bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structures and isomerizations of carbenoids H2CCCLiX (X  F, Cl)
Authors: Bing‐Ze Wang , Cong‐Hao Deng 
Published: April 2011

AbstractNovel structures of H2CCCLiX (X  F, Cl) were determined using HF/STO‐3G gradient method. Both of the carbenoids have two equilibrium structures, askew and linear forms, at the level of calculation. In the case XF, the former is more stable, but in the case X=Cl, the latter is more stable. The frontier MOs are given and analyzed.
Mechanisms of ring contraction, C—H insertion and 1,2‐hydrogen migration of cyclobutylidene
Authors: Bing‐Ze Wang , Cong‐Hao Deng 
Published: April 2011

AbstractIsomerizations of cyclobutylidene 1 to methylenecyclopropane 2, cyclobutene 3 and bicyclobutane 4 have been studied using ab initio method. Equilibrium and transition structures are fully optimized with 3–21G basis set. The reaction barriers are 78, 75 and 110 kJ/mol at 6–31 G**, respectively, 1→2 occurs via the outward disrotation of two end C‐C bonds, 1→3 via the attack of an exo hydrogen to the carbene p AO before the transition state, and 1→4 is unable to compete with 1→2 and 1→3 for its higher barrier.
Theoretical calculation of the singlet‐triplet electronic transition and photochemical reactivity in carbonyl fluoride, trifluoroacetyl fluoride and perfluoromethyl perfluoroacetate
Authors: Ottavianelli E. , Castro E. A. , Jubert A. H. 
Published: April 2011

AbstractMolecular properties following electronic excitation were studied and calculations were performed for the singlet‐triplet electronic transitions of carbonyl fluoride, perfluoroacetyl fluoride and perfluoromethyl perfluoroacetate by means of the CNDO/S‐CI method. Various approximations were used to evaluate the core Hamiltonian matrix elements.
Studies on organo‐phosphorus, ‐arsonic, and ‐antimony polytungstates and polymolybdates: VI. A new guanidinium hexamolybdobisphenylarsonate monohydrate (CN3H6)5 [(C6H5As)2Mo6O25H]·H2O
Authors: Ben‐Yao Liu , Yih‐Tong (Gu, Yi‐Dong) Ku , Ming Wang , Pei‐Ju Zheng 
Published: April 2011

AbstractA new guanidinium hexamolybdobisphenylarsonate which is quite different from that reported in literature has been synthesized and characterized. This new salt which is isostructural with its tungsten congener crystallized as monoclinic, space group P21/a with cell dimensions of a=15.005 (1), b = 17.559(1), c = 18.008(2) Å, β = 97.24(1)°. Its elemental analyses, IR and UV spectra have been reported and discussed. Its thermal properties and electrochemical behavior have also been reported.
Stability of ternary amino acid complexes and its computer simulation under physiological conditions
Authors: Zhong‐Xian Huang , Xiao‐Yin Dai , Xiao Hua , Xu Chang 
Published: April 2011

AbstractThe binary and ternary formation constants of mixed amino acid complexes with Zn(II), Cu(II), Ni(II) and Cd(II) have been potentiometrically determined under physiological conditions. The symbiosis of HSAB does play a role in the formation of ternary amino acid complexes. Comparing with Zn(II), as a softer Lewis acid Ni(II) shows its preference to softer Lewis bases cysteinate and histidinate. These soft Lewis bases more likely gather together in the mixed amino acid complexes. It is expected that the ternary amino acid complexes are overwhelming in the distribution of complex species especially at biological conditions. In the case of zinc, differring from previous study the alaninate‐containing mixed complexes become the predominant species formed in the region of pH 7.4.
The formation and properties of glass in the ZrF4‐BaF2‐ThF4 system
Authors: Ke‐Li Zhang , You‐Lan Xia , Zhen‐Duo Li , Qi‐Hua Yuan 
Published: April 2011

AbstractThe formation and properties of fluoride glasses in the ZrF4‐BaF2‐ThF4 system were examined. The limits of the glassforming region were defined. A series of new quaternary glasses ZrF4‐BaF2‐ThF4‐MFx (x = 1, 2, 3, and M = Li, Na, Ca, Sr, Zn, Cd, Pb, Al, Y, La, Gd) were obtained. The ultraviolet‐visible and infrared transmission spectra, characteristic temperatures, refractive indices and densities for the fluoride glasses were determined. Glass in the quaternary systems was more stable than that in ternary system. These glasses were promising materials for infrared transmission, because of their good optical qualities and stability against devitrification.
Preparation and photochromism of piperidine decatungstate
Authors: Song Yuan , Huang Qin , Yih‐Tong (Gu, Yi‐Dong) Ku 
Published: April 2011

AbstractA new photochromic compound, piperidine decatungstate (PiPdDT), (C5H10NH2)4W10O32 was prepared; its TG curve, UV and IR spectra were studied. On exposure to UV light, both its crystal and aqueous solution turn blue with absorption spectra appearing at 756 and 720–742 nm. The ESR signal, recorded at 100 K on a frozen solution of PiPdDT in water after exposure to UV light, centered around g = 1.839. The fading rate constant after exposure to UV light, is k = 7.9 × 10−4s−1, and its quantum yield was determined as ϕw(v) = 22.2, which is higher than the values yet reported for polytungstates in literature.
Synthesis, crystal structure of Z‐1,2‐dimethyl‐1,2‐bis‐(m‐ferrocenyl‐phenyl)ethene
Authors: Xiu‐Ren Bu , Xiao‐Zeng You , Qing‐Jin Meng , Man‐Fang Wang 
Published: April 2011

AbstractThe binuclear ferrocene derivative, Z‐1, 2‐dimethyl‐1, 2‐bis (m‐ferrocenylphenyl)e hene (Z‐DDFP) has been isolated from the mixture of the coupling reaction of m‐ferrocenylacetophenone (m‐FAP) by the low‐valent titanium salts obtained from zinc/titanium tetrachloride in THF. The single crystal X‐ray structure of the complex as benzene solvate has been determined and found to be triclinic with cell constants a=7.748(5), b=10.600(7), c=18.550(4)Å, α=97.565(5)°, β=98.551(8)°, γ=90.318(8)° and V=1494.2Å3. The structure was refined by [least‐squares method for 5151 independent reflections with I>3σ(I) to a final R=0.0363 and Rw=0.0523. The two cyclopentadienyl rings in each ferrocenyl unit are approximately parallel. The two phenyl rings are significantly twisted by 66.80° from each other in the stable configuration. Both the ferrocenyl units on the same side of the C=C double bond are not co‐planar with a mean dihedral angle of 96.28°. The structural analysis shows that the chain linking two central iron atoms is about 18Å, significantly close to those found in some biological models.
The chemical characterization of the cephalic secretion of the Australian colletid bee, Hylaeus albonitens (Gnathoprosop's Cockerell)
Authors: Zheng‐Ming Li , Batra S. W. T. , Plimmer J. R. 
Published: April 2011

AbstractThe cephalic extract of Australian colletid bee, Hylaeus albonitens, comprises 10 components: linalool, citronellal, neral, geranial, nerolic acid, geranic acid, heptadecane, pentacosane, Z,Z‐ and E,E‐9,12‐octadecadienoic acid. Quantification of these major components suggested it to be an aggregation pheromone composition. The fairly large amounts of 9,12‐octadecadienoic acids have not been reported before in the cephalic extract of bees. The chromatographic pattern is quite different from the previous reports on the constituents of mandibular glands of American Hylaeus modestus and the related European and North American Colletes bees.
Product distribution of the reaction of unsymmetrical β‐diketones with hydroxylamine hydrochloride
Authors: Ben‐Li Zhang , Jin‐Cong Zhuo , Zhen‐Heng Gao 
Published: April 2011

AbstractTwo series of unsymmetrical β‐diketones (1‐aryl‐3‐tolylpropane‐1, 3‐diones and 1‐alkylbutane‐1, 3‐diones) were synthesized and treated with hydroxylamine hydrochloride. The product distributions of the reactions were studied based on 1H NMR data. The systematical influence of the substituents on the structures of the products is discussed.
Studies on sulfinato‐dehalogenation: XI. Sodium dithionite‐initiated perfluoroalkylation of electron‐rich aromatic
Authors: Wei‐Yuan Huang , Wu‐Ping Ma , Wei Wang 
Published: April 2011

AbstractThe intermediary perfluoroalkyl radical generated from the reaction of perfluoroalkyl iodide with sodium dithionite was shown to be reactive toward phenols and aromatic amines, and resulted in the formation of a mixture of ortho‐ and para‐substituted products. Thus, the reaction provides a new method for the synthesis of ortho‐ and para‐perfluoroalkyl substituted phenols and anilines.
Sensitized photooxygenation: IV. Synthesis and singlet oxygenation of ethyl 6‐ethyl‐3, 4‐dihydro‐2H‐pyran‐5‐carboxylate and ethyl 6‐isopropyl‐3, 4‐dihydro‐2H‐pyran‐5‐carboxylate
Authors: Ze‐En Huang , Xiao‐Guang (Hiu‐Kwong Leung) Liang , Leung Hiu‐Kwong , Yuk‐Yee Chan 
Published: April 2011

AbstractTitle compound 2b and 2c were synthesized via the condensation of 1, 3‐dibromopropane with the appropriate β‐keto ester under mildly basic condition. Photooxygenation of them under singlet oxygenation condition gives two kinds of product, namely, dioxetane‐product and ene‐product, with polar solvents, favoring the formation of the former. Comparison of the present study with that of the 6‐methyl substrate 2a indicates that the effect of steric hindrance at the 6‐position is significant, but not in a simple linear relationship to the reaction.
Theoretical study on the isomerization reaction of fluorine substituted disilene
Authors: Ju Guan‐Zhi , Ma Wan‐Yong , Christoffel Kurt 
Published: April 2011

AbstractFor the isomerization reaction of monofluoro‐disilene, the geometrical structures of reactant, product and transition state have been optimized and energy constant, vibrational frequency calculated. By means of the statistical thermodynamics and Eyring's transition state theory, the equilibrium constant, rate constant and heat of isomerization have also been computed. Hence, this reaction has been analysed completely.
INDO/GIAO calculations of 13C, 15N and 17O NMR chemical shifts in some organo‐iron complexes
Authors: Wu Wei‐Xiong , Cao Yang , You Xiao‐Zeng , Dai An‐Bang 
Published: April 2011

AbstractIn this paper, INDO perturbation theory has been extended to calculate the NMR chemical shifts of transition metal compounds. The nitrogen and oxygen INDO parameters have been refined by using a set of nitrogen and oxygen containing compounds to minimize the differences between calculated and experimental 13C, 15N, and 17O shielding constants. These refined parameters, together with optimally selected iron INDO parameters, were used to evaluate the 13C chemical shifts of three iron complexes (C5H5)Fe(CO)2CN, (C5H4CHO)2Fe2, and (C5H4CH2OH)2Fe. The calculated 13C, 15N and 17O shielding constants were fairly in agreement with experimental results. In addition, a good linear relationship between the calculated [diamagnetic shielding constants σd(M) of 13C, 15N and 17O nuclei and the net charge ρ (M) of these atoms was noticed.
Catalyt properties of tungsten oxycarbide and carbide in hydrocarbon conversion
Authors: Gao Zi , Qin Dai‐Yi 
Published: April 2011

AbstractTungsten oxycarbide with specific surface area ⋍ 24 m2/g was prepared from white tungstic acid by reduction and carburization with CO and H2. XRD and EXAFS measurements confirmed that the WOC obtained has a simple hexagonal structure isotypic with α‐WC and the oxygen is inserted into the trigonal prismatic interstices of the crystal lattice. The reactions of n‐hexane, n‐heptane and cyclohexane on WOC were studied and compared with WC prepared by direct synthesis at high temperature. WOC and WC are active for the hydrogenolysis, isomerization and dehydrocyclization of alkanes and dehydrogenation of cyclohexane and their catalytic properties are in many ways similar to Pt catalysts. Oxygen insertion inhibits the catalytic activities of tungsten carbide for hydrocarbon conversion reactions probably due to electronic effect.
Theoretical studies on silathione and its unimolecular reactions
Authors: Han Yun‐Zhu , Zhao Cheng‐Da 
Published: April 2011

AbstractThe unimolecular reactions of silathione: (a) dehydrogenation, (b) trans‐isomerization, (c) cis‐isomerization, are investigated by ab initio MO calculations using RHF/4‐31G basis set. The geometries and energies of the reactant, transition states and products have been determined on the singlet potential energy surface of the ground state. The reaction ergodography along the intrinsic reaction coordinate (IRC) for the three reactions has also been performed.
Reaction ergodography for the 1,2‐H shift and inversion processes of amino‐carbene
Authors: Chen Bin , Zhao Cheng‐Da , Fu Qiang 
Published: April 2011

AbstractThe ab initio calculations have been performed on the reaction paths of 1,2‐H shift and inversion processes of amino‐carbene molecule by the Intrinsic Reaction Coordinate (IRC) method. We have determined the equilibrium geometries and energies of the reactant, transition state and product, and obtained the activation energies, reaction heats, frequency factors and the activation entropies of these two reaction processes. The vibrational correlation from reactant to transition state indicated that the IRCs of 1,2‐H shift and inversion processes were associated with the deformation modes of 1540 and 1208 cm−1, respectively. The vibrational coupling between normal coordinates in the inversion process would be helpful for selecting the inversion reaction channel.
The essential aspect and regular pattern of ion transfer across the liquid‐liquid interface
Authors: Wang Er‐Kang , Sun Zhi‐Sheng 
Published: April 2011

AbstractThree empirical rules of interfacial potential and Gibb's energy with the radius, charge number of transfer ions and dielectric constant of organic phase are obtained for the ion transfer across the liquid‐liquid interface, which are verified by the transfer of simple anions, dye ions and metal ions facilitated by neutral ionophores across the interface between water and some organic solvents, and deduced theoretically based on the electrostatic interaction of ion and high‐permittivity solvent. The rules are proved to be effective of choosing supporting electrolytes and searching for new transfer system which follows the rule that r/n of transfer ion should be larger than that of electrolytes ion in water phase and less than that in organic phase. A rule for judgement of the charge sign of transfer ion is suggested firstly based on the relationship between interfacial half‐wave potential and dielectric constant of organic phase.
An investigation of chemically deposited Ni‐P alloys by EXAFS and XRD
Authors: Ma Li‐Dun , Lü Gang , Shen Xiao‐Liang 
Published: April 2011

AbstractFive samples of chemically desposited Ni‐P amorphous alloys were prepared and investigated. In these amorphous alloys there are Ni‐P atom groups in which phosphorus and nickel are connected with strong interaction. Nickel atoms and Ni‐P groups are deposited in a random manner on the surface of matrix and a quasilayer structure is formed. The spacing between two layers in alloys resembles that in (111) plane in the nickel crystal. Therefore there is a peak at the same position of 2θ=44.4° as that of the (111) reflection of crystalline nickel in the X‐ray powder diffraction pattern of alloys. However, the dimension of Ni‐P groups is different from that of a nickel atom and the atomic arrangement in the layer is in disorder. These result in the space change and there is a distribution of spacing around the average. As a consequence of distribution of spacings, the peak at 2θ=44.4° is broadened and enhanced as the amount of P increases.
Assignment of the non‐exchangeable proton resonances and conformational analysis of oligonucleotide DNA d(TTGGGGTT) by two‐dimensional nuclear magnetic resonance methods;
Authors: Dong Yan‐Hong , Tang Wen‐Xia , Dai An‐Bang , Wu Jia‐Zhen , Boom J. H. , Reedijk J. , Struik A. F. 
Published: April 2011

AbstractTwo‐dimensional NMR study on the single‐stranded octadeoxynucleotide, d(TT‐GGGGTT) is presented. Assignments of the base protons, the H1′, H2′ and H2″ protons were made by two‐dimensional Nuclear Overhauser Enhancement Spectroscopy (NOESY) and two‐dimensional homonuclear J‐correlated Spectroscopy (COSY). The result indicates that the overall structure of the single‐stranded d (TTGGGGTT) is a right‐handed B‐type helix.
Studies on the primary structure of chicken apolipoprotein A‐I using HPLC technique
Authors: Gu Zi‐Wei , Weng Shi‐Ai , Kim T. W. , Yang Chao‐Yuh 
Published: April 2011

AbstractThe complete amino acid sequence of chicken plasma apolipoprotein (apo) A‐I was determined by sequencing overlapping peptide fragments produced by trypsin, S. aureus V8 protease, and cyanogen bromide cleavage respectively. All of the peptide fragments were purified on a Waters or on a Beckman HPLC system with a Vydac C18 column using 0.1% TFA in water as buffer A, and 0.08% TFA in 95% acetonitrile and 5% water as buffer B. Most of the peaks separated by these systems were pure. The partially purified fractions were subjected to rechromatography with a Hypersil ODS column using 0.005M sodium phosphate, pH 6.0, as buffer A, and 90% acetonitrile and 10% water as buffer B. The N‐terminus of chicken apo A‐I was determined to be aspartic acid by directly sequencing the intact protein up to 30 residues, while the C‐terminus was identified as alanine by carboxypeptidase Y cleavage. There are 240 amino acid residues in mature chicken apo A‐I. By direct analysis of cyanogen bromide peptide, we also determined the sequence of a 6 amino acid prosegment, which is present at approximately 10% of the molar amount of the mature protein in chicken plasma.
Studies on the reaction of cupric(II) perfluoroalkanesulfinate
Authors: Huang Wei‐Yuan , Xie Yuan 
Published: April 2011

AbstractReaction of aqueous solution of sodium perfluoroalkanesulfinate with cupric sulphate gave a high yield of cupric perfluoroalkanesulfinate, which decomposed slowly in the air on exposure to light to give perfluorocarboxylic acid. The reaction between cupric perfluoroalkanesulfinate and olefins in the presence of potassium iodide and excess CuSO4 in ether at low temperature (‐30 to‐20°C) formed two kinds of adducts, namely the normal adducts, Rf SO2CH2CHIR(2) and the adducts resulting from the loss of SO2 moiety, Rf CH2CHIR(3) in yields ranging from morderate to good. These results were identical with that of the addition of perfluoroalkanesulfonyl iodide to olefins. A radical reaction mechanism is proposed.
The Wittig sigmatropic rearrangement in a conjugated diene system I
Authors: Li Zheng‐Ming , Wang Tian‐Sheng , Yao En‐Yun , Gao Zheng‐Heng 
Published: April 2011

AbstractA conjugated dienic benzyl ether was shown to undergo Wittig sigmatropic rearrangement to give a mixture of [1,2] and [1,4] besides the expected [2,3] rearrangement product. The solvent effect as well as the reaction pathways were discussed.
The crystal structure of a new gossypol derivative: — 8,8′‐Dibromo‐6,6′,7,7′‐tetramethoxy‐5,5′‐diisopropyl‐3,3′‐ oxydimethylene dinaphtho[2,1‐b:2′,1′‐d]furan
Authors: Gui‐Dong Zhu , De‐Hua Chen , Jian‐Hua Huang , Ching‐Sung Chi , Jun Dong , Min‐Qin Chen , Pei‐Ju Zheng 
Published: April 2011

Abstract8,8′‐Dibromo‐6,6′, 7,7′‐tetramethoxy‐5,5′‐diisopropyl‐3,3′‐oxydimethylene dinaphtho[2,1‐b:2′, 1′‐dlfuran, C32H30Br2*; M.W. = 670; triclinic; space group P1; a = 8.896(2), b = 10.216(1), c = 10.423(1)Å, a = 108.48(1), β = 119.36(1); γ = 99.26(1); V = 723.5 Å3; Z = 1, Dcal. = 1.479 g.cm−3. Mo Kα = 28.11 cm−1, F(000) = 326, T = 293 K. The structure was solved by direct method and full‐matrix least‐squares refinement converged at R = 0.034 for 2377 observed reflections. The oxygen atom in seven‐membered ring exists in a disordered arrangement. Both bisnaphthalene and oxygen‐containing five‐membered ring have planar conformations with dihedral angle 6*, showing marked aromatic feature.
XPS study of tungsten carbide
Authors: Dai‐Yi Qin , Zi Gao 
Published: April 2011

AbstractThe surface composition and electronic structure of tungsten carbides prepared by direct synthesis and carburization of white tungstic acid were studied with X‐ray photoelectron spectroscopy. The experimental results show that WO3 and free carbon are present on the surface of the carbides. For the high surface area tungsten carbide prepared from white tungstic acid a large extent of oxygen insertion into the crystal lattice was observed. Measurements of the binding energies of the W4f7 2, C1S and O18 core levels indicate that charge transfer is from the W to the C and O atoms, forming W5d‐C3p and W5d‐O2p bonding. The catalytic behavior of the tungsten carbides in hydrocarbon conversion reactions is mentioned and compared with Pt catalysts.
Infrared multiphoton dissociation of acetic anhydride: Experimental study
Authors: Tian‐Xiang Xiang 
Published: April 2011

AbstractThe infrared multi‐photon dissociation (IRMPD) of acetic anhydride to generate state‐selected CH2 has been investigated by using time and wavelength resolved fluorescence techniques. It has been observed that the generation of the nascent ground state CH2 (a1A1) is delayed by about 0.6 μ relative to the onset time of the excited CH2 (b1B1). The relative population of the ground and excited state CH2 and the onset time for the appearance of the ground state CH2 have been found to depend strongly on CO2 laser output fluences. These results appear to have a strong bearing on the structure of the potential energy surfaces of the intermediate CH2CO. A possible photolysis mechanism is proposed to explain these experimental results.
The determination of the crystal structure of tetrapotassium uranyl tricarbonate by powder X‐ray diffraction method
Authors: Jian‐Cheng Han , Suo‐Bao Rong , Qi‐Ming Chen , Xin‐Ran Wu 
Published: April 2011

AbstractA uranyl compound, K4UO2(CO3)3 has been characterized by powder X‐ray diffraction method. M.W. = 606.46, monoclinic, C2/c (No. 15), a = 1.0240(7), b = 0.9198(4), c = 1.2222(12) nm, β = 95.12 (4)°, V = 1.1466(5) nm3, Z = 4, D = 3.468 g/cm3, Dc = 3.513 g/cm, λ(Cu Ka1) = 0.1540598nm, T = 298K. The structure was solved by heavy atom method and Fourier synthesis, and refined by full‐matrix least‐squares method to R = 0.1185 for 275 reflections. The uranium (VI) atom is in an eight‐coordinate distorted hexagonal‐bipyramidal environment with creasy fan shape. The linear uranyl group approaches to perpendicular to the equatorial plane in which three carbonate groups are chelated. U(VI) has two linear oxygen atoms closer to it (U]—0 = 0.1767 (5) nm) than six other neighbours (U—O ranging from 0.2516 to 0.2568 nm). The distances between carbon atoms and uncoordinated oxygen atoms are 0.122 (1) and 0.123(1) nm, which are distinctly different from those between carbon and coordinated oxygen atoms (mean 0.134(6) nm). This fact reveals the non‐equivalence of one oxygen atom to the other two in each carbonate. In K4UO2(CO3)3, the O—O distance for the adjacent carbonate groups is 0.2794(4)nm approaching to the sum of Van der Waals radii of two oxygen atoms. The K—O distances vary between 0.2667 and 0.3131 nm, and each anion is immediately surrounded by six potassium ions, only four of which can be considered to belong to the same structural formula unit, and they are symmetrically located above and below the equatorial plane.
Effects of heteroatoms on 1,2‐rearrangements of 3‐membered ring carbenes
Authors: Bing‐Ze Wang , Jin‐Ting Liu , Xiao‐Fang Li , Cong‐Hao Deng 
Published: April 2011

Abstract1,2‐rearrangements of carbenes: CCH2X(X = CH2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X = CH8>NH>0. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.