bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Syntheses and the X-Ray Crystal Structure of Tetramethylammonium Tetrakis- and Tris(thiocyanato)cadmates(II), [(CH3)4N]2[Cd(SCN)4] and [(CH3)4N][Cd(SCN)3]
Authors: Kuniyasu Yasumitsu , Suzuki Yasuo , Taniguchi Masahiro , Ouchi Akira 
Published: July 2006

Abstract
The crystal and molecular structure of the two new thiocyanatocadmate(II) complexes indicated in the title were determined by the single-crystal X-ray-diffraction technique. [(CH3)4N]2[Cd(SCN)4] is tri-clinic, with a space group of P\bar1; a=7.300(2), b=13.019(4), c=5.8920(9) Å, α=96.32(2), β=93.080(18), γ=104.63(2)°, and Z=1, while [(CH3)4N][Cd(SCN)3] is orthorhombic with a space group of Pna21; a=10.506(3), b=13.797(5), c=9.4506(18) Å, Z=4. In both complexes, the cadmium atom is in an octahedral geometry. In 1, the metal atom is at the center of symmetry, and respective pairs of side-by-side metal atoms are bridged by two thiocyanate (SCN) ions, where one SCN ion is S-coordinated and the other is N-coordinated to the same-side metal atom. Also bonded with two nitrogen atoms of unidentate SCN ions, the metal atom is 4N2S-hexa-coordinated, and they line up along the c-axis in a polymeric form. In 2, respective pairs of side-by-side metal atoms are bridged by three SCN ions, two of those SCN ions being S-coordinated, and one N-coordinated, to the same-side metal atom; each metal atom is 3S3N-hexa-coordinated, and the chain of the polymeric complex lines up along the a-axis. The tetramethylammonium ions bond with the polymeric complex only by the ionic bonding. The final R values obtained are 1=0.039 and 2=0.050.
Thermal Condensation in Solid State of N-Hydroxyalkyl-2-imidazolidinone
Authors: Shimasaki Choichiro , Kanayama Ryosei , Yoshida Hiroaki , Yugamidani Makoto 
Published: July 2006

Abstract
N-(1-Hydroxyalkyl)-2-imidazolidinones (1) were prepared by a reaction of 2-imidazolidinone with form-, acet-, propion-, and butyraldehyde. In all of these reactions, 1 were unstable and moisture-sensitive substances. The pyrolysis reaction of 1 was found to be a thermal decomposition via a condensation reaction stage after a molten state. The condensation stage obeyed 1/2- and the first-order kinetics. The kinetic data regarding the condensation reaction were evaluated by analyses of the dependences of the area of isothermal DSC curves upon the reaction time. It may be concluded that the difference provided by the reaction order and the activation parameters were caused by the number of the hydrogen atoms on the β-carbon atom adjacent to the carbon attacked the hydroxyl group of side chain in 1. In the decomposition by electron impact of 1 and dimer of 1, the cleavage of the five-membered ring which corresponded to the molecular-ion peak for 2-imidazolidinone (m⁄z 86) was considered to take place after a successive cleavage of the side chain. On the basis of both kinetic studies and ESR or Mass spectral observations, the dimerization mechanism is fully discussed.
Highly Regioselective α-Addition of Alkynyl and Alkenyl Grignard Reagents to 1-Alkoxycarbonylpyridinium Salts and Its Application to Synthesis of 1-Azabicycloalkanes and (±)-Solenopsin A
Authors: Yamaguchi Ryohei , Nakazono Yutaka , Matsuki Toshitsugu , Hata Ei-ichiro , Kawanisi Mituyosi 
Published: July 2006

Abstract
Nucleophilic addition of a variety of alkynyl and alkenyl Grignard reagents to 1-methoxycarbonylpyridinium chloride takes place at the α-position in a highly regioselective manner to give 2-substituted 1-methoxycarbonyl-1,2-dihydropyridines exclusively, while, with alkyl Grignard reagents, a lack of the regioselectivity is observed. These results may be explained by the HSAB principle. The high α-regioselectivity is preserved in the cases of 2-substituted pyridines as well, giving 2,6-disubstituted 1,2-dihydropyridines exclusively, which can be transformed stereoselectively into cis- and trans-2,6-dialkylated piperidines. These highly regioselective α-alkynylations of 1-methoxycarbonylpyridinium salts are exploited in synthesis of 1-azabicycloalkanes as well as (±)-solenopsin A.
Comparison of Stability Constants of Alkaline Earth Chlorides between Conductometric and Potentiometric Studies
Authors: Doe Hidekazu , Wakamiya Kenichi , Kitagawa Toyokichi 
Published: July 2006

Abstract
The stability constants of alkaline-earth metal chlorides, MCl+ (M2+=Ca, Sr, Ba), were determined by conductometric and potentiometric measurements in methanol. The conductometric study was made at 5, 15, 25, 35, and 45°C; the potentiometric study was at 25°C. The formation of MCl2 was neglected in the conductometric study, while in the potentiometric study it was taken into account, though it was too slight to determine a reliable value of the stability constant of MCl2. The stability constants of MCl+, K1, determined by conductometric measurements were compared with the previous conductometric results of the same metal(II) perchlorates, K1A. The magnitudes of K1 and K1A increase in the orders Ca \simeqSr&lt;Ba and Ca&lt;Sr&lt;Ba, respectively. K1 is larger than K1A for calcium and strontium, though the K1 and K1A values for barium are similar to each other; that is, the degree of such an increase in K1A is larger than that in K1. Both enthalpy and entropy changes determined by conductometric measurements were positive for all the chlorides and perchlorates. However, the enthalpy changes of the chlorides were 1.2–1.4 times as large as those of the perchlorates. On the other hand, the K1 from potentiometry was smaller for every chloride and also increased more steeply (in the order Ca&lt;Sr&lt;Ba) than that from conductometry. Therefore, the difference of K1 between conductometry and potentiometry decreases in going from Ca to Ba.
Mössbauer Spectroscopic Study on the Mixed-Valence States of 1′,1'″-Dimethyl-, 1′,1'″-Dipentyl-, 1′,1'″-Dihexyl-, and 1′,1'″-Didecylbiferrocenium Triiodide
Authors: Nakashima Satoru , Katada Motomi , Motoyama Izumi , Sano Hirotoshi 
Published: July 2006

Abstract
1′,1'″-Dimethyl-, 1′,1'″-dipentyl-, 1′,1'″-dihexyl-, and 1′,1'″-didecylbiferrocene were synthesized and Mössbauer spectroscopic measurements of their monocation salts were carried out at various temperatures in order to know the mixed-valence states. Effects of alkyl substituent on the valence states of iron atoms in the monocation salts of 1′,1'″-dialkylbiferrocenes are discussed.
The ν8 Infrared Band of Ethylidynephosphine CH3C≡P and Its Perdeuteride CD3C≡P
Authors: Ohno Keiichi , Matsuura Hiroatsu 
Published: July 2006

Abstract
The gas-phase infrared spectra of ethylidynephosphine CH3C≡P and its perdeuteride CD3C≡P were measured in the 50–400 cm−1 region with a resolution of 0.12 cm−1. The molecular constants for the ν8±1 and 2ν80–ν8±1 bands were determined by the P,RQK branch analysis.
Topological Charge Stabilization Rule and Quasi-Aromaticity
Authors: Aihara Jun-ichi 
Published: July 2006

Abstract
Stabilities of the oxocarbon dianions and some quasi-aromatic compounds can be rationalized in terms of Gimarc’s topological charge stabilization rule. The term “quasi-aromatic” is recommended for describing those non-aromatic compounds which behave like aromatics owing to the operation of this rule.
X-Ray Structure of μ-Oxo-μ-sulfido-bis[(cysteinato)oxomolybdate(V)] Complex, Ca[Mo2O3S(SCH2CH(NH2)CO2)2]·3H2O
Authors: Shibahara Takashi , Kuroya Hisao , Matsumoto Keiji , Ooi Shun’ichiro 
Published: July 2006

Abstract
The crystal structure of μ-oxo-μ-sulfido cysteinato Mo(V) dimer, Ca[Mo2O3S(SCH2CH(NH2)CO2)2]·3H2O has been determined from X-ray diffraction data. The structure of the complex anion is similar to those of di-μ-oxo- and di-μ-sulfido- Mo(V) dimers. The trans influence of sulfur atoms is observed.
Reactions of Trimethylsilyl Isothiocyanate with Aldehydes and Acetals. Synthesis of Symmetrically and Unsymmetrically Isothiocyanato-Substituted Ethers
Authors: Nishiyama Kozaburo , Oba Makoto 
Published: July 2006

Abstract
The reactions of trimethylsilyl isothiocyanate (TMSTC) with aldehydes catalyzed by Lewis acid gave α,α′-diisothiocyanato ethers in good to excellent yields. Similarly, unsymmetrical α-isothiocyanato ethers were obtained from the reactions of TMSTC with acetals in appropriate yields.
Improved Synthesis of Dibenzo[a,j]perylene-8,16-dione
Authors: Hirakawa Kiyoichi , Ogiue Eriko , Motoyoshiya Jiro , Kakurai Toshio 
Published: July 2006

Abstract
An improved method for the synthesis of the title compound 1 has been achieved through an application of the Scholl reaction. The key to the new approach is to use the dimeric compounds of 10-methyleneanthrone as the precursors of 1.
Hydrates of Organic Compounds. XIII. The Confirmation of the Formation of Clathrate-Like Hydrates of Tetrabutylammonium and of Tetraisopentylammonium Polyacrylates
Authors: Nakayama Haruo 
Published: July 2006

Abstract
A thermal analytic method using a differential scanning calorimeter has been applied to aqueous solutions of a series of tetraalkylammonium polyacrylates ((R4NOOCCHCH2)n; R=CH3, C2H5, n-C3H7, n-C4H9, n-C5H11, and i-C5H11). It was found that only tetrabutylammonium polyacrylate and tetraisopentylammonium polyacrylate could form stable hydrates having a large number of moles of water per single R4NOOCCHCH2 unit of the polyacrylates (hydration numbers). The melting points and hydration numbers of these two hydrates were 11.2 °C, 30±1 for the tetrabutylammonium polyacrylate hydrate and 19.5 °C, 42±2 for the tetraisopentylammonium polyacrylate hydrate, respectively. Judging from the melting points, hydration numbers, and the concentration dependence of the dissolution temperatures, these hydrates were regarded as clathrate-like. The tetrabutylammonium polyacrylate hydrate seems to be iso-structural with (n-C4H9)4NF hydrate and the tetraisopentylammonium polyacrylate hydrate with (i-C5H11)4NF hydrate.
Adsorption of Dodecyltrimethylammonium Chloride from the Micellar Solution at Water/Air Interface
Authors: Aratono Makoto , Okamoto Toru , Motomura Kinsi 
Published: July 2006

Abstract
The surface tension of the aqueous solution of dodecyltrimethylammonium chloride (DTAC) was measured as a function of temperature under atmospheric pressure at concentrations below and above the critical micelle concentration. The thermodynamic quantity changes associated with the adsorption of DTAC from its monomeric and micellar states were evaluated and proved to satisfy the thermodynamic relation derived on the assumption that the micelle formation can be treated as the appearance of a macroscopic bulk phase in the solution. Further their values were compared with those of the aqueous solution of dodecylammonium chloride and the influence of the chemical structure of the head group on the adsorption and micelle formation were discussed from the thermodynamic viewpoint.
Preparation and Properties of Ammonium Hexachlorozirconate(IV) and Its Reaction with Gaseous Ammonia
Authors: Ohashi Masao , Yamanaka Shoji , Morimoto Yuhki , Hattori Makoto 
Published: July 2006

Abstract
Ammonium hexachlorozirconate (NH4)2ZrCl6 was prepared by the direct reaction of ZrCl4 with NH4Cl. The X-ray powder diffraction and the density measurements showed that it has a face-centered cubic lattice with a=10.127(2) Å and is isostructural with K2PtCl6. The hexachlorozirconate undergoes ammonolysis in gaseous ammonia at room temperature, forming ZrCl3(NH2)·xNH3 and NH4Cl. The ammonolysis product reverts to the initial (NH4)2ZrCl6 on heating to 250 °C in the ammonia atmosphere. The hexachlorozirconate vaporizes at about 450 °C. The reaction of ZrCl4 with gaseous ammonia was also studied in comparison with that of the hexachlorozirconate.
Synthesis of (E,E)- and (Z,Z)-1,5-Cycloalkadienes by Means of the Electrochemical Cyclization of Allylic 1,ω-Dibromides
Authors: Tokuda Masao , Satoh Kuniaki , Suginome Hiroshi 
Published: July 2006

Abstract
Electrolysis of (E,E)-1,n-dibromo-2,(n-2)-alkadienes (n=12, 14) in tetrahydrofuran gave the corresponding twelve or fourteen-membered (E,E)-1,5-cycloalkadienes, albeit in low yields, together with (E)-4-vinylcycloalkenes and isomeric alkadienes. Similar electrolysis of (Z,Z)-1,n-dibromo-2,(n-2)-alkadienes (n=10, 12, 14) gave the corresponding ten, twelve, or fourteen-membered (Z,Z)-1,5-cycloalkadienes in 11 to 13% yields, with the accompanying formation of (Z)-4-vinylcycloalkenes and isomeric alkadienes.
Effect of Lattice Anions on the Ligand Substitution Reaction of Tris(1,10-phenanthroline)metal(II) Complexes: [M(phen)3]SO4 and [M(phen)3]X2 (M: Fe(II), Co(II), Ni(II); X: Cl−, Br−, I−)
Authors: Yamasaki Shoji , Fujiwara Terufumi , Yamamoto Yuroku 
Published: July 2006

Abstract
The kinetics of the ligand substitution reaction of the title complexes in the solid state have been studied using thermogravimetry (TG) and differential scanning calorimeter (DSC) techniques. For these complex salts, an exothermic peak appears in the DSC curve which correlates with a ligand substitution in which anionatobis(1,10-phenanthroline)metal(II) complexes are formed. The heats of the exothermic reaction for ligand substitution of the sulfates decrease in the order Co(II)&gt;Ni(II)&gt;Fe(II). Isothermal and nonisothermal kinetic analyses were carried out using the exothermic peak. Activation energies of the ligand substitution for the same counterion generally increase with the metal in the order Co(II)&lt;Ni(II)&lt;Fe(II) and for the same metal, Ni(II) or Fe(II), increase with the counterion in the order Cl−&lt;Br−&lt;I−&lt;SO42−. However, for the cobalt complex, the activation energies are almost identical for this series of counterions. From the trends in activation parameters for the ligand substitution, we propose a dissociative mechanism for the sulfates of all complexes studied and for the cobalt complex halides studied. For the halides of the iron(II) and nickel(II) complexes studied, a mechanism involving nucleophilic attack of the halide ions is important.
Synthesis of Dibromoacetyl Derivatives by Use of Benzyltrimethylammonium Tribromide
Authors: Kajigaeshi Shoji , Kakinami Takaaki , Tokiyama Hajime , Hirakawa Takahiro , Okamoto Tsuyoshi 
Published: July 2006

Abstract
The reaction of acetyl derivatives with double the molar quantity of benzyltrimethylammoniun tribromide in dichloromethane–methanol solution at room temperature gave dibromoacetyl derivatives in fairly good yields.
Electrical Double Layer Formed on the Monolayer of Crown Ether Compounds
Authors: Matsumura Hideo , Watanabe Tsutomu , Furusawa Kunio , Inokuma Seiichi , Kuwamura Tsunehiko 
Published: July 2006

Abstract
The binding behavior of metal ions to the monolayers of a crown ether compound has been studied by the surface potential measurements. The obtained data are analyzed from the viewpoint of interfacial electrochemistry, i.e., the electrical double layer theory at the interfaces. The analysis reveals that the generated double layer at a membrane–solution interface after the complexing of metal ions with crown ethers is well described by the Stern model for the electrical double layer; it shows that there exists a possibility to evaluate the binding constants of metal ions with crown ethers under interfacial circumstances.
Use of Propagators in the Hückel Model. VIII. Intermolecular Interaction
Authors: Kano Toshiharu , Nishikawa Kiyoshi , Aono Shigeyuki 
Published: July 2006

Abstract
Intermolecular interactions are analyzed by the propagator method, under the tight-binding approximation. The stabilization energy or the change of charge density due to the intermolecular interaction are expressed in terms of propagators, so that the mechanism resulting above effects is satisfactorily realized. As an interesting example, the intermolecular interaction between guanine and benzo[a]pyrene (a famous chemical carcinogen) is investigated.
Mechanistic Approach to the Sensitization Process of Aromatic Ketones in the Isomerization between Norbornadiene and Quadricyclane
Authors: Arai Tatsuo , Oguchi Takahisa , Wakabayashi Toshio , Tsuchiya Masahiro , Nishimura Yoshinobu , Oishi Shigero , Sakuragi Hirochika , Tokumaru Katsumi 
Published: July 2006

Abstract
The quantum yields for norbornadiene(N)→quadricyclane(Q) and Q→N isomerization were determined in acetonitrile using several substituted benzophenones (BPs) as triplet sensitizers. For the N→Q isomerization, BPs with electron-donating substituents exhibited higher quantum efficiency (0.4–0.6) than BPs with electronaccepting substituents. The quantum yields for Q→N isomerization increased with electron-accepting ability of the substituents on BPs, but were lower than 0.1. The rate constants for quenching of triplet BPs by N and Q were also determined in acetonitrile by means of laser flash photolysis. The rate constants for N were not dependent on the triplet energies (ET) of BPs but dependent on electronic properties of the substituents on BPs. On the contrary, those for Q increased with decreasing ET of BPs and with increasing Hammett’s σ constants of the substituents of BPs. Based on these observations an addition-elimination process is proposed for the N→Q isomerization, and an electron transfer process for the Q→N isomerization.
Radical Switch Reaction. A Novel Reaction between Two Free Radicals in a Solvent Cage
Authors: Kobayashi Michio , Gotoh Michiko , Yoshida Masato 
Published: July 2006

Abstract
Studies on the thermal decomposition of t-butyl phenylazo sulfone suggested the occurrence of a radical switch reaction, a novel type of reaction between two radicals. A primary geminate radical pair, t-butanesulfonyl and phenyl radical pair, exchange sulfur dioxide to form a new radical pair consisting of t-butyl and benzenesulfonyl radicals. The generation of benzenesulfonyl radical was confirmed by its ESR spectrum and the isolation of products containing a benzenesulfonyl group.
Protein Engineering of Dihydrofolate Reductase. Improved Catalytic Step of Mutant-Enzymes
Authors: Taira Kazunari , Chen Jin-Tann , Mayer Ruth J , Benkovic Stephen J 
Published: July 2006

Abstract
Two site-specific mutations on dihydrofolate reductase from Escherichia coli have been carried out at the Phe-31 site. From the crystallographic structure the Phe-31 is located at the dihydrofolate binding site and interacts with both the pteridine ring and the p-aminobenzoyl moiety of the substrate. Two mutant enzymes (Phe-31→Tyr and Val) have been purified to homogeneity and characterized by steady-state kinetics. The two mutations are aimed at assessing the hydrophobic interaction between the phenyl ring and the aromatic ring moiety of the substrate. Despite the fact that the first mutation has introduced a polar Tyr-group into a hydrophobic binding site, the Michaelis constant KDHF (KM with saturating NADPH and varying dihydrofolate) has increased only five-fold. The second mutation (Phe-31 →Val-31) results in a 25-fold increase in KDHF. More importantly, the maximum velocity of both mutant enzymes has increased more than 100%, indicating that these are better enzymes under the condition of [substrate]&gt;KDHF. Thus, in both mutant enzymes the decrease in binding has not been translated into a loss of catalytic efficiency.
The Superconductive Compound of the Ba–Y–Cu Oxide
Authors: Ono Akira , Tsutsumi Masayuki 
Published: July 2006

Abstract
Chemical composition of a novel compound in the Ba–Y–Cu–O system is determined. Formulae of the phase is Ba4Y2Cu7O14. X-Ray powder pattern can be indexed successfully on the basis of an orthorhombic unit cell. Stability of the phase is preliminary studied by a thermogravimetric method.
An Improved Synthesis of 8-Amino-8-demethylriboflavin
Authors: Kasai Sabu , Fritz Bernhard J , Matsui Kunio 
Published: July 2006

Abstract
8-Amino-8-demethylriboflavin was synthesized from 3-nitro-4-methylaniline N-d-riboside by selective reduction of the N-glycoside with sodium borohydride, followed by hydrogenation of the nitro group in the presence of Raney’s catalyst. The obtained phenylenediamine was condensed with violuric acid to give the flavin in a high yield.
Effect of Polymer Matrices on Oxygen-Binding of a Cobalt Porphyrin Complex
Authors: Ohyanagi Manshi , Nishide Hiroyuki , Suenaga Koichi , Nakamura Takehiko , Tsuchida Eishun 
Published: July 2006

Abstract
Oxygen-binding of the (1-methylimidazole)-[α,α′,α″, α'″-5,l0,15,20-tetrakis(o-pivalamidophenyl)porphinato]cobalt(II) complex fixed in polymer membranes, poly-(dimethylsiloxane), poly(butyl methacrylate), and poly(methylmethacrylate), was studied spectroscopically. The apparent oxygen-binding affinity increased with oxygen solubility in the polymer matrix, which was corrected with the solubility coefficient of oxygen in the polymer.
Multi-Ionic Potential and Membrane Permeability Matrix. II. Na+–Ca2+ Bi-Ionic System with a Cation-Exchange Membrane and Effects of Cl− on Cation Transport
Authors: Kaibara Kozue , Inoue Hiroyoshi , Kimizuka Hideo 
Published: July 2006

Abstract
Transport characteristics of Na+–Ca2+ bi-ionic system with a highly selective cation-exchange membrane were investigated on the basis of nonequilibrium thermodynamic theory. As a principal transport parameter, the membrane permeability matrix or membrane conductance matrix can be estimated from the membrane potential, conductance, and ion flux data. Significances of diffusional and electroconductive processes of ion transport across membrane were systematically discussed in terms of these matrix elements. Partial contributions of inter-cationic (Na+–Na+, Na+–Ca2+, and Ca2+–Ca2+) correlations to the membrane transport process of ions were examined by means of comparing the estimated values of corresponding matrix elements. It was suggested that Ca2+ ions, of which membrane concentrations are kept at high level independently of the Na+/Ca2+ concentration ratio of external aqueous solutions, play a critical role in the membrane transport phenomena. Participations of Cl− transport in the cation-exchange processes were also discussed on the basis of membrane conductance matrix theory.
Optical and ESR Spectra for High-Spin Tetrahedral Complexes of Co(III) and Co(II) in Keggin-Structure Heteropolytungstate
Authors: Kojima Kazuo , Matsuda Jiro , Kojima Norimichi , Ban Toshiro , Tsujikawa Ikuji 
Published: July 2006

Abstract
The ligand-field spectra for the cobalt complexes in the single crystals of K3H2[CoIIIW12O40]·16H2O and K4H2[(COII, ZnII)W12O40]·nH2O have been observed at several temperatures above 1.4 K and assigned under D2 site symmetry. In the spectrum of the elongated CoIIIO4 complex, two absorption bands of 8250 and 8953 cm−1 strengthen with increasing temperature by vibronic mechanism. The X-band ESR spectra of both complexes have also been measured at 77 K. The signal from the Co(III) complex is not observed. The signal of the high-spin Co(II) complex of tetrahedral symmetry is unequivocally observed even at relatively high temperature of 77 K. From the analysis of the ESR spectrum, it is concluded that the CoIIO4 tetrahedron of D2 symmetry is flattened and deviated slightly from axial symmetry.
Optical Resolution by Preferential Crystallization of Dl-Thiazolidine-4-carboxylic Acid
Authors: Shiraiwa Tadashi , Sado Yujin , Komure Masamitsu , Kurokawa Hidemoto 
Published: July 2006

Abstract
Infrared spectrum, solubility, and ternary solubility diagram indicated that Dl-thiazolidine-4-carboxylic acid (Dl-THC) is a conglomerate at room temperature. The free energy of critical nucleation in supersaturated solutions for the crystallization of d- and l-THC was examined to resolve Dl-THC efficiently by preferential crystallization. Successive preferential crystallization of Dl-THC was experimented at 20 °C for an aqueous racemic solution with a supersaturation of 150%, and d- and l-THC with optical purity of 96–100% were obtained in the range of resolution of 58–76%. The optical resolution was more successfully done in 1 mol dm−3 aqueous glycine to give d- and l-THC with optical purity of 93–99% in the degree of resolution of 77–87%. Recrystallization of d- and l-THC obtained with a succeeding treatment with hydroxylamine hydrochloride gave d- and l-cysteine with 100% optical purity.