bluuebunny/crossref_metadata_2025 huggingface dataset:
The Specific Effects of Tetraalkylammonium and Alkali Metal Ions on the Polarographic Reduction of Nitroalkanes and Nitrobenzenes in Acetonitrile
Authors: Hojo Masashi , Nishikawa Kazukiyo , Akita Yoshihiro , Imai Yoshihiko
Published: July 2006

The polarographic behavior of 2-methyl-2-nitropropane ((CH3)3CNO2) was examined at DME in acetonitrile with various supporting electrolytes. The addition of Et4N+ or n-Bu4N+ caused the half-wave potential (E1⁄2) of (CH3)3CNO2 to shift negatively in the presence of a fixed concentration of NaClO4. The negative shift was explained in terms of the interaction between tetraalkylammonium cations and the unreduced molecule of (CH3)3CNO2. The formation of (CH3)3CNO2\ewdot(Na+)2 was also suggested, and the conditional formation constants of the species were obtained by the positive shift in the E1⁄2 of (CH3)3CNO2 with increasing concentration of Na+ at certain concentrations of Et4N+ and n-Bu4N+. Other nitroalkanes and nitrobenzenes were also examined. The effect of water on the half-wave potentials of the first waves of the nitro compounds suggested the formation of RNO2\ewdot(H2O)2-type species.
Superconductivity and Characterization of the High-Pressure Reaction Products of Carbon Diselenide, CSe2
Authors: Kobayashi Akiko , Sasaki Yukiyoshi , Watanabe Tokuko , Ikehata Seiichiro , Kishida Haruo , Kawamura Haruki , Kato Reizo , Kobayashi Hayao
Published: July 2006

The physical properties and the structure of black solids obtained by the high-pressure reaction of CSe2 were examined by IR, X-ray diffraction, scanning electron microscope, electron diffraction, thermal analyses and magnetic experiments. The crystalline solid, which was metallic (σ(RT)≈50 S cm−1) at ambient pressure became superconductor above 20 GPa(Tc(onset)=6 K), while the amorphous solid was insulating. Contrary to the previously proposed one- or two-dimensional polymerization structure of (CSe2)x, it has been revealed that the metallic CSe2 sample have a rather complex structure that is composed of the crystalline hexagonal Se, graphite and some amorphous parts. Thus, the high conductivity and the diamagnetism of the crystalline solid at ambient pressure seems to come from graphite part and the superconductivity seems to come from hexagonal Se part. The superconducting transition behavior depended on the path of the pressure-cooling steps. The superconducting state was observed only when the pressure was increased at the low temperature.
Extraction Equilibria of Mercury(II) from Hydrochloric Acid with Trialkylphosphine Sulfides
Authors: Baba Yoshinari , Umezaki Yukihiro , Ueda Takashi , Inoue Katsutoshi
Published: July 2006

The extraction of mercury(II) from hydrochloric acid was compared using five kinds of sulfur-containing extractants. Mercury(II) was extracted most effectively by trialkylphosphine sulfides. Subsequently, the distribution equilibria of mercury(II) from hydrochloric acid with triisobutylphosphine sulfide (TIBPS=\barS) and trioctylphosphine sulfide (TOPS=\barS) in toluene have been measured at 303 K in order to clarify the concentration dependencies of the reactant species. It was found that mercury(II) is extracted according to the solvation reaction by TIBPS or TOPS as a mercury(II): extractant 1:2 complex, HgCl2S2, in the range of low loading ratio of mercury(II) to the extractants, and as a 1:1 binuclear complex, (HgCl2)2S2, in the region of high loading ratios, as follows:

HgCl2+2\barS\ightleftharpoons‾HgCl2S2  Ke

2HgCl2+2\barS\ightleftharpoons‾(HgCl2)2S2  Ke′

The extraction equilibrium constants, Ke and Ke′, were evaluated as Ke=4.0×105 (dm3 mol−1)2 and Ke′=2.0×108 (dm3 mol−1)3 for TIBPS and as Ke=7.2×106 (dm3 mol−1)2 for TOPS.
Solvation and Ionic Association of Bis(2,4-pentanedionato)(diamine)cobalt(III) Perchlorates in 1-Propanol, Acetone, and Their Mixtures
Authors: Ito Kazuaki , Iwamoto Etsuro , Suehisa Shigehito , Isono Hiroyuki , Yamamoto Yuroku
Published: July 2006

The conductances of bis(2,4-pentanedionato)(diamine)cobalt(III) perchlorates ([Co(acac)2(diamine)]ClO4, diamine: en=ethylenediamine, pn=1,2-propanediamine, N,N-dmen=N,N-dimethylethylenediamine, N,N′-dmen=N,N′-dimethylethylenediamine, N,N,N′-trimen=N,N,N′-trimethylethylenediamine, N,N,N′,N′-tmen=N,N,N′,N′-tetrametnylethylenediamine) were measured in isodielectric solvents, 1-propanol (n-PrOH), acetone (Me2CO), and 60 and 80 mol% acetone in 1-propanol (n-PrOH–Me2CO) at 25 °C. In spite of the increase in size of [Co(acac)2(diamine)]+ due to the introduction of N-methyl groups, the Walden products (λ0+·η) of the chelate cations were found to increase in all solvents. The contribution per N-methyl group was large in n-PrOH. The variation in the ionic association constants (Ka) with the number of NH protons in the chelate cations was small in all solvents. The Ka values for [Co(acac)2(N,N′-dmen)]ClO4 were larger than those for other chelate salts in all solvents. These results could be explained in terms of the solvation of the NH protons (diamine in [Co(acac)2(diamine)]+) by oxygen atoms of n-PrOH and Me2CO, and of oxygen atoms (acac) by the OH proton of n-PrOH owing to hydrogen bonding interactions and desolvation resulting from the introduction of the N-methyl groups. For [Co(acac)2(en)]+ in n-PrOH a solvation model to form a six-membered ring was proposed.
Pyrolyse und Massenspektren von 5-(Hydroxyphenoxymethyl)-2-oxazolidinon und p- oder m-Bis(2-oxooxazolidin-5-ylmethoxy)benzol
Authors: Shimasaki Choichiro , Wakabayashi Mariko , Yoshida Shizuo
Published: July 2006

5-(Hydroxyphenoxymethyl)-2-oxazolidinone (1) and p- or m-bis(2-oxooxazolidin-5-ylmethoxy)benzene (2 or 3) were prepared by the reaction of tris(2,3-epoxypropyl)-1,3,5-triazin-2,4,6(1H,3H,5H)-trione with hydroquinone and resorcinol. These compounds were found by the thermal analysis to be thermally stable. The activation energies of the pyrolysis for 1, 2, and 3 were calculated from the DTA curves to be 142.7, 158.8, and 130.0 kJ mol−1, respectively. The mechanism of the main fragmentation of the linkages between the benzene and oxazolidinone rings by electron impact was found to consist of two processes; a simple cleavage and a rearrangement reaction. Further, each process had the three cleavage modes. In mass spectra of 2 and 3, the fragment ion which corresponded to the molecular ion peak for 1 was detected. High resolution mass spectrometry established the composition of many peaks in the low resolution spectra of the compounds studied.
The Lithium Diisopropylamide-Induced Fragmentation of 2,2-Diphenyl-1,3-dithiolane S-Oxide and Several 2,2-Diaryl-1,3-dithiolane S,S′-Dioxides
Authors: Inoue Yoshihiko , Tanimoto Shigeo , Oida Tatsuo
Published: July 2006

The reaction of 2,2-diphenyl-1,3-dithiolane S-oxide with lithium diisopropylamide results in fragmentation to thiobenzophenone followed by further conversion leading to alkyl diphenylmethyl sulfide on trapping with alkyl halide. The reaction of 2,2-diaryl-1,3-dithiolane S,S′-dioxides with lithium diisopropylamide proceeded smoothly to afford 1,1-diaryl-N,N-diisopropylmethanesulfinamides in moderate yields via the intermediate diaryl thioketone S-oxides.
The Preparation and Properties of the Manganese(II) Ion-Selective Electrode
Authors: Motonaka Junko , Nishioka Hiroshi , Ikeda Sanae , Tanaka Nobuyuki
Published: July 2006

For the measurement of manganese(II)-ion activity, manganese(II) ion-selective electrodes were prepared and tested. As electrodes, heterogeneous membranes were prepared by dispersing sensitive materials, such as manganese sulfide, manganese borate, or manganese dibenzyldithiocarbamate, in silicone rubber, poly(vinyl chloride), or poly(vinyl acetate). A manganese chloride solution (0.1 mol dm−3) was used as the internal reference solution, along with an Ag/AgCl internal reference electrode. The manganese(II) ion-selective electrodes thus made were then examined in terms of their response curves, response times, the effect of the pH, the variation in the response slopes with the temperature, and selectivity coefficients. The response time of the manganese dibenzyldithiocarbamate electrode was within 15 s in the concentration range of 10−8–10−1 mol dm−3. The response slope was 33.14 mV/pMn2+ in the linear part, and the coefficient of correlation was 0.999. The selectivity coefficients were examined by the separate-solution method.
Exo/Endo Stereoselectivity in 1,3-Dipolar Cycloaddition of Trifluoroacetonitrile Oxide and -nitrilimine with Bicyclic Olefins
Authors: Tanaka Kiyoshi , Masuda Hideyuki , Mitsuhashi Keiryo
Published: July 2006

Trifluoroacetonitrile oxide and N-phenyl-C-(trifluoromethyl)nitrilimine cycloadded with norbornenes, resulting in the exclusive formation of the exo-adducts, while the concomitant formation of the endo-adducts was observed in their cycloadditions with norbornadienes. The nitrile oxide was subjected to the cycloaddition with 2,3-disubstituted norbornadienes to evaluate the effect of the substituents on the exo/endo stereoselectivity. The electron-withdrawing substituents tend to favor the formation of the exo-adducts.
Radiation-Induced Alkylation of Quinoline Derivatives with Alcohol
Authors: Sugimori Akira , Yamada Tetsuo , Ishida Hiroaki , Nose Masayuki , Terashima Keiko , Oohata Noriko
Published: July 2006

Gamma-irradiation of quinoline and its derivatives in alcohols brings about alkylation at the 2- or 4-position of pyridine ring. Hydroxyalkyl radicals play important roles in the radiation-induced alkylation with alcohol. The radiation-induced substitution of CF3CH2– and CF3CH(OH)– for H in pyridine and pyrimidine rings occurs in low yields.
Reactivity of (Porphinato)aluminum Phenoxide and Alkoxide as Active Initiators for Polymerization of Epoxide and Lactone
Authors: Yasuda Tomokazu , Aida Takuzo , Inoue Shohei
Published: July 2006

Reactivity of the axial aluminum-phenoxyl and -alkoxyl bond (Al-X) of aluminum porphyrin (1, (TPP)AIX, (TPP): (5,10,15,20-tetraphenylporphinato)) toward epoxide, β-lactone, and ε-lactone was examined in relation to the ring-opening polymerization of these cyclic compounds catalyzed by 1. The reactivity of

(Remark: Graphics omitted.)

aluminum phenoxide was in the order, epoxide>β-lactone>ε-lactone, while that of the alkoxide, ε-lactone>β-lactone.
Solvation of Carboxylic Acids in Nonaqueous Binaries. Solvation Models for Butyric and Trichloroacetic Acids in Nitrobenzene–Toluene Mixtures
Authors: Hegazi Mohamed M Fahmi
Published: July 2006

The partitions of trichloroacetic and butyric acids between aqueous solutions and various nitrobenzene–toluene mixtures have been carried out at 25.0 and 30.0 °C, respectively. The observed nonlinearities for both acids of the monomer partition constants and the dimerization constants with the nitrobenzene mole fraction are interpreted in terms of the fractionation factors of effective exchangeable solvation sites of the involved species. Butyric acid monomer is concluded to have three sites for the solvation of the carboxylic hydrogen, carboxylate region, and alkyl chain. Desolvation of the former two sites is necessary for the formation of the dimer for which only two sites corresponding to its two alkyl chain are identified. The solvation sites of trichloroacetic acid monomer and dimer are identical and a singly hydrogen-bonded structure for the dimer is deduced. Dimerization of this acid in the organic phase proceeds by desolvation of what is equivalent to the sites of only one monomer.
Structural Study of the Methylnaphthazarins. X-Ray Structure of the Tetramethylnaphthazarin, a Charge Transfer Complex
Authors: Rodriguez José-Gonzalo , Pablo Alfonso De , Smith-Verdier Pilar , Florencio Feliciana , Garcia-Blanco Severino
Published: July 2006

The synthesis and analysis by 1H NMR of the methyl substituted naphthazarins were attempted. The chemical shifts of the substituents and of the ring protons were compared with those in their diacetates and were then correlated with the quinonoid or benzenoid nature of the rings. X-Ray diffraction analysis of tetramethylnaphthazarin, 2,3,6,7-tetramethyl-5,8-dihydroxy-1,4-naphthoquinone, has shown that this exists, in solid state, as a centrosymmetric charge-transfer complex with itself. The compound crystallizes in the Ibam space group, with an orthorhombic cell of dimensions a=17.479(1), b=9.983(1), c=6.752(1) Å, and four molecules in the unit cell. The crystal is built from molecules stacked up the c-axis and the interplanar distance between two overlapping molecules is 3.38 Å.
Photoinduced Hydrogen Evolution with Viologen Linked Porphyrin in a Micellar System
Authors: Okura Ichiro , Kaji Naruhiko , Aono Shigetoshi , Nishisaka Tsuyoshi
Published: July 2006

Viologen linked porphyrins, ZnP(CnV)4, with various methylene chain lengths (n=2–5) between the porphyrin and the viologen have been synthesized. These compounds were applied to photoinduced hydrogen evolution in a system containing NADPH–ZnP(CnV)4–hydrogenase under steady state irradiation. On the addition of surfactant to the system, a remarkable rate increase of hydrogen evolution was observed in the case of ZnP(C5V)4.
Size Effects of Small Platinum Particles on the Electrocatalytic Oxidation of Methanol
Authors: Takasu Yoshio , Fujii Yuichi , Matsuda Yoshiharu
Published: July 2006

A cyclic voltammetry study of a platinum-glassy carbon model catalyst-electrode (Pt/GC) in an aqueous solution of H2SO4 revealed that the peak potentials for the anodic oxidation of methanol shifted a little to the negative potential and that the current densities decreased greatly with the decrease in the size of the platinum particles.
Novel Synthesis of Enol Ethers from β-Alkoxy Alcohols through t-BuOK-Promoted Elimination Reaction
Authors: Otera Junzo , Niibo Yoshihisa
Published: July 2006

A new synthesis of enol ethers from β-alkoxy alcohols was achieved through a t-BuOK-promoted elimination reaction.
Synthesis of Substituted Crown Ether Acetals
Authors: Oshima Takumi , Nagai Toshikazu
Published: July 2006

Reactions of phenyldiazomethane with chloranil and of 1-phenyldiazoethane and 9-diazofluorene with 2,3-dichloro-5,6-dicyano-p-benzoquinone in the presence of oligoethylene glycols and its monomethyl ethers gave the corresponding substituted crown ether acetals and open-chain analogues.
The Structure of Isoaplysin, a Brominated Rearranged Cuparane-Type Sesquiterpenoid from the Red Alga Laurencia okamurai Yamada
Authors: Suzuki Minoru , Kurata Kazuya , Kurosawa Etsuro
Published: July 2006

The structure of isoaplysin isolated from the red alga Laurencia okamurai Yamada has been established by the spectral and chemical methods.
Conductometric Determination of the Association Constants of β-Cyclodextrin with Amphiphilic Ions
Authors: Satake Iwao , Yoshida Shoji , Hayakawa Katumitu , Maeda Tamaki , Kusumoto Yoshihumi
Published: July 2006

The association constants (K) of β-cyclodextrin with 13 amphiphilic ions were determined. For a homologous series 1-alkanesulfonate ions, the saturation phenomenon of K occurred at the number of carbon atoms of 10. The values of K for amphiphilic ions with dodecyl chain were similar to one another.
The Crystal and Molecular Structure of Inner Triple-Layered Paracyclophanequinone
Authors: Toyoda Toshihiro , Tatemitsu Hitoshi , Sakata Yoshiteru , Kasai Nobutami , Misumi Soichi
Published: July 2006

The molecular structure of inner quinone isomer of two triple-layered paracyclophanequinones has been determined by means of X-ray diffraction. C26H24O2, M 368.5, orthorhombic, space group Pbcn, a=12.923(1), b=11.507(1), c=12.550(1) Å, V=1866.2(3) Å3, Z=4. The structure was solved by the direct method. Anisotropic refinement by the block-diagonal least-squares procedure gave R=0.042 for non-zero reflections. The molecule has a two-fold symmetry. The benzoquinone moiety is sandwiched by two donor benzene rings, and the two-fold axis passes through the O=C···C=O bonds of the twisted benzoquinone moiety. The outer benzene rings take a boat-form and the central benzoquinone ring is twisted.
α-d-Glucosylation by 6-O-Acetyl-2,3,4-tri-O-benzyl-d-glucopyranose Using Trimethylsilyl Triflate and Pyridine. Synthesis of α-Maltosyl and α-Isomaltosyl α-d-Glucosides
Authors: Koto Shinkiti , Yago Kazuo , Zen Shonosuke , Tomonaga Fumiya , Shimada Shigehiko
Published: July 2006

The d-glucosylation of methyl 2,3,4-tri-O-benzyl-α-d-glucopyranoside and methyl 2,3,6-tri-O-benzyl-β-d-glucopyranoside by 2,3,4,6-tetra-O-benzyl-α-d-glucopyranose using pyridine and excess trimethylsilyl triflate was carried out in dichloromethane, 1,2-dimethoxyethane, and acetonitrile. In a given solvent, the selectivity of the reaction varied depending on the type of hydroxyl group of the glucosyl acceptors. The d-glucosylation of these acceptors with 6-O-acetyl-2,3,4-tri-O-benzyl-d-glucopyranose employing this reagent system in dichloromethane proceeded with good α-selectivity irrespective of the type of the hydroxyl group. This α-d-glucosylation was applied for the synthesis of O-α-d-glucopyranosyl-(1→4)- and -(1→6)-α-d-glucopyranosyl α-d-glucopyranosides from α,α-trehalose.
A Simple and Efficient Synthesis of Optically Active (+)-4-Demethoxydaunomycinone
Authors: Kimura Yoshikazu , Suzuki Michiyo , Matsumoto Teruyo , Abe Rumiko , Terashima Shiro
Published: July 2006

Diels-Alder reaction of 2-chloro-1,3-butadiene with anthracene-1,4,9,10-tetrone was found to occur exclusively at the external (C2,3) double bond, giving the adduct in an excellent yield. The adduct was elaborated to 5,12-dihydroxy-1,2,3,4-tetrahydro-2,6,11-naphthacenetrione. The conventional cyanohydrin formation of this sample followed by acid hydrolysis gave (±)-2,5,12-trihydroxy-6,11-dioxo-1,2,3,4-tetrahydro-2-naphthacenecarboxylic acid. The racemic acid was found to be cleanly resolved by forming a salt with (−)-N-methylephedrine, furnishing optically pure (R)-carboxylic acid. Successive treatments of the (R)-carboxylic acid with N,N′-carbonyldiimidazole and methylmagnesium bromide in the presence of trimethylsilyl triflate readily produced optically pure (R)-(−)-7-deoxy-4-demethoxydaunomycinone, the key synthetic intermediate of (+)-4-demethoxydaunomycinone.
Perfluoroalkylations of Carbanions with (Perfluoroalkyl)phenyliodonium Triflates (FITS Reagents)
Authors: Umemoto Teruo , Gotoh Yoshihiko
Published: July 2006

FITS reagents reacted with primary alkylmagnesium halides in THF at −78 °C to give the corresponding perfluoroalkyl(Rf)-alkanes in moderate to good yields. But an alkyl-lithium or -copper gave a poor yield of the Rf-product. The reaction of FITS with secondary or tertiary alkylmagnesium halides resulted in low yields of the products. Alkynyl-lithiums or -magnesium halides produced Rf-alkynes in favorable yields. The reaction with aryl or vinylmagnesium halide was complex and the yields of Rf derivatives were low. FITS also reacted smoothly with enolate anions of active methylene compounds such as 2-methyl-1,3-cyclopentanedione, ethyl 2-methylacetoacetate, and ethyl 2-oxocyclopentanecarboxylate in a polar solvent to afford O- and C-perfluoroalkylation products in moderate yields, ratios O-/C-Rf products depending on the reaction temperature. Anions of diethyl 2-methylmalonate and 2-nitropropane afforded C-Rf-compounds only.
Addition Reaction of 1,4-Dibromo-2,5-piperazinedione with 3,4-Dihydro-2H-pyran
Authors: Itoh Kuniaki , Sera Akira
Published: July 2006

Reaction of 1,4-dibromo-2,5-piperazinedione (1) with 3,4-dihydro-2H-pyran (2) under irradiation gave 1 : 1 and 1 : 2-addition products (3,4) and corresponding secondary products (5–7). The adducts were considered to be produced separately by photoinduced free radical addition as well as concomitant ionic addition reactions.
Preparation of Sydnone Compounds Substituted by Thio and Seleno Functional Groups at the 4-Positions
Authors: Fuchigami Toshio , Chen Ching-Sy , Nonaka Tsutomu , Yen Mou-Yung , Tien Hsien-Ju
Published: July 2006

The introduction of thio and seleno functional groups to the 4-position of a sydnone ring was successfully attempted using 4-lithiosydnones (2) and 4-bromosydnones (3) as starting compounds. The reaction of 2 with tetraalkylthiuram disulfides, bis[alkoxy(thiocarbonyl)] disulfides, and bis[alkylthio(thiocarbonyl)] disulfides provided 4-sydnonyl dithiocarbamates, O-alkyl S-(4-sydnonyl) dithiocarbonates, and dialkyl 4-sydnonyl trithiocarbonates, respectively in good yields. In addition, treatment of 2 with thiocyanogen and selenocyanogen gave rise to bis(4-sydnonyl) sulfides (11) and bis(4-sydnonyl) selenides (12), respectively. These products, 11 and 12 were also formed by the reaction of 3 with potassium thiocyanate and selenocyanate, respectively. Furthermore, it was found that 3 reacted with selenourea and potassium O-ethyl dithiocarbonate under heating to provide 12 and 11, respectively. It was also found that the reactivity of these sydnone compounds 2 and 3 was quite different in many cases from that of the corresponding ordinary aromatic analogues, though the sydnone ring has a somewhat aromatic nature.
The Cerium(IV) Ammonium Nitrate Oxidation of 5-Hydroxy-2-methoxytropone to Bitropolonyl Derivatives and One-Step Synthesis of 3-Methoxy-p-tropoquinone
Authors: Mori Akira , Isayama Yasutoshi , Takeshita Hitoshi
Published: July 2006

Unlike the benzenoid equivalent, p-methoxyphenol, the cerium(IV) ammonium nitrate (CAN)-oxidation of 5-hydroxy-2-methoxytropone gave C–C coupling products. On the other hand, either by thallium(III) nitrate (TTN) or CAN at 50 °C, 5-hydroxytropolone, a free tropolone, gave 3-methoxy-p-tropoquinone together with p-tropoquinone and 8-oxabicyclo[3.2.1]octenone derivatives, but no dimeric product.
The Ion-Association Sorption and Extraction of Metal Thiocyanate Complexes to Cellulose Acetate Polymer and Organic Solvents. Similarity in Distribution Mechanisms
Authors: Hayashita Takashi , Takagi Makoto
Published: July 2006

The sorption and extraction of heavy metal thiocyanate complexes from an aqueous solution were studied for a cellulose acetate polymer and conventional organic solvents. The ease of metal sorption to solid cellulose acetate correlated well with the ease of metal extraction to liquid glycerol triacetate. The distribution behavior of ammonium thiocyanatozincate complexes was studied in detail and compared among cellulose acetate, isobutyl methyl ketone, and glycerol triacetate. The chemical processes involved in the metal distribution to the organic phase were found to be essentially the same for these three media. Thus, cellulose acetate was conveniently considered a polymer solvent. The results were discussed in relation to metalselective hyperfiltration through cellulose acetate membranes.
Rearrangement Approaches to Cyclic Skeletons. III. Practical Route to cis-Bicyclo[4.3.0]non-4-en-7-ones Based on Photochemical [1,3] Acyl Migration of Bicyclo[3.2.2]non-6-en-2-ones
Authors: Uyehara Tadao , Kabasawa Yasuhiro , Furuta Toshiaki , Kato Tadahiro
Published: July 2006

1-Methoxybicyclo[3.2.2]non-6-en-2-ones and the related compounds were derived I) from the Diels-Alder type 1,4-addition products of tropones with ethylene by selective reduction of the α,β-unsaturated carbonyl part (hydrosilylation followed by hydrolysis) and/or II) from bicyclo[2.2.2]oct-5-en-2-ones a) by the ring-enlargement utilizing Tieffeneau-Demjanov type conditions (1, TMS–CN; 2, LiAlH4; 3, NaNO2–AcOH) and/or b) by the related ringexpansion using trimethylsilyldiazomethane and boron trifluoride etherate. These bridged compounds were transformed into the respective [1,3] acyl migration products, cis-bicyclo[4.3.0]non-4-en-7-ones, in practical yields by direct irradiation through a Pyrex filter.
Catalytic Hydration of Unsaturated Nitriles to Unsaturated Amides Using Colloidal Copper Dispersions
Authors: Hirai Hidefumi , Wakabayashi Hidehiko , Komiyama Makoto
Published: July 2006

Homogeneous hydrations of unsaturated nitriles such as acrylonitrile, methacrylonitrile, and crotononitrile to the corresponding unsaturated amides have been carried out in water at 80°C by use of colloidal copper dispersions as catalysts. The dispersions are prepared by reduction of copper(II) sulfate, copper(II) chloride, and copper(II) acetate with sodium tetrahydroborate in the presence of various polymers. The dispersions with poly(N-vinyl-2-pyrrolidone), poly(vinyl alcohol), methylamylopectin, methylcellulose, ethylcellulose, and (2-hydroxyethyl)cellulose exhibit much larger catalytic activities than the copper precipitates prepared by reduction of the copper salts with sodium tetrahydroborate in the absence of the polymers. For all the catalytic reactions with the colloidal dispersions, selectivity for the unsaturated amides is 100% and formation of any by-products is not detected at all. Electron microscopy shows that no significant structural change occurs in the dispersions during the catalytic hydration. The catalytic activity monotonously increases with increasing amount of poly(N-vinyl-2-pyrrolidone) up to the charged ratio 20 of the monomeric residue to copper(II) ion, showing saturation at the ratio larger than 20. When the degree of the polymerization of poly(N-vinyl-2-pyrrolidone) is varied at a fixed residual molar ratio 40, the activity shows a maximum at the degree of polymerization 1440. The results are interpreted both by the change in the size of the colloidal copper particles and by the difference in the magnitude of the interactions between the polymers and the copper particles.
Electrolytic Recovery of Silver from Photographic Fixing Solutions with a Fluidized Bed Electrode
Authors: Sekine Isao , Ishii Hiroyuki
Published: July 2006

For an effective electrolytic recovery of silver from photographic fixing solutions, polarization measurements and potentiostatic electrolysis were carried out using active carbon as a fluidized bed electrode. The optimum conditions, determined by the electrolytic recovery, required a static bed height was 4 mm, a bed expansion rate 14%, and an initial set potential −0.84 V vs. SCE. The current efficiency in this case was about 75%, and the limiting concentration for recovery of silver was about 5 ppm. The electrolytic duration for recovery of the silver was reduced to about half by enlarging the electrolytic cell. Other products formed during the electrolysis were hydrogen sulfide (H2S) and silver sulfide (Ag2S). When silver deposited under the optimum conditions was dissolved in 5M-HNO3 (1M=1 mol dm−3) of 100 ml, the recovery efficiency of the silver was about 75%.
Crystal Structures of Trimethylammonium Hexaiodotellurate(IV) and Heptaiodotellurate(IV)
Authors: Kiriyama Hideko , Mizuhashi Yukiko , Ootani Junji
Published: July 2006

Crystal structures of the title compounds were determined by X-ray diffraction method. The crystal data and the final R values are: [(CH3)3NH]2TeI6, cubic, Pa3, a=13.210(2) Å, V=2305.2(9) Å3, Z=4, R=0.057 for 263 observed unique reflections and [(CH3)3NH]2TeI7, tetragonal, P4⁄nmm, a=13.921(3), c=6.224(2) Å, V=1206.4(8) Å3, Z=2, R=0.051 for 553 reflections. The structure of hexaiodo complex is a modified K2PtCl6 type. The discrete[TeI6]2− octahedra are practically regular with a Te–I distance of 2.952(2) Å. The trimethylammonium cations lie on the unit cell triad axes and form trifurcated, weak hydrogen bonds of NH···3I. In contrast, the TeIV coordination in the heptaiodo complex is an elongated octahedron with Te–I(1)=2.934(1) and Te–I(2)=3.124(4), 3.100(4) Å. These TeI6 octahedra form linear trans TeI5 chains running along c by sharing each pair of opposite vertices. Extra iodine atoms also stack along c with nearly equidistant I–I separations of 3.091(6) and 3.133(6) Å. The trimethylammonium cation is distributed randomly over four configurations in a cavity formed by two [TeI5]nn− and two [I]2nn− columns. Thus, the chemical constitution of the heptaiodo complex can be expressed as di-trimethylammonium catena-μ-iodo-tetraiodo tellurate(1-) catena-diiodide(1-), [(CH3)3NH]2n2n+[TeI5]nn−[I]2nn−.
Effects of Bivalent Metal Cations on the Conformation and Aggregation of Poly(l-glutamic acid)
Authors: Maeda Hiroshi , Hiramatsu Tsuyoshi , Ikeda Shoichi
Published: July 2006

In the solution of fully neutralized poly(l-glutamic acid) in the absence of supporting electrolytes, the α-helix was induced by the addition of five transition metal chlorides in the following order: CuCl2\gtrsimCdCl2>ZnCl2>NiCl2>CoCl2. The induction did not occur by the addition of BaCl2, CaCl2, or MgCl2. The induction by transition metal cations was inhibited in the presence of a supporting electrolyte (NaCl). Distortion of circular dichroism (CD) spectra occurred as the induction of the α-helix proceeded, which was shown to be recognizable when apparent aggregation number m exceeded about 100. Conformation of the polypeptide in these aggregates was expected to be the α-helix based on the conformation in the precipitates obtained at these mixing ratios which gave distorted CD spectra, which was determined by infrared absorption spectra.
Chemistry of 1,2-Thiaphosphole 2-Sulfides. II. Reactions of 1,2-Thiaphosphole 2-Sulfides with Some Nucleophiles
Authors: Tanaka Hideyuki , Saito Takao , Motoki Shinichi
Published: July 2006

5-t-Butyl-1,2-thiaphosphole 2-sulfides reacted with alcohols, thiols, and amines to give the 1,4-adducts, 2-alkoxy-, 2-(p-tolylthio)-, and 2-alkyl(aryl)amino-1,2-thiaphosphol-3-ene 2-sulfides, respectively. However, the reactions of 5-phenyl-1,2-thiaphosphole 2-sulfides with cyclohexyl- and arylamines afforded 1,2,3-dithiaphosphorins.
Electrochemical Behavior of p-Type Indium Selenide Single Crystal Electrodes in Dark and under Illumination
Authors: Uosaki Kohei , Kaneko Susumu , Kita Hideaki , Chevy A
Published: July 2006

The electrochemical behaviors of van der Waals face of p-InSe single crystal electrodes in 0.5M H2SO4 and 1M NaOH (1M=1 mol dm−3) with and without illumination have been thoroughly investigated. In 0.5M H2SO4, relatively large cathodic dark current was observed and the onset potentials for the current in dark and under illumination were ca. −0.8 V (vs. Ag/AgCl) and ca. −0.5 V, respectively, at as-prepared electrode. The current seemed to be mainly due to hydrogen evolution reaction. The dark current decreased significantly and the photo-current increased by removing surface steps. These results and impedance analyses show that the surface steps create surface states which act as recombination centers and mediators for charge transfer. Both the dark- and photocurrent onset potentials in 1M NaOH were more negative than those in 0.5M H2SO4 by ca. 0.5 V. The dark current was quite large and the photocurrent was small in 1M NaOH even after removing surface steps. By depositing Pt on p-InSe, the photocurrent onset potential shifted towards positive by several hundred mV. The reaction mechanism of photoelectrochemical hydrogen evolution was discussed by considering the above results.
Preparation and Coercivity of Cobalt Ultrafine Particles by Reduction of Multilayered CoO–SiO Films
Authors: Bando Yoshichika , Terashima Takahito
Published: July 2006

Films containing Co ultrafine particles were prepared by hydrogen reduction of periodically multilayered CoO–SiO films which were formed by alternating deposition of CoO and SiO. The films containing Co particles maintained the periodicity similar to the original films. Using samples of CoO single layer sandwiched between SiO layers, highly dispersed Co particles in the reduced sample were observed by transmission electron microscopy. The average size of the Co particles was almost as large as the thickness of CoO layer. The coercivities of the multilayered films containing Co particles were measured at room temperature and 77 K; they decreased with decreasing particle size from 20 nm to 3nm. Superparamagnetism was observed for the Co particles with average sizes below 4nm at room temperature. The formation and the magnetic property of the Co ultrafine particles in the Co–SiO system is dicussed.
Kinetics and Mechanism of Replacement of Glycinate in Bis(glycinato)oxovanadium(IV) by Oxalate
Authors: Kim Jung-Sung , Jung Woo-Sik , Tomiyasu Hiroshi , Fukutomi Hiroshi
Published: July 2006

The kinetics of formation of bis(oxalato)oxovanadate(IV) [VO(ox)2(H2O)]2− (hereafter water molecule will be omitted) from the reaction of bis(glycinato)oxovanadium(IV) [VO(gly)2] with oxalate has been studied by the stopped-flow method. The reaction was found to consist of two consecutive steps, a relatively slow step (k1) and a fast one (k2). The values of rate constants k1 and k2 were independent of the concentration of free oxalate and of the pH of solution ranging from 4.2 to 6.5. Similar behavior was also observed in the acid decomposition of [VO(gly)2]. A mechanism passing through an intermediate, [VO(ox)(gly)]−, was proposed.
New Multi-Sulfur 1,2-Dithiolene Complexes. Preparation, Structure, and Electrochemical Properties
Authors: Kato Reizo , Kobayashi Hayao , Kobayashi Akiko , Sasaki Yukiyoshi
Published: July 2006

New multi-sulfur 1,2-dithiolene complexes in which the 1,2-dithiolene moiety is extended by incorporating heterorings have been prepared and characterized by IR spectroscopy, X-ray diffraction method, and cyclic voltammetry. Partial oxidation of these complexes are expected to provide the multi-dimensional molecular conductors. Electrochemical properties of these complexes are compared with those of the dmit-complexes (dmit=2-thioxo-1,3-dithiole-4,5-dithiolate).
Aftereffects of Nuclear Decay in 57CoCl2·nH2O (n=2 and 6) Investigated by γ-X Ray Coincidence Mössbauer Spectroscopy
Authors: Kobayashi Takayuki , Friedt Jean M
Published: July 2006

The anomalous states produced by electron capture decay of 57Co in CoCl2·2H2O and CoCl2·6H2O are investigated using conventional Mössbauer emission spectroscopy and a γ-X ray coincidence method which allows to isolate events with a reduced influence of the Auger electron self-irradiation. The formation of the anomalous electronic and structural configuration is assigned to the self-radiolysis of the water ligands. The mechanism involves both the nearest and the next nearest H2O coordination shell according to the densities of these ligand molecules in the respective shells.
The Crystal and Molecular Structure of Δ-(8-Methyl-1,3,6,10,13,16,19-heptaazabicyclo[6.6.6]icosane)cobalt(III) Perchlorate Monohydrate
Authors: Sakaguchi Ushio , Ito Tasuku
Published: July 2006

The structure of Δ-(8-methyl-1,3,6,10,13,16,19-heptaazabicyclo[6.6.6]icosane)cobalt(III) perchlorate monohydrate, Δ-[Co(C14H33N7)](ClO4)3·H2O, has been determined by single crystal X-ray diffraction techniques. Crystal data are the following: space group P212121, a=16.379(2) Å, b=16.388(2) Å, c=9.753(1) Å, V=2617.9(5) Å3, Z=4, 3983 nonzero structure factors (|Fo|>3σ(|Fo|)), R=0.0447, and Rw=0.0491. The geometry of the cation can be approximated very closely by a composite of [Co(sen)]3+ and [Co(sep)]3+, where sen=1,1,1-tris(4-amino-2-azabutyl)ethane and sep=1,3,6,8,10,13,16,19-octaazabicyclo[6.6.6]icosane.
EXAFS Studies of the Behavior of Rh6(CO)16 Supported on γ-Al2O3 Surface
Authors: Asakura Kiyotaka , Iwasawa Yasuhiro , Kuroda Haruo
Published: July 2006

The structural change of Rh6(CO)16 supported on γ-Al2O3 surface during a decarbonylation–recarbonylation cycle was studied by means of EXAFS (extended X-ray absorption fine structure) spectroscopy. Rh6(CO)16 cluster framework was found to be decomposed into Rh(CO)2(OAl(Remark: Graphics omitted.))2 after the reaction with a mixture of O2 and H2O, and reversely regenerated by the subsequent treatment with a mixture of CO and H2O.
Crystal and Molecular Structure of a Potentially Five-Coordinate Palladium(II) Complex Containing 1,10-Phenanthroline. Chlorobis(triphenylphosphine)(1,10-phenanthroline)palladium(II) Tetrafluoroborate
Authors: Taira Zenei , Yamazaki Shinsaku
Published: July 2006

The X-ray crystal structure of a potentially five-coordinate palladium(II) complex containing 1,10-phenanthroline, [PdCl(PPh3)2(phen)][BF4]·(CH3)2CO has been determined. The structure was solved by the heavy-atom method and refined to R=0.051.
Total Synthesis of (±)-Zeylena
Authors: Ogawa Seiichiro , Takagaki Tohei
Published: July 2006

Zeylena, isolated from the roots of Uvaria zeylanica L. (Annonaceae), has been synthesized as a racemic modification by an intramolecular cyclo-addition reaction of Dl-trans-2,3-dihydroxy-1-(benzoyloxymethyl)cyclohexa-4,6-diene 3-(E)-cinnamate or its acetate.
Stereoselective Synthesis of Allyl- or Alkynyl-Substituted (Z)-Vinylsilanes via Organoboranes
Authors: Hoshi Masayuki , Masuda Yuzuru , Arase Akira
Published: July 2006

Copper(I) iodide-catalyzed cross-coupling reactions of (Z)-(1-trimethylsilyl-1-alkenyl)dicyclohexylboranes with allyl bromide or 1-bromo-1-hexyne gave stereoselectively (Z)-1,4-dienes or conjugated (Z)-enynes having a trimethylsilyl group on the internal carbon atom of the double bond.
The Structure of Bis(dibenzyl sulfoxide)tris(O,O′-diethyl dithiophosphato)lanthanum(III), La{(C2H5O)2PS2}3{(C6H5CH2)2SO}2
Authors: Imai Takashi , Shimoi Mamoru , Ouchi Akira
Published: July 2006

The crystal and molecular structure of the title complex has been determined by the use of the single-crystal X-ray diffraction method. The crystal of LaC40H58O8P3S8, F.W.=1155.20, is triclinic; space group P\bar1, a=13.300(5), b=19.816(8), c=11.257(4) Å, α=92.79(4), β=114.92(3), γ=75.40(4)°, U=2598(2) Å3, Z=2, Dm=1.48(3), Dx=1.48 g cm−3, and μ(Mo Kα)=1.29mm−1. Each lanthanum(III) atom is octa-coordinated and is in a dodecahedral geometry. The oxygen atoms of dibenzyl sulfoxide molecules are ligated at both ends of the base of a trapezia, and the chelating O,O′-diethyl dithiophosphates span two m edges and one a edge.
Platinum-Catalyzed Oxidation of Cholesterol
Authors: Akihisa (ne Itoh) Toshihiro , Matsumoto Taro , Sakamaki Hiroshi , Take Masa-aki , Ichinohe Yoshiyuki
Published: July 2006

Cholesterol was oxidized (12% conversion) with platinum and oxygen to give several 7-oxygenated products, cholest-5-en-3-one, and cholest-4-en-3-one accompanied with its further oxygenation products at C-6. The pathways and mechanisms of the catalytic oxidation are discussed.
Preparation of Solid Catalysts for Vapor-Phase Decomposition of Carbonyl Sulfide
Authors: Akimoto Masamichi , Suto Hirotoshi , Niiyama Hiroo
Published: July 2006

The vapor-phase catalytic decomposition of COS (COS→CO+1/xSx and 2COS→CO2+CS2) has been mechanistically investigated so as to prepare solid catalysts which are active and selective for the first reaction. The comparison of the catalytic activity and selectivity of a series of Al2O3 catalysts with their acid-base properties and the different behavior of these two catalytic decomposition reactions in the poisoning of an Al2O3 catalyst with SO2 demonstrate that electron-donating sites catalyze the first reaction whereas Lewis acidic sites do so the second reaction. CaO catalysts are prepared by thermal decomposition of CaCO3 at elevated temperatures and their catalytic activity is compared with their amount of electron-donating sites. The greatest catalytic activity and selectivity for the first reaction(yield of CO+Sx=21.4%, selectivity=80.2% at 873 K) are obtained over CaO catalyst prepared at 1123 K which has the greatest electron-donating ability. These values of the yield and selectivity to CO+Sx are much greater than those obtained over Al2O3 catalysts.
Catalysis by Transition-Metal Carbides. VII. Kinetic and XPS Studies of the Decomposition of Methanol on TiC, TaC, Mo2C, WC, and W2C
Authors: Orita Masahiro , Kojima Isao , Miyazaki Eizo
Published: July 2006

The catalytic decomposition of methanol was investigated on a series of powdered transition-metal carbides, such as TiC, TaC, Mo2C, WC, and W2C, which had been catalytically activated by evacuation at high temperatures. WC was found to produce methyl formate (HCOOCH3) with a high selectivity (above 80%), whereas CO and H2 were mainly produced on clean TaC, Mo2C, and W2C surfaces. XPS measurements combined with an analysis of the peak intensities revealed that the catalytic activation of WC and TaC was attributable to the removal of surface oxygen and the subsequent formation of monocarbide surfaces. On the other hand, the minor activities leading to the formation of methyl formate on W2C and Mo2C were concluded to be due to the formation of oxycarbide surfaces. The deuterium distributions in the products during the reaction of CH3OD suggest that the methyl formate is produced via the dimerization of the intermediate adspecies, CH2O.
Kinetic Study of Liquid-Phase Esterification with Sulfonic Acid Cation-Exchange Resin of the Macroreticular Type. I. Heterogeneous–Pseudohomogeneous Resin Catalysis
Authors: Shimizu Shoichi , Hirai Choichiro
Published: July 2006

The rates of the esterification of octanoic acid with 1-butanol catalyzed by macroreticular sulfonated ion-exchange resin were measured by the use of a batch reactor. The effects on the rate were investigated for variations in the amount of the catalyst, the temperature, and the reactant alcohol concentrations as well as those of water and butyl octanoate. From these data, it is considered that alcohol and water solvate the matrix-bound sulfo groups, and so this esterification system consists of a heterogeneous reaction catalyzed by un-ionized sulfo groups and a pseudo-homogeneous reaction catalyzed by solvated protons; in other words, catalysis by sulfonic acid resin is both heterogeneous and pseudo-homogeneous in liquid-phase esterification.
Pulse Radiolysis Study of Reaction of OH Radicals with Triose Reductone
Authors: Horii Hideo , Abe Yasuo , Taniguchi Setsuo
Published: July 2006

The reaction between the hydroxyl radical (OH) and triose reductone (2,3-dihydroxy-2-propenal) in an aqueous solution has been studied by spectrophotometric pulse radiolysis. The OH radical adds to triose reductone (TRH2) to form the transient OH adduct (TRH(OH)−·) with an absorption maximum at 398 nm, ε=3150 M−1 cm−1 (1 M=1 mol dm−3) in a neutral solution. The OH adduct decays by second-order kinetics in the pH range 2–12. The rate constants for the reactions of the OH radical with dissociated and undissociated triose reductone are 1.4×1010 M−1 s−1 and 9.9×109 M−1 s−1, respectively. The dependence of the transient absorption on the pH shows that the OH adduct has a pKa value of 4.7.
Electrocatalysis in Metal Hydride Electrode. I. Hydrogen Electrode Reaction on Group-IB and VIII Metals Deposited on Palladium Substrates
Authors: Machida Ken-ichi , Enyo Michio
Published: July 2006

Hydrogen electrode reactions (HER) on thin-layer electrodes of group-IB and VIII metals (Cu, Ag, Au, Ni, and Pt) prepared by electro-deposition on Pd foil substrates were studied (together with the Pd foil itself) in 0.5 M H2SO4 and 1.0 M NaOH (M=mol dm−3) at 303 K by a transient technique. The reactions on these metals were concluded to proceed via a Volmer-Tafel reaction route and the exchange current densities of the elementary steps, ioV and ioT, were then evaluated. The electrocatalytic activities towards the Volmer step were observed to be in the order Pt>Pd>Au>Ag>Cu in an acidic solution and Pt>Pd>Ni≥Ag≥Au≥Cu in an alkaline solution. The activities towards the Tafel step were Pt≥Pd>Au>Cu>Ag in an acidic solution and Pd>Pt>Au>Cu=Ag>Ni in an alkaline solution. The results were summarized in terms of the parameter mo (=ioV⁄ioT). This parameter was used to describe the electrochemistry of the energy efficiency of a hydride-type hydrogen-storage electrode, when the metals were employed for the purpose of modifying the electrode surface. Pt and Ag (among the group-IB metals) in both acidic and alkaline solutions were revealed to be suitable electrocatalysts.
Geometrical Isomerism of Phenylhydrazones of α-Keto Esters. II. p-Substituted Phenylhydrazones of Ethyl Pyruvate and 2,4-Dinitrophenylhydrazones of Some α-Keto Esters
Authors: Ishibashi Fumihide , Nashima Takeo , Nishino Junko , Kobayashi Ikuko , Ichihara Yoshinori , Kitagawa Yoshimi , Sasaki Shigeko , Yoshikawa Masako , Matsuoka Atsuko , Yamamoto Keiko
Published: July 2006

Each geometrical isomer of various substituted phenylhydrazones of ethyl pyruvate and 2,4-dinitrophenylhydrazones of some α-keto esters was isolated in a pure state. Partial isomerizations of the E-isomers of the former hydrazones to the Z-isomers took place by keeping solutions of the hydrazones in organic solvents containing C, H, and Cl in the dark. An E- or Z-structure was assigned to each molecule on the basis of IR and 1H NMR spectra. In all cases, isomers with higher Rf-values on a silica gel TLC (using benzene as a developing solvent) involved an intramolecular hydrogen bonding between the imino hydrogen and the ester carbonyl oxygen. Thus, the Z-structure was assigned. An E-structure was assigned to other isomers with lower Rf-values. The present assignment is, thus, entirely the same as that proposed in a previous investigation.
Stereoselectivity in the Synthesis of Enol Esters from Chloromercurio Aldehydes and Acyl Chlorides
Authors: Fukuda Wakichi , Sato Hozumi , Kakiuchi Hiroshi
Published: July 2006

Reactions of chloromercurio aldehydes with acyl chlorides gave a variety of (Z)- and (E)-enol esters. The Z/E ratio of the enol esters is dependent on the structure of chloromercurio aldehydes but independent of that of acyl chlorides. Z-Rich enol esters were prepared by acylation of 2-chloromercurio aldehydes derived from propanal, butanal, and 2-phenylethanal, while E-rich 1-acyloxy-1,3-butadiene was obtained by acylation of (E)-4-chloromercurio-2-butenal. Reaction mechanisms for the stereoselective formation of these enol esters are discussed together with the isomer composition of starting enol acetates from which the chloromercurio aldehydes were prepared.
Studies of Polystyrene-Based Ion-Exchange Fiber. V. Immobilization of Microorganism Cells by Adsorption on a Novel Fiber-Form Anion Exchanger
Authors: Yoshioka Toshio , Shimamura Masaharu
Published: July 2006

Immobilization of microorganism cells by adsorption on a new polystyrene-based ion-exchange fiber has been studied. Microorganism cells, such as yeasts, bacteria, and actinomycetes, were well adsorbed on the anion-exchange fibers through an electrostatic force. The adsorption capacity for the cells became much greater as the water-holding capacity of the fibers increased. The adsorption and desorption behavior of the cells was different between actinomycetes and yeasts, and also between strong and weak anionexchange fibers. The enzyme activities of the immobilized actinomycetes containing glucose isomerase and yeasts containing l-aminolactam hydrolase were ca. 70 and 60% of those of the native cells respectively. The stability of the immobilized yeasts in the hydrolysis of Dl-cyclic lysine anhydride was also investigated.
Optical and Magnetic Properties of (DBTTF)2(Cu2Cl6) and (DBTTF)2(Cu2Br6) Complexes
Authors: Tanaka Masashi
Published: July 2006

Optical reflection and magnetic susceptibility measurements of (DBTTF)2(Cu2Cl6) and (DBTTF)2(Cu2Br6) complexes were carried out. The analysis of the reflection spectra of the single crystals of these complexes shows that the electronic structure of DBTTF+ cation molecules is typical of the dimer type configuration. The magnetic susceptibilities of these complexes were measured over a temperature range of 2–300 K. The magnetic behavior conforms to a modified Bleaney-Bowers equation, indicating the existence of the spin coupling within the Cu2Cl62− or Cu2Br62− dimers and the antiferromagnetic spin interaction between Cu2Br62− dimers.
Formation of the N,N-Bidentate Chelates of 2-(2-Pyridylazo)phenolic Ligands with Nickel(II) in Nonaqueous Solvents
Authors: Kudo Yoshihiro , Yoshida Noboru , Fujimoto Masatoshi
Published: July 2006

The formation of N,N-bidentate 1:2 complexes of nickel(II) with various N,N,O-terdentate 2-(2-pyridylazo)phenolic ligands was detected spectrophotometrically in ethyl acetate and was examined with respect to the influences of Brønsted bases, the counter anions in the nickel(II) salts employed, solvent basicity, and the steric requirements around the donor nitrogen atoms in the ligand in the 1:2 complex. It is concluded that the stability of the N,N-bidentate complex species in solutions predominantly depends on the basicity of the counter anions X in NiX2 and of the solvent. In the case of 1-(2-pyridylazo)-2-naphthol, owing to a high steric hindrance of the naphthalene ring, the formation of the N,N-bidentate complex was not observed even in the solvent of low basicity such as dioxane.