bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron Spin Resonance of X-Irradiated Single Crystals of Dicyclohexyldiazene 1,2-Dioxide
Authors: Fujii Yoshihisa , Kashiwagi Michio , Nakada Hideki , Kurita Yukio 
Published: July 2006

Abstract
ESR studies of X-irradiated single crystals of dicyclohexyldiazene 1,2-dioxide, (C6H12NO)2, revealed the generation of the stably trapped radicals C6H11N(O)N′H″(O′)C6H11. The principal elements of the g value were found to be 2.0030, 2.0060, and 2.0086. The principal elements of the hyperfine coupling constants were found to be 3.88, 1.53, and 1.38 mT for N, and 1.53, 1.41, and 1.14 mT for H″. The direction cosines of these principal elements, when compared with those of the bonds in the parent molecule, indicate that the radical is formed by addition of a hydrogen atom to the N=N′ double bond without causing a large change in the molecular framework. The spin densities for this radical were calculated to be 0.041 and 0.47 in the 2s and 2p orbitals of the atom N, respectively.
Solvent Dependence of the Circular Dichroism Spectra of Some cis-Dianionobis(ethylenediamine)cobalt(III) Complexes
Authors: Sakaguchi Ushio , Nakazawa Hiroshi , Sakai Kazuhisa , Yoneda Hayami 
Published: July 2006

Abstract
The circular dichroism spectra of some cis-bis(ethylenediamine)cobalt(III) complexes have been measured in several solvents. Among these complexes, the diisothiocyanato complex was found to exhibit a marked solvent dependence; the dominant circular dichroism band in the lowest energy spin-allowed transition region changed its sign upon going from, e.g., water, dimethyl sulfoxide, methanol, or acetone to pyridine or its analogues. Coupled with the proton NMR spectra and a similar solvent dependence of the circular dichroism spectra of nitroisothiocyanatobis(ethylenediamine)cobalt(III) and diisothiocyanatobis(ethylenediamine)chromium(III) complexes, we ascribed the origin of the sign inversion of the diisothiocyanato complex to the stereoselective hydrogen bonding of cis N–HB with pyridine-like molecules, where cis N–HB is the hydrogen bonded to the nitrogen atom cis to NCS− and directed off the molecular twofold axis.
Mechanisms of Enzymatic S-Oxygenation of Thioanisole Derivatives and O-Demethylation of Anisole Derivatives Promoted by Both Microsomes and a Reconstituted System with Purified Cytochrome P-450
Authors: Watanabe Yoshihito , Oae Shigeru , Iyanagi Takashi 
Published: July 2006

Abstract
Oxygenations of thioanisole derivatives have been shown to be promoted with phenobarbital induced rabbit liver microsomes. In order to understand the mechanistic details of the oxygenations, a kinetic study on the S-oxygenation promoted by a reconstituted system with purified cytochrome P-450 has been carried out. Log(Vmax) were correlated with the one electron oxidation potentials of the sulfides (Ep). The oxygenation is considered to proceed via one electron transfer from the sulfides to the iron-bound “oxenoid” intermediate of the enzyme. A similar O-demethylation of anisoles has been investigated. In the oxidative O-demethylation of p-methoxy-d3-anisole with rabbit liver microsomes, an intramolecular kinetic isotope effect of 3.4 was observed. Meanwhile, a large isotope effect of 5.1 was observed in the competitive O-demethylation of p-dimethoxybenzene and p-di(methoxy-d3) benzene. In order to clarify the oxidation pathway of O-demethylation with the enzymatic system of cytochrome P-450, the rates of the O-demethylation of p-substituted anisoles have been measured. Unlike the enzymatic oxygenation of sulfides, there was no correlation between the rates of O-demethylation reaction and one electron oxidation potentials of anisoles. These observations suggest that the O-demethylation of anisoles proceeds via the initial hydrogen abstraction with the iron-bound “oxenoid” intermediate of the cytochrome P-450.
The Thermodynamics of Ion Exchange of Singly Charged Cobalt(III) Complex with Sodium Ions on Cation Exchange Resin
Authors: Kurotaki Katsumi , Kawamura Shoichi 
Published: July 2006

Abstract
Thermodynamic values of the ion exchange of [CoIIIL4B2]+ (L=NH3, ethylenediamine/2 (=en/2), or dimethylglyoximato (1−) anion/2 (=dmgH/2); B=NO2−, NCS−, CO32−/2, NH3, or C2H5NH2) with Na+ on Dowex AG 50W-X2 resin were determined at 25 °C by measurements of selectivity coefficient and heat of exchange. Heats and entropies are negative for the uptake of [Co(NH3)4(NO2)2]+ and [Co(en)2B2]+, while they are positive for the uptake of [Co(dmgH)2(C2H5NH2)2]+.
Effect of Polymorphic Transition on Molecular Diffusion in Some Molecular Complexes, as Evidenced by Exchange Reaction Rate and by Electrical Resistivity
Authors: Inabe Tamotsu , Matsunaga Yoshio 
Published: July 2006

Abstract
Marked increases in electron donor and acceptor-exchange reaction rates and also large differences in the temperature dependence of the electrical resistivity of polycrystalline compactions between the first and the second heating processes indicate the enhanced molecular diffusion near and above the polymorphic transition temperatures of some molecular complexes.
Liquid Crystal Formation in Binary Systems. VI. Smectic Liquid Crystals Induced in N-[4-(Diethylamino)benzylidene]-4-ethoxyaniline-N-(4-Nitrobenzylidene)-4-ethoxy-aniline and Related Systems
Authors: Araya Kotaro , Homura Noriko , Matsunaga Yoshio 
Published: July 2006

Abstract
The replacement of the dimethylamino group in the combinations of the 4-dimethylamino-4-alkoxy and 4-nitro-4-alkoxy derivatives of N-benzylideneaniline by a diethylamino group favors the induction of smectic phases in their mixtures.
Zero-field Energy Levels in Near-doubly-degenerate Triplet States
Authors: Higuchi Jiro 
Published: July 2006

Abstract
The zero-field energy levels in neardoubly-degenerate triplet states are discussed on molecules which are distorted so as to lose their trigonal symmetry axes. As an example, the second excited triplet states of a deformed benzene molecule are calculated from the electron spin-spin interactions.
Comparison of Association Constants Derived from CD and UV Measurements. The Case of Λ-Tris(ethylenediamine)cobalt(III) and Δ-Tris((1R, 2R)-1,2-cyclohexanediamine)cobalt(III) with Thiosulfate Ion
Authors: Yoneda Hayami , Miyoshi Katsuhiko , Matsukawa Hitoshi 
Published: July 2006

Abstract
The association constant KA determined by CD measurement is much smaller than that by UV measurement for the Λ-[Co(en)3]3+–S2O32− system in water, whereas the two kinds of measurements yield almost the same KA values for the Δ-[Co(l-chxn)3]3+–S2O32− system. These results are discussed in relation to possible interaction modes involved.
Dynamic Structure of Pyrimidine-polyribonucleotides in Solution. 1H NMR Studies
Authors: Yamada-Nosaka Atsuko , Nosaka Yoshio , Akasaka Kazuyuki , Hatano Hiroyuki 
Published: July 2006

Abstract
Temperature dependent conformations and molecular motions of pyrimidine polyribonucleotides, poly(C) and poly(U), have been studied in 2H2O solutions (pH 5.8±0.3, 5–72 °C by measuring 1H NMR intensities, chemical shifts, coupling constants, and spin-lattice relaxation times. Below 50 °C, poly(C) exists as a slowly exchanging mixture of double-stranded and single-stranded forms of which only the single-stranded form is observable by 1H NMR. In this temperature range, the single-stranded poly(C) shows a strong base-stacking with dominated C3′-endo anti conformation, whereas above 50 °C it takes partly C2′-endo conformation with destabilization of the helical structure. Poly(U) exists as single strand within the whole temperature range studied, and the bases are nearly unstacked with 58% of C2′-endo conformer. Poly(U) is more flexible than poly(C), which was characterized with rotational correlation times in the order of 10−9–10−10 s.
Studies on Molecular Motion in Lyotropic Mesophases of Hexaethylene Glycol Dodecyl Ether–D2O System by 13C Nuclear Magnetic Resonance
Authors: Mita Shigeru , Kondo Shoichi , Takeda Masatami 
Published: July 2006

Abstract
The 13C spin-lattice relaxation time(T1) and the resonance line width corresponding to T2* were measured for each of the carbons in hexaethylene glycol dodecyl ether–water(D2O) system, which exists as two distinct lyotropic mesophases(neat and middle phase). The line width is very narrow in the isotropic state, such as in organic solvents and in a lower concentration aqueous solution, whereas in a mesophase and in a higher concentration aqueous solution, the line width of the alkyl chain was broadened. Here the line widths for glycol carbons were about an order of magnitude smaller than for an alkyl chain, demonstrating the difference of molecular motion. The chemical shifts of the alkyl chain in the middle phase were different from those in the isotropic state; this difference was clearly shown in the spectrum of the middle/isotropic coexistent phase. 13C-T1 was not sensitive enough to differentiate between the isotropic and the lyotropic phase at room temperature. It was found that T1 did not equal T2* for any of the methylene carbons, the difference being most marked for the terminal methyl carbon in the alkyl chain. The orientational order in the phases had an influence on the T2* values.
Circular Dichroism of N-Acetyl-l-amino Acid Methylamides with Aromatic Side Groups
Authors: Matsuura Hiroatsu , Hasegawa Kodo , Miyazawa Tatsuo 
Published: July 2006

Abstract
The circular dichroism (CD) and its temperature dependence were studied on N-acetyl-l-phenylalanine methylamide, N-acetyl-l-tyrosine methylamide, and N-acetyl-l-tryptophan methylamide, as model molecules of aromatic amino acid residues in proteins. The CD spectra indicated that the increase in temperature and the decrease in solvent polarity give a similar effect on the amide π*←n transition. The CD behavior of the tryptophan derivative was different from that of the phenylalanine and tyrosine derivatives, suggesting that the bulkier indolyl side group interacts with the peptide backbone in a different way. The noticeable temperature dependence of the CD intensities in the 250–300 nm region observed for the phenylalanine and tryptophan derivatives suggested the coexistence of various conformers at higher temperatures.
A Conductance Study of Alkali Metal Ion-Benzo-15-crown-5 Complexes in Propylene Carbonate
Authors: Takeda Yasuyuki 
Published: July 2006

Abstract
The formation constants (KML+) for 1:1 complexes of benzo-15-crown-5 (B15C5) with alkali metal ions at 25 °C, and the enthalpy (ΔH) and entropy changes (ΔS) of the K+–B15C5 complex in propylene carbonate (PC) have been determined conductometrically. The KML+ series of B15C5 for the alkali metal ions are given in the order Na+&gt;Li+&gt;K+&gt;Rb+&gt;Cs+. The selectivity tendency of B15C5 for the alkali metal ions is consistent with the size-fit concept, however, B15C5 shows poor selectivity. Both the ΔH and ΔS values for the complexation reaction of B15C5 with K+ are negative. In the cases of Na+, K+, Rb+, and Cs+, the size of the moving entity in PC is larger for the B15C5 complex than for the corresponding alkali metal ion, while, in the case of Li+, that is completely the reverse.
Distinct Activation Energies for Temporal and Spatial Oscillations in the Belousov-Zhabotinskii Reaction
Authors: Yoshikawa Kenichi 
Published: July 2006

Abstract
Temperature dependence of the frequencies in temporal oscillations and of the moving-wave velocities of concentric waves in spatial oscillation in the Belousov-Zhabotinskii reaction was studied in detail using the same starting concentrations of the reactants. When cerium ions were used as catalyst, the activation energies were found to be 60–65 kJ/mol for the temporal oscillation and 46±4 kJ/mol for the spatial oscillation. The difference in the activation energies was well explained by the theoretical prediction based on kinetic-diffusion coupling. When [Fe(phen)32+] or [Fe(bpy)32+] was used as catalyst, the apparent activation energy in the temporal oscillation depends markedly on the concentration of the catalyst used.
Optical Studies on the Lowest Triplet State of Chromone
Authors: Yamada Yasuko , Yamauchi Seigo , Hirota Noboru 
Published: July 2006

Abstract
The lowest excited triplet state of chromone was investigated via high resolution phosphorescence spectra, phosphorescence excitation spectra and triplet lifetimes in the neat crystal, in the single crystals of durene and benzoic acid at liquid helium temperature. Including the cases in other solvents such as 3-methylpentane, methylcyclohexane and ethanol, the lowest triplet state was assigned to be ππ* type contrary to the previous assignment. The triplet sublevel properties including the sublevel spectra were obtained in the benzoic acid host. Ty is radiative at the 0-0 band. Tz is radiative at the non to tally symmetric bands and is active in nonradiative transitions. These properties are discussed and compared with those of other carbonyl compounds. A brief comment on the photochemical reactions are given.
The Structure and Properties of (η-Cyclopentadienyl)(O-methyl dithiocarbonato)(triphenylphosphine)nickel(II)
Authors: Shimoi Mamoru , Ouchi Akira , Sato Shoichi , Saito Yoshihiko 
Published: July 2006

Abstract
The title complex was synthesized, and the structure was determined by means of the X-ray diffraction technique. The crystal is triclinic; space group P\bar1, a=9.944(1), b=14.336(2), c=9.759(1) Å, α=107.00(1), β=117.35(1), γ=76.55(1)°, Z=2, Dx=1.40, Dm=1.36(3) g cm−3, μ(Mo Kα)=1.08 mm−1. The O-methyl dithiocarbonato ion acts as a unidentate ligand, and it is coordinated with the metal through one sulfur atom. The coordination number of the metal is 3 if the cyclopentadienyl is regarded as a unidentate ligand. A series of [(η-cyclopentadienyl)(O-alkyl dithiocarbonato)(trialkyl- or triarylphosphine)nickel(II)], [Ni(C5H5)(S2COR)(PR′3)], where R=CH3, C2H5, CH3(CH2)2, (CH3)2CH, or CH3(CH2)3; R′=C6H5, C6H5CH2, or CH3(CH2)3, were also obtained. The dissociation of the phosphine ligand of the complexes in solution was studied spectrophotometrically, and it was found that the more electron-donative the alkyl group of the O-alkyl dithiocarbonato ligand is, the weaker the phosphorus-nickel bond is.
Syntheses and Structure of Bis(O,O′-diethyl dithiophosphato)bis(hexamethylenetetramine)cadmium(II) and Related Adducts
Authors: Shimoi Mamoru , Ouchi Akira , Aikawa Masahiko , Sato Shoichi , Saito Yoshihiko 
Published: July 2006

Abstract
The title complex was synthesized, and the crystal structure was determined by means of the X-ray diffraction technique. The crystal is monoclinic; space group P21/n, a=16.310(3), b=6.777(1), c=14.576(3) Å, β=96.13(1)°, Z=2, Dx=1.58, Dm=1.55(3) g cm−3, μ(Mo Kα)=1.12 mm−1. The molecule has a center of symmetry, and a distorted octahedron is formed around the central cadmium atom; two O,O′-diethyl dithiophosphato ions (dtp) act as bidentate ligands, and each ligand forms a four-membered chelate ring with its two sulfur atoms on the equatorial plane, while two hexamethylenetetramine molecules are coordinated to the metal atom by their nitrogen atoms from the axial direction. Related adducts, Cd(II)(dtp)2·Xn, where X is a donor and n=1 or 2, were also synthesized, and their structures were compared with those of the corresponding Co(II)(dtp)2·Xn−type complexes.
A New Type of P–C and C–C Bond Cleavage Reactions in α-Trimethylsilyloxy-β-oxo Phosphonates and α-Ethoxy-β-oxo Phosphonates. The Synthesis of Unsymmetrical α-Hydroxy Ketones Utilizing 1:1 Carbonyl Adducts of Diethyl Trimethylsilyl Phosphite with Benzaldehyde
Authors: Sekine Mitsuo , Nakajima Masashi , Hata Tsujiaki 
Published: July 2006

Abstract
α-Lithiated diethyl α-(trimethylsilyloxy)benzylphosphonate underwent facile acylation with various acylating agents to afford the corresponding α-acylated products in good yields. On treatment of the α-acylated products with 1 M NaOH–EtOH (1:1, v/v) the P–C bond was cleaved with elimination of diethyl phosphate to give α-hydroxy ketones predominantly. On the other hand, when diethyl α-acyl-α-ethoxybenzylphosphonates were treated under the same conditions, they were rather stable and recovered. However, the prolonged alkaline treatment or the use of 4 M NaOH–EtOH (1:1, v/v) resulted in the C–C bond cleavage giving carboxylic acids and diethyl α-ethoxybenzylphosphonate in quantitative yields, respectively. The mechanisms of the above two reactions were proposed and discussed in connection with the Perkow reaction and related reactions.
The Photocycloaddition of 6-Substituted Phenanthridines to Electron-rich Olefins
Authors: Futamura Shigeru , Ohta Hiroyuki , Kamiya Yoshio 
Published: July 2006

Abstract
The photocycloaddition reaction of 6-substituted phenanthridines and electron-rich olefins, such as trans-anethole and phenyl vinyl ether, is described. This reaction proceeds from the 1(π,π*) states of 6-substituted phenanthridines via the exciplex to give azocine and/or azetidine derivatives in ethanol.
Silyl Phosphites. XVIII. Versatile Utility of α-(Trimethylsilyloxy)alkylphosphonates as Key Intermediates for Transformation of Aldehydes into Several Carbonyl Derivatives
Authors: Sekine Mitsuo , Nakajima Masashi , Kume Akiko , Hashizume Akio , Hata Tsujiaki 
Published: July 2006

Abstract
Carbonyl addition compounds of diethyl trimethylsilyl phosphite (DTMSP) with aldehydes were converted, by treatment with lithium diisopropylamide (LDA) followed by the successive alkylation and alkaline hydrolysis, to carbonyl derivatives involving aldehydes, unsymmetrical ketones, β,γ-unsaturated ketones, and carboxylic acids. β-Substituted carboxylic esters and γ-substituted lactones were prepared by use of the carbonyl addition compounds of DTMSP with α,β-unsaturated aldehydes.
Synthesis of Naturally Occurring Prenylated Benzophenones. Vismiaphenone A, Vismiaphenone B, and Isovismiaphenone B
Authors: Pathak Ved Prakash , Khanna Rajinder Nath 
Published: July 2006

Abstract
2,4,6-Trihydroxybenzophenone on prenylation with 2-methyl-3-buten-2-ol in the presence of (C2H5)2O·BF3 yielded 2,4,6-trihydroxy-3,5-diprenylbenzophenone (3), 2,6-dihydroxy-4-prenyloxybenzophenone, 2,6-dihydroxy-3-prenyl-4-prenyloxybenzophenone, a benzodipyran and 6-benzoyl-5,7-dihydroxy-2,2-dimethyl-3-prenylchroman. 3 on reaction with 2 moles of p-toluenesulfonyl chloride followed by methylation and detosylation gave a naturally occurring benzophenone, vismiaphenone A (12). Cyclodehydrogenation of 6-hydroxy-3,5-diprenyl-2,4-ditosyloxybenzophenone gave 8-benzoyl-2,2-dimethyl-6-prenyl-5,7-ditosyloxy-2H-1-benzopyran, which on detosylation gave another naturally occurring benzophenone, isovismiaphenone B, while cyclodehydrogenation of 3 gave vismiaphenone B, another naturally occurring benzophenone. 2,4-Dihydroxy-6-methoxy-benzophenone on similar treatment with 2-methyl-3-buten-2-ol afforded 12 directly.
The Condensation of Isatin with o-Phenylenediamine
Authors: Niume Kazuma , Kurosawa Shigeru , Toda Fujio , Hasegawa Masaki , Iwakura Yoshio 
Published: July 2006

Abstract
The condensation of isatin with o-phenylenediamine has been studied in various kinds of solvents. The reaction gave pure indolo[2,3-b]quinoxaline (1) in acidic solvents, while it gave a mixture containing at least two out three compounds, 1, an anil and a spiro compound, in neutral or basic organic solvents. The anil and spiro compounds were converted to 1 in the presence of acid or by heating them above their melting points. The mechanism of the formation of these compounds and the conversion could be explained by the presence of the intermediate of the adduct formed between the amino groups of o-phenylenediamine and the β-carbonyl of isatin.
The Disproportionation of cis-Bicyclo[4.3.0]nona-3,7-diene Catalyzed by Fe(CO)5 and Cp2Fe2(CO)4
Authors: Kagayama Takashi , Okabayashi Shinji , Amaike Yoichi , Matsukawa Yasuo , Ishii Yasutaka , Ogawa Masaya 
Published: July 2006

Abstract
cis-Bicyclo[4.3.0]nona-3,7-diene (1) was catalytically disproportionated by the use of Fe(CO)5 and Cp2Fe2(CO)4 to bicyclo[4.3.0]non-1(6)-ene (3) and indan (4). However, the same reaction catalyzed by the use of other metal carbonyls gave merely small amounts of 3 and 4, while those using Pd– and Rh–carbons yielded only 4 and the starting material, 1, respectively.
Optical Resolution of 2-(Anilinomethyl)pyrrolidine
Authors: Saigo Kazuhiko , Tanaka Jun , Nohira Hiroyuki 
Published: July 2006

Abstract
(±)-2-(Anilinomethyl)pyrrolidine, prepared from (±)-5-oxopyrrolidine-2-carboxylic acid, was effectively resolved into a pair of the enantiomers by fractional crystallization of its mandelic acid salt. Moreover, the preferential crystallization of its p-hydroxybenzoic acid salt was found to give both enantiomers in high optical purities by alternate seeding.
A Cyclization of Humulene by Means of a Mercuric Salt in Aceto- and Benzonitrile
Authors: Hayano Kiyoharu , Shirahama Haruhisa , Matsumoto Takeshi 
Published: July 2006

Abstract
Humulene was converted to 3,6-secoprotoilludane derivatives by treatment with mercury(II) trifluoroacetate in aceto- and benzonitrile.
In-vitro Clot Forming Properties of Polyelectrolyte Complexes of [2-(Diethylamino)ethyl]dextran Hydrochloride with Poly(sodium-l-glutamate) and of Sodium Carboxymethyldextran with Chitosan
Authors: Kikuchi Yasuo , Takebayashi Tsutomu 
Published: July 2006

Abstract
Polyelectrolyte complexes prepared at higher hydrogen ion concentrations may form clots in higher quantities than those prepared at lower hydrogen ion concentrations, irrespective of the content of anticoagulant reagents. This difference is attributable to the difference in molecular structure of polyelectrolyte complexes, especially to the presence of carboxyl groups.
Conformation en Solution des Benzile-monoximes et des Dichloro-4,4′ benzile-monoximes E et Z
Authors: Bernadou Jean , Fayet Jean Pierre , Bonnafous Monique , Mauret Pierre 
Published: July 2006

Abstract
Les auteurs ont synthétisé deux benzile-monoximes et deux dichloro-4,4′ benzile-monoximes. L’ introduction de deux atomes de chlore en para sur les cycles permet, par comparaison des moments dipolaires expérimentaux et calculés, de confirmer les configurations et de préciser les conformations de chaque isomère.
Hydrogenolysis and Hydrogenation of Ethylene on LaCoO3
Authors: Ulla Maria Alicia , Lombardo Eduardo Agustin 
Published: July 2006

Abstract
The hydrogenation and hydrogenolitic activity of LaCoO3 reported by Ichimura et al. can be rationalized in terms of the current literature by a model in which Co°, produced under reaction conditions, is the locus of catalytic activity. This interpretation disagrees with the model supported by the authors.
The Extractability of Potassium as Picrates (KPic and K(L)Pic, L: 18-Crown-6) and Its Relationship to the Properties of the Solvents
Authors: Iwachido Tadashi , Minami Masayoshi , Naito Hirohiko , Tôei Kyoji 
Published: July 2006

Abstract
The distribution ratios, D,of potassium between an aqueous KCl solution and 57 organic solvents (8 alcohols, 12 ketones, 6 esters, 3 ethers, and 28 hydrocarbons(24 halo- and 2 nitro-substituted and 2 unsubstituted)) were determined in the presence or in the absence of L. The presence of L markedly enhances the extractability of potassium when the halogenated hydrocarbon solvents are used, but only a slight enhancement can be observed for the oxygen-containing solvents. Among the properties showing good correlations with D, Hansen’s three-dimensional solubility parameters and Dimroth’s ET values are most satisfactory for their applicability to a wide variety of solvents.