bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Crystal and Molecular Structure of the Aquabis(cyclo-l-histidyl-l-histidylato)dicopper(II) Perchlorate Hydrate [H2O Cu2(C12H13N6O2)2](ClO4)2·3.5H2O
Authors: Kojima Yoshitane , Hirotsu Ken , Matsumoto Keiji 
Published: July 2006

Abstract
The crystal structure of the title compound has been determined by a three-dimensional X-ray structure analysis, using 4563 counter intensity data. The crystals are monoclinic, with a=22.97(2), b=15.89(1), c=10.00(1) Å, β=100.1(1)°, space group P21, and Z=4. The structure was solved by the Patterson and Fourier technique and was refined by the block-diagonal least-squares method to R=0.061. The unit cell contains two crystallographically independent complex cations, the structure of which are very similar to each other. The complex cation is dimeric; there are two Cu atoms, and each of the two cyclo-l-histidyl-l-histidylato ligands bridges two metal atoms. Except for the aqua ligand, the main body of the complex has an approximate twofold axis which passes through the two metal atoms and relates the ligands to each other. The two Gu atoms have different coordination geometries. One Gu atom has a flattened tetrahedral coordination by 4N atoms, whereas the other is surrounded by 2N and 3O atoms and is intermediate between the square pyramid and the trigonal bipyramid.
A Re-investigation of the Dimer ESR Spectra in Several Quadridentate Schiff Base Complexes of Copper(II)
Authors: Chikira Makoto , Yokoi Hiroshi 
Published: July 2006

Abstract
The angle between the g⁄⁄ axis and the copper-copper axis in most parallel planar dimers of the quadridentate salicylaldehyde Schiff base complexes of copper(II) in toluene or xylene has been reconfirmed to be not ≈35°, but ≈17°, by a computer simulation of the dimer ESR spectra at both the K and X-bands. In order to remedy the shortcomings of the so-called point-dipole approximation generally used in the simulation, a delocalization model, in which the delocalization of each unpaired electron on the copper atom and its surrounding four ligand atoms is explicitly taken into consideration, has been discussed in some detail. The delocalization effect has been proven to be highly significant in estimating dimeric structures reliably. An application of this model to the structural estimation of several dimers in solutions has also been made.
Preparation and Properties of Pd(II) and Pt(II) Complexes of N-Picolinoyl-S,S-tetramethylenesulfilimine, N-Trimethyl-ammoniopicolinamidate, and Related Ylides
Authors: Kise Hideo , End\={o} Hiroyuki , Sen\={o} Manabu 
Published: July 2006

Abstract
The reactions of N-picolinoyl-S,S-tetramethylenesulrilimine and N-trimethylammoniopicolinamidate with dichlorobis(benzonitrile)palladium(II) and dipotassium tetrachloroplatinate(II) afforded chelate complexes of formula MCl2[Ylide]. The structures of the complexes were examined by IR and NMR spectroscopy, and determined as mononuclear complexes with ligands coordinated through two nitrogen atoms. A reverse relationship between pKa values of the ylides and C=O stretching band frequency shifts on complex formation was found, and the nature of the coordination via ylidic nitrogen was discussed in terms of σ- and π-character of the ligands in the chelate complexes and several related bis-ylide complexes.
The Consitution of NaPO3–GeO2 Melts
Authors: Watanabe Makoto , Ito Masao , Sato Shoji , Yamada Tamotsu 
Published: July 2006

Abstract
The glassy and crystalline thermal products were prepared by heating a mixture of sodium phosphate glass and germanium dioxide with P/Ge ratios of 1.0–300 at 1000 °C for 3 h in a platinum crucible, and by then rapidly quenching the resulting melt. The thermal products with P/Ge ratios larger than 50 were glassy. The products with P/Ge ratios smaller than 30 were a mixture of glassy and crystalline substances, and the quantity of the glassy substance in the mixture increased with an increase in the P/Ge ratio. The crystalline substance was insoluble in water. From the results of the distribution and the average chain length of the condensed phosphates present in the glassy thermal products, it was concluded that the glass has P–O–Ge linkages and that the most reasonable chemical structure of the glass is (Remark: Graphics omitted.). The colorimetric determination of the phosphorus and germanium contained in the crystalline thermal product showed that the P/Ge ratio of the crystalline substance is 1.3. The value of the P/Ge ratio corresponds to that of Ge3(PO4)4.
Photochemistry of Heterocyclic Compounds. VII. Photochemical Reaction of 2,5-Diphenyl-1,3,4-oxadiazole with Benzo[b]thiophenes
Authors: Oe K\={o}ji , Tashiro Masashi , Tsuge Otohiko 
Published: July 2006

Abstract
Irradiation of 2,5-diphenyloxadiazole 1 with benzothiophene 6a gives 3-benzoylbenzothiophene 7, its benzoylhydrazone 8, and/or the oxadiazepine 9; the yields depended on the nature of solvents. With benzophenone as a sensitizer, the photochemical reaction of 1 with 6a forms the [2+2] cycloadduct 12. It is found that 9 is photochemically dissociated to 1 and 6a. In the case of 2-methylbenzothiophene 6b, 3-benzoyl-2-methylbenzothiophene benzoylhydrazone 18 is formed, and with benzophenone as a sensitizer the [2+2] cycloadduct 19 is obtained. In the absence or presence of benzophenone, however, irradiation of 1 with 3-methylbenzothiophene 6c gives the [2+2] cycloadduct 20. The photochemical reaction of 1 with 6a or 6b in the presence of iodine gives the corresponding 3-benzoylbenzothiophene, 7 or 21, and benzoylhydrazone, 8 or 18, respectively. In the case of 6c, however, the [2+2] cycloadduct 23 is formed, together with 2-benzoyl-3-methylbenzothiophene 22. Mechanistic considerations of these reactions are also described.
A New Synthesis of Flavones by the Reaction of 2-Phenyl-2H-1-benzopyrans with Potassium Permanganate
Authors: Ashihara Yoshihiro , Nagata Yasuyuki , Kurosawa Kazu 
Published: July 2006

Abstract
The oxidation often 2-phenyl-2H-1-benzopyrans with potassium permanganate in acetone has been found to give the corresponding flavones in 8–73% yields. The reaction mechanism is discussed on the basis of the substituent effect and the oxidations of related compounds.
The Reaction of N-Imidoylsulfimides with Carbon Disulfide
Authors: Yoshida Hiroshi , Ogata Tsuyoshi , Inokawa Saburo 
Published: July 2006

Abstract
The reaction of S,S-diphenyl- and S,S-dimethyl-N-imidoylsulfimides (1 and 2) with carbon disulfide was studied. 1 yielded nitrile, isothiocyanate, diphenyl sulfide, and sulfur, whereas 2 gave N-thiocarbonyl-S,S-dimethylsulfimide together with isothiocyanate. Kinetic studies indicate that the reaction proceeds via a [2+2]cycloaddition mechnism, as is shown by the small effects of the solvents and the substitutent on the rate.
1,3-Dipolar Cycloadditions to Bicyclic Olefins. II. The Effects of Non-aromatic Polar Solvents on the exo/endo Product Ratios in 1,3-Dipolar Cycloadditions to Norbornadienes
Authors: Taniguchi Hisaji , Yoshida Yoshihiro , Imoto Eiji 
Published: July 2006

Abstract
The exo/endo product ratios for three types of 1,3-dipolar cycloadditions of phenylglyoxylonitrile oxide(1) to 2,3-bis(methoxycarbonyl)norbornadiene(2a), norbornadiene, and 2,3-dicyanonorbornadiene decrease with increasing ET value of the non-aromatic polar solvent used. The exo/endo ratio in the reaction of 1 with 2a is larger than unity, but the value of ΔHexo\eweq−ΔHendo\eweq is nevertheless positive. This phenomenon is attributed to the relatively large positive value of ΔSexo\eweq−ΔSendo\eweq, that is, ΔGexo\eweq−ΔGendo\eweq&lt;0 at ordinary temperatures. On the basis of these results, the conditions, under which the exo/endo ratio in the reaction of 1 with 2a is smaller than unity, were determined. The results can be reasonably explained by the assumption that the dipole moment of the endo-form in the transition state is greater than that of the exo-form.
Solid-Phase Syntheses of Glu20Ala20Phe and Ala20Glu20Phe by the Step-by-step Coupling of Dipeptide and Tetrapeptide
Authors: Takahashi Sho 
Published: July 2006

Abstract
Glu20Ala20Phe, (I), and Ala20Glu20Phe, (II), were synthesized by the step-by-step coupling of Nα-t-butoxycarbonyl (BOC-) derivatives of Ala–Ala and (γ-benzyl–Glu)4 to phenylalanyl-1% crosslinked polystyrene resin using dicyclohexylcarbodiimide. The products were cleaved from the resin with hydrogen bromide in acetic acid and purified by gel filtration, followed by DEAE-cellulose chromatography, with yields of approximately 10% for both of the hentetracontapeptides. The optical purities of the glutamic acid and alanine incorporated in the pep tides, I and II, were estimated as 1 and 5% respectively from the analysis of the diastereomeric mixture of dipeptides derived from the reaction between the total acid hydrolyzate of I or II with the N-hydroxysucinimidyl ester of BOC–l-Leu.
Water Vapor Affinity of Potassium Bromide Coated with Potassium Oleate
Authors: Chikazawa Masatoshi , Yamamoto Fujio , Saita Eiko , Kaiho Mamoru , Kanazawa Takafumi 
Published: July 2006

Abstract
The amounts of adsorbed water and the isosteric heats for water vapor adsorption on fine crystals of KBr treated with various amounts of potassium oleate (KOI) were measured. In the adsorption isotherm of untreated KBr, a slight stepped rise of the amount adsorbed was observed, and this step is considered to be due to the two-dimensional condensation of water molecules adsorbed on the uniform surfaces of KBr particles. The monolayer capacity, determined from the adsorption isotherm of KBr by the point B method, agreed with the value calculated according to an adsorptive structure based on the two assumptions that all the surfaces of the KBr particles consist of (100) planes and that one water molecule is adsorbed per regularly distributed Br− site.
A small amount of pre-adsorbed KOI was recognized to prevent the water vapor adsorption on KBr, and conversely, this effect disappeared with increasing KOI content while the hygroscopicity of the sample increased markedly. This abnormal increase in the adsorbed amount suggests that the adsorbed water molecules penetrate into the multilayer films of KOI on the KBr.
Chemical Studies on Tuberactinomycin. XII. Syntheses and Antimicrobial Activities of [Ala3, Ala4]-, [Ala3]-, and [Ala4]-Tuberactinomycin O
Authors: Teshima Tadashi , Nomoto Shinya , Wakamiya Tateaki , Shiba Tetsuo 
Published: July 2006

Abstract
Total syntheses of [Ala3, Ala4]-, [Ala3]-, and [Ala4]-tuberactinomycin O corresponding to deoxy analogs of natural antibiotic tuberactinomycin O were achieved for the purpose of elucidation of relationship between chemical structure and biological activity. Cyclization of the pentapeptide intermediates at two different positions was investigated. Minimum inhibitory concentrations of the synthetic analogs against Mycobacterium or Corynebacterium indicated that both hydroxy groups of two serine residues of tuberactinomycins are not required for antibacterial activity, nor participated to drug-resistancy of bacilli. These analogs were found to have the same conformations in solution as those of natural antibiotic from the results of NMR, ORD, and CD measurements.
Silyl Radicals. XV. Stereochemical Course of Chlorine Abstraction by 1-Methyl-4-t-butyl-1-silacyclohexyl Radicals from Polychloroalkane
Authors: Sakurai Hideki , Murakami Masashi 
Published: July 2006

Abstract
The isomerically pure cis and trans 1-methyl-4-t-butyl-1-silacyclohexane were subjected to the free radical chlorination with carbon tetrachloride in the presence of a catalytic amount of benzoyl peroxide under UV irradiation at 0 °C, affording the corresponding chlorosilanes with retention of configuration. With less reactive polyhalocarbons, however, less stereospecific products were obtained. A mechanism that inversion of silyl radicals competes with chlorine abstraction is proposed. Relative rates of each reaction were analyzed with a steadystate assumption.
Hetera-p-carbophanes. IX. Effect of the Chain-Length of Alkoxyl Groups on the Barrier to Internal Rotation of Dialkoxybenzene Rings in Dialkoxydioxodioxa[n]paracyclophanes
Authors: Sakamoto Kazuhiko , Oki Michinori 
Published: July 2006

Abstract
Dioxodioxa[n]paracyclophanes which carry two methoxyl, ethoxyl, or propoxyl groups at the aromatic rings were prepared by condensation of α,ω-diols with corresponding 2,5-dialkoxy-1,4-phenylenediacetyl dichlorides under high dilution conditions. Dynamic 1H NMR spectra of these compounds show that barriers to internal rotation of the dialkoxybenzene rings are affected by the chain-length of the alkoxyl groups; the longer the chain length, the higher the barrier.
Electrophilic Sulfides(II) as a Novel Catalyst. V. Structure, Nucleophilicity, and Steric Compression of Stabilized Sulfur Ylides as Observed by 13C-NMR Spectroscopy
Authors: Matsuyama Haruo , Minato Hiroshi , Kobayashi Michio 
Published: July 2006

Abstract
13C chemical shifts and 13C–H spin coupling constants (179.7 Hz) of the ylide carbons of two dialkylsulfonium phenacylides show that the ylide carbons are basically sp2. Large upfield shifts (−9.5–−11.8 ppm) of carbonyl carbon signals (δC 181.7 and 179.2) of the ylides from those of the corresponding salts (δC 191.2 and 191.0) suggest significant contribution of a betaine structure. The 13C-NMR spectrum of methylisopropylsulfonium phenacylide showed two non-equivalent methyl signals (δC 17.9 and 18.4) for the isopropyl group. Steric γ-effects on ylide carbon chemical shifts were observed with several alkylsulfonium bis(methoxycarbonyl)methylides and trialkylsulfonium salts.
Annihilation of the Catalytic Activity in Butene Isomerization of Porous Vycor Glass by Washing with EDTA Aqueous Solution
Authors: Hirai Shoji , Morikawa Akira , Ishinaga Yoshio , Otsuka Kiyoshi , Wada Yuji 
Published: July 2006

Abstract
The catalytic activity of porous Vycor glass in the isomerization of butenes was eliminated by washing the glass with EDTA aqueous solution, though the contents of Al and Zr in the glass remained unchanged. Destruction by decationation of active sites of silica-alumina character has been suggested.
Effect of a Polymer Ligand on Oxidation of Thiophenol Catalyzed by Cobaloximes
Authors: Nishikawa Hiroshi , Kasai Masanori , Terada Ei-ichi , Tsuchida Eishun 
Published: July 2006

Abstract
The oxidation mechanism of thiophenol catalyzed by cobaloximes was deduced by spectroscopic measurement of the oxidation rate at various concentrations of the reactants, the reaction being a Michaelis-Menten type reaction. Addition of polymer ligands such as poly(4-vinylpyridine) and 4-vinylpyridine-styrene copolymer, stabilizing the intermediate similar to a Michaelis complex, resulted in an increase in the oxidation rate under low substrate concentration.
Oxidation Activity and Acid-base Properties of Mixed Oxide Catalysts Containing Titania. II. The TiO2–V2O5–P2O5 System
Authors: Ai Mamoru 
Published: July 2006

Abstract
The acidity and basicity of a series of TiO2–V2O5–P2O5(atomic ratio Ti : V : P=9 : 1 : x) catalysts with different P2O5 contents (x=0–18), were measured by studying the adsorption of the basic and acidic molecules in the gas phase, using both the static and pulse methods. TiO2–V2O5(V/Ti=1/9) is rather basic, but this catalyst can be modified from basic to acidic by the introduction of P2O5. The vapor-phase oxidation of butadiene and 1-butene, which were chosen as electron-donor-type reactants, and that of acetic acid, as an acidic reactant, were carried out in the presence of an excess of air, and then the relationship between the catalytic behavior and the acid-base properties was investigated. The results support an earlier proposal that the activity and selectivity in mild oxidation can be interpreted in terms of the acid-base properties of the catalyst and the reactant.
The Interaction of Bovine Plasma Albumin with Cationic Detergent. Studies by Binding Isotherm, Optical Rotation and Difference Spectrum
Authors: Hiramatsu Koichi , Ueda Chiaki , Iwata Koji , Arikawa Kinichi , Aoki Koichiro 
Published: July 2006

Abstract
Binding isotherms were determined at pH 6.9 for systems of bovine plasma albumin (BPA) and cationic detergents at 25°C and 5 °C. Detergents used were: hexadecyltrimethylammonium bromide (HTAB), tetradecyltrimethylammonium bromide (TTAB), dodecyltrimethylammonium bromide (DTAB) and decyltrimethylammonium bromide (DeTAB). Binding affinity of the cationic detergent to BPA increased with the increase in the carbon number of the detergent, and with the increase in temperature. The first five detergent ions were bound to BPA statistically at 25 °C, and succeeding detergent ions were bound cooperatively. Thermodynamic parameters indicated that the statistical binding was caused mainly by the hydrophobic bonding. Measurements of −[α]233 and −[α]313 at pH 5.2 revealed that the conformation of BPA changed when it complexed with the cationic detergent. The conformation of BPA changed slightly when 5–8 HTAB or TTAB’s were bound, and a second large conformational change occurred when 15–20 of these detergent ions were bound. DTAB and DeTAB caused only the first conformational change. Thus HTAB and TTAB are stronger unfolders of BPA than DTAB and DeTAB. The UV difference spectrum of the complex BPA–TTAB showed a red shift of the peak of Try residue (e.g. 292 nm), being in contrast to the blue shift of the same peak in the complex BPA–sodium dodecyl sulfate. It is suggested that BPA is unfolded, at least, in the NH2 terminal half by binding with cationic detergent.
Molecular Structure of Molybdenum Tetrafluoride Oxide Studied by Gas Electron Diffraction
Authors: Iijima Kinya 
Published: July 2006

Abstract
The molecular structure of molybdenum tetrafluoride oxide was determined to be square-pyramidal by a sector-microphotometer method of gas electron diffraction. The following molecular parameters were obtained by a least-squares method: rg(Mo–F)=1.836±0.003 Å, rg(Mo–O)=1.650±0.007 Å, and rg(F···F(s))=2.522±0.005 Å. The molecular structure is similar to those of WCl4O and MoCl4O, but significantly different from those of XeF4O and IF5. The molecular intensities calculated using the TFD or RHFS phase angle for molybdenum atom were in disagreement with the observed ones.
An INDO-UHF Molecular Orbital Study of the Conformations and Electronic Structures of Some σ-Type Radicals
Authors: Ohkubo Katsutoshi , Sato Hiroyuki 
Published: July 2006

Abstract
The equilibrium geometric parameters determined for XC=Y radicals (HC=O, CH3C=O, NH2C=O, and HC=CH2) are not characterized by their bond lengths but by their X–C–Y angles, which are wide compared with the angles in their parent molecules (XHC=Y). The %s character of the a orbitals on the C atom in XHC=Y was found to be conserved in the %s character and the s-orbital spin density of the same atom in XC=Y radicals: there are linear relationships between them. Some notable features of the unpaired-electron distribution on the frameworks of XC=Y radicals are also discussed in connection with the electronic properties of the σ radicals.
Determination of Chlorine in Rocks, Soils and Organic Materials by Heating Powdered Sample in Strong Phosphoric Acid, and Some Additional Investigations on the Related Reactions
Authors: Terada Kikuo , Hirakawa Saburo , Kiba Toshiyasu 
Published: July 2006

Abstract
The decomposition of several salts in strong phosphoric acid (SPA) was examined. These halides were decomposed and hydrogen halides evolved by heating the samples with SPA at various temperatures. Based on these data an adequate reagent was chosen for the efficient separation of various elements which can form volatile halides. The recommended distillation condition was applied to determine the chlorine content in solid samples, such as rocks, soils or some organic materials. The sample was heated in an SPA medium and a distillate of hydrogen chloride was absorbed in a sodium hydroxide solution. The solution was subjected to volumetric analysis with a silver nitrate solution for chlorine in the range of 10−2 to 10−4 mol and to spectrophotometric determination with mercury thiocyanate for elements less than 10−4 mol. Furthermore, from the results of X-ray diffraction measurements of the original and the SPA-treated samples, it was confirmed that the main crystal structure of a rock sample could be decomposed by heating with SPA. The chlorine analysis was performed for Japan Geological Survey standard rocks, JG-1 and JB-1, and a synthesized complex compound.
Thermal Behavior of the Clathrate Compounds of the Type M(diam)M′(CN)4·2C6H6
Authors: Ohyama Jun-ichi , Tsuchiya Ryokichi , Uehara Akira , Kyuno Eishin 
Published: July 2006

Abstract
The thermal behavior of the guest molecule trapped in the clathrate compounds, M(diam)M′(CN)4·2C6H6, where M and M′ are bivalent metal atoms and diam is two ammonia molecules or one molecule of diamine, and the structural changes of the host lattice upon heating were studied by means of derivatographic and isothermal measurements. In Cd(NH3)2Ni(CN)4·2C6H6, the elimination of guest benzene molecules was found to proceed in two steps. X-Ray powder diffraction patterns suggest that the skeleton of the host is preserved, at least during the first liberation of 1 mol of benzene, but the skeleton collapses after the complete liberation of benzene and ammonia. The host skeleton of Cd(en)Ni(CN)4·2C6H6 was preserved till the liberation of 75% of benzene. The activation energies were a little larger than the respective enthalpy changes. The replacement of M′=Ni by Pd or of M′=Cd by Hg in the clathrate compounds, if M and diamine are the same, scarcely changes the activation energy for the liberation of the guest molecule, but the replacement of M and diamine by other ones somewhat changes the activation energy.
Reaction of Dimethyl Sulfoxide–Trifluoroacetic Anhydride with Anilines, Phenols, and Thiophenols
Authors: Hiraki Yuji , Kamiya Masahiro , Tanikaga Rikuhei , Ono Noboru , Kaji Aritsune 
Published: July 2006

Abstract
The reaction of dimethyl sulfoxide–trifluoroacetic anhydride complex with anilines, phenols, and thiophenols was studied, and the following results were obtained. (1) The yields of a methylthiomethylated product were improved with anilines. The reaction proceeded without significant amount of tar, the unreacted anilines being easily recovered. (2) Selective ortho-methylthiomethylation took place with phenols in good yields at lower temperature, para-methylthiomethylation occurring at higher temperature. (3) Methylthiomethylation took place with thiophenols on a sulfur atom of thiophenol at room temperature in a simple process.
Photolysis in Rigid Matrixes at Low Temperatures. An Intermediate of Photo-dehydrobromination
Authors: Hirayama Satoshi 
Published: July 2006

Abstract
The intermediate of the photo-dehydrobromination of 9-(α-bromopropionyl)anthracene (I) to yield 9-anthryl vinyl ketone (IV) was detected by its electronic spectrum upon photolysis in polar solvent matrixes at 77 K. Approximately 80% of the initial photo-products is trapped as the intermediate. The remainder is observed as the final product IV formed directly from I. The intermediate is stable only below ca. 83 K in EPA. Above this temperature, it decomposes rapidly to form IV. No intermediate was detected for this reaction in the non-polar solvent matrixes at 77 K. Instead, a conformational change of IV with temperature was noticed. Based on the temperature and solvent effects on the stability of the intermediate, a loose structure where a hydrogen bromide is almost completely eliminated via a concerted mechanism is postulated for the intermediate. This is supported by the evidence that the main electrochemical reduction product of I is only 9-propionylanthracene. The temperature effects on the other photochemical reactions of I are also discussed in relation to the allowed molecular motions in rigid matrixes.