bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on 2-Aziridinecarboxylic Acid, II. A Novel Synthesis of Threonine O-Peptide Derivatives via (2S,3S)-3-Methyl-2-aziridinecarboxylic Acid
Authors: Tanaka Takumi , Nakajima Kiichiro , Maeda Toru , Nakamura Akihiro , Hayashi Noboru , Okawa Kenji
Published: July 2006

A new synthesis of threonine O-peptides via the ring opening reaction of aziridine peptide with carboxylic acid has been investigated. Benzyl (2S,3S)-1-[N-(benzyloxycarbonyl)glycyl]-3-methyl-2-aziridinecarbonylglycinate was treated with several N-protected amino acids or dipeptides at their mixed melting point, and the corresponding O-aminoacyl or dipeptidyl esters of l-threonine peptide derivative were obtained in good yields without racemization.
A Synthesis of Neamine
Authors: Harayama Akihiko , Tsuchiya Tsutomu , Umezawa Sumio
Published: July 2006

Neamine and its position isomer were synthesized from 3,4-di-O-acetyl-2-deoxy-2-(p-methoxybenzylidene-amino)-6-O-tosyl-α-d-glucopyranosyl bromide and racemic 5,6(4,5)-O-cyclohexylidene-2-deoxy-1,3-bis-N-(ethoxycarbonyl) streptamine. Influence of the N-protecting groups of 2-deoxystreptamine derivatives for glycosylation was discussed. The unusual Δ[M]TACu value of the position isomer of neamine was ascribed to the interaction between the 6′-amino group and other groups.
Synthesis and Properties of o-Thioquinone Methides Having Ketene Aminal, Ketene Acetal, Ketene Monothioacetal, or Ketene Dithioacetal Group
Authors: Kang Kyung-Tae , Okazaki Renji , Inamoto Naoki
Published: July 2006

Reaction of 1,2-benzodithiole-3-thione with N,N′-dialkyl-1,2-ethanedianiine afforded o-thioquinone methides with a ketene aminal group (6) in high yields. Two similar thionaphthoquinone methides were also prepared. o-Thioquinone methide derived from N,N′-dimethyl-o-phenylenediamine was prepared from 3-chloro-1,2-benzodithiol-3-ylium chloride (10). These compounds were found to exist as a monomer of a considerable betaine nature. Reactions of 6a (N,N′-dimethyl derivative) with dimethyl acetylenedicarboxylate and dibenzoylacetylene led to [4+2] adducts. o-Thioquinone methides with a ketene acetal group were obtained from desulfurization of spiro[1,3-benzodioxole-2,3′-[1,2]benzodithiole] with trimethyl phosphite, which are equilibrated with two kinds of aggregates; one is a dimer and the other is a trimer or a higher oligomer. Reactions of 10 with o-mercaptophenol and 1,2-benzenedithiols gave spiro[1,2-benzodithiole-3,2′-[1,3]benzoxathiole] (29) and spiro[1,2-benzodithiole-3,2′-[1,3]benzodithiole] (39 and 40), respectively. o-Thioquinone methide with a ketene monothioacetal group (30) was prepared by desulfurization of 29. The violet compound 30 is equilibrated with a colorless dimer. This o-thioquinone methide reacted with olefins and an acetylene having electron-withdrawing groups to give 1,4-cycloaddition products. Similar desulfurization of 39 and 40 gave o-thioquinone methides with dithioacetal group. Their properties were very similar to those of o-thioquinone methides with dithioacetal group prepared by the photoreaction of 2 with olefins.
The Crystal and Molecular Structure of Benzanilide
Authors: Kashino Setsuo , Ito Kuniaki , Haisa Masao
Published: July 2006

The crystal structure of benzanilide has been determined from Weissenberg photographs using Cu Kα radiations and refined to an R value of 0.075 for 766 independent reflections. The crystals are monoclinic, space group C2/c, Z=4, with a=24.34(4), b=5.325(3), c=8.012(8) Å, β=107.2(3)°, Dm=1.32 and Dx=1.321 g cm−3. Dihedral angle between the benzene rings is 62.6°, and each benzene ring makes dihedral angle of 31.3 and 31.6° with the plane of amido group as found in Kevlar and Nomex polymers. The molecules related by a b-translation are linked together by N–H…O hydrogen bond [N…O 3.112(6), H…O 2.03 Å, N–H…O 157°] to form a chain along b. The chains are held together primarily by dipole forces of carbonyl groups of the molecules related by inversion centers to form a sheet parallel to the bc plane. The sheets are stacked along a with disorder by van der Waals interactions.
The Modification of Porous Polymer Beads; Use Packing Material in Gas Chromatography
Authors: Takayama Yuzi
Published: July 2006

A new method of the surface modification of a porous polymer has been developed and applied to packing materials for gas chromatography. The porous polymer was coated with a α,β-unsaturated polyester solid polymer, which had a high acid value and which was cross-linked on the porous polymer by polymerization. By using this in gas chromatography, formic acid peaks are completely separated from acetic acid and water peaks without any apparent tailing. This polyester layer was not extractable and could stably be used at 230 °C or higher. If the diallyl phthalate polymer is used instead of the α,β-unsaturated polyester, propionic acid and acrylic acid, which are very diffecult to separate, were resolved. The present method may be applicable to some components of composite materials.
Gas and Solid Phase Photoelectron Spectra of 5,6,11,12-Tetra-phenylnaphthacene (Rubrene)
Authors: Takahashi Takashi , Harada Yoshiya , Sato Naoki , Seki Kazuhiko , Inokuchi Hiroo , Fujisawa Shoji
Published: July 2006

The gas and solid phase UV photoelectron spectra of rubrene were measured. In the molecule there is little conjugation of π-electrons between four substituent phenyl groups and the naphthacene skeleton owing to the effect of the steric hindrance of the phenyl groups. Therefore, the lower IP bands in the gas phase spectrum could be correlated to the π-bands in the photoelectron spectra of benzene and naphthacene. The features of the solid phase spectrum are similar to those of the gas phase one except for a large peak due to inelastically scattered electrons. The polarization energy due to the molecular ion in the solid, the peak to peak difference between the gas and solid phase spectra, was observed to be 0.6 eV, which is about half the polarization energy for naphthacene. This means that rubrene molecules are loosely packed in the solid as a result of the steric hindrance of four phenyl groups.
Interdiffusion of Zinc Ions in Aluminium Cobalt(II) Oxide and Aluminium Nickel(II) Oxide
Authors: Koumoto Kunihito , Matsubara Takao , Takata Masasuke , Yanagida Hiroaki
Published: July 2006

The interdiffusion coefficients \ ildeD of Zn2+ ions in aluminium cobalt(II) oxide (cobalt aluminate) and aluminium nickel(II) oxide (nickel aluminate) were measured. In the former \ ildeD is independent of the concentration of the composition-dependent cation vacancies, while in the latter it decreases with increase in the concentration of cation vacancies. The difference in the distribution of cations and cation vacancies in the spinel lattice has a great effect on the interdiffusion coefficients of Zn2+ ions. The results were interpreted by means of the vacancy mechanism for Co2+ and Ni2+ ions and the interstitial or interstitialcy mechanism for Zn2+ ions. The activation energy is independent of the concentration of Zn2+ ions or cation vacancies; 355 kJ mol−1 for cobalt aluminate and 364 kJ mol−1 for nickel aluminate.
Single Crystal Growth of Zirconium Nitride by Modified Filament-Method
Authors: Sugiyama Kohzo , Watanabe Kunio , Motojima Seiji , Takahashi Yasutaka
Published: July 2006

Single crystals of zirconium nitride (ZrN) have been grown by the modified filament-method from a gas mixture of ZrCl4, N2, H2, and Ar. The cubic crystals grew at 2000–2200 °C with a gas flow ratio 2N2/ZrCl4 of 2–6, and evaporation of ZrN took place above 2400 °C. Linear growth rates along the <100> direction have been measured in terms of sequential micrographs, and attained a maximum of 60–75 μm/min at 2100–2200 °C. The atomic ratio N/Zr of grown crystals increased with an increase of the flow ratio 2N2/ZrCl4, and reached a constant of 0.93 above the flow ratio of 3.
Dimer and Excimer Fluorescence Spectra of Highly Polar Molecules, 3,5-Dialkyl-4-methoxybenzylidenemalononitrile
Authors: Inoue Kenji , Itoh Michiya
Published: July 2006

Dual fluorescence of the ground state dimer of highly polar molecules of 3,5-dialkyl-4-methoxybenzylidenemalononitrile in 3-methylpentane solution at low temperature was investigated by steady-state and nonsecond fluorescence spectroscopies. The dimerization of these compounds was confirmed by concentration dependence of absorption and fluorescence spectra at 77 K. The dimer exhibits dual fluorescence consisting of a short-lived dimer fluorescence and a long-lived excimer fluorescence, while the monomer is almost nonfluorescent at room temperature to 77 K. The excimer formation by an orientational relaxation from the excited state of the dimer was discussed in terms of determination of the activation barrier and the fluorescence polarization.
Electron-transfer Reduction of α-Substituted Ketones and 1,2-Diketones with Benzenethiol Mediated by Iron Polyphthalocyanine
Authors: Inoue Hiroo , Nagata Tadashi , Hata Hiroyuki , Imoto Eiji
Published: July 2006

Iron polyphthalocyanine (Fe-poly PC) has been found to act as an electron-transfer reagent in the reductions of α-substituted ketones, α-bromodeoxybenzoin (1a), 2-bromopropiophenone (1b), α,α-bis(phenylthio)deoxybenzoin (4), and 1,2-diketones, benzil (5) and 4,5-octanedione (8), with benzenethiol. The α-bromo ketones (1a and 1b) have been debrominated to their parent ketones. 4 has been reduced to α-(phenylthio)deoxybenzoin and deoxybenzoin via the cleavage of the carbon-sulfur bond, and 5 and 8 to the corresponding α-hydroxy ketones. The ability of Fe-poly PC to perform these reactions is superior to that of iron phthalocyanine (Fe-PC), particularly those reactions in dry benzene. The catalytic action of Fe-poly PC and Fe-PC becomes evident when methanol or 80 vol % aqueous methanol is used as solvent. Furthermore, the reductions of related compounds by the Fe-poly PC-benzenethiol system are described.
Ligand Effects of Amine Chelates in the Decomposition of 1,2,3,4-Tetrahydro-1-naphthyl Hydroperoxide Catalyzed by Cobalt(II) and Copper(II) Salts
Authors: Yamada Teruaki , Kamiya Yoshio
Published: July 2006

The ligand effects of 2,2′-bipyridine, ethylenediamine, and diethylenetriamine on the rate of decomposition of 1,2,3,4-tetrahydro-1-naphthyl hydroperoxide catalyzed by cobalt(II) decanoate and copper(II) decanoate in chlorobenzene were kinetically studied. The results were compared with the redox potentials measured in nonaqueous media and the spectral data of cobalt(II) and copper(II) complexes. It was found that the catalytic activity of Me(II) decanoate–ethylenediamine, or -diethylenetriamine complex (Me=Co, Cu) becomes maximum at 1/2 the molar ratio of ethylenediamine to Me(II), or at 1/3 that of diethylenetriamine to Me(II), and that further addition of these amines deactivates the catalysts. The activity of copper(II) decanoate increased from k=0 to k=1.4×10−3 s−1 on addition of 2,2′-bipyridine when the molar ratio of 2,2′–bipyridine to copper(II) decanoate was 0–4. No maximum activity was observed in copper(II) decanoate-2,2′-bipyridine system. A large excess of 2,2′-bipyridine, 150 times the quantity of copper(II) salt, did not decrease the decomposition rate in contrast to the case of the cobalt(II) decanoate–2,2′-bipyridine system. The difference in ligand effect of ethylenediamine, diethylenetriamine and 2,2′-bipyridine on cobalt(II) ion and copper(II) ion was discussed on the basis of the properties of these complexes.
Further Study of Methanol Carbonylation Catalyzed by Cobalt, Rhodium, and Iridium Catalysts
Authors: Mizoroki Tsutomu , Matsumoto Toshio , Ozaki Atsumu
Published: July 2006

The effect of iodide ion was examined in methanol carbonylation with use of Co-, Rh-, and Ir-catalysts. Sodium iodide gives no noticeable effect on carbonylation catalyzed by Rh-catalyst to give acetic acid, and retards that catalyzed by Ir-catalyst. Methyl iodide is effective for methanol carbonylation with Co-catalyst in the presence of hydrogen to give mainly acetaldehyde, which is readily hydrogenated to ethanol during the course of carbonylation on addition of a catalytic amount of Ru3(CO)12. Sodium iodide is also effective for acetaldehyde formation, although it strongly retards the hydrogenation of acetaldehyde with Ru-catalyst. The different effect of iodide ion on methanol carbonylation catalyzed by Co-, Rh-, or Ir-catalyst is discussed in terms of neucleophilicity of the active catalyst species.
Synthesis and Reactions of o-Benzothioquinonemethides
Authors: Okazaki Renji , Sunagawa Kazuhiko , Kang Kyung-Tae , Inamoto Naoki
Published: July 2006

Photoreactions of 1,2-benzodithiole-3-thione with olefins (cyclopentene, cyclohexene, cyclooctene, and 2,3-dimethyl-2-butene) afforded deep blue o-thioquinonemethides (4) in high yields. The thione 4 is equilibrated with a colorless head-to-head dimer having an eight-membered ring. The mode of the dimerization has been discussed in comparison with other o-quinonoid compounds. Cycloaddition reactions of 4 with electron-deficient acetylenes and olefins gave rise to [4+2] adducts. It was confirmed that these cycloadditions proceeded stereoselectively as well as regioselectively. Reactions of 4 with diphenylketene, phenyl isocyanate, and phenyl isothiocyanate led to six-membered 1 : 1 adducts. Reduction by hydride reagents has been also described.
Syntheses and Spectral Observation on the Structure of Several 2(1H)-Pyridinethionato Zinc Complexes
Authors: Masaki Mitsuo , Matsunami Satoshi , Kimura Takayuki , Oshima Tokio
Published: July 2006

Although bis[2(1H)-pyridinethionato]zinc (1) is prepared by the reaction of 2(1H)-pyridinethione with zinc chloride in the presence of stoichiometric amount of sodium hydroxide, a similar reaction in the presence of a large excess amount of the base gave μ4-oxo-hexakis-μ-[2(1H)-pyridinethionato-(N,S)]-tetrazinc (2) which is the first example of L6Zn4O (L=ligand) type complexes having heterocyclic thiolato groups as ligands. The complex 2 was also prepared by several routes, which involve hydrolysis of 1 and the reaction of 1 with zinc oxide. In these complexes 2(1H)-pyridinethionato ligand acts as a bidentate or bridging ligand. Attempts to convert bis(4,6-dimethyl-2-pyridylthio)zinc or bis(1-oxido-2-pyridylthio)zinc into a complex of L6Zn4O type were failed. Complexes of L6Zn4O type were also prepared when L were 2-thiazolidinethionato, 5-methyl-2-thiazolidinethionato, and 1-methyl-4-imidazoline-2-thionato.
Substituent Effects in Heterogeneous Catalysis. III. Competitive Hydrogenation of Cyclohexanone and 2-Alkylcyclo-hexanones over Platinum Group Metals
Authors: Chihara Teiji , Tanaka Kazunori
Published: July 2006

Cyclohexanone (1) and one of its 2-alkyl (methyl, ethyl, or propyl) derivatives (2) were hydrogenated competitively at 30 °C in cyclohexane over platinum group metals. The alkyl derivatives 2 were all less reactive than 1 on all the catalysts used. The relative reactivity R2⁄R1 was given by log10(R2⁄R1)=σ**+k, with σ** depending only upon the substituent and k upon the catalyst. The greater the substituent size, the more negative was the substituent constant σ**. The catalyst-dependent constant K was in general more negative for a catalyst metal having a smaller atomic radius. The above empirical rate expression has been interpreted based on the absolute reaction rate theory. The σ** values calculated on this theoretical ground were in excellent agreement with the observed values.
ortho-Disubstituted F-Benzenes. I. Preparation of (F-Benzo)heterocyclic Compounds from F-Aniline and the Reactions of Some Intermediate (F-Phenyl)amino Compoundst
Authors: Inukai Yoshinari , Oono Yoshitsugu , Sonoda Takaaki , Kobayashi Hiroshi
Published: July 2006

With the intention of achieving the selective ortho-disubstitution of F-aniline via intramolecular nucleophilic cyclization, syntheses of some requisite intermediate (F-phenyl)amino compounds and (F-benzo)heterocyclic compounds were investigated. 2-Phenyl-F-benzoxazole, 2-phenyl-F-benzimidazole, and 2,3-dihydro-1,4-(F-denz)oxazin-3-one were obtained from the respective precursors: benz-F-anilide, N-(F-phenyl)benzamidine, and hydroxyacet-F-anilide. 2-Phenyl-F-benzothiazole was obtained by treating benz-F-anilide with phosphorus pentasulfide. Hydrolytic dehalogenation of haloacet-F-anilide failed to give hydroxyacet-F-anilide, but it was obtained successfully by catalytic debenzylation of benzyloxyacet-F-anilide. The reactions of iodoacet-F-anilide with silver nitrate and acetate yielded 2-nitrate and 2-acetate, respectively. The reaction with diamminesilver(I) nitrate resulted in a reductive deiodination which gave acet-F-anilide. This exceptional reactivity was ascribed to the strong electron-withdrawing effect of the F-phenyl group.
Syntheses of Polymerizable Carbodiimides Bearing a Terminal Vinyl Group
Authors: Kamogawa Hiroyoshi , Nanasawa Masato , Uehara Shigeki , Osawa Keisuke
Published: July 2006

N-(p- or m-Vinylphenyl)-N′-isopropyl- and cyclohexylcarbodiimides (3) have been synthesized in reasonable yields by first synthesizing the substituted ureas by the reactions p- or m-vinylaniline with isopropyl or cyclohexyl isocyanate in THF and the subsequent dehydration with p-toluenesulfonyl chloride in pyridine. The monomers 3 were found to polymerize smoothly with AIBN to afford vinyl polymers bearing the corresponding carbodiimide units as pendants in more or less cross-linked forms. The cross-linked insoluble polymers thus obtained can act as a dehydrative coupling agent in reactions such as the formation of peptide linkages.
Syntheses of Chlorozinc Complexes of 2(1H)-Pyridinethione and Their Mutual Transformations
Authors: Matsunami Satoshi , Fujimura Susumu , Okimoto Kiyomi , Masaki Mitsuo
Published: July 2006

Three types of zinc complexes, chlorotris[2(1H)-pyridinethionato]dizinc (3), dichlorotetrakis[2(1H)-pyridinethionato]trizinc (4), and chloro[2(1H)-pyridinethionato]zinc (5) were produced by the reactions of bis[2(1H)-pyridinethionato]zinc (2) and zinc chloride. The product in the reactions varies depending on the solvent. The mutual transformation reactions among 3, 4, 5, 2, and oxohexakis[2(1H)-pyridinethionato]tetrazinc were described. The formations of 5, 4, and 3 were explained by stepwise additions of 2 to zinc chloride based upon a view that these complexes are the adducts of 2 with zinc chloride in molar ratios of 1 : 1,2 : 1, and 3 : 1. Analogously, the correlation of the known polynuclear zinc complexes was systematically rationalized by stepwise additions of L2Zn (L=ligand) to ZnX2 (X=Cl or OH) or ZnO.
Synthesis and Sintering of Active Manganese(II) Zinc Ferrite Powders
Authors: Murthy M N Sankarshana , Deshpande C E , Bakare P P , Shrotri J J
Published: July 2006

Manganese(II) monoxide which is spontaneously oxidized in air is stabilized by solid solution with zinc oxide and then employed as a raw material in the synthesis of manganese(II) zinc ferrites in an inert atmosphere, giving thereby no chance for Mn2+ to get oxidized. Sintering is done in a static controlled atmosphere created by the thermal dissociation of pellets of active iron(III) oxide kept in oxygen-free nitrogen along with the ferrite toroids. The ferrite formation and the sintering are performed at 950 and 1150 °C respectively by employing active oxide raw materials.
Medium Effect on the Ionisation Constants of Some Hydroxy Derivatives of 1-Ethyl-2-styrylpyridinium and -quinolinium Iodides
Authors: Mahmoud M R , Abd-El-Hamide R , Idriss K A
Published: July 2006

The pKa values of 1-ethyl-2-(4 or 2-hydroxystyryl)pyridinium and -quinolinium iodides in different organic solvent–water mixtures were determined. The organic solvents used are methanol, ethanol, acetone, DMF and DMSO. The ionisation of the compounds under investigation depends largely on both the proportion and the nature of the organic co-solvent used. The ionisation constant decreases with increase in the proportion of the organic co-solvent in the medium. The major important effect responsible for this is the difference in the stabilization of base by donor hydrogen bond from solvent molecules. The free energy of solvation of both acid and proton by electrostatic interaction and that of the base by donor hydrogen bond from solvent molecules were calculated. The effect of the molecular structure of the compound on pKa is also discussed.
Rare Earth Complexes of 1-(2-Pyridylazo)-2-naphthol
Authors: Rao I M , Satyanarayana D , Agarwala Umesh
Published: July 2006

The rare earth complexes of 1-(2-pyridylazo)-2-naphthol (PAN=Hpan) are prepared in the solid state. The analytical, molecular weight and differential thermal analysis data of the complexes indicated the metal-ligand ratio as 1:3 with the general formulae Ln(pan)3·H2O (Ln=Pr3+, Nd3+, and Sm3+) and Ln(pan)3 (Ln=La3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, and Yb3+). Based on IR, UV, and visible absorption spectra, electrical conductance and magnetic susceptibility data, an octahedral structure having the metal ion bonded through nitrogen of azo and oxygen of carbonyl groups of the ligand has been postulated to these complexes.
Indirect Polarographic Estimation of Palladium
Authors: Kalapurna P B
Published: July 2006

Chemical displacement of palladium by mercury at the DME, has been found to be quantitative (that is, instantaneous and proportional to the id of mercury). Therefore the mercury(I) wave has been exploited for the indirect estimation of palladium using the DME. The conditions of estimation are standardized and the method applied to a mixture (dental alloy) containing palladium. The results are within experimental accuracy. The indirect method has certain advantages over the direct methods.
Preparation of Potassium Glycinatotrihydroxonitrosylruthenate(II)
Authors: Ishiyama Toshio , Matsumura Takashi
Published: July 2006

A new mono-glycinato complex of hydroxonitrosylruthenium(II), K[Ru(gly)(OH)3NO] was isolated by use of ion exchange resin from the product formed by the reaction of [RuCl3(H2O)2NO] with glycine. The complex was characterized by means of infrared, visible, and ultraviolet absorption spectra, capillary type isotachophoresis, magnetic moment and molar conductivity.
2,2′-Bipyridine Derivatives of Hexarhodium Carbonyl Cluster
Authors: Nomiya Kenji , Suzuki Hisashi
Published: July 2006

The properties of [Rh6(CO)12(bpy)2] (bpy:2,2′-bipyridine), prepared recently from substitution of carbonyl ligands in [Rh6(CO)16] by 2,2′-bipyridine have been investigated.
Preparations and Paramagnetic Contact Shifts of Some Tris(β-diketonato)vanadium(III) Complexes
Authors: Hiraki Katsuma , Onishi Masayoshi , Nakashima Yutaka , Obayashi Yayoi
Published: July 2006

New tris(dehydroacetato)-, tris (methylacetoacetato)-, and tris(ethyl acetopyruvato)vanadium(III) complexes were prepared and characterized by IR and NMR spectroscopies. Paramagnetic contact shifts of these complexes were discussed.
O-Methylation of Aromatic (E)-Oximes by Dimethylsulfonium Methylide
Authors: Tanimoto Shigeo , Yamadera Takashi , Sugimoto Toyonari , Okano Masaya
Published: July 2006

The reactions of dimethylsulfonium methylide with (E)-aldoxiroes and (E)-ketoximes proceeded smoothly at room temperature and gave moderately good yields of O-methyl (E)-aldoximes and O-methyl (E)-ketoximes, respectively. A possible scheme for the formation of O-methyl (E)-oximes has been discussed.
The Reaction of Methyl cis-Decahydro-5,8-dioxonaphthalene-1-carboxylates
Authors: Irikawa Hajime , Koyama Tsuyoshi , Okumura Yasuaki
Published: July 2006

Methyl cis-decahydro-5,8-dioxonaphthalene-1-carboxylates (1b and 1c) were derived from the Diels-Alder adducts of p-toluquinone or p-xyloquinone and methyl sorbate, respectively. The 13C NMR spectra of 1b and 1c suggest the existence of 1b and 1c in the form (A), which is in line with the formation of the keto γ-lactone from 1b and of the keto alcohol from 1c.
Stereoselectivity in Hydride Reduction of [n.3.2]Propellanones
Authors: Tobe Yoshito , Doi Akifumi , Kimura Koji , Odaira Yoshinobu
Published: July 2006

Stereoselectivity in hydride reduction of [n.3.2]propellanones is described. The observed stereoselectivity is attributed to conformational flexibility of the third ring, that is, from five- to eight-membered alidyclic rings.
Chemical Ionization Mass Spectrometry of Alkyl Nitrates and Nitrites
Authors: Das Rebati C , Koga Osamu , Suzuki Shin
Published: July 2006

The mass spectrometry of alkyl nitrites and alkyl nitrates with chemical ionization using methane and isobutane as reagent gases produces quasi-molecular ions, (M+1)+ and/or (M−1)+. These ions have maximum abundance for lower nitrates and nitrites. The chemical ionization mass spectrometry, in conjunction with gas chromatography, can be used for quantitative estimation of alkyl nitrates and nitrites in very low amounts.
Mixed Monolayers of Long Normal Chain Fatty Acids with Long Normal Chain Esters. II. Fatty Acids–Hexadecyl Acetate System
Authors: Matuo Hirosi , Motomura Kinsi , Matuura Ryohei
Published: July 2006

In order to clarify the effect of molecular structure on states and properties of mixed monolayers, surface pressure-area(π-A) curves of the two-component surface films of long normal chain fatty acids with hexadecyl acetate were measured at various compositions and temperatures. By use of thermodynamic analysis, the phase diagrams and partial molar enthalpy changes were calculated. For four systems studied in the present paper it was found that the diagram and enthalpy change vary characteristically with the number of carbon atoms of acids, but the dependence on the chain length of acid in fatty acid–hexadecyl acetate systems was very different from that in fatty acid–ethyl hexadecanoate systems.
The Crystal and Molecular Structures of 6-Deoxyversicolorin A and Versicolorin A, Metabolites from Aspergillus versicolor
Authors: Fukuyama Keiichi , Ashida Tamaichi , Katsube Yukiteru , Kakudo Masao
Published: July 2006

The structures of 6-deoxyversicolorin A, C18H10O6, and versicolorin A, C18H10O7, both isolated from Aspergillus versicolor, have been determined by the X-ray diffraction method. Both compounds crystallized in the space group P212121, with four molecules per unit cell. The cell dimensions of 6-deoxyversicolorin A are a=9.588, b=18.083, c=7.769 Å, and those of versicolorin A are a=9.524, b=18.629, c=7.629 Å. The structure was refined to R=0.055 for 6-deoxyversicolorin A and to R=0.043 for versicolorin A. Both structures are in agreement with those assigned by chemical and spectroscopic methods. There are two intramolecular hydrogen bonds in each molecule. Although an intermolecular hydrogen bond is present in versicolorin A, both structures are isotypic. The dimensions of the anthraquinone skeleton and the dihydrofuro[2,3-b]furan moiety are compared with those in related compounds whose structures have been determined.
Heterogeneous Catalysis in the Liquid-phase Oxidation of Olefins. III. Activity of Supported Vanadium–Chromium Binary Oxide Catalyst for the Oxidation of Cyclohexene
Authors: Takehira Katsuomi , Hayakawa Takashi , Ishikawa Toshio
Published: July 2006

The liquid-phase oxidation of cyclohexene has been conducted in benzene using a vanadium–chromium binary oxide supported on γ-Al2O3 or SiO2 as the catalyst. Three series of catalysts have been prepared by a kneading method using the following combinations of raw materials; NH4VO3+Cr(NO3)3·9H2O+alumina hydrate (Catalyst G), NH4VO3+(NH4)2CrO4+alumina hydrate (H), and NH4VO3+Cr(NO3)3·9H2O+silica sol (I). It has been found that the activity of the supported binary system is due to the interactions between the metal oxides and the carrier. The contributions of compounds such as the chromium isopolyvanadates appear to add to the above activity. The order of catalytic activity has been established as : I>H>G. The V2O5–SiO2 system in the I series showed the highest activity, but rapidly became depleted in the course of reaction. The second highest activity was given by Cr2O3–SiO2 system, on which Cr5+ species was observed. In both cases, the vanadium and chromium metal ions may be coordinated tetrahedrally on SiO2. The Cr2O3–Al2O3 in the H series contained Cr5+ ions and exhibited high activity which may be attributed to the tetrahedral configuration. It is thought that the tetrahedral complexes catalyze the autoxidation of cyclohexene by decomposing 1-cyclohexenyl hydroperoxide.
High-resolutional Calorimetric Study on Solid Solutions SnCl2(H2O)x(D2O)2−x
Authors: Tatsumi Masami , Matsuo Takasuke , Suga Hiroshi , Seki Syûzô
Published: July 2006

Heat capacities of the system of solid solutions SnCl2(H2O)x(D2O)2−x (x=2.00, 1.97, 1.75, 0.96, 0.50, 0.25, and 0.03) were measured by an adiabatic calorimeter capable of determinations of heat capacity with the temperature step of 5–10 mK. The heat capacity peak due to order-disorder change of hydrogens becomes broader and its transition temperature rises as the deuteron concentration is increased. A small first-order component was found in the crystals of x=2.00, 1.97, and 1.75. Measurements were repeated for aged crystals of x=0.96, 0.50, and 0.03. Nature of the phase transition has been discussed in analogy with the liquid-vapor critical point. From the heat capacity data around the glass transition it is concluded that the motion of the hydrogen atoms is strongly correlated with each other over a range whose size is large enough that fluctuation of the local isotopic composition from the average is negligible.
The Mechanism of the Spin-Spin Coupling of Dimethyllead(IV) Complexes with ONNO Quadridentate Schiff Base Ligands and the Magnetically Non-equivalent Methyl Protons of a Dimethyllead(IV) Complex
Authors: Majima Tetsuro , Kawasaki Yoshikane
Published: July 2006

Several dimethyllead(IV) complexes with ONNO quadridentate Schiff base ligands have been prepared. The spin-spin couplings between the lead nucleus and the azomethine proton of the ligands, 3J(207Pb–N=CH), as well as the lead-methyl proton couplings, 2J(207Pb–CH3), have been observed in various solvents. Both J values inclease with an increase in donor strength of the solvents. The mean excitation energy, the ΔE term in the Fermi contact term plays a dominating role for the lead-proton spin-spin coupling constants. Two methyl proton signals were, for the first time, found to be magnetically non-equivalent in the dimethyllead(IV) complex of sapr.
The Crystal and Molecular Structure of (Carboxymethyl)(pyridine)-(triphenylphosphine)palladium(II) Dichloromethane Solvate,[Pd(C2H2O2)(PPh3)(py)]·0.6 CH2Cl2
Authors: Kai Yasushi , Yasuoka Noritake , Kasai Nobutami
Published: July 2006

The molecular structure of carboxymethylpalladium(triphenylphosphine)pyridine has been determined by X-ray crystal structure analysis of its dichloromethane solvate, [Pd(C2H2O2)(PPh3)(py)]·0.6 CH2Cl2. The crystal belongs to the monoclinic system, space group P21/c, with four formula units in a cell with dimensions of a=8.791(4), b=14.623(7), c=19.862(5) Å, and β=101.53(4)°. R=0.091 for 2806 non-zero reflections. The feature of the structure is that the palladium atom is C,O-chelated by an acetic acid to form a four-membered ring [Pd–C=2.004 (16) and Pd–O=2.093 (11) Å], and the palladium atom has approximately square-planar geometry.
Circular Dichroism Spectra of Cobalt(III) Complexes of the Type, trans-[CoX2(1,3-Diamine)2]n+ (X=Cl−, CN−, or NH3)
Authors: Kashiwabara Kazuo , Kojima Masaaki , Fujita Junnosuke
Published: July 2006

Four new complexes of the type, trans-[Co(CN)2(1,3-diamine)2]+ were prepared, where 1,3-diamine is (S,S)-1,3-diphenyl-1,3-propanediamine, (R,R)-2,4-pentanediamine, (S)-1,3-butanediamine, or (S)-1-phenyl-1,3-propanediamine. Two diammine complexes of the same type with (S)-1,3-butanediamine and (S)-1-phenyl-1,3-propanediamine, and trans-[Co(CN)2((R,R)-1,2-diphenyl-1,2-ethanediamine)2]+ were also newly prepared. The circular dichroism (CD) spectra of the new complexes measured in several solvents were compared with those of the corresponding dichloro and diammine complexes. The CD spectra of the dicyano complexes of (S)-1,3-butanediamine and (S)-1-phenyl-1,3-propanediamine showed remarkable solvent dependence, while those of the other complexes small or little dependence.
Syntheses of N-Acyl Dipeptide Derivatives by Metalloproteinases
Authors: Isowa Yoshikazu , Ichikawa Tetsuya
Published: July 2006

X–Dipeptides (X=Z, Z(OMe), or Z(3Me)) have been catalytically synthesized by several microbial metalloproteinases. Among the enzymes used, Thermolysin showed the most remarkable ability in the coupling reactions of the esters or the amides of phenylalanine, leucine, isoleucine, and valine (and methionine in the case of the amide) with various X–amino acids. This method has been applied to the syntheses of ZPhePheOMe and ZPhePeOMe on a practical scale. Ammonium sulfate and sodium chloride had a marked effect on the condensed products, increasing the yield.
The Reaction of Group V Metal Alkoxides with Sulfur Dioxide and Selenium Dioxide
Authors: Ando Fumio , Koketsu Jugo , Ishii Yoshio
Published: July 2006

Trialkoxyarsines (I) and -stibines (II) react with sulfur dioxide to give the corresponding dialkyl sulfites and arsenic trioxide or polymeric residues containing antimony. The reactivity of the compounds (I) is very low, and the yield is poor. Reactions of I and II with selenium dioxide afford dialkyl selenites together with arsenic trioxide or the same polymeric residues containing antimony as in the case of the reaction with sulfur dioxide. The reaction followed a stoichiometry of three moles of trialkyl phosphites (III) and one mole of selenium dioxide yields a 2 : 1 molar ratio of the phosphates : the phosphoroselenoates. A similar reaction of the phosphites with selenium dioxide in a 2 : 1 stoichiometry gives the phosphates and red selenium quantitatively. The rate of oxidation of the phosphorus compounds by selenium dioxide decreases in the order Bu3P>BuP(OEt)2>P(OEt)3. Based on these results, the possible mechanisms have been discussed.
Synthesis of Decachloro-4-allylidenecyclopentene and Its Chemistry
Authors: Kusuda Kousuke , Roedig Alfred
Published: July 2006

Decachloro-4-allylidenecyclopentene (6) was synthesized by the reaction of pentachlorocyclopentadiene with hexachloropropene in the presence of anhydrous aluminium chloride. Hexachloro-2-allylidene-4-cyclopentene-1,3-dione (11), prepared from 6 by treatment with coned nitric acid, cyclized to hexachloro-2,5-dihydrocyclopenta[b]pyran-5-one (14) on heating. In a solvent such as acetone and acetonitrile, 4 rearranged to hexachloro-2,5-dihydrocyclopenta[b]pyran-2-one (18) at room temperature. The mechanism of this rearrangement is discussed. Hydrolysis of 14 by 90% sulfuric acid afforded tetrachloro-2,5-dihydrocyclopenta[b]pyran-2,5-dione (15), which was obtained directly from 6 by treatment with sulfuric acid. The reactions of 11 with anhydrous methanol, and of 15 with diazomethane were investigated.
S
N2 Reactions in Dipolar Aprotic Solvents. VII. Kinetic and Equilibrium Secondary α-Deuterium Isotope Effects in Chlorine Isotopic Exchange Reactions of Substituted Chloromethanes in Acetonitrile
Authors: Hayami Jun-ichi , Hihara Nobuhisa , Tanaka Nobuo , Kaji Aritsune
Published: July 2006

Secondary α-deuterium isotope effects were studied in the symmetrical nucleophilic substitution of the substituted chloromethanes in acetonitrile. The apparent second order rate coefficients show a significant isotope effect for chloromethyl aryl ethers and sulfides (1.11–1.14 per D), and an intermediate value of 1.05 for cinnamyl chlorides. 2-Arylethyl chlorides were shown to give an appreciable isotope effect of 1.03–1.04, and arylchloromethanes to give varying amount of the isotope effect from 1.006 to 1.050 depending upon the ring substituent. The deuterium label also gave rise to a significant equilibrium isotope effect on the substrate-nucleophile association in the reaction mixture. The observation of an equilibrium isotope effect suggested a possibility that an apparent isotope effect was a composite of the thermodynamic and the kinetic isotope effects. Thus the dissection resulted in a uniform and a fairly large kinetic isotope effect for all the activated substrates studied and in a small kinetic isotope effect for 2-arylethyl chloride. The results are explained in a framework of loose–tight transition state.
Photo-induced Transformation of Polyalkylbenzyl Thiocyanates into Polyalkylbenzyl Isothiocyanates. A Synthesis of Some Bis- and Tris(isothiocyanatomethyl)polymethylbenzenes by Multiple Thiocyanate Isomerization
Authors: Suzuki Hitomi , Usuki Michiyo , Hanafusa Terukiyo
Published: July 2006

Polyalkylbenzyl thiocyanates, upon irradiation in acetic acid, readily undergo reversible photoisomerization, giving an equilibrium mixture composed mostly of the corresponding isothiocyanates. Several new bis- and tris(isothiocyanatomethyl)polymethylbenzenes have been prepared by utilizing the photoinduced multiple thiocyanate isomerization.
Syntheses of Polymerizable Acetals. II. Readily Hydrolyzable Acetals from Citronellol and Vitamins
Authors: Kamogawa Hiroyoshi , Haramoto Yuichiro , Nanasawa Masato
Published: July 2006

Three perfume acetals and four vitamin acetals have been synthesized by the acid-catalyzed reactions of vinylbenzyloxy- and methoxy-substituted benzaldehydes with citronellol and the reactions of vinylbenzaldehyde with vitamins B6, C, B1 and B2, respectively. The acid hydrolyses of these novel acetals readily released citronellol and vitamins under mild conditions, some accelerations of the hydrolysis rate by the electron-donating para substituents being observed in the case of the perfume acetals.
Preparation of Diphenyl(tricyclohexylphosphine)manganese(II) and Its Reactions with Carbon Dioxide and Organic Carbonyl Compounds
Authors: Maruyama Kazunori , Ito Takashi , Yamamoto Akio
Published: July 2006

Treatment of Mn(acac)3 (acac=acetylacetonato ligand) with AlPh3·Et2O in the presence of PCy3 (Cy=cyclo-C6H11) gave a new diphenylmanganese(II) complex, Ph2MnPCy3 (1). Complex 1 reacted with allylic compounds, CH2=CHCH2X (X=Br, OPh, OCH2CH=CH2, and OCOCH3), to give allylbenzene. Carbon dioxide was found to be inserted into the phenyl-manganese σ-bond of 1 to give bis(benzoato)manganese complex, (PhCOO)2MnPCy3, 2, which on successive treatment with HCl and diazomethane produced methyl benzoate. Complex 1 reacted with aldehydes, ketones, and esters having no active α-hydrogen atom to give alkoxomanganese species in solution, indicating that the insertion of C=O double bond into the phenyl-manganese σ-bond occurred. On the other hand, acetone and acetophenone reacted with Ph2MnPCy3 to give benzene and 2-oxoalkyl complexes, (RCOCH2)2Mn(PCy3)m (R=Me, Ph), 3. Reaction of alcohols with 1 afforded alkoxomanganese compounds which catalyze the Tishchenko type and Meerwein-Pondorf type reactions as well as transesterification reactions at room temperature.
Functionalization of trans-Decalin. II. A Synthesis of dl-Isopetasol from trans-5-Oxodecalin-8a,2-carbolactone
Authors: Torii Sigeru , Inokuchi Tsutomu , Kawai Kiyoto
Published: July 2006

A stereocontrollcd synthesis of dl-isopetasol (1a) from trans-5-oxodecalin-8a,2-carbolactone (2a) is described. The key intermediate, trans-5,5-ethylenedioxy-1β,8aβ-dimethyldecalin-2-one (7b) was prepared by reductive methylation of trans-5,5-ethylenedioxydecahydrocyclopropa[d]naphthalen-2-one (5) for introducing the vicinal two methyl groups at C-1 and C-8a carbon atoms. The cyclopropyl ketone 5 was obtained by reduction of the acetal of 2a followed by (1) tosylation of the primary alcohol, (2) oxidation of the secondary alcohol with Corey’s NCS–DMS reagent, and (3) cyclization with t-BuOK. Reduction of 5 with lithium in liquid ammonia provides initially the corresponding enolate anion, which can be trapped with methyl iodide to give trans-5,5-ethylenedioxy-1α,8aβ-dimethyldecalin-2-one (7a), smoothly. Epimerization of 7a with MeONa in MeOH gave the desired intermediate 7b. Reduction of 7b with lithium in liquid ammonia gives the 2α-alcohol 8b, stereoselectively. The conversion of 8b into 1a was carried out as follows: (1) deacetalization of 8b followed with acetylation, giving trans-6α-acetoxy-4aβ,5β-dimethyldecalin-1-one (9b); (2) reduction of 9b with NaBH4 and subsequent dehydration affording the olefinic acetate 11; (3) oxidation of 11 with CrO3–pyridine complex, giving the enone 12; (4) aldol condensation of 12 with acetone followed by dehydration, isomerization of double bond, and hydrolysis, providing the desired 1a.
Stereochemistry of Elimination Reactions of Halohydrin Derivatives and Related Compounds with Butyllithium
Authors: Sugita Toshio , Nakagawa Junichi , Nishimoto Kazuhito , Kasai Yasuhiro , Ichikawa Katsuhiko
Published: July 2006

The erythro and threo isomers of 1-bromo-2-methoxy-1,2-diphenylethane (1), 1-bromo-2-acetoxy-1,2-diphenylethane (2), 1-bromo-2-methylsulfonyloxy-1,2-diphenylethane (3), 1-bromo-2-methylthio-1,2-diphenylethane (4), stilbene dibromide (6), and stilbene dichloride have been prepared. These compounds were allowed to react with butyllithium in various solvents to give cis- and trans-stilbenes. Depending on the solvent, the stereochemistry of the elimination of 1 changed from a complete syn-type (in nonpolar solvents) to a less-selective type. The same tendency was observed in the cases of 2 and 3. In contrast, anti-elimination was favored for 4 and 6, and a different type of solvent effect was observed. Elimination reactions with lithium metal and pentylmagnesium bromide were also carried out. Possible mechanisms for eliminations are discussed.
Molecular Dynamics in Lyotropic Mesophases Studied by 23Na NMR and ESR
Authors: Kanazawa Yoko , Kamei Hirotake
Published: July 2006

The hexagonal phases of sodium octadecanoate–water system NaS and sodium hexadecanoate–sodium tetradecanoate–water system Na(P+M) were studied by sodium-23 NMR and spin label ESR in the temperature range 40–100 °C, covering the transition temperature of isotropic-liquid crystal TI-L and that of liquid crystal-gel TL-G. The ESR spectrum of liquid crystal systems aligned by the magnetic field and the center line of 23Na NMR spectrum were analyzed. The motions of the alkyl chain and sodium ion are reflected on the ESR and NMR spectral shape and width. The NMR line width is predominantly determined by the local motion of the cation attached on the hydrocarbon rod. During the phase separation region its correlation time τc\simeq10−10 s is constant, comparable to that of chain motion. The change in the local motions of these two species is similar, being continuous across TI-L but drastic across TL-G.
Electrochemical Behavior of the Oxygen Radical. IV. The Reaction Mechanism of the Electrogenerated Hyperoxide Ion with Bis(acetylacetonato)cobalt(II) in Dimethyl Sulfoxide and Acetone
Authors: Kudo Setsuko , Iwase Akio
Published: July 2006

The reaction mechanism of the electrogenerated hyperoxide ion with bis(acetylacetonato)cobalt(II) in dimethyl sulfoxide and acetone has been investigated. The reaction was conducted in a 0.05 mol dm−3 TBAP solution at 20 °C in an open system. Co(acac)2 reacted with the hyperoxide ion which was generated by the controlled potential electrolysis of dissolved oxygen to afford the following product, [(acac)2 Co–O2–Co(acac)2]2−. The complex was separated in solution by column chromatography using alumina as the adsorbent. The electronic spectrum and oxidation state are discussed.
Gas-Chromatographic Studies of the Thermal Decomposition of Nitropentaammine-, Dinitrotetraammine-, Trinitrotriammine-, Tetranitrodiammine-, and Pentanitroamminecobalt(III) Complexes in the Solid State
Authors: Onodera Sukeo
Published: July 2006

The gas-chromatographic study of the thermal decompositions of the complexes, [Co(NO2)(NH3)5]Cl2 (I), cis- (II) and trans-[Co(NO2)2(NH3)4]Cl (III), [Co(NO2)3(NH3)3] (IV), K[Co(NO2)4(NH3)2] (V), and K2[Co(NO2)5NH3] (VI) are reported. The EGA curves for these complexes show that the compounds decompose in two or three stages. In the first stage (ca. 140–240 °C), all complexes evolve nitrogen with the evolution of ammonia and/or nitrogen monoxide. The second stage (ca. 210–300 °C) has been ascribed to the evolution of ammonia from the intermediate dissociation products of compound I, II, and III. The third stage (ca. 275–350 °C) has been ascribed to the evolution of nitrogen monoxide from the solid residue with the exception of IV.
The X-Ray Structure of Bis((S,S)-2,4-pentanediamine)platinum(II) Ion, [Pt(SS-ptn)2]2+
Authors: Nakayama Yasuji , Ooi Shun’ichiro , Kuroya Hisao
Published: July 2006

The bis((S,S)-2,4-pentanediamine)platinum(II) chloride monohydrate crystallizes in the space group P212121 with four formula units in a unit cell of dimensions a=12.089(3), b=13.547(3), c=10.697(2) Å. The crystal structure has been determined from diffractometer data and refined to R=0.052 for 1903 independent reflections. The Pt atom has a square planar coordination by four N atoms, the average value of the Pt-N distance being 2.05 Å. The complex has a pseudo two-fold axis which is perpendicular to the coordination plane defined by the four N atoms. The 6-membered chelate ring is of a chair conformation and one methyl group is axial with respect to the chelate ring, while the other is equatorial. From a comparison of the circular dichroism spectra of the diammine-(S,S)-2,4-pentanediamineplatinum(II) and the bis((S,S)-2,4-pentanediamine)platinum(II) ions, the effect of the (S,S)-2,4-pentanediamine on the rotatory strength of the Pt(II) complex has been found to be not additive.
Fluorescence from Bound Ionic States of Neat Molecular Crystals: p-Substituted N,N-Dimethylanilines
Authors: Araya Kotaro , Aihara Jun-ichi
Published: July 2006

Fluorescences were detected from bound ionic states (i.e., charge-transfer exciton states) of two neat molecular crystals, each formed by a single molecular component. These fluorescent compounds are p-(2,2-dicyanovinyl)-N,N-dimethylaniline and p-(2-nitrovinyl)-N,N-dimethylaniline. They are dimorphic in the solid state.
Mechanism of the Ferroelectric Phase Transition in K4[Fe(CN)6]·3H2O and K4[Fe(CN)6]·3D2O
Authors: Oguni Masaharu , Matsuo Takasuke , Suga Hiroshi , Seki Syûzô
Published: July 2006

Mechanism of the ferroelectric phase transition in potassium hexacyanoferrate trihydrate is discussed from static and dynamic points of view, and a new model is proposed. The model takes into account four states as accessible for a water trimer, instead of two in the earlier model. If the four states were equally probable in the disordered phase, the predicted transition entropy is R In 4 compatible with the experimental value. It is expected that a glass transition, if possible, occurs at 50–60 K for the model. Since the anomalous heat capacity in this temperature region is effectively zero, the model is consistent with absence of a glass transition. Occupancy fractions of hydrogen sites are given for the earlier and the present models.
Super High Sensitivity of CuSe–Ag2S Solid Membrane Copper(II) Ion Selective Electrode in Several Metal Buffer Solutions
Authors: Umezawa Yoshio , Imanishi Yuichiro , Sawatari Katsuhiko , Fujiwara Shizuo
Published: July 2006

A CuSe–Ag2S solid membrane Cu(II) ion electrode in certain metal buffer solutions gave detection limit of free Cu(II) ion as low as 10−18M.
Reaction of Optically Active 1-Dimethylaminoethylferrocene Palladium Complexes
Authors: Kasahara Akira , Izumi Taeko , Watabe Hiroyuki
Published: July 2006

ortho-Palladation products of optically active 1-dimethylaminoethylferrocene were treated with phenyl vinyl ketone and carbon monoxide and a variety of optically active 1,2-disubstituted ferrocene derivatives were obtained.
Nature of Bonding in Pyrazine-2,3-dicarboxamide Complexes of Copper(II), Cobalt(II), and Nickel(II)
Authors: Sanyal G S , Mondal S K
Published: July 2006

Pyrazine-2,3-dicarboxamide complexes with the perchlorates of copper(II), cobalt(II), and nickel(II) have been prepared and characterised, copper having a square planar configuration and cobalt and nickel an octahedral geometry. Bonding takes place through a ring nitrogen and the oxygen atom of the adjacent amide group.