bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topological Ligand Design. II. The Definition and Derivation of Extended and Complex Ligand Graphs
Authors: Takamoto Susumu 
Published: July 2006

Abstract
An extended ligand graph is a set of several points corresponding to donor atoms, where each pair of points is connected by n lines when these atoms are able to form n chelate rings with a metal ion. These graphs can cover all the ligands, but they may not express the geometrical patterns of some complicated ligands clearely enough for them to be discriminated. A complex ligand graph is a set of some main points and sub-points connected by sub-lines, where the main points, sub-points, and sub-lines correspond to donor atoms, carbon atoms forming chelate bonds, and chemical bonds among them respectively. All the complex ligand graphs can then be systematically derived from donor-atomic graphs, which are composed of only main points and main lines and are equivalent to the simple ligand graphs previously designed. Another designing method of ligands is proposed for a certain coordination sturcture. A complex ligand graph to which no more sub-points or sub-lines can be added is called a parent ligand graph. Then all the complex ligand graphs for such a coordination are derived from the parent ligand graphs by neglecting some sub-points or by removing some sub-lines successively.
Solution Properties of Phycocyanin. VI. The Characterization of the Phycocyanin Monomer
Authors: Saito Takahide , Iso Naomichi , Mizuno Haruo , Ozeki Fumiaki , Matsui Yoshiyuki 
Published: July 2006

Abstract
The monomer molecular weight of phycocyanin was determined by sedimentation equilibrium measurements in 6 mol/1 guanidine hydrochloride (GndCl) and by sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis. The former measurement gave the monomer molecular weight of 4.0×104. From the latter, the phycocyanin was found to be composed of two kinds of subunits, the molecular weights of which were 1.7×104 and 2.0×104. Assumimg that the phycocyanin monomer consists of two polypeptide chains, the molecular weight becomes 3.7×104. These values coincide with the value of 4.2×104 assumed in our previous works, which corresponds to onesixth of the hexamer molecular weight. The sedimentation coefficient, s25w, was 2.21 Svedberg unit, and the intrinsic viscosity in 6 mol/1 GndCl was 19.5 ml/g, at 25.0 °C. From these values, it was clear that the phycocyanin monomer was unfolded in the solvent.
A Plot of the pH vs. the Logarithm of the Titrant Volume in Potentiometric Titration. The Determination of Phenol in Water
Authors: Kamakura Katsuyoshi 
Published: July 2006

Abstract
The determination of phenol in water was successfully carried out by means of a new plot of the potentiometric titration data. The plot of the pH vs. the logarithm of the titrant volume gave a titration curve with an inflection between two linear portions, and the center of the inflection obtained by a graphical method was found to correspond to the equivalence point. In the titration of phenol, the data fitted well to the theoretical curve by taking into account the hydrolysis of the phenol ion. The mean of the results obtained from the apparent equivalence point in the concentration range of 1.0–7.7×10−3 mol dm−3 was 101.2% of the results obtained iodometrically after the bromination of phenol, and the precision of the results was ±2.7% (S.D.).
Kinetic Studies of the Acid Hydrolysis of Aquaoxo[N-(2-pyridylmethyl)iminodiacetato]vanadium(IV) and Aqua(nitrilotriacetato)oxovanadate(IV) in Aqueous Perchloric Acid Solution
Authors: Nishizawa Masato , Saito Kazuo 
Published: July 2006

Abstract
Acid hydrolysis of aquaoxo[N-(2-pyridylmethyl)iminodiacetato]vandium(IV) [VO(pmida)H2O], ([H+]=0.1–2.0 M, 1M=1 mol dm−3) and aqua(nitrilotriacetato)oxovanadate(IV) [VO(nta)H2O]−, ([H+]=0.2–2.0 M) has been studied by the stopped-flow method in aqueous perchloric acid solution at an ionic strength 2.0 (LiClO4). The pseudo first-order rate constant ko is dependent on the proton concentration. The rate formula is expressed by ko=(k1K1[H+]+k2K1K2[H+]2)⁄(1+K1[H+]+K1K2[H+]2). A simulation curve fitting treatment gave the figures: k1=0.02 and 0 s−1, k2=6 and 3000 s−1, K1=1.5 and 0.2 M−1, and K2=0.2 and 0.004 M−1 at 25 °C for [VO(pmida)H2O] and [VO(nta)H2O]−, respectively. These data indicate that the rate determining step corresponds to the dissociation of the second basal bond of the singly or doubly protonated oxovanadium(IV) complexes.
Reactions of CO2 with Cu(I) Alkoxides and Amides to Give Alkylcarbonato-, μ-Carbonato-, Hydrogencarbonato-, and Carbamato-copper Complexes
Authors: Yamamoto Takakazu , Kubota Minoru , Yamamoto Akio 
Published: July 2006

Abstract
Carbon dioxide reacts with ROCu(PPh3)2 (R=C2H5, C6H5CH2; PPh3=triphenylphosphine) to produce ROCO2Cu(PPh3)2. Hydrolysis or thermolysis of the alkylcarbonatocopper(I) complexes gives a binuclear carbonatocopper(I) complex (PPh3)2CuOCO2Cu(PPh3)2, which is further converted into a hydrogencarbonatocopper(I) complex [HOCO2Cu(PPh3)2]n by the reaction with CO2 in moist solvents. The IR spectrum of [HOCO2Cu(PPh3)2]n shows association of the HOCO2Cu(PPh3)2 units through hydrogen bonds. The IR spectrum of [HOCO2Cu(PPh3)2]n also reveals that the mode of the association depends on conditions of the crystallization of the complex. The reaction of (PPh3)2CuOCO2Cu(PPh3)2 with CH3I gives (CH3O)2CO and the reaction of [HOCO2Cu(PPh3)2]n with C6H5NH2 affords C6H5NHCO2Cu(PPh3)2 in high yields. Carbon dioxide reacts also with an amidocopper(I) complex C6H5NHCu(PPh3)2 to yield a carbamatocopper(I) complex C6H5NHCO2Cu(PPh3)2. The reaction of CH3Cu(PPh3)2(diethyl ether)0.5 with CO2 in the presence of HN(C2H5)2 affords (C2H5)2NHCO2Cu(PPh3)2. The isocyanate group of phenyl isocyanate is inserted into the C2H5O–Cu bond of C2H5OCu(PPh3)2 to give a (ethyl N-phenylcarbamato)copper complex.
Asymmetric Transformation of α-Amino Acids Promoted by Optically Active Cobalt(III) Complexes. II. N-Methylalaninatocobalt(III) Complexes with Tetramines
Authors: Yamaguchi Motowo , Yano Shigenobu , Saburi Masahiko , Yoshikawa Sadao 
Published: July 2006

Abstract
The preparation and structural assignments of N-methyl-(S)- and -(R)-alaninatocobalt(III) complexes with a few chiral derivatives of 2,3,2-tet (=3,7-diazanonane-1,9-diamine) and triethylenetetramine are described. The hydroxide ion-catalyzed epimerizations of these complexes are examined at pH 10. In the N-methylalaninato complexes the isomer ratio for Λ-S/Λ-R ranged from 76/24 to 90/10. In the most favorable case where tetramine is 2(S)10(S)-4,8-diazaundecane-2,10-diamine (abbreviated as 2(S)10(S)-Me2-2,3,2-tet) the energy differences among the four possible diastereomers are discussed in relation to the prediction from strain energy minimization calculations.
Structure of a Guaioxide-type Sesquiterpene from “San-shion”
Authors: Hirota Hiroshi , Tanahashi Yoshiaki , Takahashi Takeyoshi 
Published: July 2006

Abstract
The structure including absolute stereochemistry of “LB”, one of the volatile constituents of “San-shion” (the roots of Ligularia species), was found to be (1S,4R,5S,7R,10R)-5,11-epoxyguaiane.
Studies of the Hydrous Titanium Oxide Ion Exchanger. V. The Stability of the Hydrogen Form in Air
Authors: Inoue Yasushi , Yamazaki Hiromichi 
Published: July 2006

Abstract
After being allowed to stand in air at room temperature, the exchanger in the hydrogen form showed an abrupt decrease in its ion-exchange capacity between 3 and 6 months after the preparation. This is attributable to the preferential destruction of the most acidic hydroxyl groups by dehydrating condensation.
Structural Dependence in a One-electron Transfer Process: Naphthalene peri Ketones
Authors: Sato Takeo , Kubo Masao , Nishigaki Kenji 
Published: July 2006

Abstract
The cyclic voltammetry of several naphthalene peri ketones was carried out in anhydrous DMF containing TBAP. The cathodic peak potential for carbonyl reduction was found to be shifted toward a more anodic potential when carbonyl, oxygen, and sulfur groups were present in the peri position. The controlled potential electrolysis of peri diketones gave an intramolecular coupling product via a bis-anion radical.
Electrolytic α-Bromination of Some α-Substituted Active Methylene Compounds
Authors: Torii Sigeru , Uneyama Kenji , Yamasaki Noritsugu 
Published: July 2006

Abstract
Electrolytic α-bromination of methyl α-substituted malonates and methyl α-substituted acetoacetates was accomplished in 73–84% yields in dichloromethane containing tetraethylammonium bromide as an electrolyte and sodium methoxide as an enolizing reagent.
Catalysis by Heteropolyacid. I. Polymerization Reaction of Benzyl Alcohols
Authors: Nomiya Kenji , Ueno Tetsuo , Miwa Makoto 
Published: July 2006

Abstract
Benzyl alcohol and its derivatives catalyzed by heteropolymolybdic acids such as H3PMo12O40 and H4SiMo12O40 have been found to polymerize, leading to the formation of polyaromatics. The properties of the polymers obtained and the function of catalysts have been studied.
On the Choice of Adsorptives for the Application of a Modified Dubinin-Radushkevich Equation
Authors: Stoeckli Fritz , Perret André , Huber Ueli 
Published: July 2006

Abstract
It is shown that great care has to be taken in the choice of the adsorptives for the assessment of microporosity and its heterogeneity. Methanol, for which selective interactions may occur, is not a suitable adsorptive to be used in the framework of the generalized Dubinin-Radushkevich equation proposed by Stoeckli.
Electron Spin Resonance of 2,2′-Bipyridyl, Dimethyl-2,2′-Bipyridyls, and 2,2′-Biquinolyl in their Phosphorescent Triplet States
Authors: Higuchi Jiro , Yagi Mikio , Iwaki Takashi , Bunden Makoto , Tanigaki Katsumi , Ito Takeshi 
Published: July 2006

Abstract
Electron spin resonance (ESR) of phosphorescent triplet states of 2,2′-bipyridyl, 3,3′-, 4,4′-, 5,5′-, and 6,6′-dimethyl-2,2′-bipyridyls, and 2,2′-biquinolyl has been studied in ethanol glasses. For 2,2′-bipyridyl, the ESR spectrum of both the E and Z conformers was observed in poly(vinyl alcohol) films and their assignment was examined by changing the direction of applied magnetic field. Using such a technique, the stretched polymer-film method has been developed for determining the molecular conformations which are difficult to be estimated from zero-field splitting (ZFS) parameters obtained in rigid glasses. As a result, the conformations in the phosphorescent triplet states of molecules studied here are confirmed to be all E in ethanol glasses, even for a case with a relatively small E value.
Formation and Spectral Properties of Some Bis(β-diketonato)copper(II)–Diazole Complexes
Authors: Kogane Tamizo , Hirota Reiko 
Published: July 2006

Abstract
The reactions of bis(β-diketonato)copper(II) with pyrazole and imidazole gave the diazole adducts Cu(β-dik)2(Hdzl) (β-dik=β-diketonate anion; Hdzl=diazole) and/or the μ-diazolato complexes [Cu(β-dik)(dzl)]n (n=2,4,….). The complexation reactions are very sensitive to the nature of the diazole and to the reaction conditions, sometimes giving different products depending upon the solvent used. In chloroform, Cu(β-dik)2-pyrazole and Cu(β-dik)2-imidazole complexes exhibited characteristic absorption maxima at approximately 570 and 555 nm, respectively, which are much shorter than the λmax values of the starting Cu(β-dik)2 chelates.
Minimum-energy Conformation of Different Tropocollagen Models Calculated for Poly(Gly–Pro–Pro) by Considering Helical Constraints
Authors: Okuyama Kenji , Eto Haruaki , Nakaya Ikuo , Takayanagi Motowo 
Published: July 2006

Abstract
The minimum conformational energies for three helical models of tropocollagen were calculated by using energy functions and values of parameters obtained by Momany et al.. Three types of helical models containing 7/1, 10/1, and 12/1 helices were employed. Among the models with the 7/1 helix, only the conformation having the N(Gly1)···O(Pro2) type hydrogen bond was found to be energetically stable. Thus all the three helical models had the same type of hydrogen bond. The minimum-energy conformation of the 7/1 helix model was found to be more stable than those of the other two models by about 7 kcal/mol per tripeptide unit. This difference mainly came from the non-bonded energy terms of both intra- and inter-chains. Since the conformation of the 7/1 helix model was widely spread in the conformational space compared with those of the other models, it was concluded that the unit twist of the 7/1 helix model is well suited for peptide chains to conform a triplehelical structure. The above results strongly supported the 7/1 helix model for tropocollagen.
ECE Mechanism as a Tool for the Investigation of Unstable Metal Complexes. II. Current-Potential Characteristics for the Reversible Deposition of an Insoluble Species: Case of Electrochemical Reduction of trans-Dibromobis(ethylenediamine)cobalt(III) Complexes
Authors: Yamada Akifumi , Yoshikuni Tadatsugu , Kato Yoshikiyo , Tanaka Nobuyuki 
Published: July 2006

Abstract
Theoretical relations were derived for the ECE mechanism involving the reversible deposition of an insoluble species at constant potential (potentiostatic method). Assuming that the activity of deposit becomes equal to unity immediately after the beginning of electrolysis, current-potential relations were obtained for the case in which the first electron transfer step is irreversible and the second one, reversible. The method was used to study the acid hydrolysis of bivalent cobalt complex in the reduction of trans-dibromobis(ethylenediamine)cobalt(III) complex. The measurement made at 5 °C in 0.1 M acetate buffer solutions (pH 4.8) gave 0.4 s−1 for the acid hydrolysis of trans-dibromobis(ethylenediamine)cobalt(II) which was produced by the reduction of cobalt(III) complex.
Pyrolytic Sulfurization Gas Chromatography. VI. The Continuous and Simultaneous Determination of the Atomic Ratio between C, H, O, and N in Various Compounds
Authors: Hara Tadashi , Fujinaga Kaoru , Okui Fujio 
Published: July 2006

Abstract
The simultaneous determination of the atomic ratio between C, H, O, and N in various compounds including a metal organic chelate one has been presented in our previous papers. With the objective of reducing the analysis time, an apparatus by which a continuous and simultaneous determination of the atomic ratio between C, H, O, and N can be carried out has been newly designed and constructed. Using this apparatus, many samples can be treated continuously at the rate of about 20 min for one sample, with satisfactory results.
Metal Complexes of Amino Acids. XII. The Deuteration of α-Hydrogen Atoms in Cobalt(III) Complexes Containing α-Amino Carboxylates
Authors: Ama Tomoharu , Kawaguchi Hiroshi , Kanekiyo Makoto , Yasui Takaji 
Published: July 2006

Abstract
The second-order rate constants (rate=kD(base)[Complex][OD−]) for the deuterium exchange of α-methylene or α-methine protons in the amino carboxylato complexes, trans(O)-, C1-cis(O)-, and C2-cis(O)-[Co(gly)2(en)]+ and -[Co(gly)2(tn)]+, [Co(gly)(NH3)4]2+, [Co(gly)(en)2]2+, [Co(gly)(tn)2]2+, [Co(sar)(en)2]2+, and Λ- and Δ-[Co(l-ala)(en)2]2+, were determined by the 1H-NMR measurement. The major factors determining the deuteration rate of α-hydrogens in the amino carboxylate chelate are the geometry and charge of the complex, and the nature of the substituent bonded to the chelate ring to be deuterated; the minor factor is the chelate-ring size of the ligands other than amino carboxylate in a complex molecule.
Spin Exchange and Translational Diffusion of Nitroxide Radicals in Micelles. ESR Experiments and Spectra Simulation by Modified Bloch Equations
Authors: Aizawa Masayuki , Komatsu Tsuyoshi , Nakagawa Tsurutaro 
Published: July 2006

Abstract
The dependence of the ESR linewidth of hydrophobic radicals on their concentration in micelles is investigated in two solubilization systems at several temperatures. One system consists of 2,2,6,6-tetramethyl-4-benzoyloxy-1-piperidinyloxyl (BzONO) as a solubilizate and hexadecyltrimethylammonium bromide (CTAB) as a surfactant, and the other, of 2,2,6,6-tetramethyl-4-myristoyloxy-1-piperidinyloxyl (MyONO) and sodium dodecyl sulfate (SDS). The plot of the linewidth against the mole fraction of the radical is not represented by a straight line, as in the previous study. The propriety of the two kinds of models for the solubilization states of radicals which were proposed in the previous paper to explain the unusual shape of these plots is examined by spectra simulation with modified Bloch equations. As these models have proved to be inadequate, a new model taking account of the distribution of the radicals among the micelles is proposed. The simulation based on this model shows a good agreement with the experimental results. The translational diffusion coefficients of radicals in micelles are estimated on the basis of this model. Their values are in the range of (1.5–2.9)×10−11 m2/s.
Temperature Effect on Gas Phase Alkylbenzene Dealkylation
Authors: Perez Giorgio 
Published: July 2006

Abstract
Dealkylation of ethylbenzene, propylbenzene, and isopropylbenzene by radiolytically formed 2H3+ ions has been studied in the gaseous phase as a function of the irradiation temperature. The extent of the reaction, which increases with the temperature follows the order ethylbenzene &lt; propylbenzene &lt; isopropylbenzene. The Arrhenius plots of empirical observed rate constants are linear over the temperature range investigated (40—100 °C) and their slopes correspond to a difference of 12.5 and 10.0 kJ mol−1 between the activation energies for dealkylation of ethylbenzene and isopropylbenzene, and of ethylbenzene and propylbenzene, respectively.
Electrolytic Behavior of Some Divalent Transition Metal Halides in Propylene Carbonate Solution
Authors: Pandey Ram Nagina , Bapat M G 
Published: July 2006

Abstract
The results of conductance measurements of cobalt(II) perchlorate, cobalt(II) chloride, cobalt(II) bromide, and zinc(II) bromide in propylene carbonate at 25 °C are reported. The conductance data for Co(ClO4)2 in PC has been analyzed by Fuoss–Edelson method. The anomalous conductance behavior of CoCl2, CoBr2, and ZnBr2 in PC has been explained on the basis of equilibria MX2 MX+ + X−; MX2 + X− MX−3; MX+ M2+ + X−; and MX+ + MX−3 (MX2)2. The equilibrium constants of 3MX2 M2+ + 2MX−3; and 2MX2 (MX2)2 equilibria for CoCl2, CoBr2, and ZnBr2 in PC have been calculated in the present investigation. The conductance data of these divalent transition metal halide solutions show the existence of dimers in PC.
Preparation and Characterization of trans- and cis-Anionobis(ethylenediamine)nitrosylruthenium(II) Complexes
Authors: Tomizawa Hiroshi , Miki Eiichi , Mizumachi Kunihiko , Ishimori Tatsujiro 
Published: July 2006

Abstract
In this study trans-[Ru(OH)(en)2NO]2+ (en = ethylenediamine) as well as trans- and cis-[RuX(en)2NO]n+ (X = Cl, Br, I, OAc (acetate), and NCS where n = 2; X = H2O where n = 3) were prepared. The complexes were characterized by IR, NMR, and UV-vis spectra. Although a decrease in the wave number of ν(NO) along with an increase in the π-donor ability of X was observed in the trans isomers, it was not observed in the cis isomers. In the 1H NMR spectra of all the complexes, the resonance signals due to methylene and the amine protons of the en were influenced by the magnetic anisotropy caused by the RuNO group. Two kinds of isomerization reactions were found to be involved in the preparation of the complexes: One was accompanied by a substitution reaction from OH− to X−; the other occurred after the substitution reaction. Moreover, ligand X was substituted immediately by OH− when sodium hydroxide was added to an aqueous solution of the complex; cis to trans isomerization then occurred for the cis isomer.
Stereoselective Preparation and Characterization of [Cr(amino acidato)2(amino acidato-N)(Me2SO)] Complexes
Authors: Oki Hisaya , Kitagawa Yoshiki , Nakata Ryuji 
Published: July 2006

Abstract
New complexes of the type [Cr(AA)2(AA-N)(Me2SO)], where AA stands for l-amino acidato ligands (valinato, isoleucinato, and leucinato) and AA-N represents monodentate l-amino acidato ligands with an amino nitrogen as a donor atom, were prepared by heating mixtures of Cr(NO3)3·9H2O and sodium salts of amino acids in Me2SO. For all the amino acids used, only complexes of the type (+)546-[Cr(AA)2(AA-N)(Me2SO)] were obtained. The presence of a Me2SO molecule as a ligand was shown by the IR spectra of the crystals of the complexes. The bis-type complexes with l-valine and l-isoleucine were converted to (−)546-isomers in MeOH and the resulting products were isolated. All the new complexes were confirmed to have facial configuration, [Cr(O)3(N)3] from their UV-vis absorption spectra, as well as the corresponding tris-type complexes, [Cr(AA)3].
Structure and Properties of (NEt4)2[MoIVO(α,2-toluenedithiolato)2]
Authors: Ueyama Norikazu , Kondo Mitsuru , Oku Hiroyuki , Nakamura Akira 
Published: July 2006

Abstract
A novel oxomolybdenum(IV) complex, (NEt4)2[MoIVO(α,2-toluenedithiolato)2], was synthesized and characterized by visible, Raman and 1H NMR spectroscopies. The complex crystallizes as (NEt4)2[MoIVO(α,2-toluenedithiolato)2]·Et2O in the space group Cc with a = 15.429(3), b = 16.618(2), c = 15.079(3) Å, β = 99.38(2)°, V = 3815(2) Å3, Z = 4, and Dcalcd = 1.315 g cm−3. The structure was solved and refinement based on 5975 reflections converged at R = 0.044and Rw = 0.052. The complex has an apical oxo and transbis(α,2-toluenedithiolato) structure with a tetragonal-pyramidal MoOS4 core. Inertness of the complex to trimethylamine-N-oxide is due to the narrow S(alkane)–Mo–S(alkane) angle preventing from its coordination to the trans position of Mo=O, and/or two strong Mo–S(alkane) bonds preventing a rearrangement from trans dioxo to cis dioxo structure.
Reactions of Diaminosulfoxonium Ylides with Aldehydes. Preparation of Cyclopropyldiaminosulfoxonium Salts
Authors: Okuma Kentaro , Sato Yasunari , Ohta Hiroshi , Yokomori Yoshinobu 
Published: July 2006

Abstract
The reaction of diaminosulfoxonium ylides with aldehydes gave the corresponding cyclopropyldiaminosulfoxonium salts in good yields when 1,8-diazabicyclo[5.4.0.]undec-7-ene (DBU) was used as a base. These ylides reacted with aldehydes to give the corresponding betaines, which resulted in the formation of vinylsulfoxonium salts. The additional ylides reacted with these salts to afford cyclopropylsulfoxonium salts. The reaction of these salts with potassium hydroxide is also described.
Addition of Hydrogen Halides to 1,2-Dialkylpyrrolium Cations
Authors: Sigalov Mark V , Toyota Shinji , Oki Michinori , Trofimov Boris A 
Published: July 2006

Abstract
Although it is believed that addition of an acid to 2-substituted pyrroles produces 5-protonated pyrrolium ions and further reaction is prevented by the stability of the product, this work shows that further addition of hydrogen halides takes place to the pyrrolium ion to produce 2-substituted 4-halo-4,5-dihydro-3H-pyrrolium ions in general. In the case where the 1-alkyl group is a 1-bromoethyl, addition of hydrogen bromide gives one stereoisomer preferentially, of which conformation was determined by NOE experiments to be two C–Br bonds anti with each other, relative stereochemistry being R*and S*. The results are discussed on the thermodynamic stability and/or the kinetic preferences of the products. Generality of the addition of hydrogen bromide to the pyrrolium ion was tested with 1,2-dimethylpyrrole, which gave a kinetically favored isomeric addition product that isomerized to a thermodynamically favored 4-bromo-1,2-dimethyl-4,5-dihydro-3H-pyrrolium bromide on standing.