bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single-crystal ESR and X-Ray Crystallographical Studies of a Binuclear Copper(II) Complex with a Coaxially Stacked Square-pyramidal Geometry
Authors: Kajikawa Yuji , Sakurai Tosio , Azuma Nagao , Kohno Shizue , Tsuboyama Sei , Kobayashi Kimiko , Mukai Kazuo , Ishizu Kazuhiko 
Published: July 2006

Abstract
A binuclear complex of bis(μ-N,N′-dipicolinoyl-1,3-propanediamine)-bis(sulfato)dicopper(II) has been isolated as a blue single crystal tridecahydrate, [{Cu(SO4)(ppda)}2]·13H2O, from an aqueous solution. The crystals are orthorhombic, C2221, with a=15.42(1), b=24.92(2), c=25.73(2) Å, and Z=8. Each copper(II) ion is in a square-pyramidal coordination with two pyridine nitrogen atoms, two carbonyl oxygen atoms, and a sulfate oxygen atom at the apex. The two equivalent copper(II) ions, about 3.9 Å apart from each other, are aligned coaxially. The eight Cu–Cu vectors are approximately parallel to one another along the c axis. The most important feature of the crystal structure is the presence of the bulky ligands and of many water molecules, which magnetically isolate the Cu–Cu coupled pair from one another. This facilitates the ESR study of the molecular anisotropies by using the single crystal, even at room temperature. The ESR parameters determined are as follows: g⁄⁄=2.280(2), g⊥=2.067(1), |D|=422.4(8), |A⁄⁄|=170(2), and |A⊥|=14(1) in 10−4 cm−1. Bleaney and Bowers treatments of the exchange coupling contribution in the D parameter indicated a ground singlet state about 7 cm−1 below a triplet state for the coupled copper(II) ions. A comparison of the ESR parameters measured for the single crystal with those in the aqueous solution enabled us to conclude that the molecular structure in the solution was very similar to that in the crystalline phase, apart from the coordination of sulfate ions.
Effects of Hg(ClO4)2, HgCl2, and AgClO4 on the Conformations of Poly(S-carboxymethyl-l-cysteine) and Poly[S-(2-carboxyethyl)-l-cysteine] in Solution
Authors: Oka Kazuki , Maeda Hiroshi , Ikeda Shoichi 
Published: July 2006

Abstract
The effects of Hg(ClO4)2, HgCl2, and AgClO4 on the conformations of fully neutralized poly(S-carboxymethyl-l-cysteine) and poly[S-(2-carboxyethyl)-l-cysteine] in the absence of supporting electrolytes were examined by circular dichroism (CD) spectra. The induction of the β-form was suggested by the addition of Hg(ClO4)2 and AgClO4, while it could not be concluded in the case of HgCl2. Spectroscopic evidence for the coordination of metals with the two polypeptides was provided in the case of Hg(ClO4)2 and HgCl2 by the appearance of a new CD band around 250–260 nm as well as the distortion of the polymer CD spectra in the region of 200–230 nm, while it was not obtained in the case of AgClO4. The decrease of pH observed on addition of the three metal compounds also suggested the conformational change. Extraordinary lowering of pH and enhanced solubility were observed on addition of HgCl2.
The Influence of Anions on the Distribution Coefficients of Hard Acid-Metals for Anion-exchange Resin in HF–H3BO3 Media
Authors: Adachi Takeo , Yoshida Hideyo , Izawa Kimie , Kihara Sorin 
Published: July 2006

Abstract
The distribution coefficients, Kd, of eighteen hard acid-metal ions for a strongly basic anion-exchange resin were determined in HF–H3BO3 media in the presence of Cl− or NO3−, SO42−, and ClO4−, and the relation between the adsorbabilities of the coexisting anions and the Kd values of the metal ions was discussed. The fluoride-ion concentration is quite low in HF–H3BO3 media because of the complex formation of the fluoride ion with boric acid, and most of the hard acid-metal ions have lower Kd values in HF–H3BO3 media than those in a hydrofluoric acid solution. By varying the kinds of coexisting anions and their concentrations in HF–H3BO3 media containing less than 0.02 M(1M=1 mol dm−3) of fluoroborate ions, the Kd values of metal ions can be controlled to allow the anion-exchange separations. As fluoroborate ions, e.g., BF4− or BF3OH−, are strongly adsorbed on the resin, metal ions which are strongly held on the resin can be eluted by media including fluoroborate ions in higher concentrations. By using HF–H3BO3 media and selecting the coexisting anions, an effective mutual separation of titanium–zirconium, titanium–uranium, tin–niobium, and molybdenum–tungsten can be attined.
The Electronic Structure of the Fulvalene Trication Radical. A Localization of the Unpaired Electron
Authors: Toyota Azumao , Nakajima Takeshi 
Published: July 2006

Abstract
The restricted Hartree-Fock (RHF) solution for the trication radical of fulvalene, obtained by using the open-shell SCF formalism of the Pariser-Parr-Pople-type MO method, is found to be doublet unstable at the conventional D2h nuclear arrangement. We calculate the broken-symmetry charge-density wave solution lower in energy than the usual symmetry-adapted RHF solution and examine its properties. It is predicted that the unpaired electron should be localized on the single five-membered ring having a smaller positive charge. Finally, on the basis of the second-order Jahn-Teller effect, we examine the molecular-symmetry reduction of the trication radical from the fully-symmetrical D2h to the C2v nuclear arrangement.
Studies of Liquid Water by Computer Simulations. III. Dynamical Properties of a 2-D Model
Authors: Kataoka Yosuke 
Published: July 2006

Abstract
Molecular dynamics simulations of a water-like system are performed at many temperatures and densities. A 2-dimensional model of water is used for the system with 144 molecules in a square cell. The calculated self-diffusion coeffcient and the dipole direction relaxation time are in good agreement with the observed values in a wide temperature-pressure plane. Cross correlation function of displacement and local orientational order parameter are computed by the time-averaged configurations, where the average of period is several times longer than the velocity correlation time. The cross correlation is observed even in the third neighbor pairs, which proves the existence of hydrogen-bonded local structure. The lifetime of this local structure is about 2×10 ps at low temperatures and low density, where density maximum is known. The lifetime of the unstable species with a rather high energy is found to be about 0.5–2 ps at low temperatures and low density.
Correlation between Axial and In-Plane Coordination Bond Lengths in Tetragonal Six-coordinate Complexes of the trans-MX2N4 Type (M=Co3+, Ni2+, and Zn2+). X-Ray Structural and ab initio Molecular Orbital Studies
Authors: Ito Tasuku , Kato Masako , Ito Haruko 
Published: July 2006

Abstract
X-Ray data of 16 structures having coordination geometry of the trans-MX2N4 type show that (i) an out-of-plane coordination bond length decreases as an in-plane distance increases, (ii) the degree of the correlation is metal ion dependent and varies in the order, Zn2+&gt;Ni2+&gt;Co3+. In the Ni(II) systems, complexes having stronger ligands (X=NCS−) at axial positions show the weaker correlation as compared with complexes with weaker axial ligands (Cl−). Electronic origin that causes such negative correlations has been investigated in terms of the potential energy surfaces obtained from ab initio MO calculations for model compounds, trans-[MCl2(NH3)4]. A section of the potential surface along the M–Cl and M–N bond axes is an ellipse and the ellipse has a tilt with respect to the metal-ligand bond axes. The dependence of the M–Cl distances on the M–N distances becomes stronger, as the tilt of the ellipse increases, and/or as the ratio of the length of long to short axes of the ellipse is increased. The degree of correlation expected from the potential energy surfaces are consistent, in all respect, with experimentally observed results. The interrelationships, found both experimentally and theoretically, are associated with softness of metal ions. Among the metal ions studied, Co(III) is the hardest, Zn(II) is the softest, and Ni(II) is intermediate.
Reactions of Sodium Salts of Tosylhydrazone Compounds with Silver Chromate. Formation of Indazole, Pyrazole, and Benzonitrile Derivatives
Authors: Saito Katsuhiro , Toda Takashi , Mukai Toshio 
Published: July 2006

Abstract
Tropone tosylhydrazone sodium salt was allowed to react with silver chromate to give 2-tosyl-2H-indazole. The reaction is thought to proceed through the cyclization of the hydrazyl radical intermediate. Under the same conditions, sodium salts of m-nitrobenzaldehyde tosylhydrazone (5), benzylideneacetone tosylhydrazone derivatives (7a and 7b), and β-ionone tosylhydrazone (9) reacted to yield m-nitrobenzonitrile from 5 and pyrazole derivatives from 7a, b, and 9, respectively. m-Nitrobenzonitrile is formed by homolytic fission of nitrogen–nitrogen bond of 5. Formation of the pyrazole derivatives can be explained by intramolecular 1,3-dipolar additions of the corresponding diazo intermediates.
Condensations of 1,4-Cyclohexanediones and Secondary Aromatic Amines. The Formation of Alkyldiarylamines and Triarylamines
Authors: Haga Kazuo , Oohashi Masayuki , Kaneko Ryohei 
Published: July 2006

Abstract
Condensation of 1,4-cyclohexanedione with N-alkylarylamines gives N-alkyl-N-arylanilines, and that with diarylamines gives triarylamines. A mechanism involving dehydration of monoenamines of the 1,4-dione is proposed for the reaction. Relative rates of substituted N-ethylanilines on competitive reactions plotted vs. Hammet’s σ values gave −2.0 as the ρ value. In separate reactions, however, a different tendency is noted for the yield, that is, the ease of reactions with p-chloro and p-nitro derivatives. This discrepancy is explained in terms of acidities of the conjugate acids of the amines used as the actual catalysts.
Infrared Intensities in Methyl Chloride. II. Binary Overtone and Combination Bands
Authors: Kondo Shigeo , Koga Yoshinori , Nakanaga Taisuke , Saëki Shinnosuke 
Published: July 2006

Abstract
Infrared intensities of binary overtones and combinations of CH3Cl and CD3Cl molecules have been measured by the pressure broadening technique. Simplified formulas for the intensities of binary overtone and combination bands of symmetric top molecules were given. Contribution from the mechanical anharmonicity was calculated by use of these equations. Contribution from the electric anharmonicity was estimated by ab initio MO method (4–31 G*). The calculated intensities were compared with the observed values and discussed.
Photochemical Reaction of Phenyl-substituted 1,3-Diketones
Authors: Yoshioka Michikazu , Suzuki Tsuneji , Oka Masashi 
Published: July 2006

Abstract
Irradiation of 2,2-dimethyl-1-phenyl-1,3-diketones with 3-ethyl or 3-isopropyl substituents gave type II cyclization product, 3-hydroxy-2,2,4-trimethyl-3-phenylcyclobutanone or 3-hydroxy-2,2,4,4-tetramethyl-3-phenylcyclobutanone, along with type I cleavage products. The type II cyclization/type I cleavage ratio is greater with a 3-isopropyl group than with a 3-ethyl group. A similar irradiation of 2,2-dimethyl-1-phenyl-1,3-butanedione gave type I cleavage products and no type II cyclization product. Irradiation of 2,4-dimethyl-1-phenyl-1,3-pentanedione gave 3-hydroxy-2,2,4-trimethy1-3-phenylcyclobutanone and propiophenone. The geometry of 3-hydroxy-2,2,4-trimethyl-3-phenylcyclobutanone which arose from 2,2-dimethyl-1-phenyl-1,3-pentanedione was cis with respect to phenyl and 4-methyl groups and that which arose from 2,4-dimethyl-1-phenyl-1,3-pentanedione was trans.
The Structure of Aquatris(m-hydroxybenzoato)cerium(III), [Ce(HOC6H4CO2)3(H2O)]n
Authors: Koizumi Yukio , Sawase Hiroshi , Suzuki Yasuo , Shimoi Mamoru , Ouchi Akira 
Published: July 2006

Abstract
The crystal and molecular structure of the title complex has been determined by the use of the single-crystal X-ray diffraction method. The crystal of CeC21H17O10, F. W. 569.48, was monoclinic; space group P21⁄c, a=13.401(2), b=19.173(5), c=8.079(1) Å, β=98.94(1)°, U=2050.6(8) Å3, Z=4, Dm=1.84(3), Dx=1.84 Mg m−3, and μ(Mo Kα)=2.31 mm−1. Each cerium(III) atom is ennea-coordinated and is in a tri-capped trigonal-prism geometry. They are in a linear polymer, and each cerium(III) atom is bridged to the next metal atom by three carboxylate ligands.
The Study of Metal Colloids Produced by Means of Gas Evaporation Technique. II. Reaction of Metal Sols in Organic Solvents
Authors: Kimura Keisaku 
Published: July 2006

Abstract
The reaction of copper colloid in ethanol was studied. In the beginning of the reaction, very small particles reacted with ethanol producing ethoxide. With the proceeding of the reaction, the 577-nm characteristic copper band showed a red shift together with the broadening of the line width. This was explaind by the size dependence of the particles on the spectrum. Lead colloid was also examined.
Induced Circular Dichroism in the Complexes of Histidine Polypeptides with Methyl Orange. Effect of Distance between Histidine Residues
Authors: Yamamoto Hiroyuki , Nakazawa Ayako , Hayakawa Tadao , Nishi Norio , Naruse Takumi 
Published: July 2006

Abstract
The induced circular dichroism (CD) spectra of the sequential histidine polypeptide–azo dye complexes were measured. The induced CD arose from the dye bound to the polypeptide in the random coil conformation. The intensity of the induced CD decreased with increasing distance between the intramolecular histidine residues.
Amperometric Determination of Silver(I) with Hydrazine Sulfide and Its Estimation in Presence of Lead(II)
Authors: Deshmukh Govind S , Kulkarni Arun G , Joshi Shashikant N 
Published: July 2006

Abstract
Silver(I) has been estimated by an amperometric method using hydrazine sulfide as titrant. The titration is carried out in ammonium tartrate–ammonia supporting electrolyte (pH≈9). Further, this method is extended to determine silver(I) in presence of lead(II). Under these conditions lead(II) reacts only after all silver(I) has been precipitated. The accuracy of the procedure is comparable with that obtained in classical method.
Solvent Effects on Optical and ESR Spectra of One-Electron Reduced Species of Cobalt(III) and Manganese(III) Tetraphenylporphyrins Produced by γ-Radiolysis at 77 K
Authors: Hoshino Mikio , Konishi Shiro , Imamura Masashi 
Published: July 2006

Abstract
One-electron reduction by γ-ray irradiation of cobalt(III) and manganese(III) tetraphenylporphyrins (ClCo(III)TPP, ClMn(III)TPP, and IMn(III)TPP) in ethanol and MTHF(2-methyltetrahydrofuran) solutions at 77 K results in the reduction of the central metals of these porphyrins. From the optical and ESR measurements, the reduced species are found to retain the axial anion, Cl− or I−, in MTHF but not in ethanol. The absorption spectroscopic studies of these porphyrins in ethanol solutions indicate that the axial halide ion is displaced by an ethanol molecule prior to γ-ray irradiation.
Saw-toothed Distributions of Deuterium in Butenes Formed by 1,3-Butadiene Deuteration on a Pt/Al2O3 Catalyst in D2SO4
Authors: Shimazu Katsuaki , Kita Hideaki 
Published: July 2006

Abstract
Saw-toothed distributions of deuterium are observed in butenes produced by the deuteration of 1,3-butadiene on Pt/Al2O3 catalysts suspended in 0.5 M D2SO4. The nature of the saw-tooth is sensitive to the purity of the solution and to the deuterium content of the solution. On the basis of the N-profiles (the distributions of hydrogen equilibrated with surface H/D pool) deduced from the observed distributions of deuterium in butenes, the saw-tooth distribution is explained by the reaction mechanism where cis- and trans-1-methyl-π-allyls are reaction intermediates for the formation of cis-2-butene and the other isomers of 1-and trans-2-butenes respectively.
Kinetic Studies of Fast Equilibrium by Means of High-performance Liquid Chromatography. VI. Separation of Rotamers of Formanilide
Authors: Moriyasu Masataka , Kawanishi Kazuko , Kato Atsushi , Hashimoto Yohei 
Published: July 2006

Abstract
The restricted rotation about the carbon–nitrogen bond of formanilide has been investigated by high-performance liquid chromatography. At lower temperatures, two peaks corresponding to two dynamic rotamers (E- and Z-form) have appeared on chromatograms, whereas at higher temperatures they have not been separated and a single peak has appeared on chromatograms, due to rapid bond rotation. The equilibrium concentration ratio of E- to Z-form has been found to vary in different solvents, suggesting the presence of solute–solvent and solute–solute interactions such as hydrogen bond formation. Determination of kinetic characteristics such as rate constant and activation energy of fast reactions has been established by high-performance liquid chromatography. The authors have named the present method “dynamic high-performance liquid chromatography,” in imitation of “dynamic nuclear magnetic resonance spectroscopy” which traces fast equilibrium.
Far Ultraviolet Electric Linear Dichroism. II. Pulsed Electric Dichroism Apparatus and Dichroic Spectra of Collagen in Aqueous Solution in the 230–187 nm Wavelength Region
Authors: Yamaoka Kiwamu , Asato Manabu , Matsuda Koichiro , Ueda Kazuyoshi 
Published: July 2006

Abstract
A Pulsed electric linear dichroism (ELD) apparatus is described for studying the optical properties and solution conformation of biologically important macromolecules whose chromophores absorb light in the far ultraviolet region. This apparatus is capable of generating a rectangular-wave electric pulse field with a duration of 5 μs–5 ms and an amplitude of 0.2–8 kV over the 360–185 nm region. A special feature to this apparatus is its ability to record both parallel and perpendicular dichroism signals simultaneously and independently. To prove the instrumental performance, some dichroic spectra of calfskin collagen solution (pH 3.16 and concentration 0.03 g dm−3) in 0.001 mol dm−3 H3PO4 were measured in the 230–187 nm region, where the peptide chromophore shows a broad absorption spectrum. The reduced dichroism of collagen was positive but not constant throughout the wavelength region. A detailed analysis revealed that the peptide spectrum contains three overlapping absorption bands centered at 219, 200, and 189 nm. These transition moments were found to be inclined at ±(50.6–51.0°) (219 nm), ±(48.8–49.5°) (200 nm), and ±(56.0–55.8°) (189 nm) relative to the orientation axis of a triple-stranded collagen helix.
Equilibrium and Rate Data on Some Arsenite Transesterification Reactions
Authors: Edwards John O , Okumura Akiko , Rieger Philip H , Taylor Catherine M , Toyomi Yuiko 
Published: July 2006

Abstract
The arsenite transesterification reaction As(OCH3)3+ HOR\ightleftharpoonsAs(OCH3)2OR+HOCH3(with R equaling benzyl and t-butyl) has been studied in acetonitrile solvent. With benzyl alcohol, K, ΔH°, and ΔS° are 3.6 (25°C), 5.0 kJ mol−1 and 27 J mol−1 K−1 respectively; with t-butyl alcohol, the values are 0.36 (25°C), 4.0 kJ mol−1, and 5 J mol−1 K−1 respectively. The rate law for the approach to equilibrium in the case of benzyl alcohol is:
\frac−d[As(OCH3)3]dt=kf′[As(OCH3)3][HOCH2Ph]2−kr′[As(OCH3)2(OCH2Ph)][HOCH3][HOCH2Ph].
A mechanism which explains the unusual law has been postulated. The slower t-butyl alcohol reaction proceeds by a different mechanism which apparently involves catalysis by small amounts of water in the solvent. The steric effects are very significant.
Cation Ordering in (NaLa)(MgW)O6 with the Perovskite Structure
Authors: Sekiya Tadashi , Yamamoto Tetsuo , Torii Yasuyoshi 
Published: July 2006

Abstract
The title compound with an ordered monoclinic (pseudotetragonal) perovskite structure has been prepared. The lattice constants are a=5.5239(5), b=5.5253(4), c=7.8936(6) Å, β=90.16(1)°, and Z=2. The superstructure was found to be due to a layer-like ordering of Na+ and La3+ ions along alternate c-planes as well as a NaCl-type ordering of Mg2+ and W6+ ions in the octahedral sites. This new compound is the first example for the occurence of cation ordering in the A site. The origin of the superstructure was discussed.
Reaction of Enamines with Acetals or Trialkyl Orthoformates Activated by Lewis Acids
Authors: Takazawa Osamu , Kogami Kunio , Hayashi Kazuo 
Published: July 2006

Abstract
Enamines, prepared readily from various carbonyl compounds, react with acetals or trialkyl orthoformates in the presence of Lewis acids such as BF3·OEt2 to give corresponding β-alkoxy carbonyl compounds or α-dialkoxymethyl carbonyl compounds in good yields. The reaction of dienamines with acetals or trialkyl orthoformates also selectively gives corresponding β,γ-unsaturated α-(α-alkoxyalkyl) carbonyl compounds or β,γ-unsaturated α-diakoxymethyl carbonyl compounds in good yields.
The Selective Extraction and Spectrophotometric Determination of Copper and Silver by the Use of a Thiocrown Compound 1,4,8,11-Tetrathiacyclotetradecane
Authors: Saito Keiitsu , Masuda Yoshitaka , Sekido Eiichi 
Published: July 2006

Abstract
A highly selective solvent extraction and spectrophotometric determination of copper and/or silver is proposed; it is based on the extraction of the ion-pair formed by the copper(I)- or silver(I)-thiocrown ether complex cation and the appropriate dye anion. A comparative study of Bromocresol Green (BCG), Thymol Blue (TB), and picrate ions as the pairing ions for the extraction of copper using a 1,4,8,11-tetrathiacyclotetradecane (TTCT) solution of 1,2-dichloroethane is described. The use of BCG gave the highest sensitivity among these three kinds of anions and made it possible to determine copper in the range of 0.6–3.2 μg ml−1. The interferences of six kinds of cations and four kinds of anions were examined; only Ni2+ and ClO4− interfered, and they slightly. The separation by the extraction of silver and/or copper with TTCT solution of 1,2-dichloroethane from an aqueous solution containing seven kinds of metal ions (Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Ag+) in the presence of picrate ion (Pic−) was also examined. Silver was first extracted quantitatively as the ion-pair compound, [Ag(ttct)2]+Pic−, and then copper as [Cu(ttct)]+Pic− after having been reduced to copper(I). The absorption maximum of both extracted species lies at 378 nm (ε:1.8×104), and the spectrophotometric determination of these metals is possible. This method was successfully applied to the determination of copper and silver in standard samples of steel.
Total Synthesis of Racemic and Optically Active Coronafacic Acids
Authors: Ohira Susumu 
Published: July 2006

Abstract
(±)-Methyl 3-ethyl-4-oxotricyclo[4.3.0.01,5]nonane-5-carboxylate (4), prepared by the stereoselective alkylation of methyl 4-oxotricyclo[4.3.0.01,5]nonane-5-carboxylate, was reduced with zinc borohydride, and the resultant hydroxy ester was treated with p-toluenesulfonyl chloride to give a mixture of α,β-unsaturated esters, having hydrindan skeletons. The mixture was submitted to hydroboration-oxidation to afford a keto ester, which was hydrolyzed to (±)-coronafacic acid (2). A diastereomeric mixture of l-menthyl 3-ethyl-4-oxotricyclo[4.3.0.01,5]nonane-5-carboxylates, prepared by a modification of the synthesis of (±)-4, was resolved by column chromatography on silica gel, and each diastereomer was converted into (+)-2 and (−)-2 in a similar way as (±)-2.