bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics and Mechanism of the Decarbonylation of Benzoylformyl Palladium(II) Complex
Authors: Chen Jwu‐Ting , Liu Chau‐In
Published: June 2015

The benzoylformyl Pd(II) complex, Pd(PPh3)2(Cl)(COCOPh), thermally decomposes to the corresponding benzoyl complex by the loss of CO. The predominant route of decarbonylation is led by a reversible dissociation of a phosphine ligand. The disappearance of the benzoylformyl complex in solutions follows first order kinetics not only in the existence of excess PPh3 but also in the absence of added PPh3. Through the treatments of both preequilibrium and the steady state approximations to the kinetic data, the rate constants of the intramolecular acyl migration, k1 and k2; as well as the equilibrium constant and the individual rate constants of the reversible phosphine dissociation step, K, kd and kd, were determined in CHCl3. The activation parameters for kd, being ΔH‡ = 25.4 Kcal Mol−1, ΔS‡ = 15.9 eu, ΔG‡ = 20.7 Kcal Mol−1;and for k−d, being ΔH‡ = 13.0 Kcal Mol−1, ΔS‡ = −7.9 eu, ΔG‡ = 15.4 Kcal Mol−1, were evaluated.
Kinetic Study of the Reduction of Bromate Ion by Tris(1,10‐Phenanthroline)Iron(II) and Aquoiron(II) Ions — Implication for the Bromate‐Gallic Acid Oscillating Reaction
Authors: Jwo Jing‐Jer , Chang Eng‐Fen
Published: June 2015

The kinetics of the bromate oxidation of tris(1,10‐phenanthroline)iron(II) (Fe(phen)32+) and aquoiron(II) (Fe2+ (aq)) have been studied in aqueous sulfuric acid solutions at μ = 1.0M and with Fe(II) complexes in great excess. The rate laws for both reactions generally can be described as ‐d [Fe(II)]/6dt = d[Br−]/dt = k[Fe(II)] [BrO−3] for [H+]0 = 0.428–1.00M. For [BrO−3]0 = 1.00 × 10−4M. [Fe2+]0 = (0.724–1.45)x 10−2 M, and [H+]0 = 1.00M, k = 3.34 ± 0.37 M−1s−1 at 25°. For [BrO−3]0 = (1.00–1.50) × 10−4M, [Fe2+]0 = 7.24 × 10−3M ([phen]0 = 0.0353M), and [H+]0 = 1.00M, k = (4.40 ± 0.16) × 10−2 M−1s−1 at 25°. Kinetic results suggest that the BrO−3‐Fe2+ reaction proceeds by an inner‐sphere mechanism while the BrO−3‐Fe(phen)32+ reaction by a dissociative mechanism. The implication of these results for the bromate‐gallic acid and other bromate oscillators is also presented.
Structural and Physical Characterization of 1:1 9,9′‐Bifluorenylidene Complex with 7,7,8,8‐Tetracyanoquinodimethane, BFL‐TCNQ
Authors: Lee Jung‐Si , Chen Ing‐Yung
Published: June 2015

The crystal and molecular structure of BFL‐TCNQ has been determined by single‐crystal X‐ray diffraction analysis. The complex crystallizes in the monoclinic space group C2/c, a=17.915(3), b=12.238(3), c=13.531(3) Å, β = 115.16(1)°, and Z=4. The complex has a mixed‐stacked crystal structure in which BFL molecules exist in a twisted conformation and TCNQ molecules are dimensionally similar to uncomplexed TCNQ. The complex is diamagnetic and is an insulator with a room‐temperature conductivity less than 10−9 s cm−1. The FT‐IR spectrum of the BFL‐TCNQ complex reveals that the degree of charge transfer between the two component molecules is essentially null.
The Hybrid Type Natural Orbitals for Excited States
Authors: Chang Tse‐Chiang , Pao Chien‐Hua , Hsue Chen‐Shiung
Published: June 2015

Under certain circumstance, natural orbitals of excited states have quite unusual hybrid behavior, which is drastically different from that of the familiar cononical orbitals, and gives ambiguous results for the one‐electron properties. We show that a simple 2×2 density matrix obtained from a multiconfiguration self‐consistent‐field calculation is sufficient to reveal the NO behavior in this situation.
The Synthesis and Reactions of N‐Hydroxy‐3‐Arylsydnone‐4‐Carboxamide Oximes
Authors: Yeh Mou‐Yung , Chan Fat‐Fong , Tien Hsien‐Ju , Fuchigami Toshio , Nonaka Tsutomu
Published: June 2015

N‐Hydroxy‐3‐arylsydnone‐4‐carboxamide oximes (7) were prepared from the corresponding 3‐arylsydnone‐4‐carbohydroximic acid chlorides (6) and hydroxylamine in high yield. The chemical reactivity of compound (2) is somewhat different from 3‐arylsydnone‐4‐carboxamide oximes (2) in that the former compounds reacted with both aromatic and aliphatic aldehydes in the presence of acid catalyst to give 3‐aryl‐4‐(5‐aryl‐1,2,4‐oxadiazol‐3‐yl)sydnones (5) and 3‐aryl‐4‐(5‐alkyl‐1,2,4‐oxadiazol‐3‐yl)sydnones (3).
Hydrolysis Behaviour of Some Heterocyclic Nitrogen Azomethines
Authors: Adam F. A. , El‐Haty M. T. , Khalafalla A. K. , Gabr A. A.
Published: June 2015

Kinetics of base hydrolysis of some new heterocyclic azomethines derived from aminotriazol and aromatic aldehydes were investigated in the presence of NaOH in 60% (wt/wt) water‐ethanol medium. The base hydrolysis of these Schiff bases is strictly first‐order with respect to OH− and Schiff. The rate‐determining step is suggested to be the attack of the hydroxide ion on the free base. Effect of the molecular structure of both aldehydes and amines and the nature of organic hydroxylic solvent on the hydrolysis rate was investigated and discussed.
Synthesis and Biological Activities of Some New Pyridazine Derivatives
Authors: Seada M. , Fawzy M.M. , Jahine H. , Abd El‐Megid M. , Saad R.R.
Published: June 2015

The reactions of 4‐carboxyhydrazide‐5,6‐diphenyl‐3(2H)‐pyridazinone (I) with aromatic aldehydes, phenyl isothiocyanate, β dicarbonyl compounds, ethyl ethoxymethylenecyanoacetate, ethyl cyanoacetate and acylating agents have been investigated. Oxadiazolines (III) and thiazolidinones (IV) were synthesized from arylidenehydrazides (II) through appropriate routes. The thiosemicarbazide derivative (V) on reaction with malonic acid and acetyl chloride gave VII, and on treatment with monochloroacetic acid and sodium acetate afforded IX. Some reactions with 3‐amino‐4,5‐diphenylpyrazolo [3,4‐b] pyridazine (XIVa) were also reported.
Advanced Methodologies for Sampling and Analysis of Toxic Organic Chemicals in Ambient Outdoor, Indoor, and Personal Respiratory Air
Authors: Lewis Robert G.
Published: June 2015

Many different kinds of sampling devices and analytical techniques are required to assess the potential adverse effects of toxic air pollutants on human health and the ecosystem. The U.S. Environmental Protection Agency has an on‐going research and development program designed to provide the necessary tools to monitor air quality both outdoors and indoors and to measure personal respiratory exposures. Particular emphasis in recent years has been placed on real‐time and integrative methods for neutral and polar volatile organic chemicals (e.g., chlorinated hydrocarbons, single‐ring aromatics, alcohols, aldehydes, ethers, thiols, nitriles) and semi‐volatile organics (e.g., polynuclear aromatics, nitrated aromatics, pesticides, phenols). Samplers capable of obtaining sufficient quantities of chemicals for ultratrace analyses and sometimes bioassay, that are also quiet, unobtrusive and user‐friendly, are being developed and evaluated for indoor, outdoor, and personal monitoring. New analytical techniques such as matrix‐isolation GC/FTIR, and supercritical fluid extraction and chromatography are being adapted to characterize collected samples.
Carbon‐13 Nuclear Magnetic Resonance Spectroscopy Study of the Glucose Stress of Human Lenses
Authors: Camli Ugur , Murray T. , Aguayo J. , Tarantino P. , Hay A. , Stark W. , Kan Lou‐Sing
Published: June 2015

The sorbitol theory in diabetic cataractogenesis was based on sorbitol accumulation under glucose stress. Sorbitol accumulation was examined by 13C nuclear magnetic resonance spectroscopy (NMR) for the first time in matched human lenses incubated in 5.5 mM and 35.5 mM C‐1 13C‐enriched glucose up to 28 hours. The results showed that sorbitol and lactate in human tens can be detected at 35.5 mM, but not in 5.5 mM glucose solution. The glycolysis metabolic pathway of human lenses may be quite different from that of animals. The accumulation of metabolites can be traced and quantified by the intensities of 13C NMR peaks. Therefore, 13C NMR spectroscopy can be used as a valuable tool to investigate human lens carbohydrate metabolism non‐interventionally.
Kinetic Study of the Catalyzed Substitution Reaction of Benzal Chloride and Sodium Iodide in Acetone
Authors: Hsu Ming‐Ching , Jwo Jing‐Jer
Published: June 2015

The substitution reaction of benzal chloride (PhCHCl2) and sodium iodide in acetone needs a metal‐ion catalyst. Without considering the effects of solubility and the dissociation of salt, salts of Cr(III), Mn(II), Fe(II, III), Co(II), Ni(II), Cu(II)m Zn(II), Cd(II), Hg(I, II), and Sb(III) ions are used to study their catalytic reactivities. It is found that the Fe(II) ion exhibits acceptable catalytic effect. The overall Fe(II)‐catalyzed PhCHCl2‐NaI reaction can be described by the following competitive consecutive scheme: PhCHCl2 → PhCHCII → PhCHI2. Under suitable conditions, coupling products such as PhCH=CHPh and PhCHClCHClPh are also found. The rate of the first‐stage substitution of the PhCHCl2‐NaI reaction increases linearly with the PhCHCl2 concentration. It increases asymptotically with the FeCl2 concentration. However, there is an optimum concentration for Nal. The apparent activation energies are 104 ± 4 kJ/mol and 133 ± 4 kJ/mol for the Fe(II)‐catalyzed PhCHCl2‐NaI and PhCHCH‐NaI reactions, respectively.
Studies on the Equilibria of α‐Phthalic and Phosphoric Acids in Mixed Methanol — Water Mixture (50% w/w)
Authors: Azab H. A. , Hassan Ahmed
Published: June 2015

The secondary dissociation constants of α‐phthalic and phosphoric acids have been determined in 50% w/w methanol‐water mixture from the e.m.f measurements of the cell of the type: Pt; H2(1 atm), M2A(m), MHA(m), MCl, AgCl; Ag at different temperatures (288.15–308.15 K) and at different ionic strengths.

The thermodynamic values ΔG°, ΔH°, ΔS° for the respective equilibria are estimated. The possibility of using these acids as basis for some buffer solutions in 50% methanol – water mixture is discussed.
Mobile Phase Selectivity in the Separation of Epimeric and Positionally Isomeric Triterpenoids by Reversed Phase High Performance Liquid Chromatography
Authors: Shiao Ming‐Shi , Lin Lee‐Juian
Published: June 2015

The chromatographic behavior of 8 lanostanoid triterpenes including 4 pairs of C‐3 epimers and 2 pairs of C‐3/C‐15 positional isomers was studied by reversed phase HPLC. A consistent elution sequence of these paired isomers in all combination of three distinct solvent systems was observed. The mobile phase selectivity to separate specific, paired isomers was mainly dependent on the polarity difference contributed by C‐3/C‐15 hydroxyl and acetoxyl groups. The stereochemistry at C‐3 played more profound role in guiding the hydrophobic interaction with C18 stationary phase in the separation of C‐3/C‐15 positional isomers.
The Preparation of β‐Cycloalkyl‐L‐Aspartate and γ‐Cycloalkyl‐L‐Glutamate by Enzymatic Hydrolyses
Authors: Lo Lee‐Chiang , Wu Shih‐Hsiung , Chen Shui‐Tein
Published: June 2015

The simple method to prepare the β‐cycloalkyl aspartate and γ‐cycloalkyl glutamate by enzymatic reactions has been developed. Compared with conventional chemical methods, the enzymatic method is more facile.
Spectroscopic Studies of Metalloproteins and Metalloenzymes
Authors: Wu Felicia Ying‐Hsiueh
Published: June 2015

Metalloproteins/enzymes play important rales in cellular function by virtue of their intrinsic metal ions, Various spectroscopic methods, such as atomic absorption (AA), UV/VIS absorption, NMR, fluorescence energy transfer (FET), circular dichroism (CD) and extended X‐ray absorption fine structure (EXAFS), were applied to the studies of three Zn proteins involved in gene expression and regulation. The role of the intrinsic Zn ions of E. coli RNA polymerase (RPase), Xenopus oocyte transcription factor 111A (TFIIIA), and E1A protein of adenovirus were investigated. Various paramagnetic‐metal substituted RPases obtained by in vivo and in vitro methods were used to elucidate the spatial relationship between the metal and other active sites of RPase. Two Zn ions of RPase were involved in the substrate and template binding, in maintaining the proper conformation of active RPase, and may be coordinated with histidine and cystidine. Thus, Zn ions of RPase play catalytic, regulatory and structural roles. Two Zn ions of TFIIIA also play multiple roles in the regulation of 5S RNA synthesis; binding TFIIIA to 5S RNA and its gene, essentiality for 5S RNA gene transcription and DNA‐activated ATPase activity of TFIIIA. CD studies of apoTFIIIA, TFIIIA and its storage 7S particle, and 5S RNA indicated (1) Zn ions may not involve in the stabilization of TFIIIA, (2) substantial confomational changes of 5S RNA upon binding to TFIIIA. Two major proteins, 289 and 243 amino acids (aa), of E1A gene contain 1 and O Zn, respectively. The extra 46‐aa internal domain of 289‐aa protein which contains a “Zn finger” motif with 4 cysteine residues as ligands is required for efficient transactivation of early viral promoters.
Syntheses of 2,4′‐and 3,4′‐Bipyridines Via Lithium Halogen Exchange of Bromopyridines and Addition to N‐Ethoxycarbonylpyridinium Chloride in the Presence of Cul
Authors: Shiao Min‐Jen , Tarng Kai‐Yih , Shyu Li‐Ming
Published: June 2015

2,4′‐Bipyridines 4a, 4c, 4d and 3,4′‐bipyridines 4b, 4e, 4f, 4g, 4h are obtained in modest yield by the addition of organocuprate reagents derived from bromopyridines 2a‐h to N‐ethoxycarbonylpyridinium chloride 1 followed by air oxidation.
The Reaction of 3‐Arylsydnone‐4‐Carbohydroximic Acid Chlorides with Active Methylene Compounds
Authors: Shih Mei‐Hsiu , Yeh Mou‐Yung
Published: June 2015

3‐Arylsydnone‐4‐carbohydroximic acid chlorides react with compounds containing activated methylene groups in the presence of bases to give 3‐aryl‐4‐(4′,5′‐disubstituted‐iso‐xazol‐3′‐yl)sydnones which have not been reported in the literature. All the products were obtained in good yields, and their structures were confirmed by spectral analysis and elemental analysis.
Crystal Structure and Magnetic Properties of a Vanadium (IV) Pyrophosphate: Rb2V3P4O17
Authors: Lii Kwang‐Hwa , Wang Yau‐Pey , Chneg Chih‐Yi , Wang Sue‐Lein , Ku Huan‐Chiu
Published: June 2015

The crystal structure of Rb2V3P4O17 has been determined from single‐crystal X‐ray diffraction data. Rb2V3P4O17 crystallizes in the orthorhombic space group Pnma (No. 62) with a = 17.502(7), b = 7.292(2), c = 11.399(6) Å3, V = 1455(1) Å3, Z=4, R=0.0295, RW = 0.0320 for 1129 unique reflections with I > 2.5 σ(I). The structure contains intersecting tunnels where the Rb+ cations are located. The framework can be described as consisting of V2O10 units formed from one VO5 square pyramid and one VO6 octahedron sharing a corner, and infinite chains of corner‐shared VO6 octahedra, which are linked in three dimensions by pyrophosphate groups. The structural formula is Rb2(VO)3(P2O7)2. A single‐phase product can be obtained by heating appropriate amounts of Rb4V2O7, VO2, V, and P2O5 in an evacuated fused silica tube at 950°C. Powder magnetic susceptibility data confirm the presence of V4+ (d1) ions without magnetic ordering down to 3 K.
Videomicroscopic Observation of Nonequilibrium Growth Patterns of Crystals
Authors: Tsai Chung‐Hsien , Hsu Tze‐Jeng , Mou Chung‐Yuan
Published: June 2015

We have developed a video‐microscopic computer imaging system for observing meso‐scale nonequilibrium physicochemical structures. Chargcd‐coupled device (CCD) in optical detection, and computer‐enhancement of digitized image, have greatly improved the resolution, sensitivity, and dynamical range of this technique. We apply this system to the observation of various complex crystallization patterns from Suberic acid melts and Camphene condensation. These patterns are of the scale one to 100 micrometers. They are resulted from nonlinear dynamical instabilities of a growing crystal fronts. The following patterns are observed: dendrites, destabilization of flat surface, cellular solidification, tip‐splitting, and dense branches. A computer simulation based on diffusion‐limited aggregates (DLA) model is performed to show this instability. The DLA model with surface tension effect is able to result in fractal‐like, dendrite, and needle‐like growth pattern.
An Efficient Synthesis of (±)‐α‐Spirovetivene and Related Compounds
Authors: Zee Sheng‐Hsu , Chou Shan‐Yen
Published: June 2015

A process for the synthesis of (±)‐α‐spirovetivene starting from I‐oxo–2‐carbethoxy‐6, 10‐dimethyl spiro[4.5]dec‐6‐ene(I)1 is described. The oxo group of I was reduced by the process of Coates2, and the resulting spiro ester (III) and spiro alcohol (IV) were transformed to (±)‐α‐spirovetivene by the process of Uijttewaal3 and by conventional methods.
Ab Initio and MNDO Calculations Comparison with the VSEPR Model
Authors: Shalabi Ahmed
Published: June 2015

Ab initio and MNDO calculations of VSEPR model were carried out on CH2, CH2+, CH2−, SiH2, SiH2+ and SiH2−. Comparisons between the second row carbon and its third row silicon analogue as unshared electron pair contributors are considered. The repulsion effects as well as the volume requirement of the unshared electron pair on several structural and energetic properties arc investigated.
Heterocycles Synthesis Through Reactions of Nucleophiles with Acrylonitriles: Part 8, Synthesis of New Dihydropyridines
Authors: Abdel‐Latif Fathy Fahim
Published: June 2015

New spirodihydropyridines were synthesised through the reaction of cycloalkylidenematononitriles with enamines.
Solvent Extraction of Vanadium with α‐Benzoin Oxime
Authors: Li Chin‐Hou , Chen Shou‐Nan , Gi Hung‐Jang
Published: June 2015

The solvent extraction of vanadium by a chloroform solution of α‐benzoin oxime was investigated. The most favorable condition for the extraction has been found in the pH rang of 1.8 to 3.0 in sulfate or chloride buffer solutions, but with better extraction efficiency when sulfate was used. A solution of 2×10−2 M α‐benzoin oxime in chloroform was used, and 1×10−4 to 2×10−2 M vanadium(V) was extracted favorably in about 89% yield by a single extraction, and in about 97% yield by a double extraction. The effects of shaking time, concentration of α‐benzoin oxime, and diverse ions have also been investigated. Vanadium(V) can be readily extracted without interference in the presence of copper(II), aluminum(III), iron(III), silver(I), zirconium(IV), and chromium(III).
A Free Radical Hyperfine Coupling Constants Calculation Using the S‐P Indo‐Mo Method
Authors: Chen Cheng , Ding Guang Rung
Published: June 2015

We apply our newly developed s‐p separation model INDO‐MO theory to the open shell problem of organic free radicals and radical ions. The linear correlation analysis between spin densities and the related hyperfine coupling constants is preformed. To show the generality of this method for various elements, we select different sets of free radicals which contain 1H, 13C, 14N, 17O and 19F for our MO calculation. We chose the appropriate values of βα2P and βπ2P (the separated bond parameters calculated by the method described in our previous publication) and we also calibrated new geometrical parameters (bond distances and bond angles). With these new sets of parameters, many types of calculations were performed for comparison. We also compare our results with the corresponding results of the INDO‐MO method of Pople et al. In all cases involving 1H, 13C, 14N, 17O and 19F our MO method gives better results. This evidence also proves that our “s‐p separation model INDO‐MO method” is a reasonable and useful MO method.
Laser Spectroscopy on the MgH A2Π ‐ X2Σ+ Band System
Authors: Hsiao Tein‐Chai , Luo Yeung‐Long , Lin King‐Chuen , Luh Wei‐Tzou
Published: June 2015

The A2Π ‐ X2Σ+ electronic transition of MgH has been studied by the laser excitation spectroscopy. Some new transitions have been observed for the first time. Rotational parameters of the X and A state have been derived and compared with other experimental values.
Kinetics of Hydrolysis of Some Bifunctional Schiff Bases
Authors: Mahmoud M.R. , El‐Nady A.M. , Adam F.A. , El‐Taher M.A.
Published: June 2015

Kinetics of hydrolysis of some bifunctional Schiff bases, bis(x‐benzylidenes)‐o‐phenylenediamine, have been investigated in aqueous media containing 0.1 mole fraction of ethanol under base and acid conditions. Under base conditions the rate determining step is the hydroxide ion attack on the protonated substrate while under weak acid conditions the attack of water rather than hydroxide ion on the protonated substrate becomes the predominant reaction pathway. The bifunctional Schiff base molecular structure‐base or acid hydrolysis reactivity relationship has been examined and discussed. Effect of medium (water content and nature of organic solvents) has been investigated and it is deduced that specific solute‐solvent interactions, namely the proton‐solvent, play a vital role on such hydrolysis reaction.
Preparation of a Heavy Metal‐Removed Seawater
Authors: Pai Su‐Cheng , Huang Shang‐Da , Hung Chin‐Chang
Published: June 2015

A purification procedure is described for preparing a heavy metal‐removed blank seawater without altering its major compositions and pH. Coastal seawater is treated sequentially by passing through a charcoal column, shaking with a dense slurry of ferric hydroxide at pH 8, and passing the surpernatant through a Chelex‐100 chelating ion‐exchange column. Experimental data show that this process efficiently removes Cd, Co, Cu, Cr(III), Fe, Mn, Ni, Pb, V and Zn from natural seawater at the spiking concentrations of 10 and 100 ppb levels.
Enhanced Kinetic Isotope Effect of the Phosphate‐Catalyzed Proton Exchange in N,N'‐Dimethylurea
Authors: Wang Wei‐Hsien , Cheng Ching‐Chih , Lee Ming‐Chao
Published: June 2015

The concerted mechanism of phosphate‐catalyzed proton exchange in N,N'‐dimethylurea has been studied. Kinetic data were measured using the technigue of NMR line‐shape analysis. A significant kinetic isotope effect was observed for the concerted proton transfer in N,N'‐dimethylurea and is attributed to the tunnelling effect.
Studies on Vilsmeier‐Haack Reaction: Application to 3‐Methyl‐1‐Phenyl‐4‐Acetyl(Iminoacetyl)‐2‐Pyrazolin‐5‐One
Authors: Awad Ibrahim M.A. , Hassan Khairy M.
Published: June 2015

3‐Methyl‐l‐phenyl‐4‐acetyl(iminoacetyl)‐2‐pyrazolinones (1a,b) underwent diformylation reaction with Vilsmeier reagent to give the aminoacrolein derivatives (2a,b). The behaviour of (2a,b) towards piperidinc, morpholine, piperazine, hydroxylamine, hydrazine and phenylhydrazine has been investigated and screened in vitro for their antibacterial activities.
Reactions of 6‐Amino‐5‐Cyano‐3‐Methyl‐1,4‐Diphenyl‐1H 4H‐Pyrano[2,3‐C]Pyrazole and its Methanimidate
Authors: Younes Mansour I. , Atta Aly H. , Metwally S.A.M.
Published: June 2015

Reaction of 6‐amino‐5‐cyano‐3‐methyl‐1,4‐diphenyl‐ 1H,4H‐pyrano[2,3‐c]pyrazole 1 with triethyl orthoformate in acetic anhydride gave its methanimidate 2, which reacts with primary aliphatic and aromatic amines to give 4,6‐dihydro‐3‐methyl‐1,4‐diphenyl‐6‐ (alkyl)pyrazolo[4′,3′:5,6]pyrano[2,3‐d]pyrimidine‐5(lH)‐ imine 3 and the starting compound 1, respectively. Treatment of 1 with o‐aminophenol gave 5‐(2‐benzoxalyl)‐ 1,4‐dihydro‐3‐methyl‐1,4‐diphenylpyrano[2,3‐c]pyrazol‐ 6‐amine 9.
Comparison between Theoretical and Experimental Deformation Density of 1,3,5,7‐Tetra‐t‐Butyl‐S‐Indacene
Authors: Wang Yu , Wang Chih‐Chieh
Published: June 2015

1,3,5,7‐Tetra‐t‐butyl‐s‐indacene is a twelve‐membered fused‐ring compound; the stabilization of the compound by bulky t‐butyl groups is discussed. The distribution of bonding electron density is depicted in terms of deformation density using the experimental X‐X method, a multipole expansion model and a calculation according to the extended Hückel molecular orbital method (EHMO). The molecules crystallize according to the space group P21/n with cell parameters a = 9.700(3), b = 11.746(3), c = 10.858(2)Å, β = 107.67(2)°, Z=2 at 100K. The molecule has a center of inversion( ) and belongs to the symmetry point group Ci. The packing of two unique t‐butyl groups in the asymmetric unit appears significantly different. However, the map of deformation density in the plane of the ring shows pseudo D2h symmetry. The accumulation of density at the midpoint of the bonds is observed as expected. The theoretical deformation densities agree with the experimental ones. Analyses of the molecular‐orbital wavefunctions provide a good illustration of the aromatic π‐electron system. A theoretical study of a series of substituents (‐H, ‐ CH3, ‐t‐butyl ) on s‐indacene illustrates the stabilization effect of the t‐butyl group on the 12‐π‐electron ring system.
Primary Structure of the Pike Eel (Muranesox Cinereus) Growth Hormone
Authors: Liu Chen‐Sheng , Wang Yi‐Chi , Chen Jin‐Mei , Chang Chen‐Hsien , Chen Shun‐Wen , Huang Fore‐Lien , Lo Tung‐Bin
Published: June 2015

By means of alkaline extraction, gel filtration and two kinds of high‐performance liquid chromatography, a growth hormone from pike eel pituitary was purified and its primary structure determined. There are two forms of growth hormone, one of which has three more amino acids at the N‐terminal. The same situation arises in the Japanese eel. With invariant four half‐cystines, it is composed of 190 amino acids; similar to the growth hormone of the Japanese eel, it differs only in six amino‐acid residues.
Application of Pulsed Field Gradients in High‐Resolution NMR Spectroscopy
Authors: Doddrell David M.
Published: June 2015

In this paper the applicability of pulsed field gradients in high‐resolution NMR spectroscopy are considered. Applications include solvent suppression, spectral editing of one‐ and two‐dimensional (2D) NMR spectra and the induction of quadrature detection in the w1, direction of many 2D experiments. The applications are analysed using simple product operator algebra. Particular attention is directed to discussing the experimental requirements of this technology in order that high‐resolution NMR conditions are maintained throughout the experiment.
Silicon‐29 NMR Study of Alkali‐Exchanged NaY Zeolites
Authors: Chern Jer‐Young , Chao Kuei‐Jung
Published: June 2015

High‐resolution solid‐state 29Si NMR has been applied to the study of partially exchanged Li, K, and Cs NaY zeolites. The order of the 29Si chemical shifts of dehydrated samples is Li, Na‐Y < Na‐Y < K, Na‐Y. The correlation between the 29Si chemical shift and the Li or K loading on Li, Na‐Y or K, Na‐Y was rationalized in terms of the interaction between the framework and the cations inside the small cages. Because of the restrictive migration of large Cs+ ions from the supercages to the small cages, the 29Si chemical shift of Cs, Na‐Y was found to be similar to that of Na‐Y.
Improved Synthesis of 9‐ and 10‐Methylbenz[a] Anthracenes
Authors: Lai Ching‐Cheng , Own Zang‐Yuan , Unruh Leonard E. , Chou Ming W.
Published: June 2015

The synthesis of 9‐ and 10‐methylbenz[a]anthracenes by improved methods are described. These new procedures are simple and convenient, and provide the title compounds in good yields and high purity.
Regiochemistry of Nucleophilic Addition to Cyclohexadienyl‐Iron Complexes Having Sterically Demanding Substituents
Authors: Ong Chi Wi , Liou Wen Tzong
Published: June 2015

The reactions of sterically hindered tricarbonyl(cyclohexadienylium)‐iron with nucleophilic reagents have been studied. The influence of the 4‐alkoxyl substituents versus the bulkiness of the 1‐alkyl substituents on the regioselectivity of nucleophilic addition was investigated. With sodium borohydride as nucleophile, substantial addition at the C‐1 dienylium terminus was observed to take place via the more crowded endo face to give the more stable exo product. We here report the importance of steric hindrance to the approach of nucleophiles versus product stability during nucleophilic addition to the dienylium complexes.
Carbon‐13 NMR Studies of 3‐Aryl‐4‐(5‐aryl‐Δ 2‐1,2,4‐oxadiazolin‐3‐yl)sydnones and 3‐Aryl‐4‐(5‐aryl‐1,2,4‐oxadiazol‐3‐yl)sydnones
Authors: Ma Sun , Huang Chin‐Lin , Yeh Mou‐Yung
Published: June 2015

The 13C NMR spectra of twelve 3‐aryl‐4‐(5‐aryl‐Δ2‐l,2,4‐oxadiazolin‐3‐yl)sydnones and twelve 3‐aryl‐4‐(5‐aryl‐l,2,4‐oxadiazol‐3‐yl)sydnones have been measured and assigned by means of proton‐noise decoupling and DEPT‐experiments. The coupling constants were determined by means of gated decoupling, and NOE effects were observed by comparison of proton‐decoupled and inverse‐gated decoupled spectra. Differences shown by the oxadiazoline and the oxadiazole rings and the substitution effects are discussed.
Synthesis and Photochemistry of syn‐ and anti‐9,10‐Epoxy‐1, 4‐dihydro‐1,4‐ethanonaphthalene‐2,3‐diones
Authors: Liao Chun‐Chen , Hseu Tzong‐Hsiung , Lin Ho‐Shen , Tang Chia‐Pin , Ueng Yih‐Gang , Wang Jinn‐Lung , Wann Gwo‐Huei , Wu Kuan‐Syh
Published: June 2015

The title epoxydiketones were prepared stereoselectively, direct epoxidation of 3a‐c with MCPBA produced syn isomers la‐c whereas epoxidation of 4a‐d followed by saponification of the spirolactone rings gave anti isomers 2a‐c. The stereochemistry of 1a and 2a was established by X‐ray diffraction, whereas that of the remaining epoxydiketones was determined from the correlation of visible, 1H, and 13C NMR spectral data; the differences between spectra of the corresponding syn and anti isomers are explained in terms of through‐space interaction and steric effects. Photolysis of syn isomers 1a‐c afforded the corresponding naphthalenes 8a‐c in almost quantitative yields; in contrast, irradiation of anti isomers 2a‐c gave complicated mixtures. The quantum yield of disappearance of 1a was 52 times that of 2a. Reaction mechanisms are proposed to account for the product formation. The differences in the photochemical behavior of the title syn and anti isomers are rationalized in terms of stereoelectronic effects of the epoxy rings in the syn isomers.
On the Discovery of Direct Ortho‐Magnesiation
Authors: Eaton Philip E. , Xiong Yusheng , Lee Chih‐Hung
Published: June 2015

Metalation of 2,4‐dicyanocubanecarboxamide (4) with lithium tetramethylpiperidide (LiTMP) followed by quenching with CO2 is non‐regioselective and results in carboxylation at the 3 (→ 5) and 6 (→ 6 ) positions. However, when the reaction was repeated with LiTMP pre‐treated with more than 0.5 equivalent of MgBr2, only 6 was produced. This was shown to occur by direct, regiospecific ortho‐magnesiation by the bases BrMgTMP and MgTMP2. This initial observation of ortho‐magnesiation has opened the way to wide application of this new methodology, a valuable and useful complement to ortho‐lithiation.
Kinetics of the Decomposition of Ferrocenium Ion and Its Derivatives
Authors: Huang Wen Hong , Jwo Jing‐Jer
Published: June 2015

The first‐order kinetics of the decomposition of ferrocenium ion (Fc+) and its substitution derivatives have been studied in aqueous sulfuric acid and in the presence of excess Ce(IV) ion. The observed first‐order rate constant (kobs) is expressed as kobs = kd for the acyl‐substituted ferrocenium ions and kobs = kd+ kox[Ce(IV)]o for the unsubstituted and alkyl‐substituted ferrocenium ions. Electron‐donating alkyl substituents stabilize the ferrocenium ion whereas electron‐withdrawing acyl substituents make it less stable. The order of relative stability toward decomposition is 1,1′‐dimethyl Fc+ ≥ butyl Fc+ > 1,1‐dimethylpropyl Fc+ > Fc+ > > formyl Fc+ > acetyl Fc+ > > benzoyl Fc+. A mechanism to interpret the kinetics is also given.
Free‐Radical Reaction of 2‐Vinylcyclopropane‐1,1‐dicarboxylate with Alkynes
Authors: Chuang Che‐Ping , Ngoi Tak Ho Johnny
Published: June 2015

A free‐radical reaction of dimethyl 2‐vinylcyclopropane‐1,1‐dicarboxylate with electron rich alkynes giving cyclopentene systems is described. This reaction can be achieved with p‐toluenesulfonyl chloride and phenyldisulfide as radical precursors.
Structural Studies of Transition Metal Compounds
Authors: Saito Yoshihiko
Published: June 2015

A historical overview will be given on the structural studies on transition metal compounds and their interaction with other fields of coordination chemistry. About three decades have passed away since the structure and absolute configuration of tris(ethylenediamine)cobalt(III) complex ion were determined. At present accumulation of the structural data for isomers has enabled us to understand structural principles of chelate complexes in considerable detail. The energy minimization calculations can predict the detailed geometries of the complexes. Differences in thermodynamic properties between different conformers are well reproduced.

Aspherical distribution of 3d electrons in transition metal complexes was detected for the first time in crystals of [Co(NH3)6][Co(CN)6] in 1973. Such an accurate electron density study provides important information on the d electrons placed in a ligand field. The high‐spin and low‐spin states can be distinguished unequivocally. In spite of a very small valence/total electron ratio, the asphericity of 4d and 5d electrons in a ligand field can be detected.

The crystal structures of a series of dimeric copper(II) carboxylate adducts of the general formula [Cu(RCOO)2L]2 have been determined or redetermined as accurately as possible. The temperature dependent magnetic susceptibility of these crystals indicated that the isolated pairs of Cu(II) ions interact strongly through exchange forces. Molecular orbital calculations revealed that the electron population in the carbon atom of the bridging OCO group plays an important role in determining the strength of the spin superexchange interaction.

In the crystals of some cobaloxime complexes, racemization of chiral groups bonded to Co proceeds on X‐ray exposure without degradation of crystallinity. Several intermediate stages could be determined by X‐ray analysis. Various reaction pathways were recognized and the reaction rate could be correlated with the atomic arrangement in the crystal.
Does He2 Exist?
Authors: Ogilvie J. F. , Wang Frank Ye Howe
Published: June 2015

For the electronic ground state X 1Σ+g, the potential‐energy function of He2 reported by Aziz et al. has been transformed into the form V(z), containing only eight parameters, which is more suitable for the investigation of the existence of states of discrete energy. We found no evidence that a bound vibration‐rotational state of the stable diatomic molecule 3He2 or 4He2, even if rotating, can exist in the electronic ground state.
Effects of Ring Size on Spectral Properties of Copper(II)‐Diaminodiamide Complexes in Aqueous Solution
Authors: Len Ching‐Hohn , Chung Chung‐Sun
Published: June 2015

The electronic absorption spectra of aqueous solutions containing copper(II) ion and N, N′‐bis(carbamoylmethyl)trimethylenediamine(L‐1, 3, 1) at 25.0 ± 0.1°C and 0.10 mol L−1 NaClO4, were measured as a function of pH. The absorption maxima and the molar absorptivities of [Cu(L‐l, 3, l)]2+, [Cu(H.1L‐1, 3, 1)]+, and [Cu(H‐2L‐l, 3, l)] were calculated from these spectra. A comparison of the spectral parameters of these complexes with those of the copper(lI)‐diaminodiamide complexes containing 6, 5, 6‐and 6, 6, 6‐membered ring systems indicates that the chelate ring size has significant effects on these spectral parameters.
Effect of Positions of Methyl Substituents in the Complexation Kinetics of Macrocyclic Tetraamines with Copper(II) in Strongly Basic Aqueous Media
Authors: Hu Mon‐Ai , Chung Chung‐Sun
Published: June 2015

The complexation kinetics of the reaction of copper(II) with isomeric tetraamine macrocyclic ligands, C‐rac‐5, 7, 7, 12, 12, 14‐hexamethyl‐l, 4, 8, 11‐tetraazacyclotetradecane (tet c), C‐meso‐5, 7, 7, 12, 12, 14‐hexamethyl‐l, 4, 8, 11‐tetraazacyclotetradecane (tet d), and C‐meso‐5, 5, 7, 12, 12, 14‐hexamethyl‐1, 4, 8, 11‐tetraazacyclotetradecane (tet a) in strongly basic aqueous media have been examined at 25.0 ± 0.1°C by means of the stopped‐flow technique. The variation in the values of the resulting rate constants indicates that the positions of the methyl substituents play a significant role in these reactions. These reactions exhibit associative character and second‐bond formation is proposed as the rate‐determining step.
Steady‐State Kinetics of Aminopeptidase Catalysis: A Stopped‐Flow Radiationless Energy Transfer Study
Authors: Lin Wann‐Yin , Lin Gang‐Hong
Published: June 2015

Stopped‐flow radiationless energy transfer experiments have been carried out to investigate the hydrolysis of some dansyl peptide substrates (S) catalyzed by aminopeptidase (E). RET between enzyme tryptophanyl residues and the dansyl group in the substrate allowed direct observation and quantitation of the enzyme‐substrate (ES) complexes. Analysis of the stopped‐flow RET traces gives kcat = 1.32 s−1 and KM = 47 μM for Leu‐Ala‐NH(CH2)2NH‐Dns (Leu‐Ala‐DED) and kcat = 4.80 s−1 and KM = 196 μM for Leu‐Gly‐NH(CH2)2NH‐Dns (Leu‐Gly‐DED). The activation energies of the enzymatic reactions were determined from the Arrhenius plots to be 57 and 38 kJ mol−1 for Leu‐Ala‐DED and Leu‐Gly‐DED, respectively. The kinetic results indicate that the enzyme binds Leu‐Ala‐DED more tightly than Leu‐Gly‐DED as revealed by a small value of KM. That this enzyme catalyzes the turnover of Leu‐Gly‐DED more efficiently than Leu‐Ala‐DED is reflected in a large value of kcat and a small activation energy. The RET signals during the hydrolysis of Leu‐Val‐NH(CH2)2NH‐Dns were extremely weak probably because of the inefficient energy transfer in the ES complex or the retention of the product in the enzyme after completion of the reaction. Aminopeptidase was inactive towards the dansyl compounds of the single amino acid studied. This fact may be due to an unfavorable conformation of these compounds in the ES complexes (small kcat) or a weak binding of the substrates to the enzyme (large KM) or both.
Steam Reforming Reactions of Methanol Over Nickel and Copper Catalysts
Authors: Su Tien‐Bau , Rei Min‐Hon
Published: June 2015

Steam‐reforming reactions of methanol over NiO/Al2O3 and CuO/ZnO have been investigated. Over the nickel catalyst, the reaction rate is of zero kinetic order with respect to either methanol or steam, and the activation energy is 12.4 kJmol−1, whereas with copper catalyst, the rate is expressed according to the literature as kPa/(1 + KaPa + Kb+Pb) in which “a” and “b” are methanol and steam, respectively. The rate‐controlling step of the reaction is assigned to the dissociation of O‐H bond with dehydrogenation of C‐H bond proceed rapidly to form carbon oxides. With copper catalyst the intrinsic participation of a water molecule during the dehydrogenation of C‐H bond leads to the formation of carbon dioxide. With nickel catalyst, the dehydrogenation proceed more rapidly than the migration of a water molecule from an alumina site to a nickel site and causes almost exclusively the formation of carbon monoxide and hydrogen at a lower reaction temperature.
Molecular Structures and Magnetic Properties of Strongly Antiferromagnetically Coupled Binuclear Copper(II) Complexes [CU2 REP(μ‐X)(Y)2]
Authors: Chyn Jong‐Pyng , Shieh Kuan‐Jiunn , Chou Jeh‐Li , Wang Yu , Lee Gene‐Hsiang , Chen Cheu‐Pyeng
Published: June 2015

The molecular structures of binuclear copper(II) complexes [Cu2REP(μ‐OH)(ClO4)2] (4) and [Cu2REP(μ‐Cl)Cl2] (5), in which REP = deprotonated 2,6‐bis(1′‐(4′‐(2″‐pyridyl)‐2′‐thiabutyl))‐4‐methylphenol, have been characterized by single‐crystal X‐ray diffraction. The former crystallizes in the triclinic space group Pl̄ with a = 10.156(3), b = 12.631(3), c = 25.128(10) Å, α = 92.03(3), β = 96.84(3), γ = 108.02(2),° and Z − 2. Complex 5 crystallizes in the monoclinic space group C2/c with a = 12.166(2), b = 11.825(2), c = 18.240(4) Å, β = 100.97(2)°, and Z =4. All copper ions are pentacoordinated with ligation to a sulfur, a nitrogen, and the bridging phenolato oxygen of the REP ligand, the exogenous bridge, and a counteranion. The coordination geometry of each copper of the binuclear copper sites is square pyramidal in both 4 and 5. Magnetic susceptibility measurements in the temperature range 6–300 K reveal a strong antiferromagnetic spin exchange in 5 (exchange integral 2J = −460 cm−1). A diamagnetic behavior is observed for 4 according to a similar cryomagnetic investigation. The diamagnetism of 4 is further confirmed by measurements of magnetic susceptibility through Evan's method at room temperature. Complex 4 has no EPR signal. The powder EPR spectrum of 5 shows the typical triplet state characteristics with Δm = ±1 transitions at g = 2.15 and a weaker Δm = 2 transition at half field with g = 4.24.
Estimation of the Total π‐Electron Energy of a Conjugated Molecule
Authors: Gutman Ivan
Published: June 2015

Some properties of a bound for total π‐electron energy are established. A topological expression for the fourth spectral moment is deduced, valid for all molecular graphs.
Superconductivity and the Anomalous Meissner Effect in La3CaBa3Cu7O15,5 + x Oxide
Authors: Wang Chi‐Ming , Yang Yu‐Fu , Kao Huey‐Chucn I. , Wci Wen‐Cheng J.
Published: June 2015

A superconducting oxide with a stoichiometry La3CaBa3Cu7O15.5+x, in which x = 0.75, was prepared. It had a tetragonal triple‐perovskite structure with lattice parameters a = 3.879 Å and c = 11.637 Å. According to resistivity measurements, a sharp superconducting transition, ΔTc(10‐90%) = 1.5 K, and Tc(zero) = 80 K were observed. When it was measured at a small magnetic field (10‐20 gauss) with field cooling, the sintered pellet showed a positive magnetic susceptibility, but the powdered sample exhibited (he diamagnetism of a typical superconductor. However, no peculiar shielding effect was found in both the sintered and powdered samples.
The Reaction of 3‐Arylsydnone‐4‐Carbohydroximic Acid Chlorides with Active Methylene Compounds (II)
Authors: Shin Mei‐Hsiu , Yeh Mou‐Yung
Published: June 2015

In the presence of triethylamine, 3‐arylsydnone‐4‐carbohydroximic acid chlorides react not only with active methylene compounds containing keto groups to give 3‐aryl‐4‐(4′,5′‐disubstituted‐isoxazol‐3′‐yl)sydnones, but also with compounds containing cyano groups to produce 3‐aryl‐4‐(4′‐substituted‐5′‐aminoisoxazol‐3′‐yl)sydnones or 3‐aryl‐4‐(4′‐cyano‐5′‐substituted‐isoxazol‐3′‐yl)sydnones.
Nucleosides: Synthesis of Some New Naphthimidazole Ribonucleosides as Potential Antibacterial Agents
Authors: Abdelal Ali M. , El‐Emam Ali A. , Moustafa M. A.
Published: June 2015

Reaction of 2‐trifluoromethyl‐ or 2‐cyanonaphth[2,3‐d] imidazole (1 or 2) with 1‐O‐acetyl‐2,3,5‐tri‐O‐ benzoyl‐β‐D‐ribofuranose (3), using the triflate or fusion method afforded 2‐trifluoromethyl‐1‐(2,3,5‐tri‐ O‐benzoyl‐α‐D‐ or ‐β‐D‐ribofuranosyl)naphth[2,3‐d]imidazole (4 or 6) and 2‐cyano‐1‐(2,3,5‐tri‐O‐benzoyl‐α‐D‐ or β‐D‐ribofuranosyl)naphth[2,3,‐d] imidazole (5 or 7), respectively. The products 4 and 5 or 6 and 7 were separated by chromatography on silica gel. Treatment of the blocked nucleosides 4‐7 with methanolic NH3 at 0 °C furnished the deblocked nucleosides 8‐11 respectively. Treatment of 10 with 5% NH3 (aq) at 60 °C gave 11. Structural elucidation is based on elemental analysis, UV, FAB‐MS and 1H NMR spectra. Compounds 4‐11 were subjected to antibacteial testing. Compounds 5, 7 and 10 have significant activity against Staphylococous aureus (gram positive) and Esherichia coli (gram negative) bacteria, whereas the other tested compounds showed no significant activity.
Benzoylformyl Complexes of Iron and Molybdenum
Authors: Yeh Yu‐Sung , Chen Jwu‐Ting , Lee Gene‐Hsiang , Wang Yu
Published: June 2015

Benzoylformyl complexes CpMo(COCOPh)(CO)3 (1) and CpFe(COCOPh)(CO)2 (2) were prepared by the reactions of [CpMo(CO)3]− and [CpFe(CO)2]− ions with PhCOCOCl, respectively. The single‐crystal structure of complex 1 has been determined by X‐ray diffraction with crystal data: P21/c, a = 6.674 (3) Å, b = 13.301 (4) Å, c= 16.903(6) Å, β = 90.82 (5)°,V = 1500(1) Å3, Z = 4. Least‐squares refinement on 894 reflections with I ≥ 2.0 σ(I) led to R = 0.041, RW = 0.042. Complex 1 contains a near perpendicular s‐trans oxalyl moiety in the benzoylformyl ligand with the torsional angle O4‐C4‐C5‐O5 being 104 (1)°. The iron complex suffers spontaneous decarbonylation at 25 °C to yield CpFe(COPh)(CO)2.
A Diepoxide Belonging to the Rare C1 Point Group
Authors: Graham Ron J. , Paquette Leo A.
Published: June 2015

2,6‐ and 2,7‐Dimethylanthracenes were reduced seriatim with lithium in liquid ammonia and lithium in methylamine to their 1,4,5,8,9,10‐hexahydro derivatives. Two‐fold epoxidation of these tetraenes provided the cis and trans diepoxides resulting from electrophilic attack at the inner double bonds. Trans diepoxide 1 has the very unusual characteristic of lacking a σ plane of symmetry but possessing an inversion center. As a consequence, the 1H NMR spectrum of C1‐symmetric 1 is simplified relative to those of its isomers 5, 9, and 10.
Deposition of Silicon Carbide Thin Films from 1,1‐Dimethyl‐1‐Silacyclobutane
Authors: Chiu Hsin‐Tien , Lee Shu‐Fen
Published: June 2015

1,1‐Dimethyl‐1‐silacyclobutane was used as a single‐source precursor to deposit SiC thin films on Si(100) and Si(111) by low‐pressure chemical vapor deposition (LPCVD). Polycrystalline β‐SiC thin films were grown at temperatures 1100 and 1200°C. At temperatures between 950 and 1100°C, amorphous thin films of silicon carbide were obtained. The films were studied by X‐ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and electron diffraction (ED).
SVD Analysis in Fitting Property Surfaces
Authors: Wang Feng , Searles Debra J. , Von Nagy‐Felsobuki Ellak I.
Published: June 2015

Previous calculated spectral properties of Li3+associated with the [6,7] vibrational band origins were rendered as uncertain, due to the exclusion of cross‐terms involving the breathe mode normal co‐ordinate in the analytic expansion of the dipole moment surface. However, by applying a singular value decomposition (SVD) analysis the exclusion of these terms is shown to be appropriate with respect to their negligible effect on fit (via the square root of the sum of the square of the residuals) thereby validating previous prognosis.
Constituents of Perltrophe Japonica (Thunb.) Bremk
Authors: Wang Chao‐Chiun , Kuoh Chang‐Sheng , Wu Tian‐Shung
Published: June 2015

A naturally occurring derivatives of pyridine, 3,5‐pyridinedicarboxamide (1), lupeol (2), a steroidal mixture [stigmasterol (3a) and β‐sitosterol (3b)], steroidal glycosides [stigmasteryl‐glucoside (4a) and β‐sitosteryl glucoside (4b)] and allantoin (5) were isolated and characterized from the aerial parts of Peritrophe japonica. Their structures were determined by spectral analysis.
Reactions of RSe− (R = Me, Ph) Groups in [RSeFe(CO)4I and [RSeCr(CO)5−]
Authors: Liaw Wen‐Feng , Liu Chen‐Ju , Lai Chia‐Huei
Published: June 2015

The anionic [MeSeFe(CO)4] and [MeSeCr(CO)5] complexes were synthesized by reaction of [PPN][HFe(CO)4] and [PPN][HCr(CO)5] with MeSeSeMe respectively via nucleophilic cleavage of the Se‐Se bond. The ease of cleavage of the Se‐Se bond follows the nucleophilic strength of metal‐hydride complexes. Methylation of [RSeCr(CO)5−] by the soft alkylating agent MeI resulted in the formation of neutral (MeSeMe)Cr(CO)5 in THF at 0°C. In contrast, the [ICr(CO)5−] was isolated at ambient temperature. Reaction of [MeSeFe(CO)4−] or [MeSeCr(CO)5−] with HBF4 yielded (CO)3Fc(μ‐SeMe)2Fe(CO)3 dimer and anionic [(CO)5Cr(μ‐SeMe)Cr(CO)5−] respectively, and no neutral (HSeMe)Fe(CO)4 and (HSeMe)Cr(CO)5 were detected spectrally (IR) even at low temperature. Reaction of NOBF4 or [Ph3C][BF4] and [MeSeCr(CO)5−] resulted in the neutral monodentate (MeSeSeMe)Cr(CO)5 complex. Addition of 1 equiv CpFe(CO)2I to 2 equiv [MeSeCr(CO)5−] gave CpFe(CO)2(SeMe) and the anionic [(CO)5Cr(μ‐SeMe)Cr(CO)5−] in THF at ambient temperature.
Transition‐Matrix Elements of Chemical Processes
Authors: Chu San‐Yan , Lee Tieh‐Sheng , Lec Shyi‐Long
Published: June 2015

We attempted to establish a qualitative classification of reactivities for various reactions by examining the nature of the corresponding transition matrix elements. We extended the idea to charge localization behavior in some highly polarizable systems and nature of bonding in hypervalent molecules.