bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redox Behavior of Simple Vitamin B12 Model Complexes and Electrochemical Catalysis of Carbon-Skeleton Rearrangements
Authors: Murakami Yukito , Hisaeda Yoshio , Fan Sheng-Di , Matsuda Yoshihisa 
Published: July 2006

Abstract
Various cobalt complexes of 4,10-dipropyl-5,9-diazatrideca-4,9-diene-3,10-dione dioxime, (C2C3)(DOH)2pn, were prepared, and redox behavior of them was investigated by means of cyclic voltammetry; Co(II)/Co(I) redox potentials in the range of −0.69 through −0.7 V vs. Ag/AgCl. The monomethylated complex, which has a cobalt–carbon bond at one axial site of the nuclear cobalt, was disproportionated to the dimethylated complex, involving two cobalt–carbon bonds at both axial sites, and the CoI species by one-electron reduction. The dimethylated complex was inactive for electrochemical reduction, but transformed into the monomethylated complex via cleavage of a cobalt–carbon bond upon electrochemical oxidation. The electrolyses of 1-bromo-2,2-bis(ethoxycarbonyl)propane, 1-bromo-2-cyano-2-ethoxycarbonylpropane, and 2-acetyl-1-bromo-2-ethoxycarbonylpropane in the presence of [CoIII{(C2C3)(DO)(DOH)pn}Br2] in N,N-dimethylformamide did not proceed in a divided cell at −2.0 V vs. Ag/AgCl, since the corresponding dialkylated complexes, inactive for electrochemical reduction, were formed in the course of reaction. When imidazole was added to solutions for the electrolysis, the reaction proceeded efficiently by the trans effect arising from the coordinated axial base and the corresponding carbon-skeleton rearrangement products were obtained. On the other hand, the carbon-skeleton rearrangement proceeded in an undivided cell even in the absence of imidazole; the dialkylated complex was decomposed to give the monoalkylated complex and the reduction and rearrangement products by electrochemical oxidation on the anode.
An Oxygen Exchange of Arsenate and Alkylarsonate Ions with Water
Authors: Niwa Nobuko , Fushimi Midori , Iida Masayasu , Horie Yuko , Yamabe Shinichi , Okumura Akiko 
Published: July 2006

Abstract
The oxygen exchange rates, R′s, between the alkylarsonates (methyl- and butyl-) and water were measured over the pH range greater than 9 and at 30 °C. The rates were analyzed in terms of the rate law, R=k1[R′-AsO3H−]+k2[R′-AsO32−] (R′-; alkyl-) to obtain k1 to be 6.64×10−4 s−1 for methyl- and 4.38×10−4 s−1 for butylarsonate ions, respectively. The first-order oxygen exchange rate constants, k1’s, on the alkylarsonate univalent anions (methyl and butyl) are almost the same values, which indicates that the steric effect on the rate is absent. The rate constants, k1’s, correlate well with energy levels of the lowest unoccupied molecular orbitals (ELUMO’s) of univalent anions of arsenic, arsenious, and alkylarsonic acids.
Pyranyl Radicals and Their Dimers
Authors: Kawata Hiroki , Niizuma Shigeya 
Published: July 2006

Abstract
Photochemical and chemical reduction of pyrylium salts in THF solution gave their corresponding radicals which were in equilibrium with dimers. The quantum yields for raidcal formation and the standard enthalpy change ΔH0 for dimerization decrease with increasing the electron-donating character of the substituting groups in the pyrylium ring. Specially, ΔH0 for pentaphenylpyranyl and pentaphenylthiopyranyl radicals, in which all carbons in the ring are substituted by phenyl groups, become possitive. The absorption maxima and their molar extinction coefficients of pyranyl radicals, and concurrently the equilibrium constants for the dimerization were determined spectrophotometrically.
The Hypervirial Condition in the Hückel Model
Authors: Isihara Makoto 
Published: July 2006

Abstract
This paper analyzes a fundamental aspect of the Hückel model through the hyperviral theorem. The analysis leads to the condition to be satisfied by bond orders and site electron densities as a set of linear equations. The condition, named the hypervirial condition, is common to all the eigenstates of the Hückel model Hamiltonian and brings information on a sort of detailed balance in electron distribution. The hypervirial and the symmetry conditions are related to each other, being consistent but not fully equivalent. Examination of the relation between the two conditions results in the concept of the “intrinsic” hypervirial condition that remains nontrivial with the symmetry condition fulfilled. Several examples provide various expressions obtainable from the hypervirial condition to facilitate understanding the nature of the condition. A few features of the hypervirial condition for alternant systems are mentioned.
Synthesis and Structural Analysis of 4-Deoxy-4-(hydroxyphosphinyl and phenylphosphinyl)-d-ribofuranoses
Authors: Hanaya Tadashi , Yamamoto Hiroshi 
Published: July 2006

Abstract
Methyl 2,3-O-isopropylidene-β-d-ribopyranoside gave efficiently (in 4 steps) methyl 4-deoxy-4-[dimethoxyphosphinyl and (methoxy)phenylphosphinyl]-2,3-O-isopropylidene-β-d-ribopyranosides (ca. 30% overall yield). These were led (in 2–3 steps) to the title compounds and then converted into 1,2,3,5-tetra-O-acetyl-4-deoxy-4-(methoxyphosphinyl and phenylphosphinyl)-d-ribofuranoses, whose structures and 3T2 (and 2T3) conformations were established by spectroscopy.
Solvent Extraction of Thallium(I) Picrate into Benzene with Mixtures of Crown Ethers and Tributyl Phosphate
Authors: Takeda Yasuyuki 
Published: July 2006

Abstract
Thallium(I) picrate was extracted into benzene at 25 °C with crown ether (15-crown-5 (15C5) and benzo-15-crown-5 (B15C5)) and/or tributyl phosphate (TBP). The crown ether complex with thallium picrate (1:1:1) accepts one TBP molecule. The thallium picrate complex with B15C5 and TBP is more stable than the corresponding 15C5 complex in benzene.
Decomposition Reaction of 3-Aryl-6-disubstituted Amino-1,4,2,5-dithiadiazines in the Solid State
Authors: Yonemoto Katsumi , Shibuya Isao 
Published: July 2006

Abstract
3-Diethylamino-6-phenyl-1,4,2,5-dithiadiazine, on standing in air at room temperature, decomposed to afford 5-diethylamino-3-phenyl- and 3,5-bis(diethylamino)-1,2,4-thiadiazoles, whereas in the melt and in solution it was remarkably stable. With increasing bulkiness of substituents (Ar and/or NR2) in 1,4,2,5-dithiadiazines, their stability in the solid state clearly enhanced. Some interstack interactions in the crystal seem to favor the decomposition.
Solubilization of Hemin in Neutral and Acidic Aqueous Solutions by Forming Complexes with Water-Soluble Macromolecules
Authors: Inamura Isamu , Isshiki Masayuki , Araki Takeo 
Published: July 2006

Abstract
Hemin was solubilized in neutral and acidic aqueous solutions by complexing with poly(N-vinylpyrrolidone) (PVP), polyethylene glycol (PEG), poly(vinyl alcohol) (PVA) and dextran. In neutral aqueous solutions, hemin in the PVP, PEG, and PVA complexes was monomeric and that in the dextran complex was dimeric. The effects of pH and ultraviolet (UV) irradiation on the spectroscopic properties of the complexes were examined.
The Crystal and Molecular Structures of Tetraethylammonium [Tetraaquatetrakis(isothiocyanato)neodymate(III) and europate(III)], [(C2H5)4N][M(NCS)4(H2O)4], (M=Nd, Eu)
Authors: Ouchi Akira 
Published: July 2006

Abstract
The crystal and molecular structures of the title new complexes were determined by means of a single-crystal X-ray diffraction method. The crystals of the neodymium(III) complex, NdC12H28N5O4S4, F. W. 578.87, are triclinic, space group P\bar1, a=14.13(2), b=15.39(1), c=12.92(1) Å, α=106.81(8), β=114.70(9), γ=90.09(10)°, U=2418(5) Å3, Z=4, Dm=1.57(3), Dx=1.59 g cm−3, μ(MoKα)=25.22 cm−1. The isomorphous europium(III) complex was also obtained: a=14.069(9), b=15.328(9), c=12.865(9) Å, α=106.98(5), β=114.57(5), γ=90.07(6)°, U=2390(3) Å3, Dm=1.60(3), Dx=1.63 g cm−3, μ(Mo Kα)=30.04 cm−1. Two crystallographically independent neodymium(III) atoms in a unit cell have approximately the same coordination geometry: square antiprism 4O,4N-octa-coodination. A pair of the O atoms as well as N atoms are in cis positions on the top square and in trans positions on the bottom square of each polyhedron, where the lines connecting both pairs of the N atoms on both squares are approximately parallel.
Physicochemical Properties of Polyacrylates Containing Tetraphenylporphinatocobalt(II) and Chloro(tetraphenylporphinato)iron(III) as Side Chains
Authors: Kamachi Mikiharu , Shibasaka Mahito , Kajiwara Atushi , Mori Wasuke , Kishita Michihiko 
Published: July 2006

Abstract
Polyacrylates containing tetraphenylporphinatocobalt(II) (TPP-Co(II)) and chloro(tetraphenylporphinato)iron(III) (TPP-Fe(III)Cl) as side chains were prepared. Their physicochemical properties were investigated by UV-visible spectroscopy, ESR spectroscopy, and magnetic susceptibility (χM) measurement. In comparison of the visible spectra of polymers with those of the corresponding monomers, hypochromism of the Soret band and some of Q bands was observed in both polymers. In the measurements of ESR spectra, hyperfine splitting constants and anisotropic g-values of TPP-Co(II) or -Fe(III)Cl moieties bound to the polymers were somewhat different from those of TPP-Co(II) and -Fe(III)Cl, respectively. These differences in spectroscopic behavior suggest that there are some interactions between porphinatometal ion moieties in the polymers. The values of χM for the polymers containing TPP-Co(II) were found to obey the Curie–Weiss law with θ=190 K, which was explained in terms not only of spin-orbit interaction of the Co(II) ion but also antiferromagnetic interaction among the Co(II) ions. The magnetic moment of the TPP-Co(II) moiety bound to the polymer is smaller than that of TPP-Co(II), indicating occurrence of an antiferromagnetic interaction between Co(II) ions in the polymer. The values of χM for polymers containing TPP-Fe(III)Cl were found to obey the Curie–Weiss law with θ=20 K. This can be explained in terms of the presence of antiferromagnetically-interacting sites. From the experimental results, it is concluded that the antiferromagnetic interaction between TPP-metal ions bound to the polymer is larger than that of the corresponding TPP-metal ions. Molecular oxygen is adsorbed to polyAOTPP-Co(II) and 5-(4-propanoyloxyphenyl)-10,15,20-triphenylporphinatocobalt(II) (POTPP-Co(II)) below 180 K. Magnetic susceptibility measurement and ESR study show that molecular oxygen is bound to the Co(II) ion by chemisorption whose binding energy is 24 kJ M−1.
Adsorption at Water/ Air Interface and Micelle Formation of Decylammonium Bromide and Decylammonium Chloride Mixture
Authors: Matsuki Hitoshi , Ando Naoko , Aratono Makoto , Motomura Kinsi 
Published: July 2006

Abstract
The surface tension of the aqueous solution of decylammonium bromide (DeAB) and decylammonium chloride (DeAC) mixture was measured as a function of the total molality and composition of surfactants at 298.15 K under atmospheric pressure. By applying the thermodynamic equations derived previously to the experimental results, the compositions in the mixed adsorbed film and mixed micelle were evaluated. It was found that the adsorbed film and micelle are rich in DeAB, which is more surface active than DeAC, compared with the aqueous solution. Further, the DeAB and DeAC molecules were concluded to mix ideally in the states of the adsorbed film and micelle. On the other hand, the compositions were compared with those of dodecylammonium chloride (DAC)–DeAC mixture at the critical micelle concentration (cmc). The discrepancy between the compositions was proved to be related closely to the differences between the cmc’s and between the surface tension values at the cmc of pure surfactants.
The Electric Birefringence and Dichroism of a Nonlinear Optical Compound, 4-[2-[4-(Dimethylamino)pheny]ethenyl]-1-ethylpyridinium Iodide, in the Presence of Poly(p-styrenesulfonate) and Poly(l-α-glutamate) in Solutions
Authors: Yamaoka Kiwamu , Hino Yasumori 
Published: July 2006

Abstract
The pulsed electric birefringence at 633 nm and dichroism at 462 nm of the title cationic compound (DAES) were measured at 20 °C over a wide electric field strength range (0.1–24 kV cm−1) in the presence of poly(p-styrenesulfonate) (NaPSS) and poly(l-α-glutamate) (PGA) in aqueous solutions at various mixing ratios (P/D) of the polymer to the ligand. The steady-state electric birefringence δ of NaPSS–DAES complexes was positive, while that of NaPSS was negative. The optical anisotropy factor of bound DAES was responsible for the sign reversal. The reduced electric dichroism of NaPSS–DAES at a P/D of 1.9 was +0.38 at infinitely high fields. A value of ±50° was found for the average angle between the orientation axis of the complex and the direction of the optical transition moment at 462 nm of bound DEAS chromophores. No appreciable permanent dipole moment was present in any of the NaPSS–DAES systems. The field orientation was due mostly to counterion-induced moments. The rotational relaxation time was determined from the decay signals. For PAG–DAES and PGA at pH 6.4 and 4.1, the sign of δ was always positive, the magnitude differing from each other by only 10–20%.
Copper(I) Salt Catalyzed Reaction of 1,1,1-Trichloro-2,2,2-trifluoroethane with Trimethylsilyl Enol Ethers. A Convenient Synthesis of β-Chloro-β-(trifluoromethyl) α,β-Unsaturated Carbonyl Compounds
Authors: Okano Takashi , Uekawa Toru , Eguchi Shoji 
Published: July 2006

Abstract
β-Chloro-β-(trifluoromethyl) α,β-unsaturated carbonyl compounds were obtained by the reaction of trimethylsilyl enol ethers with CF3CCl3 and CuCl, followed by dehydrochlorination with triethylamine or DBN. Aromatic enol ethers gave moderate to good yields of the chloro(trifluoromethyl)methylene ketone derivatives but aliphatic enol ethers and silyl ketene acetal gave only lower yields.
The Synthesis of 4,5-Ethylenedithio-4′,5′-vinylenedithiotetrathiafulvalene (EVT) and Its Methyl and Dimethyl Derivatives (EMVT, EDMVT), and the Molecular and Crystal Structures of EVT
Authors: Nakano Hideyuki , Miyawaki Kenji , Nogami Takashi , Shirota Yasuhiko , Harada Shigeharu , Kasai Nobutami 
Published: July 2006

Abstract
New donor molecules, 4,5-ethylenedithio-4′5′-vinylenedithiotetrathiafulvalene (EVT) and its methyl and dimethyl derivatives (EMVT and EDMVT), were synthesized for the study of conducting organic salts. They are unsymmetrical TTF derivatives possessing moieties of both BEDT-TTF and bis(vinylenedithio)tetrathiafulvalene (VT) or its methyl and dimethyl derivatives. Their oxidation potentials were measured and then compared with those of the related donor molecules. The X-ray crystal structure analysis of EVT revealed that its molecular and crystal structures are very close to that of BEDT-TTF.
Cobalt(III) Complexes with Quadridentate Ligands. IX. High-Resolution Solid-State 13C CP/MAS NMR Spectra of the Salicylato-, Carbonato-, Dichloro-, and Dinitro(quadridentate amine)cobalt(III) Complexes
Authors: Yamamoto Yoshihisa , Toyota Eiko , Shimokawa Shigezo 
Published: July 2006

Abstract
High-resolution solid-state 13C CP/MAS NMR was applied to many cobalt(III) complexes, such as salicylato-, carbonato-, dichloro-, and dinitro(quadridentate amine)cobalt(III) complexes, [CoL2(quadridentate amine)]+ (L: 1/2sal, 1/2CO3 Cl, NO2; quadridentate amine: tren, trien, 2,3,2-tet, 3,2,3-tet, 3,3,3-tet). The signals of the methylene carbons of the coordinated quadridentate amine ligands in their complexes have been assigned to the center, NH2– side, NH– side, and N– side methylene carbons. Also, the signals of the ring carbons of the coordinated salicylato ligand in their complexes have been assigned to the individual carbon atoms. It has been found that the signals of nonprotonated carbons (C-1, C-2, and C-7) of the coordinated salicylato ligand have been very high and that the 13C CP/MAS NMR method is well-suited for studies of unstable compounds in solutions.
Hydrogenation of Carbon Dioxide on Unpromoted and Potassium-Promoted Iron Catalysts
Authors: Lee Min-Dar , Lee Jyh-Fu , Chang Chau-Shang 
Published: July 2006

Abstract
The promotional effect of potassium was studied on catalytic behavior of iron in CO2 hydrogenation. A higher product selectivity toward light olefins and long-chain hydrocarbons was obtained on promoted catalyst than on unpromoted catalyst. This can be attributed to the enhancement of carburization on iron catalyst by potassium, as evidenced by Mössbauer spectroscopy and temperature-programmed decarburization.
A Transition Sequence of Complex Oscillations in a Chemical Oscillation Model Showing Chaos
Authors: Morita Makoto , Iwamoto Kazutoshi , Sen\={o} Manabu 
Published: July 2006

Abstract
A three-variable model system exhibiting complex oscillations was analyzed. Our analysis reveals a bifurcation structure of complex oscillations including chaotic oscillations. The bifurcation structure reproduces well the transition sequences of oscillatory states observed in the experiments of the Belousov–Zhabotinskii reaction and the chlorite oscillators. The transition sequence to chaotic oscillations in our model system shows period-doubling sequences. When the number F is defined as a ratio of the number of large amplitude to the total number of oscillations per period in the complex oscillation, the number constitutes a monotonous, stepwise-increasing function of a control parameter. The sequence of the complex oscillations is described well by the Farey arithmetric. Also, the average flux of reaction was found to change abruptly at the bifurcation points of the complex oscillations.
Synthesis and Chromogenic Properties of Disulfonated (1-Naphthyl)(2-quinolyl)methanone 5-Nitro-2-pyridylhydrazone and Its Application to the Spectrophotometric and Analogue-Derivative Spectrophotometric Determination of Trace Amounts of Zinc
Authors: Ishii Hajime , Kohata Katsunori , Odashima Tsugikatsu , Kawamonzen Yoshiaki 
Published: July 2006

Abstract
A water-soluble hydrazone, disulfonated (1-naphthyl)(2-quinolyl)methanone 5-nitro-2-pyridylhydrazone (NQNPH), in which one nitro group and two sulfo groups are introduced for the purpose of increasing sensitivity and solubility in water, has been synthesized and its chromogenic property and reactivity with metal ions investigated. NQNPH reacts with various metal ions including zinc(II) to form 1:2 (metal: ligand) colored stable complexes with high molar absorptivities. On this basis, sensitive and practical spectrophotometric and analogue-derivative spectrophotometric methods for the determination of trace amounts of zinc with NQNPH have been proposed. The zinc(II)–NQNPH complex is formed quantitatively in the pH range 6.9–9.6 and its absorption spectrum shows an absorption maximum at 516 nm. Beer’s law is obeyed over the range 0.07–1.5 ppm of zinc and the apparent molar absorptivity of the complex is 4.33×104 dm3 mol−1 cm−1 at 516 nm. The proposed method was applied to the determination of zinc in Kuroko and water samples, with satisfactory results. In addition, the acid dissociation constants of NQNPH and the overall formation constant of its zinc complex were also determined spectrophotometrically.
Racemization of Phenylalanine Coordinated to Bis(2,2′-bipyridine)ruthenium(II) Complexes in Basic Aqueous Solutions
Authors: Nagai Takashi 
Published: July 2006

Abstract
Racemization of the phenylalaninato ligand in Λ- and Δ-[Ru(phe)(bpy)2]+ (phe; phenylalaninate anion, bpy; 2,2′-bipyridine) complexes was found in basic aqueous solutions. It was proceeding without conformational change around the ruthenium ion in the dark. The equilibrium and rate constants of the racemization were determined in basic solutions at 100 °C. The reaction was base-catalyzed and not affected by photoexcitation of the complex ions.
Reinvestigation of the Nontotally Symmetric g-Type Normal Vibrations of [1H4]- and [2H4]Pyrazines
Authors: Hieida Toshikazu , Maehara Masayoshi , Nibu Yoshinori , Shimada Hiroko , Shimada Ryoichi 
Published: July 2006

Abstract
The assignment of the nontotally symmetric g-type normal vibrations of [1H4]- and [2H4]pyrazines was reinvestigated through the analyses of the single vibronic level fluorescence spectrum. The assignment given in this work was consistent with the assignment made based on the polarization behavior of the phosphorescence spectrum.
Sulfur Pressure Control in an H2–Sulfur Vapor System
Authors: Wada Hiroaki 
Published: July 2006

Abstract
A direct sulfur pressure control method by a N2–sulfur vapor system was modified by using an H2–sulfur vapor system. A ratio of H2S/H2 in the atmosphere was found to be controlled very well in the range from 10−2 to 10−4 only by the temperature regulation.
Synthesis of the 1H,5H-Naphtho[1,8-ef][1,3]dithiocin System
Authors: Kamada Toshihiro , Gama Yasuo , Wasada Nobuhide 
Published: July 2006

Abstract
The titled new pericyclized naphthalene system has been prepared in four steps from 1,8-naphthalenedicarboxylic anhydride in an overall yield of 35–78%. The key step in the synthesis employed a dithioacetal-cyclization reaction of 1,8-bis(mercaptomethyl)naphthalene with carbonyl compounds using boron trifluoride etherate as a catalyst.
The Selectivity of Sulfided NiW/Al2O3 Catalyst in the Hydrodesulfurization of Dibenzothiophene
Authors: Nagai Masatoshi 
Published: July 2006

Abstract
The selectivity of a sulfided NiW/Al2O3 catalyst for hydrodesulfurization has been studied at 300 °C and 10.1 MPa total pressure. The presence of oxygen and sulfur compounds depressed the desulfurization of dibenzothiophene, but not the hydrogenation. The addition of large amounts of acridine improved the catalytic activity significantly for the desulfurization of dibenzothiophene to biphenyl while preventing hydrogenation.
Isomerization of 1-Butene on High-Temperature-Chlorinated Alumina
Authors: Ayame Akimi , Sawada Goro 
Published: July 2006

Abstract
Regarding aluminas chlorinated at 973–1223 K, which have only a Lewis acidic character without hydroxyl groups and basic sites, the IR spectra of the adsorbed 1-butene were measured and the isomerization of 1-butene and cis-2-butene was performed at 273–323 K. The obtained results were compared with those for aluminas dehydrated at the same temperatures. The IR spectra of the adsorbed 1-butene well resembled that of cis-2-butene, including the absence of peaks due to double-bond and π-allyl carbanion species, observed even after outgassing at 473 K. During isomerization at 273 K, the initial isomerization reaction rates and cis/trans ratios were greater than those for dehydrated alumina. The ratio decreased rapidly with increasing reaction temperature. The specific reaction rates and the ratio were independent of the chlorination temperature. In the isomerization of cis-2-butene the most thermodynamically unstable molecule, 1-butene, was formed preferentially. The obtained results could be interpreted by an isomerization mechanism through a doubly bonded intermediate, i.e., the allylic butenyl cation.
Intramolecular [2+2] Photocycloaddition. 5. Synthetic Methods toward [2.n]-, [3.n]-, and [4.n]Naphthalenophane Skeletons by Using α,ω-Bis(vinylnaphthyl)alkanes
Authors: Nishimura Jun , Takeuchi Motoharu , Takahashi Hideo , Ueda Eiji , Matsuda Yasuhiro , Oku Akira 
Published: July 2006

Abstract
[2+2] Photocycloaddition, cationic cyclocodimerization, and reductive ring enlargement were developed for the syntheses of [2.n]-, [3.n]-, and [4.n]naphthalenophanes, respectively, from α,ω-bis(vinylnaphthyl)alkanes as a single starting material. Using the exclusive syn selectivity of the former two methods, the room required for the intraannular naphthalene-ring rotation in the ring system is determined.