bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Phase Transitions of 1,4-Dialkyl-1,4-diazoniabicydo[2.2.2]octane Bis(tetrafluoroborate), Cn–DABCO–Cn–(BF4)2 (10≤n≤22)
Authors: Terada Tohru , Nogami Takashi , Shirota Yasuhiko 
Published: July 2006

Abstract
The phase transitions of a series of title compounds were investigated by means of DSC, IR absorption spectra, and measurements of ionic conductivities. All of the compounds exhibited phase transitions in the range of 77–110 °C. The IR absorption spectra clarified that conformational change in the alkyl chain occurred above the transition temperature. The temperature dependences of the ionic conductivities of BF4− showed conductivity jumps by a factor of 9–120 around the transition temperatures. A comparison of the DSC results and the ionic conductivities of BF4-salts with those of the corresponding Br-salts showed that the former compounds have higher transition temperatures, smaller transition enthalpies (and, accordingly, smaller transition entropies), and smaller values of the conductivity jumps than the latter. These results show that BF4-salts are more rigid than Br-salts in the low temperature phase and that the motion of the alkyl group of the former salts is less vigorous than the latter in the high-temperature phase. By observing the crystal with a polarization microscope under crossed Nicols condition, it was found that optical anisotropy was diminished gradually with the elevation of the temperature and disappeared completely above Tc without changing the crystal shape.
Study on Conjugated Redox Membranes Containing an Intercellular Component of Wool as an Electron Carrier
Authors: Nakamura Yoshiharu , Kamon Noriaki , Hori Teruo 
Published: July 2006

Abstract
To realize artificially such a conjugated redox reaction as that which is drived across the biological cell membrane, two enzymic redox reactions were conjugated across a hydrogel membrane prepared with urethane prepolymer holding stabilized isocyanate groups. As redox couples, glucose 6-phosphate (G6P)/glucose 6-phosphate dehydrogenase (G6PD)/gluconolactone 6-phosphate (GL6P) and glutathione oxidized form (GSSG)/glutathione reductase (GRD)/glutathione reduced form (GSH) were chosen together with their common coenzyme, NADP+/NADPH. The driving of a system consisting of two redox couples separated with the hydrogel membrane containing the coenzyme NADP+ was intiated by the reduction of NADP+ on the membrane surface in contact with the G6PD/G6P solution. The conjugated redox reaction proceeded by electron exchange between coenzymes in the membrane and the reproducing of NADP+, which was accompanied with the GRD/GSSG solution. The rate of electron transfer across the urethane membrane was markedly accelerated by incorporating a nonkeratinous intercellular cement compound extracted from wool into the membrane. From cyclic voltammograms of a methyl viologen mediator, using a bare electrode and an intercellular compound modified carbon electrode, it was confirmed that the intercellular component could surely act as a good electron carrier.
Gamma-X Ray Coincidence Mössbauer Study with FeSO4·7H2O(57Co)
Authors: Kobayashi Takayuki 
Published: July 2006

Abstract
The anomalous charge states formed after the EC decay of 57Co in FeSO4·7H2O doped with 57Co are investigated in detail using the gamma-X ray coincidence Mössbauer spectroscopy. The mechanism to form these states is explained in terms of the H2O and SO42− coordination shells around the decaying atom.
A Facile Reductive Removal of Bromine Atom(s) of 6,6-Dibromo- and 6-Bromopenicillanate Derivatives in a Pb/Al Bimetal System
Authors: Tanaka Hideo , Tanaka Motoaki , Nakai Akira , Katayama Yasumi , Torii Sigeru 
Published: July 2006

Abstract
Reductive removal of the bromine atom(s) of 6,6-dibromo- and 6-bromopenicillanate 1-oxides has been performed successfully on treatment with aluminum metal in the presence of a catalytic amount of lead(II) bromide in methanol containing 1% aqueous hydrobromic acid. In a similar manner, 6,6-dibromopenicillanates and their 1,1-dioxides can be convened to the corresponding debromination products, respectively.
Asymmetric Radical Reaction in the Coordination Sphere. IV. Ruthenium(II)-Catalyzed Asymmetric Addition of Sulfonyl Chloride to 1-Phenylpropene
Authors: Kameyama Masayuki , Kamigata Nobumasa 
Published: July 2006

Abstract
The asymmetric addition of methane- and p-toluenesulfonyl chloride to 1-phenylpropene catalyzed by Ru2Cl4[(−)-diop]3 affords optically active 1:1 adducts, (+)-(1R,2RS)-1-chloro-2-methylsulfonyl-1-phenylpropane (2) and (+)-(1R,2RS)-1-chloro-1-phenyl-2-tosylpropane (3), with about 13–19%ee. Similarly, (−)-(1S,2RS)-2 and (−)-(1S,2RS)-3 were obtained when Ru2Cl4[(+)-diop]3 was employed. A enantiolace differentiation is considered to occur in the chlorine atom transferring step from the ruthenium(III) species to the carbon radical in the coordination sphere.
The Preparation and Structure of the Copper(II) Chloride Complex of 5,5′-Carbonylbis[1,3-dimethyl-3,4,5,6-tetrahydro-1,3,5-triazin-2(1H)-one]
Authors: Ebisuno Toichi , Takimoto Michiaki , Takahashi Miyuki , Shiba Ryuichi 
Published: July 2006

Abstract
A new 1,3-dimethylurea–formaldehyde condensate like a crown compound with two rings, 5,5′-carbonylbis[1,3-dimethyl-3,4,5,6-tetrahydro-1,3,5-triazin-2(1H)-one], was prepared. The molecular structure of the complex with the condensate and copper(II) chloride (1:1) was determined by means of X-ray analysis. The copper(II) ion was coordinated intermolecularly between two oxygen atoms (O(2) and O(2)′ in the adjacent molecule).
The Meaning of the Equilibrium Spreading Pressure of Fatty Acid Being Relatively Soluble in an Underlying Subphase
Authors: Iwahashi Makio , Iiduka Kimiyo , Watanabe Takashi , Seimiya Tsutomu 
Published: July 2006

Abstract
The spreading pressure of a lipid monolayer in equilibrium with its crystal placed at the air/water interface is a thermodynamical property—i.e., the equilibrium spreading pressure (ESP). It is, however, quite likely that the apparently constant spreading pressure of a lipid with a relatively large desorption rate into the underlying subphase is not a thermodynamical property but merely a steady-state one. Mutual comparisons were, therefore, carried out for the rate constants of the six possible processes associated with the spreading pressure of tetradecanoic acid, whose monolayer has a relatively large desorption rate into the underlying subphase; it was found that monolayer formation from its crystal was predominant and that the desorption from the monolayer little affected the spreading pressure, even at high temperatures. Consequently, the apparently constant spreading pressure for the tetradecanoic acid can be regarded as the ESP even at high temperatures, in which the dissolution of the monolayer into the subphase occurs very rapidly.
Parametrized Equations-of-Motion Method at the (1p-1h)+(2h-2p) Level and Its Application to Linear Polyenes
Authors: Shibuya Tai-ichi , Funada Tadashi , Narita Susumu 
Published: July 2006

Abstract
The previously proposed idea of parametrizing the equations-of-motion method [Int. J. Quantum Chem., 18, 205 (1980)] has been worked out for the π→π* transitions of linear polyenes. The excitation operator consists of not only 1p-1h creation and annihilation operators but also 2p-2h creation and annihilation operators. [Bull. Chem. Soc. Jpn., 61, 1103 (1988)]. The proposed scheme accounts for the effect of σ→σ* mixings in contrast with the traditional pi-electron theories. In the present work, the two-center Coulomb integrals are evaluated by 1/R, and all the one-center integrals on the C atom are assumed to be the same. Values of the three parameters (a, b, ζ) introduced in the scheme are so determined that the computed excitation energies of ethylene and s-trans-butadiene fit the observed values. The scheme has been applied to a series of all-s-trans linear polyenes through dodecahexaene. Some notable results are: (1) The σ→σ* mixings play a significant role in lowering the excitation energies of the allowed transition to 11Bu; (2) the 21Ag state is of Ag− type and almost free from this effect; (3) double excitations (2p-2h states) are dominant in the 21Ag state but practically negligible in the 11Bu state.
Preparation of μ-Cyano Dinuclear Chromium(III) Complexes MI[F(en or tn)2Cr(NC)Cr(CN)5] from the Doubly Complexed Salts of the Form MI[CrF(H2O)(en or tn)2][Cr(Cn)6]
Authors: Johda Makoto , Suzuki Masatatsu , Uehara Akira 
Published: July 2006

Abstract
Preparation of the μ-cyano dinuclear complexes MI[F(en or tn)2Cr(NC)Cr(CN)5]·nH2O from the double complexes MI[CrF(H2O)(en or tn)2][Cr(CN)6]·nH2O was carried out both in the solid state and in solution, where MI is Li+, Na+, K+, or Rb+ ion; en and tn stand for 1,2-ethanediamine and 1,3-propanediamine, respectively. The desired μ-cyano dinuclear complexes were successfully obtained in solution, but the mixture of di- and trinuclear complexes was formed along with unknown polymeric species in the solid state. The electronic spectra of the dinuclear complexes exhibited a small but clear band due to spin-forbidden transition (4A2g→2Eg). Magnetic moments of the dinuclear complexes were 3.4–3.5 μβ at ambient temperatures and 2.2–2.4 μβ at 80 K, which are substantially smaller than the spin-only value (3.87 B.M.). The J values for the dinuclear complexes were estimated to be −19–−20 cm−1, indicating that an antiferromagnetic superexchange interaction is exerted between two chromium(IH) ions through μ-CN group, but the magnitude of the interaction is smaller than that of the μ-oxo complexes (J=−450 cm−1) and comparable to that of the μ-hydroxo complexes (J=−23 cm−1) reported previously.
Studies on Mixed Chelates. XVII. Crystal Structure and Spectral Properties of Mixed Nickel(II) Nitrate Complexes Containing 1,2-Dipiperidinoethane and β-Diketonate Ligands
Authors: Fukuda Yutaka , Fujita Chiori , Miyamae Hiroshi , Nakagawa Hiroko , Sone Kozo 
Published: July 2006

Abstract
Several new mixed nickel(II) nitrate complexes with 1,2-dipiperidinoethane (dipe) and β-diketonate ions (dike), [Ni(NO3)(dike)(dipe)], have been obtained and characterized. The crystal structure of one of them, [Ni(NO3)(acac)(dipe)], was determined by X-ray crystallography. The crystal is monoclinic with the space group Cc, Z=4, a=9.0517(4), b=21.932(1), c=9.8814(6) Å, β=88.151°. Block-diagonal least-squares refinements have led to a final R value of 0.036 for 2471 reflections. It was confirmed that the nitrate ion in the octahedral complex acts as a bidentate ligand and that the conformation of the piperidine ring in dipe is a chair form. The spectral behaviors of these complexes in various organic solvents are discussed in comparison with those of similar complexes with other N,N′-alkylated ethylenediamine ligands (diam). It was concluded that, in a solvent with low polarity, the complexes are dissolved unchanged; in a more polar solvent, however, dissociation of NO3− takes place, producing solvated or unsolvated cationic species ([Ni(dike)(diam)(Solvent)2]+ (Oh) or [Ni(dike)(diam)]+ (Square Planar)) according to the donor and acceptor properties of the solvent.
Base-Catalyzed Isomerization and Racemization Reactions of [Co(L1)(L2)]Type Complexes (L1=Iminodiacetato or N-Methyliminodiacetato and L2=3-Azapentane-1,5-diamine or 3-Methyl-3-azapentane-1,5-diamine)
Authors: Kawaguchi Hiroshi , Shimizu Masato , Ama Tomoharu , Yasui Takaji 
Published: July 2006

Abstract
The isomerization and racemization reactions of the [Co(ida)(dien)]+ and [Co(ida)(mdien)]+ systems were studied in an aqueous solution. The main isomerization path of the [Co(ida)(dien)]+ system was u-fac\ightleftharpoonsmer\ightleftharpoonss-fac and the rate law for each of the processes could be described as R=k[complex][OH−]. In the [Co(ida)(mdien)]+ system, there was an additional isomerization path of u-fac→s-fac. The equilibrium mole ratio of three isomers was u-fac:mer:s-fac=25:19:56% for [Co(ida)(dien)]+ and u-fac:mer:s-fac=3:3:94% for [Co(ida)(mdien)]+. In the isomerization of (+)564CD-u-fac-[Co(mida)(mdien)]+, (+)582CD-mer isomer was stereoselectively produced. The racemization mechanisms of mer-[Co(ida)(dien)]+ and mer-[Co(mida)(dien)]+ are also discussed.
The Zinc(II)-Catalyzed Henkel Reaction of Dipotassium 1,8-Naphthalenedicarboxylate in a Dispersion Medium
Authors: Fujishiro Koichi , Mitamura Shuichi 
Published: July 2006

Abstract
The Henkel reaction of dipotassium 1,8-naphthalenedicarboxylate in naphthalene as a dispersion medium gave dipotassium 2,6-naphthalenedicarboxylate (1) in a higher yield and with a better reproducibility than the reaction without a dispersion medium. Catalysts, particularly zinc catalysts, were examined in detail. The anion moiety of zinc catalysts affected the reaction, and the halide anion was effective for the selective formation of 1. The addition of potassium halide to the zinc catalysts also increased the yield of 1. The catalytic activity of the halide anion increased in the order; Cl−&lt;Br−&lt;I−. The activity of the zinc catalysts was also compared with that of cadmium catalysts.
Formation of N-Tributylstannyl Heterocycle from Bis(tributyltin) Oxide and ω-Haloalkyl Isocyanate. One-Pot Convenient Synthesis of 2-Oxazolidinones and Tetrahydro-2H-1,3-oxazin-2-one
Authors: Shibata Ikuya , Nakamura Kenji , Baba Akio , Matsuda Haruo 
Published: July 2006

Abstract
Novel types of compounds, N-tributylstannyl-2-oxazolidinone (4a) and tetrahydro-2H-1,3-oxazin-2-one (4b), are formed from the adduct of (n-Bu3Sn)2O (1) with ω-haloalkyl isocyanate (2), and the subsequent coupling reaction with alkyl halides gives a variety of N-substituted 2-oxazolidinones and tetrahydro-2-oxazinones in a one-pot procedure. Both the cyclization and the coupling reaction proceed quantitatively in the presence of HMPA which enhances the reactivity of the Sn–heteroatom bond by coordination.
Synthesis of Ba2YCu3O7–δ Superconductor through Organometallic Route
Authors: Hirano Shin-ichi , Hayashi Takashi , Miura Masashi , Tomonaga Hiroyuki 
Published: July 2006

Abstract
The chemical synthesis of a high-Tc Ba2YCu3O7–δ superconductor was investigated through the organometallic route, using Ba metal, Y(OPri)3, and Cu–alkoxides or Cu–acetylacetonate as starting materials. Chemically homogeneous submicron powders of single phase Ba2YCu3O7–δ were successfully prepared at 750 °C by controlled partial hydrolysis of metal alkoxides. The utilization of ozone for favorable decomposition of Ba2YCu3O7–δ precursors was found to have a remarkable effect on suppressing the formation of BaCO3 and lowering the formation temperature of Ba2YCu3O7–δ to about 650 °C. The single phase Ba2YCu3O7–δ ceramics exhibited superconductivity at approximately 83 K (Tc end).
Quadrupole Coupling Constants in the Symmetric Tetrasubstituted Germanes
Authors: Harazono Toshie , Tanaka Katsumi , Takeuchi Yoshito 
Published: July 2006

Abstract
The quadrupole coupling constants in the symmetric tetrasubstituted germanes, GeR4 (R=CH3, C2H5, n-C3H7, n-C4H9, Cl, and Br) were obtained by measuring the 73Ge spin-lattice relaxation times (T1) and the reorientational correlation times (τc) of the chloroform solutions. Quadrupole coupling constants of GeR4 were in the range of 0.72 MHz (R=n-C4H9) to 1.51 MHz (R=CH3), and these decreased slightly as the molecular radius increased.
Organic Photochemical Reactions. XXXI. Photosensitized Ring-Cleavage Reactions of 2,2-Diaryloxetanes by Aromatic Nitriles
Authors: Nakabayashi Kenichi , Kojima Jun-ichi , Tanabe Kimiko , Yasuda Masahide , Shima Kensuke 
Published: July 2006

Abstract
Photosensitized reactions of 2,2-diaryloxetanes by 1,4-dicyanonaphthalene, 1-cyanonaphthalene, and 9,10-dicyanoanthracene, which give such ring-cleavage products as substituted benzophenones and alkenes, have been investigated. Quantum yields for the ring cleavage vary with the substituents on both the aryl group and oxetane ring. The quantum yield increases with increase in electron-donating ability of the oxetane. The limiting quantum yields in the case of 1,4-dicyanonaphthalene-photosensitized reaction of 2,2-di-p-tolyl- or 2,2-bis(p-mechoxyphenyl)-3,3,4-uimethyloxetane exceed unity. The mechanism is discussed in terms of electron transfer from oxetanes to the excited singlet state of the sensitizer as well as the regeneration process of the oxetane cation radical involving the hole transfer from substituted benzophenone cation radicals to oxetanes in the chain process.
A Conductometric Study on the Phenylglyoxylic Acid–Strychnine Complex
Authors: Sakai Yasuzo , Sato Kenichi , Ito Ikuko , Takahashi Fujio 
Published: July 2006

Abstract
In order to elucidate the mechanism by which phenylglyoxylic acid (PGA) is reduced electrochemically in the presence of strychnine (SC) to form mandelic acid (MA), which exhibits an optically active property, conductometric studies were carried out. The formation of a 1:1 complex between PGA (or MA) and SC was suggested from the results that equimolar mixture of PGA (or MA) and SC showed a maximum decrease of conductivity. Equilibrium constants of the 1:1 complex of PGA–SC or MA–SC were determined from the results of conductivity measurements at various temperatures. The thermodynamic data were calculated. ΔH and ΔS were found to be +22 kJ mol−1 and +1.1×102 J K−1 mol−1 for both the PGA–SC complex and MA–SC complex.
A Least-Squares Method for Computing Rate Constants of Reversible, First-Order, Triangular Network Reactions and Its Application to the Intermolecular Rearrangements of Acetylacetonatobis(4,4,4-trifluoro-1-phenyl-1,3-butanedionato)ruthenium(III)
Authors: Hoshino Yoshimasa , Takahashi Ryouta , Shimizu Kunio , Satô Gen P , Aoki Koichi 
Published: July 2006

Abstract
A useful method for computing the rate constants of reversible, first-order, triangular network reactions (B1\ightleftarrowsB2, B2\ightleftarrowsB3, B3\ightleftarrowsB1) is developed. It gives the best-fit set of the rate constants from the experimental data of the equilibrium constants and the mole fraction-time curves through an iterative least-squares method. This type of reaction can be classified into three categories for different shapes of the mole fraction-time curves. The method was successfully applied to determining the rate constants of the rearrangement reactions among the three isomers of [Ru(acac)(tfpb)2] (acac−=acetylacetonate ion, tfpb−=4,4,4-trifluoro-1-phenyl-1,3-butanedionate ion) in N,N-dimethylformamide at 90 °C. The direct conversion between the de,fc-bis(tfpb) isomer and the cf,ed-bis(tfpb) isomer was forbidden. The twist mechanisms are incompatible with this fact.
Natural-Abundance Oxygen-17 Magnetic Relaxation in Aqueous Solutions of Apolar Amino Acids and Glycine Peptides
Authors: Ishimura Miyuki , Uedaira Hisashi 
Published: July 2006

Abstract
The spin-lattice relaxation times, T1, of H217O have been measured for the aqueous solutions of 11 apolar amino acids and 5 glycine peptides as a function of the concentration at 25°C. The coordination numbers, nh, and the rotational correlation times, τch, of water molecules around the amino acids and peptides were estimated and compared with that of pure water, τc0. The value of τch⁄τc0=1.87 for norleucine is the largest, while those of τch⁄τc0 for glycine peptides are almost the same 1.2. The value of nh(τch⁄τc0−1) was defined as the dynamic hydration number (DHN). The DHN showed a good correlation with several physicochemical properties, such as the molecular weights, partial molar volumes, adiabatic compressibilities, heat capacities, B-coefficients of the activity coefficent, and limiting diffusion coefficients of amino acids and glycine peptides in aqueous solutions.
Stereoselective Construction of Acyclic Structures with Four Consecutive Asymmetric Centers
Authors: Hanamoto Takeshi , Katsuki Tsutomu , Yamaguchi Masaru 
Published: July 2006

Abstract
All the eight possible diastereomers of 6,8-dihydroxy-5,7-dimethyltridecane, taken as the model example for the construction of four consecutive asymmetric centers, were stereoselectively synthesized from two common starting materials, α-hydroxy-β-methyl-γ,δ-unsaturated acids (1a and 1b), wherein a newly introduced stereoselective epoxidation of β-methylhomoallylic alcohols and the subsequent alkylative opening of epoxide rings were utilized as key steps.
Conjugated Systems with Identical Circuit Resonance Energies
Authors: Gutman Ivan , Mizoguchi Noriyuki 
Published: July 2006

Abstract
Circuit resonance energy CE defined by Aihara is one of indices for local aromaticity. The CE for a circuit of a polycyclic conjugated molecule is calculated from the roots of the reference polynomial and circuit characteristic polynomial. It is reported that there exist polycyclic conjugated molecules which have identical reference polynomials and identical circuit characteristic polynomials and thus identical circuit resonance energies.
Substituent Effects. XX. Highly Electron-Deficient Carbocation Solvolyses
Authors: Murata Akihisa , Sakaguchi Shin-ichi , Fujiyama Ryoji , Mishima Masaaki , Fujio Mizue , Tsuno Yuho 
Published: July 2006

Abstract
The solvolysis rates of 1-aryl-2,2,2-trifluoroethyl tosylates (1-OTs) and m-nitrobenzenesulfonates (1-ONs) were determined conductometrically in aqueous ethanol and aqueous TFE. While the Brown ρ+σ+ equation does not give a simple linear plots, but a remarkably split pattern, there is a linear free energy relationship between the solvolyses of 1-OTs and 1-aryl-1-(trifluoromethyl)ethyl tosylates (2) with a slope of unity over a wide range (108 in reactivity) of substituents from p-MeO to unsubstituted derivatives. The substituent effect on the solvolysis of 1 should be closer to that on the solvolysis of 2, rather than to the σ+ substituent effect. The ρ value for this system was estimated to be identical to the value of −6.3 assigned for 2, and the r value in the LArSR correlation to be comparable with or even higher than the r=1.4 of 2. The enhanced r value of this system must be caused from a strong destabilization of the transition state by the α-CF3 substituent. Extremely high ρ+ values have recently been pointed out for many solvolyses generating highly electron-deficient carbocations; however, in no case is the ρ+ value equally high for the electron-attracting region of the substituent. In fact, they all resulted in significantly concave σ+ plots, suggesting a mechanistic transition. All of the conflicts must be attributed to the inadequacy of the simple application of σ+. The use of the Brown σ+ scale must be the only cause of a curve break in the correlation plot of such a system having a significantly different resonance demand.
Electron Spin Resonance Spectra of Sulfinamidyl Radicals and a Comparison of Hyperfine Splitting Constants with Sulfenamidyl and Sulfonamidyl Radicals
Authors: Miura Yozo , Nakamura Yuji 
Published: July 2006

Abstract
An ESR spectroscopic study of N-arylsulfinyl- and N-alkylsulfinyl-3,5-di-t-butylphenylaminyls (2) is described. The sulfinamidyls 2, generated by the reaction of the corresponding sulfinamides (7) with di-t-butyl diperoxyoxalate (DBPO) in benzene at 21 or 40°C, give hyperfine splitting (hfs) constants which indicate that the unpaired electron is slightly delocalized onto the sulfinyl group. A comparison of the hfs constants for 2 with those for structurally related sulfenamidyl and sulfonamidyl radicals indicates that the abilities of –SR, –S(O)R, and –S(O2)R to delocalize the unpaired electron are in the order –SR&gt;–S(O)R&gt;–(O2)R. The reaction of 7 with DBPO has been examined on the basis of product analyses. The mechanism accounting for the formation of the isolated products is briefly discussed.