3-nO(O2CMe)6(H2O)3]+(1, n=0; 2, n=1;3, n=3), and crystallized as three of approximate isomorphs. Crystal 2 is monoclinic with space group C2/c, a=27.454(5)A, b=11.789(1)A, c=16.570(3)A, B=118.78(1), V=4700.8A, z=4, u(MoKa)=11.64cm-1, F(000)=2056, final R=0.058 and Rw=0.066 for 3479 reflections with I > 3o(I). The Fe and Cr atoms in the cation are all +3 oxide state and disordered in the lattice, which is also supported by its Mossbauer studies. The [Cr2Fe2O2]8+ core can be thought of as being derived from two edge-sharing M3O units (M=Fe or Cr), and as a butterfly-like structure. The cations' structure of all three crystals are similar to each other and have C2 symmetry. The species are characterized by IR spectra and magnetic techniques, with particular emphasis on different     

DFT Study of Oxygenated Organic Pollutants Catalyzed by Molybdenum Oxides: Comparison of Reaction Mechanisms of MoO_x + HCHO(x = 1, 2, 3)

The reaction mechanisms between formaldehyde and MoO_x(x = 1, 2, 3) have been studied thoroughly in this paper. Five reaction pathways were found in three reactions(reactions Ⅰ to Ⅲ) through studying the mechanisms of MoO_x(x = 1, 2, 3) catalyzing formaldehyde. Different products were obtained from three reactions. Of all three reactions, the barrier energy of Route ⅡA is the lowest(4.70 kcal/mol), which means in MoO_x(x = 1, 2, 3), MoO_2 has the best catalytic effect. Compared with other similar non-toxic treatments of formaldehyde, our barrier energy is the lowest. In this research, there was no good leaving group of the compound, so the mechanisms are addition reaction. We speculate that there must be an addition reaction to the more complex reactions to molybdenum oxides and aldehydes. As a chemical reagent for removing formaldehyde, it only absorbs formaldehyde and does not emit other toxic substances outward. Molybdenum oxides retain its original structures of the final products, which means it has excellent stability in the reaction of MoO_x(x = 1, 2, 3) + HCHO. The mechanisms of all three reactions are addition reactions, but they are entirely different. As the number of oxygen atoms increases, the reaction mechanisms become simpler.     

Mass Spectrometric Studies on Metal-hexafluorobenzene Anionic Complexes（M=Ag, Au, Pd, Pt, Pb and Bi）

The anionic products from the reactions between metal(M=Ag, Au, Pd, Pt, Pb and Bi) vapour produced by laser ablation and hexafluorobenzene seeded in carrier gas(Ar) were studied by means of a homemade reflectron time-of-flight mass spectrometry(RTOF-MS). Experimental results show that the dominant products were [MmC6F6]-complexes for the reactions of Ag, Au, Pd and Pt with C6F6, while the dominant products were [MmC6F5]-complexes for the reactions of Pb and Bi with C6F6. The formation mechanisms of the prod...