bluuebunny/crossref_metadata_2025 huggingface dataset:
The Addition Effect of CH3I on the Ignition of CH4
Authors: Takahashi Kazuo , Inomata Tadaaki , Moriwaki Takao , Okazaki Satiko
Published: July 2006

Measurements and calculations of ignition delay times were performed in a mixture of CH4–CH3I–O2–Ar in order to understand the characteristics of compouds including iodine during ignition. CH3I accelerated the ignition of CH4 more than CH3Cl did, but less than CH3Br did. The remarkably small bond-dissociation energies of CH3I and HI, in comparison to these of other halomethanes, were the major cause of the characteristic behavior.
Structure of a Cumulene Bearing Bulky Substituents. X-Ray Study of 1,1,4,4-Tetrakis(trimethylsilyl)butatriene
Authors: Morimoto Yoshihiro , Higuchi Yoshiki , Wakamatsu Kuni , Oshima Koichiro , Utimoto Kiitiro , Yasuoka Noritake
Published: July 2006

The structure of cumulene bearing bulky substituents, 1,1,4,4-tetrakis(trimethylsilyl)butatriene, has been determined by an X-ray diffraction method. The molecule is centrosymmetric, and the variation in carbon–carbon double bonds has been observed. The distance of the central C=C bond is 1.276(8) Å, whereas that of the terminal C=C bond is 1.319(6) Å. These bond lengths are very similar to the unsubstituted butatrienes and the influence of bulky trimethylsilyl groups is not recognized in this context. Some distortions have been observed in the bond angles concerning the trimethylsilyl groups; the overcrowded environment of the central C=C bond seems to make this less reactive.
Activation of Dinitrogen over Various Raney Type Metal Catalysts
Authors: Ogata Yoichi , Aika Ken-ichi , Onishi Takaharu
Published: July 2006

Raney Ni, Rh, Re, and Ir adsorbed molecular nitrogen which was stable up to about 300 K. Raney Fe, Co, Ni, Ru, Rh, Ir, and Pt adsorbed atomic nitrogen which was desorbed around 700 or 800 K. The XPS spectra of atomically adsorbed nitrogen was observed on Co, Ni, and Ru samples. While the per-weight activity of Raney Ru for isotopic equilibration of N2 is much higher than that of 5% Ru–K/AC, those of other Raney metals are lower than those of 5% metal–K/AC.
The High-Temperature Reaction of Iron with Sulfur Dioxide
Authors: Ota Ken-ichiro , Sugimoto Hiroyuki , Fueki Kazuo
Published: July 2006

The reaction of Fe with SO2 has been studied in the temperature range from 923 K to 1123 K and in the pressure range from 1.3 kPa to 101 kPa. The reaction obeyed the parabolic law except for the initial period, and the rate constant was equal to that in O2. In the scale, Fe3O4, FeO, and FeS were found as the reaction products. Among them, FeS was formed only in the initial period of the reaction and stayed at the scale/metal interface. The constant amount of sulfide in the scale became larger at higher temperatures or at lower SO2 pressures. The sulfide formation in the initial period of the reaction might cause the increase in the corrosion of Fe at low pressures of SO2 and cause the difference from the corrosion by O2.
Study of Conformers of 2,2′-, 3,3′-, and 4,4′-Dimethylbiphenyls in the Phosphorescent Triplet States by Electron Spin Resonance and Phosphorescence
Authors: Tanigaki Katsumi , Taguchi Noriyuki , Yagi Mikio , Higuchi Jiro
Published: July 2006

For the phosphorescent triplet (T1) states of symmetrically-substituted dimethylbiphenyls, the relationship between the twisting angle of the two aromatic rings and the zero-field splitting parameters is discussed in terms of the ESR spectra. Two sets of ESR spectra observed for 2,2′- and 3,3′-dimethylbiphenyls (2DMBP and 3DMBP) are precisely assigned to the corresponding s-cis or s-trans conformer. The results clarify the inadequate assignment of the spectra of these molecular species in the previous literature. The lifetime obtained for the s-cis conformer is different from that of the s-trans one for both 2DMBP and 3DMBP. Examining the T1–T1 energy transfer from one conformer to the other, the relative locations for the T1 states of s-cis and s-trans conformers are obtained, even if phosphorescence measurements do not provide each isolated spectrum: ET (s-cis-3DMBP)ET(s-trans-2DMBF).
Syntheses of Acetyl-1-bromopyrenes
Authors: Minabe Masahiro , Mochizuki Hidehiro , Yoshida Masaaki , Toda Takashi
Published: July 2006

The reaction of 1-bromopyrene with acetic anhydride in the presence of aluminium chloride afforded an ipso-substituted compound, 1-acetylpyrene, in addition to the expected compounds, 6-acetyl- and 8-acetyl-1-bromopyrene. 7-Acetyl-1-bromopyrene was prepared via the acetylation of 2-acetylamino-1-bromo-4,5,9,10-tetrahydropyrene. The structures of the acetylbromopyrenes were assigned according to the two-dimensional NMR spectra.
Proton and Carbon-13 NMR Study of 1,1,4,4-Tetraphenyl- and 1,4-Diphenyl-1,3-butadiene Dianions in Solution. The Charge Distributions, Structural Features and Rotational Barriers of Phenyl Groups
Authors: Yokoyama Yukihiro , Takakura Yutaka , Sawasaki Takeshi , Takahashi Kensuke
Published: July 2006

The dicarbanions (1 and 2) produced from 1,1,4,4-tetraphenyl- and 1,4-diphenylbutadienes (1a and 2a) were investigated by means of the 1H and 13C NMR techniques. Large upfield shifts of the proton and carbon signals caused by the conversion of the hydrocarbons into the dianions were observed. Such shifts were used for evaluating the excess charge distributions in the dianions. From the coupling constants obtained it is concluded that the configuration of the central bond of the anion is the trans one for 1 but the cis one for 2. Thermodynamical parameters were obtained for the restricted rotation of the phenyl group of the lithium salt of 2.
The State of Polarization of Light Scattered by Anisotropic Spheroids
Authors: Sano Yoh
Published: July 2006

Using the light scattering theory of Rayleigh–Gans, theoretical expressions were derived for the state of polarization of light scattered by anisotropic spheroids in the case of linearly polarized incident light whose electric vector is inclined by ψ to the scattering plane. The azimuth of the ellipse of the light scattered is a function of the two scattering angles, θ and ψ, only and the scattered light is linearly polarized for linearly polarized incident light. The degree of polarization of the scattered light, which is defined as the ratio of the polarized component to the intensity of the scattered light, depends on the intrinsic anisotropy, pm; the relative refractive index of the spheroid to the solvent, m, and θ, together with the ψ angle. The degree of polarization varies from 1.0 to 0, depending strongly on pm, p and m. It has been suggested that the determination of the degree of polarization as a function of ψ and θ provides good information about the optically intrinsic anisotropy of the spheroid.
Electrochemistry of Tris(β-diketonato)ruthenium(III) Complexes at Platinum Electrodes in Nonaqueous Solutions and Substituent Effects on Their Reversible Half-Wave Potentials
Authors: Endo Akira , Hoshino Yoshimasa , Hirakata Keigo , Takeuchi Yasushi , Shimizu Kunio , Furushima Yuriko , Ikeuchi Haruko , Satô Gen P
Published: July 2006

The one-electron oxidation and reduction processes at platinum electrodes of a series of β-substituted and γ-substituted tris(β-diketonato)ruthenium(III) complexes are studied in acetonitrile, N,N-dimethylformamide, and nitromethane solutions, each containing 0.1 mol dm−3 (C2H5)4NClO4 at 25 °C. Syntheses of three new γ-substituted derivatives are described. Attempts to isolate the immediate product of the one-electron oxidation of [Ru(acac)3] in acetonitrile failed; bis(acetonitrile)bis(acetylacetonato)ruthenium(III) was obtained instead. Diffusion coefficients of the complexes in the acetonitrile medium are presented. The reversible half-wave potentials for the oxidation and the reduction in the acetonitrile medium depended linearly on the sum of the Hammett constants of the substituents (σp for the β-substituents and σm for the γ-substituents). Analysis of the dependence of the half-wave potentials on several kinds of substituent parameters suggests that the inductive effect is operative at both the β-positions and the γ-position, while the resonance effect is operative only at the β-positions.
Catalysis by Heteropoly Compounds. XII. Absorption Properties of 12-Tungstophosphoric Acid and Its Salts
Authors: Okuhara Toshio , Tatematsu Shin , Lee Kwan Young , Misono Makoto
Published: July 2006

The absorption of organic molecules into the bulk of H3PW12O40 and its salts was studied. Polar (or basic) molecules, such as alcohols and amines, were readily absorbed into H3PW12O40, but nonpolar hydrocarbons were not absorbed. The absorption depended not only on the polarity but also on the molecular size. The diffusion coefficients of the absorption of C1–C4 alcohols were of similar magnitudes, and were much smaller than that of the intracrystalline diffusion of methanol in ZSM-5. The amounts of absorbed molecules in H3PW12O40 tended to be in discrete values: that is, integral multiples of the number of protons (3, 6, etc.). This fact indicates that these polar molecules are protonated and form stable secondary structures throughout the bulk. It was confirmed in the case of methanol or ethanol that the transition between the states of 6 and 9 molecules/anion took place through the pressure changes. The absorptivity was greatly suppressed by the substitution of Cs+ for more than two H+, while the Na salts showed an absorptivity similar to that of H3PW12O40.
Cobalt(III) Complexes with Quadridentate Ligands. VIII. The Preparation and Properties of Cis-β1 and β2-Isomers of the Thiosalicylato(quadridentate amine)cobalt(III) Complexes
Authors: Yamamoto Yoshihisa , Yoshii Kayoko , Toyota Eiko , Konno Kazuko
Published: July 2006

cis-β1 and β2-Thiosalicylato(quadridentate amine)cobalt(III) complexes, cis-β1, β2-[Co(thiosal)L]X·nH2O (L: trien (2,2,2-tet), 3,2,3-tet; X: Cl, NO3), have been prepared from a reaction mixture of [CoCl2L]Cl·nH2O (L: trien, 3,2,3-tet), Ag2O, thiosalicylic acid (o-mercaptobenzoic acid), and 28% aqueous ammonia. Two geometrical isomers (cis-β1 and β2) of their complexes were separated by Dowex 50W-X2 column chromatography. The isomerization between the cis-β1 and β2-isomers is reversible in water at 40 °C. The IR spectra of these complexes showed four or five absorption bands in the 990–1100 cm−1 region and four absorption bands in the 3000–3300 cm−1 region. This indicates that these complexes assume the cis-β1-form. Their cis-β1 and β2 configurations have been established by their absorption and NMR spectra. The cis-β1 and β2-thiosalicylato(trien)cobalt(III) complexes have been tentatively assigned to the RR,SS diastereoisomer by their 1H NMR spectra. The color of solid state materials, solubilities in alcohols, isomerization at 40 °C, reaction in 60% nitric acid, absorption spectra, and chemical shift of Co–S–C carbon of the coordinated thiosalicylato ligand for the title complexes are different from those of the corresponding cis-β1 and β2-salicylato(quadridentate amine)cobalt(III) complexes, cis-β1, β1-[Co(sal)L]Cl·nH2O (L: trien, 2,3,2-tet, 3,2,3-tet, 3,3,3-tet), reported previously.
Photochemical Generation of Sn(III) in Hydrochloric Acid Solutions
Authors: Shinohara Nobuyoshi , Inoue Makoto
Published: July 2006

In the flash photolysis of Sn(II) in a deaerated hydrochloric acid solution, Sn(III) was produced. Sn(III) has an absorption maximum at 280 nm in a l mol dm−3 hydrochloric acid solution. In the flash photolysis of a deaerated Sn(IV) solution, intermediates of Sn(III) and Cl2− were produced. Transient absorption spectra of intermediates generated by the flashed Sn(IV) solutions were measured under various concentrations of dissolved oxygen. Since Sn(III) reacts with oxygen very rapidly, only Cl2− was confirmed in the oxygen-saturated Sn(IV) solution. In the flash photolysis of Sn(IV) solutions containing Sn(II), the yield of Sn(III) increased with an increase of the added Sn(II), due to the generation of Sn(III) by the reaction of Cl2− with Sn(II). It was found that only Sn(III) was produced in the irradiation of 5.0×10−4 mol dm−3 Sn(IV) solution containing Sn(II) at concentrations of more than ca. 7×10−5 mol dm−3. The reaction rate constant for the reaction of Sn(II) with Cl2− was estimated to be 8.9×108 mol−1 dm3 s−1. The mechanisms for the photochemical generation of Sn(III) are discussed.
Crystal Structures of [VO(sal-l-ala)(OCH3)(CH3OH)] (sal-l-ala=N-salicylidene-l-alaninate) and {[VO(sal-l-ala)]2O}2·2CH2Cl2, and the Catalytic Activity of These and Related Complexes on Asymmetric Oxidation of Methyl Phenyl Sulfide with t-Butyl Hydroperoxide
Authors: Nakajima Kiyohiko , Kojima Masaaki , Toriumi Koshiro , Saito Kazuo , Fujita Junnosuke
Published: July 2006

A reddish brown oxovanadium(V) complex, [VVO(sal-l-ala)(OCH3)(CH3OH)] (2a, sal-l-ala=N-salicylidene-l-alaninate) was formed by dissolving [VIVO(sal-l-ala)(H2O)] (1a) in methanol. Treatment of 2a with wet dichloromethane yielded deep blue crystals of {[VVO(sal-l-ala)]2O}2·2CH2Cl2 (3a). The structures of 2a and 3a have been determined by X-ray analyses. Crystal data are: [VO(sal-l-ala)(OCH3)(CH3OH)] (2a), monoclinic, C2, a=19.621(6), b=6.734(1), c=12.059(4) Å, β=117.72(2)° and Z=4. {[VO(sal-l-ala)]2O}2·2CH2Cl2 (3a), orthorhombic, P212121, a=19.938(4), b=23.854(5), c=11.526(2) Å, and Z=4. In 2a, the tridentate sal-l-ala ligand and a methoxide ion occupy the basal positions, and form distorted octahedral geometry around the vanadium(V) ion together with one methanol molecule (V–O distance: 2.384(4) Å) and the oxide ion of oxovanadium(V). The tetranuclear complex (3a) consists of two μ-oxo dinuclear vanadium(V) complexes, and each vanadium(V) ion has a distorted octahedral coordination. The Schiff base coordinates equatorially to each vanadium(V) ion, of which one axial site is occupied by O2− and the other is weakly linked to the carboxylate O atom of a nearby Schiff base (V–O distance: 2.34–2.56 Å). Octahedral coordination on each vanadium(V) is achieved by sharing an equatorial O2− ligand. The brown complexes, [VO(sal-l-aa)(OCH3)(CH3OH)] (2, sal-l-aa=N-salicylidene l-amino carboxylate) catalyze the oxidation of methyl phenyl sulfide with t-butyl hydroperoxide in dichloromethane at 4 °C to give (R)-methyl phenyl sulfoxide with optical yields (e.e.) of 8–14%.
Individuality of Amino Acid Residues in Protected Peptides. Conformational and β-Sheet Structure-Disrupted Behaviors of Resin-Bound Peptides
Authors: Narita Mitsuaki , Isokawa Shizuko , Honda Shinya , Umeyama Hiroshi , Kakei Hideaki , Obana Satoshi
Published: July 2006

The conformational behavior of cross-linked polystyrene resin-bound peptides swollen in CH2Cl2 was analyzed using IR absorption spectroscopy. All of the resin-bound peptides easily aggregated with each other through intermolecular hydrogen bonding to form a β-sheet structure. The disruption of the β-sheet structure was further investigated by a solvent titration method in order to clarify the individuality of amino acid residues. At a pentapeptide level, the β-sheet structure was easily disrupted by the addition of a small amount of HFIP. On the other hand, at a larger peptide level, the disrupted behavior of the β-sheet structure was different from each other according to the amino acid composition. Based on the view that the secondary structure of globular proteins reflects the individuality of the 20 kinds of amino acid residues in proteins, we attempted to evaluate how easily the β-sheet structure of peptides is disrupted by HFIP using the average conformation values: 〈Pα〉, 〈Pβ〉, and 〈Pc〉. As a result, the β-sheet structure-disruption of peptides having a low potential for a β-sheet→helix transformation as well as for the randomness was difficult by adding increasing amounts of HFIP. On the other hand, that of the peptides having a 〈Pc〉 value larger than 0.85 and/or a high potential for the β-sheet→helix transformation proceeded smoothly upon adding increasing amounts of HFIP.
Selectivities of Aromatic Methyl Metalation. Unexpectedly Strong Interactions of Carbanions with Aromatic Rings
Authors: Inagaki Satoshi , Imai Takeo , Mori Yoshio
Published: July 2006

The site selectivities of the metalation reactions of dimethylnaphthalenes and dimethylanthracenes followed by MeOD quenching were investigated experimentally and theoretically. The 2(3)-methyl groups were found to be more effectively metalated than expected from the LUMO amplitudes of the aromatic rings. The MNDO calculations suggested that the naphthylmethyl and anthrylmethyl anions are not the aromatic rings perturbed by the carbanions, but the significantly different conjugated rings doubly bonded to the exocyclic carbon atoms. The unexpectedly strong interactions of the carbanion centers with the aromatic rings can account for the discrepancies between the selectivities and the LUMO amplitudes.
Physicochemical Stabilization of Lipid Microspheres by Coating with Polysaccharide Derivatives
Authors: Carlsson Anders , Sato Toshinori , Sunamoto Junzo
Published: July 2006

A methodology to improve lipid microspheres (LM) as a carrier for lipophilic drugs and their physicochemical properties are described. The LM were prepared from glycerides, glycerol, and phospholipids. The method involves coating of the surface of the LM with a naturally occurring or chemically modified polysaccharide. Special emphasis will be made on cholesterol-bearing pullulan and amylopectin. This is the same approach as that adopted for the stabilization of liposomes. Turbidity measurement revealed that the coating effectively depressed the Ca2+-induced aggregation of the LM. From fluorescence polarization measurements, it was concluded that the fluidity of the LM surface decreased with the polysaccharide coating. Furthermore, the coating effect was investigated by zeta-potential measurements. The coating reduced the negative zeta-potential of the LM to an apparently neutral value.
Effects of Substituents and Solvents on the Electronic Spectra of 9,10-Dihydro-9,10-o-benzenoanthracene-1,4-diones: Intramolecular Charge Transfer
Authors: Kitaguchi Nobuya
Published: July 2006

Electronic spectra of substituted 9,10-dihydro-9,10-o-benzenoanthracene-1,4-diones (triptycenequinones) in various solvents and that of benzo- and dibenzotriptycenequinones were investigated in this paper. Intramolecular charge-transfer (CT) bands ware observed in triptycenequinone system as a result of intramolecular interaction between benzene ring and benzoquinone moiety. Substituents on the benzene rings strongly affected the CT bands. Electron-donating groups gave absorption maxima at long wavelength. Naphthalene ring gave similar but stronger CT bands than benzene ring. Hammett σ+ value of substituents gave good linear relationship with the energy of the CT bands. Calculations of reduced charge matrix of triptycenequinones by extended Hückel theory showed that the charge of aromatic ring(s) were transferred to benzoquinone moiety accompanying HOMO–LUMO excitation. Especially, absorption maxima of the methyl-substituted triptycenequinones gave good correlation with the amounts of charge transferred from benzene ring to benzoquinone moiety. These analysis confirmed clearly CT character of the absorption maxima of triptycenequinones. However, solvent effect of these CT bands maxima is not so clear as the substituent effect.
Facile Construction of Optically Active 1,3-Diols. Synthesis of (2S,4R)-7-Octene-2,4-diol and endo-(1S,3S,5R)- and exo-(1R,3S,5S)-1,3-Dimethyl-2,9-dioxabicyclo[3.3.1]nonane
Authors: Chikashita Hidenori , Kittaka Eiji , Kimura Yasunori , Itoh Kazuyoshi
Published: July 2006

A short and stereoselective asymmetric synthesis of (2S,4R)-7-octene-2,4-diol (a key intermediate in the Bartlett synthesis of nonactic acid) and two stereoisomers of a biologically active substance isolated from Norway spruce infested by ambrosia beetle, endo-(1S,3S,5R)- and exo-(1R,3S,5S)-1,3-dimethyl-2,9-dioxabicyclo-[3.3.1]nonane, was effectively accomplished in three and four reaction steps, respectively, by starting with easily obtainable (S)-1-(1,3-dithian-2-yl)-2-propanol by baker’s yeast asymmetric reduction. The main strategy was based on a facile construction of optically active β-hydroxy ketones via alkylation of the dianion of (S)-1-(1,3-dithian-2-yl)-2-propanol with alkyl halides, followed by their stereoselective reductions.
Stereoselective β-C- and β-S-Glycosylation of 2-Deoxyribofuranose Derivatives Controlled by the 3-Hydroxy Protective Group
Authors: Ichikawa Yuh-ichiro , Kubota Hideki , Fujita Ken’ichi , Okauchi Tatsuo , Narasaka Koichi
Published: July 2006

β-C-2-Deoxyribofuranosides and β-S-2-deoxyribofuranosides are prepared stereoselectively from 1-O-acetyl-5-O-benzyl-3-O-[2-(methylsulfinyl)ethyl]-2-deoxy-d-erythro-pentofuranose or the corresponding 3-O-(2-pyridyl-methyl)pentofuranose N-oxide by the reaction with silyl enol ethers or trimethlsilyl sulfides in the presence of a Lewis acid.
New Synthesis of 2-Oxo-3-alkenylphosphonates and Hetero Diels–Alder Reactions with Vinyl Ethers Leading to 5-Substituted 2-Phosphiny 1-2-cyclohexen-1-ones
Authors: Wada Eiji , Kanemasa Shuji , Tsuge Otohiko
Published: July 2006

A new method of synthesizing phosphinyl-substituted enones, 2-oxo-3-alkenylphosphonates, is developed via the dianion of diethyl 2-oxopropylphosphonate. The enones serve as hetero dienes in thermal reactions with vinly ethers producing 2-alkoxy-6-(phosphinylmethyl)-3,4-dihydro-2H-pyrans. Acid-catalyzed cleavage of these cycloadducts is followed spontaneously by internal condensation furnishing 2-phosphinyl-2-cyclohexen-1-one derivatives.
Stereochemical Control in Microbial Reduction. 8. Stereochemical Control in Microbial Reduction of β-Keto Esters
Authors: Nakamura Kaoru , Kawai Yasushi , Oka Shinzaburo , Ohno Atsuyoshi
Published: July 2006

Stereochemistry of the reduction of β-keto esters with bakers’ yeast is controlled by the addition of a certain α,β-unsaturated carbonyl compound (or its reduced form). Glucose also exerts the same effect. The additives tend to shift the stereochemistry of the reduction toward the production of d-hydroxy ester. Namely, methyl 3-oxopentanoate and ethyl 3-oxo-6-heptenoate were reduced to the corresponding d-hydroxy esters with excellent stereoselectivities and chemical yields. The enones are supposed to inhibit the enzymes that produce the l-hydroxy ester, whereas glucose plays a role to activate the enzymes that produce the d-hydroxy ester.
The Decomposition of Arenediazonium Tetrafluoroborates with Halo- and Azidotrimethylsilanes in Nonaqueous Solvents
Authors: Keumi Takashi , Umeda Toshiaki , Inoue Yoshinori , Kitajima Hidehiko
Published: July 2006

The reaction of arenediazonium tetrafluoroborates with chlorotrimethylsilane in a tetrahydrofuran/N,N-dimethylformamide (DMF) (5v/3v) solution afforded the protodediazotization products in high yields. The reactions of the diazonium salts with halotrimethylsilanes in DMF were found to give the corresponding haloarenes. Among the halodediazotization reactions, the iododediazotization with iodotrimethylsilane proceeded smoothly at room temperature to give the iodoarenes in excellent yields. In a similar manner, a variety of azidoarenes were obtained in consistently high yields by the treatment of arenediazonium tetrafluoroborates with azidotrimethylsilane in a DMF solution.
Preparation and Characterization of Hydrogen Molybdenum Bronzes, HxMoO3
Authors: Sotani Noriyuki , Eda Kazuo , Sadamatu Masayasu , Takagi Sadao
Published: July 2006

Hydrogen molybdenum bronzes, HxMoO3, of Type-I (x=0.21), Type-III (x=1.55), and Type-IV (x=1.90) were prepared by the Glemser’s method. Type-II (x=0.91) was obtained from Type-III by standing in air for 120 days. The bronzes with low hydrogen contents were stable, but those with high contents were not so stable. All these bronzes have been studied by X-ray diffraction, IR spectroscopy, and TG-DTA. Bronzes with high hydrogen contents were changed upon heating in air, successively, to those with low hydrogen contents by the evolution of H2.
Rotational Lattice Vibrations of [1H4]- and [2H4]Pyrazine Crystals
Authors: Hieida Toshikazu , Maehara Masayoshi , Nibu Yoshinori , Shimada Hiroko , Shimada Ryoichi
Published: July 2006

Low-frequency Raman bands ot the [1H4]- and [2H4]pyrazine crystals were studied at various temperatures between 4.2 and 300 K. All six rotational lattice vibrations were identified based on the isotopic factor (the ratio of the vibrational frequency of the [1H4]- and [2H4]pyrazine crystals) of the individual vibrations. Classification of the rotational lattice vibrations into symmetry species was made through the polarization measurement of the Raman bands in single crystals.
The Ultraviolet Spectrum of Ozone Produced in the γ-Irradiated Liquid Nitrogen Containing a Small Amount of Oxygen
Authors: Hase Hirotomo , Jin Guangchuan , Higashimura Takenobu
Published: July 2006

The ultraviolet spectrum observed in γ-irradiated liquid nitrogen containing a small amount of oxygen has been ascribed to ozone. The εG value was obtained. The dose rate effect on the yield of ozone was observed. The value of εmG was inversely proportional to the square root of the dose rate. This allowed us to discuss the formation mechanism of ozone in liquid nitrogen.
Inversion at the Sulfur Atom in Bis(diethyl sulfide)(1,1,2,2-tetraacetylethane-C,O′)platinum(II)
Authors: Yamazaki Shinsaku , Ama Tomoharu
Published: July 2006

Variable temperature 1H NMR suggests that the metal–carbon bonded Pt(II) complex of 1,1,2,2-tetraacetylethane(dahd=3,4-diacetyl-2,4-hexadiene-2,5-diol), [Pt(dahd-C3,O′)(SEt2)2] undergoes two distinct rearrangements at the sulfides, one of which is accompanied by an anomalous dissociation process. From a comparison of the estimated kinetic parameters for inversion, an arrangement of the two sulfides in planar geometry is proposed.
Asymmetric Hydrogenation Using Diphenylphosphinite Derivatives of Carbohydrates as the Chiral Ligand of Rhodium Catalysts
Authors: Yamashita Mitsuji , Naoi Manabu , Imoto Hiroyuki , Oshikawa Tatsuo
Published: July 2006

Diphenylphosphinite derivatives of carbohydrates (l-rhamnose, d-mannitol, and cellulose), which have asymmetric centers on the skeletons were synthesized. Asymmetric hydrogenations of prochiral substrates using rhodium catalysts with the prepared chiral phosphinite ligand were carried out to obtain chiral substances in 8–78% optical yield.
A Simple Synthesis of (±)-cis-(6-Methyltetrahydro-2-pyranyl)acetic Acid, a Constituent of Civet
Authors: Kobayashi Kazuhiro , Suginome Hiroshi
Published: July 2006

The title compound was synthesized stereoselectively starting with readily available 5-hexanolide in a 47% overall yield.
Effect of the Particle Size of Catalyst Metal on the Stereochemistry of Hydrogenation
Authors: Senda Yasuhisa , Kobayashi Kazuhito , Kamiyama Shin-ichi , Ishiyama Jun-ichi , Imaizumi Shin , Ueno Akifumi , Sugi Yoshihiro
Published: July 2006

Particle size of the metal catalysts controlled the stereoselectivity in the hydrogenation of methylenecyclohexanes. No effect of particle size, on the contrary, was observed in the hydrogenation of substituted 3-methylenetetrahydropyran and 5-methylene-1,3-dioxane which contain oxygen atom/atoms in the molecule.
Production of l-Tryptophan from γ-Glutamaldehydic Acid
Authors: Eto Hirozumi , Eguchi Chikahiko , Kagawa Teruhiko
Published: July 2006

Labile γ-glutamaldehydic acid (1) was first converted to tryptophan via its phenylhydrazone; no racemization occurred during the reaction. The stability of 1 was shown to be remarkably enhanced in the presence of additives.
Preparation of Nickel Complexes with η2-Coordinated Fluorinated Ketones from Dialkylnickel Complexes
Authors: Kim Yong-Joo , Osakada Kohtaro , Yamamoto Akio
Published: July 2006

Reactions of hexafluoroacetone and 2,2,2-trifluoroacetophenone with dialkylnickel complexes cause extrusion of the alkyl ligands to give nickel complexes having an η2-coordinated ketone and an auxiliary ligand such as bpy (2,2′-bipyridine) or dpe (1,2-bis(diphenylphosphino)ethane).
Reaction of Triarylchloroallenes with Nudeophiles under Solvolytic Conditions
Authors: Kitamura Tsugio , Miyake Sumiya , Kobayashi Shinjiro , Taniguchi Hiroshi
Published: July 2006

Solvolytic reactions of triarylchloroallenes in the presence of thiocyanate and O-ethyl dithiocarbonate anions gave the corresponding allenyl derivatives, while the reaction in the presence of cyanate anion afforded the corresponding propargyl derivative. These results are interpreted in terms of a steric factor of the nucleophiles.
1,1′-(1,32-Dotriacontanediyl)bis[2-acetyl-sn-glycero(3)phosphocholine]: A Long Persisting Agonist as a Potential Antihypertension Agent
Authors: Yamauchi Kiyoshi , Hihara Mitsuyoshi , Kinoshita Masayoshi , Watanabe Masahiro , Kondo Takao , Kuwahara Shigeki
Published: July 2006

A dimer of platelet activating factor (PAF), 1,1′-(1,32-dotriacontanediyl)bis[2-acetyl-sn-glycero(3)phosphocholine] (7), was synthesized and examined for platelet aggregation and antihypertension activities. The compound 7 showed both activities with the maximum levels of 1/50–1/100-fold of those of PAF, but the antihypertension effect of 7 persisted much longer and appeared with time lag of 1–3 min. The unique expression of the activities was discussed in conjunction with the molecular structure.
Structures and Spectral Properties of Some Bis(β-diketonato)copper(II)–Diazole Complexes. II. The 1:1,1:2, and 1:3 Adducts of Bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)copper(II) and 4-Methyl-1H-pyrazole
Authors: Kogane Tamizo , Ishii Minoru , Harada Kazumasa , Hirota Reiko , Nakahara Masayoshi
Published: July 2006

The preparation of Cu(hfac)2(4-Hmpz) (1), Cu(hfac)2(4-Hmpz)2 (2), and Cu(hfac)2(4-Hmpz)3 (3) by stoichiometric reactions of Cu(hfac)2 (Hhfac=1,1,1,5,5,5-hexafluoro-2,4-pentanedione) with 4-methyl-1H-pyrazole (4-Hmpz) in petroleum ether is reported. The structure of 2 has been determined by X-ray analysis. Crystal data for 2: triclinic, P\bar1, a=9.301(3), b=10.815(2), c=6.457(1) Å, α=104.71(2), β=101.38(2), γ=75.41(2)°, V=601.8(3) Å3, Z=1, and R=0.057. The geometry about each copper atom is approximately a tetragonal bipyramid. The axial positions are occupied by two oxygen atoms one from each of the bidentate hfac ligands, the other oxygen atoms of which are in the basal plane with two nitrogen atoms from 4-Hmpz molecules. The two nitrogen atoms are situated trans to each other. The axial oxygen atoms have a considerably long Cu–O(2) distance (2.346(3) Å). In the IR spectrum of 2, unsplit ν C–O and ν N–H bands were observed at 1678 and 3441 cm−1, respectively. The structures of 1 and 3 are estimated on the basis of their IR spectra.
Enzyme-Catalyzed Enantioselective and Regioselective Hydrolyses of (2RS,7SR)-2,7-Diacetoxybicyclo[2.2.1]heptane and (2RS,7RS)-2,7-Diacetoxybicydo[2.2.1]heptane
Authors: Naemura Koichiro , Takahashi Nobuo , Tanaka Shunsuke , Ueno Michi , Chikamatsu Hiroaki
Published: July 2006

Enzyme-catalyzed hydrolyses of (2RS,7SR)-2,7-diacetoxybicyclo[2.2.1]heptane (2) and its (2RS,7RS)-isomer 6 occurred with regiospecificity combined with enantiomeric specificity to give the diacetates and the monoacetates in optically active forms, and the acetoxyl group located on the methano bridge in the diacetates was preferentially hydrolyzed to give the monoacetates. Treatment with lithium aluminum hydride converted (−)-2 and (+)-(2S,7R)-2-acetoxybicyclo[2.2.1]heptan-7-ol into (+)-(2R,7S)-bicyclo[2.2.1]heptane-2,7-diol (1) and (−)-(2S,7R)-bicyclo[2.2.1]heptane-2,7-diol (1), respectively, from which both enantiomers of 1 with ≥98% e.e. were readily obtained by further recrystallization. Similarly, (−)-(2R,7R)-2,7-diacetoxybicyclo[2.2.1]heptane (6) and (+)-(2S,7S)-2-acetoxybicyclo[2.2.1]heptan-7-ol (6) were converted into (+)-(2R,7R)-bicyclo[2.2.1]heptane-2,7-diol (5) and (−)-(2S,7S)-bicyclo[2.2.1]heptane-2,7-diol (5), respectively. The absolute configurations of the products were determined by a chemical correlation with exo-2-acetoxybicyclo[2.2.1]heptane of known absolute configuration.
Photochemical and Photophysical Behavior of p-Methoxyphenylalkenyl Phenanthrenecarboxylates. II. Kinetic Investigation of Intramolecular Cycloaddition
Authors: Sakuragi Hirochika , Tokumaru Katsumi , Itoh Hiroki , Terakawa Kohki , Kikuchi Katsuo , Caldwell R A , Hsu Chien-Chung
Published: July 2006

The efficiency of [2+2] photocycloadduct formation was examined by measuring fluorescence lifetimes and the quantum yields of fluorescence and product formation in two series of p-methoxyphenylalkenyl 9-phenanthrenecarboxylates (A-nE and B-nE). In (E)-3-(p-methoxyphenyl)-3-pentenyl, (E)-4-(p-methoxyphenyl)-4-hexenyl, and (E)-5-(p-methoxyphenyl)-5-heptenyl 9-phenanthrenecarboxylates (B-2E, B-3E, and B-4E, respectively) the intramolecular quenching leads to product (cyclobutane+oxetane) formation in almost unit efficiency, while in (E)-4-(p-methoxyphenyl)-3-butenyl and (E)-5-(p-methoxyphenyl)-4-pentenyl 9-phenanthrenecarboxylates (A-2E and A-3E, respectively) exciplex→product efficiency is a half to three quarters. Intermediacy of plural exciplex intermediates is suggested in the present bichromophoric systems on the basis of exciplex quenching results.
A New Synthesis of o-Quinonemethides and Their Inter- and Intramolecular Cyclization Reactions
Authors: Inoue Tsutomu , Inoue Seiichi , Sato Kikumasa
Published: July 2006

The reaction of o-[1-(alkylthio)alkyl]phenols with silver(I) oxide at room temperature generated o-quinonemethides in good yields along with silver alkanethiolate. This mechanism, based upon one-electron oxidation, is excluded in view of several experimental facts. The resulting o-quinonemethides reacted efficiently with ethyl vinyl ether to afford cis-chromans as the result of endo cycloaddition between (E)-o-quinonemethides and the ether. Similarly, o-[1-(alkylthio)allyl]phenols were converted to cis-chromans via the corresponding (E)-o-quinonemethides (6-allylidenecyclohexadienone). In the absence of dienophiles, some chromenes were obtained from the allylphenols.
Mechanistic Studies of Tetraphenylstibonium Iodide-Catalyzed Cycloaddition of Oxiranes with Heterocumulenes
Authors: Fujiwara Masahiro , Baba Akio , Matsuda Haruo
Published: July 2006

In the selective α-cleavage cycloaddition of oxiranes with heterocumulenes catalyzed by tetraphenylstibonium iodide, the direction of oxirane fission at first stage is not significant, while the difference of reaction behaviors of two antimony alkoxide intermediates (Ph4SbOCH2CH(R1)I and Ph4SbOCH(R1)CH2I), insertion of heterocumulenes and cyclization to original oxiranes, is responsible for the unusual selectivity.
Effect of Pd Dispersion on Methanol Decomposition over Supported Pd Catalysts
Authors: Saitoh Yasuo , Ohtsu Satoshi , Makie Yasuo , Okada Takashi , Satoh Kenji , Tsuruta Norio , Terunuma Yasuhiro
Published: July 2006

The turnover frequency (TF) for the methanol decomposition over various supported Pd catalysts is dependent upon both supporting materials and Pd crystallite sizes. On the other hand, the apparent activity (gas evolution rate per g-catalyst) is roughly proportional to the degree of Pd dispersion. This variation in the apparent activity is related to starting materials for the preparation of supports as well as to properties of supports. The highest dispersion of Pd was obtained with TiO2 prepared from Ti[OCH(CH3)2]4 or TiCl4, but at an elevated temperature (above 773 K) in the reduction treatment applied, it showed a suppressed activity. Pd particles on ZrO2 support gave a high value of TF when the Pd/ZrO2 catalyst was calcined in air at an elevated temperature (873–1073 K). The findings about the influence of heat treatment suggest that thermal stabilization of the ZrO2 support would play an important role in the development of catalytic properties of Pd. TF curves for the methanol decomposition over TiO2- and ZrO2-supported Pd catalysts change discontinously at about 10 Å of Pd particle size. In the case of Al2O3 support, characteristic behavior of TF curve are significantly different from those observed in the case of TiO2 and ZrO2 supports.
Mechanism of Delocalization of σ-Electrons from Bonds to Bonds. Conformationally Dependent Delocalization between Geminal Bonds in Antiperiplanar Effects
Authors: Inagaki Satoshi , Mori Yoshio , Goto Naomi
Published: July 2006

A theory is presented for bond-to-bond delocalization of σ-electrons and applied to the antiperiplanar effects including anomeric and gauche effects. The delocalization between geminal bonds is, surprisingly, dependent on the conformation. The geminal delocalization from the intervening bond between donor and acceptor bonds to the latter is proposed to be important as well as the vicinal delocalization from the donor to acceptor bond. Each delocalization is controlled by the orbital phase.
Solvent Influence on UV, 59Co, and 13C NMR of [Co(CN)6]3− and Its Solvation Site
Authors: Taura Toshiaki
Published: July 2006

The electronic absorption (UV) spectrum, 59Co, and 13C NMR of potassium hexacyanocobaltate(III), K3[Co(CN)6], were measured in water and a variety of organic solvents: ethylene glycol, methanol, formamide, ethanol, chloroform, nitromethane, dichloromethane, dimethyl sulfoxide, acetonitrile, N,N-dimethylformamide, benzonitrile, and nitrobenzene. The complex salt was dissolved in organic solvents by macrobicyclic polyether, cryptand 222. It was found that the spectra are influenced by the solvent, and vary according to the electrophilic ability (Gutmann’s acceptor number) of solvents. Especially, the 13C NMR chemical shifts of coordinated cyano carbons (octet) have shifted downfield as the acceptor number becomes larger. This means that the solvent influence is caused by direct interaction between the ligand CN− and solvent molecules as electron acceptors. The result concerning the linear correlation between the solvent influence on the peak position (nm) of the first d–d transition band and on the chemical shift of 59Co NMR suggests that this influence is due to the d–d transition-energy change of [Co(CN)6]3 by solvation. Finally, the plausible structure of the outersphere complex of [Co(CN)6]3− with solvent molecules is proposed on the basis of the result obtained and an examination of molecular models.
Stereoselective Isomerization and Racemization of (N-Methyliminodiacetato)(ethylenediamine-N-acetato)cobalt(III), [Co(mida)(edma)], in a Basic Aqueous Solution
Authors: Kawaguchi Hiroshi , Tsuji Kenji , Ama Tomoharu , Yasui Takaji
Published: July 2006

Isomerization reactions of four geometrical isomers (pink, violet, brown, and light-brown) of [Co(mida)(edma)] were studied in a basic aqueous solution. In a reaction of the (−)565CD-pink isomer, two isomers of (−)561CD-brown and racemic light-brown formed simultaneously. The light-brown isomer isomerized mainly to the brown isomer. In reactions of the (+)572CD-violet and (+)561CD-brown isomers, the formations of other isomers were not observed but the racemizations occurred. The racemization reaction of the (+)572CD-violet isomer proceeded at a considerable rate. These reactions are discussed in connection with those for the [Co(ida)(edma)] system.
Substituent Effects. XVIII. The Resonance Demand in the Acetolysis of Neophyl Brosylates
Authors: Fujio Mizue , Goto Mutsuo , Mishima Masaaki , Tsuno Yuho
Published: July 2006

The substituent effect in the acetolysis of neophyl brosylates was analyzed statistically based on the Yukawa–Tsuno LArSR equation. Though the Brown ρ+σ+ equation did not provide a linear correlation, the LArSR equation gave an excellent linear correlation with an r value of 0.57, substantiating our basic LArSR concept of varying resonance demands with different systems. For a statistical examination of the reliability of this nonunity r value, the change in the standard deviation of the LArSR correlation was followed as a function of varying r by an iterative least-squares method. The r value of the neophyl solvolysis must have sufficient statistical significance to distinguish between the LArSR and simple Brown ρ+σ+ correlations of this system. The significance of the best-fit correlation was found to strongly depend upon the number and combination as well as the range of the effective substituents. The study was extended to various aryl-assisted processes of complex mechanisms, solvolyses of 2-arylethyl, 2-aryl-1-methylethyl, 2-aryl-1-methylpropyl, and (1-arylcyclobutyl)methyl arenesulfonates. A precise dissection analysis of non-crossover kΔ and ks processes has been realized by the Gauss–Newton type nonlinear least-squares method based on the assumption of LArSR correlations for both processes. The generality of the unique rΔ value of neophyl solvolysis was verified regarding these β-aryl-assisted processes. The substituent effect on the kΔ process can be characterized far more appropriately in terms of the \barσΔ of r=0.6, rather than σ+ of r=1.00.
Substituent Effects. XXI. Solvolysis of Benzyl Tosylates
Authors: Fujio Mizue , Goto Mutsuo , Susuki Toshihiro , Akasaka Izumi , Mishima Masaaki , Tsuno Yuho
Published: July 2006

The rates of solvolyses of a series of substituted benzyl tosylates were determined in 80% aqueous acetone, and the substituent effect was analyzed based on the Yukawa–Tsuno LArSR Eq. The LArSR Eq. as well as Hammett–Brown treatment failed to give any simple linear plot for the effect of the full range of substituents, indicating a significant mechanistic shift. The σ+ plot gave a split pattern of parallel curvatures with significant gaps for strong π-donors, weak π-donors, and non-conjugative substituents, respectively. The widely split σ+ plot conflicts with the accepted interpretation in terms of the kc–ks mechanistic transition, since the kc–ks mechanistic change should result in a single smooth-curved plot, only if plotted against an appropriate substituent constant scale. The plots of para π-donors against an appropriate \barσ scale with r=1.3 coalesced into a single smooth curve including the meta correlation curve. A sufficiently linear LArSR plot with r=1.3 for the reactive substituents down to 4-MeS-3-CN group can be referred to the substituent effect correlation for the kc mechanism of this system. The result of a correlation analysis confirmed this conclusion, giving a best ρ value of −5.23 and an r value of 1.28 for a range of substituents more activating than 4-MeS-3-CN. The r value for the kc solvolysis of activated range of substituents was found to be identical with the r value obtained for the gas-phase stability of benzyl cation. The enhanced resonance demand (r=1.28) obtained in the benzyl solvolysis must be an intrinsic feature characterizing the nature of the transition state of kc solvolysis of benzyl tosylate, rather than a correlational artifact of the nonlinearity caused from mechanistic complexity.
Chemisty on Isoindoles. Novel Synthesis of Various Functionalized Isoindoles from 2,3-Dicyanobenzaldehyde
Authors: Sato Ryu , Endoh Hidenori , Abe Akihito , Yamaichi Shizuko , Goto Takehiko , Saito Minoru
Published: July 2006

Various isoindoles having carbonyl, imino, cyano, formyl, and hydroxymethyl groups on the pyrrole or benzene ring were synthesized by new reactions of synthetically versatile 2,3-dicyanobenzaldehyde with a variety of nucleophiles. The obtained isoindoles were further converted to some functionalized isoindoles and phthalazine via recyclization with sodium borohydride and hydrazine. Whereas, N-(2,3-dicyanobenzylidene)anilines, obtained by treating 2,3-dicyanobenzaldehyde with aniline derivatives reacted with elemental sulfur in liquid ammonia or diethylamine to give 7-cyano-2,3-dihydro-3-(4-substituted phenylimino)-1H-isoindole-1-thiones, which were converted into 3-alkylthio-4-cyano-N-(4-substituted phenyl)-1H-isoindol-1-imines by alkylation with alkyl halides in the presence of phase-transfer catalyst.
Synthesis and Structural Analysis of 5-Deoxy-5-[(R)- and (S)-methylphosphinyl]-α,β-d-manno- and -l-gulopyranoses
Authors: Hanaya Tadashi , Ohmori Katsuhiko , Yamamoto Hiroshi , Armour Margaret-Ann , Hogg Alan M
Published: July 2006

Methyl 5,6-dideoxy-2,3-O-isopropylidene-6-nitro-α-d-lyxo-hex-5-enofuranoside (10) was prepared from d-mannose in 7 steps. Addition of methyl methylphosphinate to 10, followed by the catalytic hydrogenation and diazotization, afforded methyl 5-deoxy-2,3-O-isopropylidene-5-[(methoxy)methylphosphinyl]-α-d-lyxo-hexofuranoside, which was then converted into 6-O-triphenylmethyl and 6-O-tetrahydropyranyl derivatives (14, 15). By reduction with sodium dihydrobis(2-methoxyethoxy)aluminate, followed by acid hydrolysis, both 14 and 15 provided the d-mannopyranoses (together with a minor proportion of l-gulopyranoses) having a methylphosphinylidene group in place of the ring oxygen. These were converted into 1,2,3,4,6-penta-O-acetyl derivatives, whose structures and conformations were established by spectroscopy.
Antibacterial Activity of Amphipathic Basic Peptides with a Long Acyl Group and Their Interaction with Phospholipid Bilayers
Authors: Nakamura Hiroshi , Aoyagi Haruhiko , Lee Sannamu , Ono Shin , Kato Tetsuo , Murata Yoshio , Sugihara Gohsuke
Published: July 2006

The antibacterial activities of CH3(CH2)nCO–(Leu–Ala–Arg–Leu)–3-NHCH3 (1, n=0; 2, n=3; 3, n=8; 4, n=14) and their interaction with phospholipid bilayers were examined. Their order in the antibacterial activity was 1>2>3>4 against Gram-positive bacteria and 2>1>3>4 against Gram-negative bacteria: the activity of 4 was essentially negative. The CD study indicated that the α-helical content of 3 and 4 was higher than that of 1 and 2. Peptides 1–3 effectively showed a dye-leakage ability, while the ability of 4 was weak. The DSC measurement indicated that the membrane-stabilizing effect of the acyl group in 4 fairly compensated for the destabilizing effect of the hydrophobic peptide moiety. These results imply that no antibacterial activity of 4 is correlated to a strong interaction of the acyl group in 4 with the acyl chain in DPPC to stabilize the membrane.
An Efficient Generation and Selective Aldol Reaction of the Boryl Enolates of N,N-Dialkyl-2,3,3,3-tetrafluoropropanamides
Authors: Kuroboshi Manabu , Ishihara Takashi
Published: July 2006

Successive treatment of N,N-dialkyl-2,3,3,3-tetrafluoropropanamide with dibutylboryl triflate at 0°C and with ethyldiisopropylamine at −10°C resulted in clean formation of the boryl enolate of the amide, which readily reacted with various aldehydes to give the corresponding 2-fluoro-3-hydroxy-2-trifluoromethylalkanamides with high threo-selectivity and in good yields.
Electrochemical Studies of Poly(mercaptohydroquinone) and Poly(mercapto-p-benzoquinone) Film Prepared by Electrochemica Polymerization. IV. Preparation of Palladium Microparticles on the Polymer Film
Authors: Arai Gorou , Matsumoto Kiyofumi , Murofushi Toshiyuki , Yasumori Iwao
Published: July 2006

The electrodeposition of Pd at microgram levels onto an electroconductive poly(hydroquinone/p-benzoquinone) film-coated glassy carbon electrodes is described. The polymer films were chemically modified with Pd pyridine complex and/or with Pd thiolate prior to the Pd electrodeposition. Controlled-potential electrolysis was applied to form Pd microparticles on the polymer film from an acid PdCl2 solution. The nucleation/growth of Pd microparticles was largely promoted by these chemical modifications. The Pd particles on the pyridine complex-modified electrode were closely dispersed and were spherically shaped, while on the thiolate-modified electrode the Pd deposits were irregular in shape. Both the electrodes thus prepared exhibited high activity toward the generation of hydrogen and had good stability in acidic solution.
Characterization of Metal Chelation with a Mutagenic Agent, 5-Bromouracil
Authors: Singh Udai P , Ghose Ranjana , Ghose Animesh K
Published: July 2006

The interaction of some trace metal ions with a chemical mutagen 5-bromouracil (5-BrU) has been studied spectroscopically and by magnetic measurements. 5-BrU is coordinated to the Mn(II), Ni(II), and Cu(II) ions through the N atom of N(1)H group and the O atom of C(4)=O group whereas to the Co(II), Zn(II), and Cd(II) ions through O atom of C(4)=O group only. The new complexes except Co(II) complex which are insoluble in water and other common organic solvents involve polymeric structures. The tentative νM–O and νM–N band assignments in the lower region favor coordination number six for all complexes.