bluuebunny/crossref_metadata_2025 huggingface dataset:
Colloidal Dispersions of Platinum and Palladium Clusters Embedded in the Micelles.Preparation and Application to the Catalysis for Hydrogenation of Olefins
Authors: Toshima Naoki , Takahashi Tadahito
Published: July 2006

Colloidal dispersions of platinum and palladium clusters were prepared by the reduction of the corresponding metal salts in the presence of various surfactants. Hydrogen- and photo-reduction methods were examined for the micellar solution of hexachloroplatinic acid. The photo-reduction was proved to be more suitable than the hydrogen-reduction from the viewpoint of small size and good dispersion in the colloidal clusters. The higher surfactant concentration than the critical micelle concentration (cmc) is favorable for the production of the homogeneous colloidal dispersions. The photo-reduction method is also available for the case of palladium. The colloidal platinum and palladium clusters, thus obtained, act as highly active catalysts for the hydrogenation of olefin in an aqueous solution. The colloidal clusters prepared by the photo-reduction method showed higher activity than those prepared by other methods. The roles of the surfactant micelle for the hydrogenation are not only protecting hydrophobic colloidal particles, but also both solubilizing the hydrophobic substrates in an aqueous solution and assisting their approach toward the active site on the surface of the cluster particles. In the hydrogenation of unsaturated fatty acids, the surfactant micelle surrounding the clusters can control the orientation of the substrates, resulting in novel regioselective hydrogenation.
A Simple Method for the Evaluation of Enthalpy of Proton Dissociation in Water
Authors: Tanaka Motoharu , Nomura Hiroyasu , Kawaizumi Fumio
Published: July 2006

A method is proposed for evaluating the ΔH° value for the proton dissociation of an acid HB from the temperature dependence of the dissociation constant Ka: Instead of differentiating the pKa (= −log Ka) value of acid HB with respect to temperature, we select an appropriate acid HA as a reference and plot the quantity X = pKa(HB)−pKa(HA) as a function of reciprocal temperature. The plot was found to be linear with sufficient accuracy for most non-charged or negatively charged acids, for which pKa itself is a complex function of temperature. ΔH° values are thus readily evaluated by linear least-squares fitting. The theoretical background is discussed.
Growth Conditions of Ta3B4 Single Crystals Prepared by the Aluminium-Flux Method
Authors: Okada Shigeru , Lundström Torsten
Published: July 2006

Tantalum boride crystals have been prepared from high temperature aluminium solution using tantalum and boron powders as starting materials in an argon atmosphere. The growth conditions for obtaining relatively large crystals of Ta3B4 in a pure form containing no extra phases were established. The optimum growth conditions for growing Ta3B4 single crystals are the following: Atomic ratios of starting materials B/Ta = 1.33 and Al/Ta = 16.77, soaking temperature 1650 °C, soaking time 5 h and cooling rate 25 °C h−1. The single crystals of Ta3B4 display a grey color, metallic cluster, and a trapezoidal shape. The largest crystals prepared have dimensions of about 0.37 mm × 0.37 mm × 0.40 mm. The crystals are orthorhombic with space group Immm and unit cell dimensions a = 3.2914(8), b = 13.994(3), c = 3.1327(6) Å, and V = 144.29(8) Å3. The X-ray density is 13.490(3) g cm−3.
Thermally Irreversible Photochromic Systems. Substituent Effect on the Absorption Wavelength of 11,12-Dicyano-5a,5b-dihydro-5a,5b-dimethylbenzo[1,2-b:6,5-b′]bis[1]benzothiophene
Authors: Uchida Kingo , Nakamura Shinichiro , Irie Masahiro
Published: July 2006

Cyano- and halogen-substituted 1,2-bis(1-benzothiophen-3-yl)ethene derivatives were synthesized in an attempt to obtain compounds with sensitivity at longer wavelengths. Under UV irradiation, the derivatives underwent ring closure reactions to form the substituted 11,12-dicyano-5a,5b-dihydro-5a,5b-dimethylbenzo[1,2b:6,5-b′]bis[1]benzothiophenes. Among cyano-substituted compounds, the 3,8-dicyano derivative showed an absorption maximum at the longest wavelength, 530 nm, which is 23 nm longer than the maximum of the unsubstituted compound. The absorption maximum of the 3,8-difluoro derivative, on the other hand, was 28 nm shorter than the maximum of the 2,9-difluoro derivative. Although the absorption maximum shift of the calculated values (MO INDO/S) by cyano substitution agreed well with the observed maxima, the calculation hardly reproduced the shift by halogen substitution.
Solvent Effects on the Solvolysis of Neophyl Tosylates
Authors: Fujio Mizue , Goto Mutsuo , Funatsu Kimito , Yoshino Takanori , Saeki Yoshihiro , Yatsugi Ken-ichi , Tsuno Yuho
Published: July 2006

Solvolysis rates of 2-phenyl-2-methylpropyl and 2-(p-methoxyphenyl)-2-methylpropyl p-toluenesulfonates were determined in a wide variety of solvents and the solvent effects were analyzed based on the Winstein–Grunwald equation. The solvent effect on neophyl solvolyses failed to give a single linear correlation with the 2-adamantyl YOTs parameter. There was dispersion behavior for the respective binary solvent series between neophyl kΔ substrates and 2-adamantyl tosylate. The pattern of dispersion could not be interpreted in terms of nucleophilic solvent assistance. The response to the solvent polarity (m value for each binary solvent series) was significantly lower for both the methoxy and the unsubstituted derivatives than the m = 1.0 for the limiting kc solvolysis, and appreciably lower for the methoxy derivative than for the unsubstituted one. Linearity of the solvent effects between both neophyl systems and also between other kΔ substrates implied the existence of a unique kinetic solvent polarity scale YΔ characteristic of the β-aryl-assisted (kΔ) solvolysis. The dispersion behavior and reduced m value for the kΔ solvolysis were compatible with the entire π-delocalization of cationic charge between the assisting aryl-ring and the reaction center in the transition state.
Complex Fluoroberyllates. Synthesis and Physicochemical Characterization of Mixed-Fluoro Complexes of Beryllium Containing Hydrogenoxalate (HC2O4−), Glycinate, and Dihydrogenphosphate (H2PO4−) as Co-Ligands
Authors: Chaudhuri Mihir K , Islam Nashreen S , Tarafder Pranab K
Published: July 2006

Synthesis of novel mixed complex fluoroberyllates of the types M2[BeF3(HC2O4)]·H2O (M = NH4 or Na), K2[BeF3(HC2O4)], M2[BeF3(NH2CH2COO)]·H2O (M = NH4 or Na), and M2[BeF2(H2PO4)2] (M = NH4 or K) has been achieved from the reaction of Be(OH)2 with MF and the corresponding co-ligands viz., oxalic acid, glycine, and orthophosphoric acid, at pH ca. 2. Vibrational spectroscopic evidences have been provided in respect of co-ordinated F− and the ligands HC2O4−, NH2CH2COO−, or H2PO4−. IR spectra of ammonium salt of the complexes demonstrate the presence of hydrogen bonding.
Substituent Effect on the Enantioface-Differentiating Reaction of (R)-[Lithiomethyl p-Tolyl Sulfoxide] with m- or p-Substituted Acetophenones
Authors: Kunieda Norio , Nokami Junzo , Kinoshita Masayoshi
Published: July 2006

When lithiomethyl p-tolyl sulfoxide derived from (R)-(+)-[methyl p-tolyl sulfoxide] was allowed to react with acetophenones which have a variety of m- or p-substituents, the corresponding diastereometic mixture of β-hydroxy sulfoxides (RsSc and RsRc) was produced. The degree of enantioselectivity was affected by the nature of the substituent on benzene ring. The logarithms of the RsSc/RsRc values thus obtained gave a good correlation with Hammett’s σ values, affording a negative straight line. The results have been discussed in view of the stereochemical cource of the reaction.
Synthesis of 3-(Alditol-1-yl)triazolo[4′,3′:2,3]-1,2,4-triazino[5,6-b]indoles
Authors: Mousaad Ahmed , Abdel Hamid Hamida , El Nemr Ahmed , H. El Ashry El Sayed
Published: July 2006

A series of the hydrazones were prepared by the reaction of 3-hydrazino-5H-1,2,4-triazino[5,6-b]indole (1) with monosaccharides, and their acetylation was studied. Cyclodehydrogenation of the hydrazones gave 3-(substituted)-10H-1,2,4-triazolo[4′,3′:2,3][1,2,4]triazino[5,6-b]indole, whose acetylation and partial acetylation were carried out. The ring-chain tautomerism of the hydrazones promoted their heterocyclization. The linear structure, and not that of the angular isomer, has been selected for the products. This structure has been confirmed from a model study of the cyclization of the acetaldehyde derivative of 1, which was found to be identical with that product obtained from the reaction of 4,5-diamino-3-methyl-1,2,4-triazole with isatin. Periodate oxidation of the hydrazones and their cyclized products was also studied.
Molecular Interactions between Triazene 1-Oxides and Tetracyanoethylene
Authors: Nour El-Din Ahmed Moukhtar , Hassan Alaa A , Mohamed Shaaban K , Abd Elatif Fathy F , El-Faham Hassan A
Published: July 2006

1,3-Diaryltriazene 1-oxides formed stable (1 : 1) charge-transfer complexes with tetracyanoethylene in different solvents, which were studied spectrophotometrically. The stability constants of the complexes were affected by substituents and solvent polarities. Likewise the thermodynamic properties ΔG, ΔH, and ΔS depend on the solvent polarities.
Efficient Preparation of a Valuable Intermediate in the Synthesis of (−)-Swainsonine
Authors: Bermejo Gonzalez Francisco , Lopez Barba Ana , Ruano Espina Myriam
Published: July 2006

The preparation of the octahydropyrano[3,2-b]pyridine-6,7,8-triol derivative 22, a highly valuable intermediate in the synthesis of (−)-swainsonine, has been achieved by application of a fifteen-step sequence starting from d-mannose with 20% overall yield.
Stereochemical Outcome of Aldol Reaction of a 6-C-Substituted d-Mannose Derivative
Authors: Bermejo Gonzalez Francisco , Ruano Espina Myriam
Published: July 2006

The base-promoted cyclization of the diketose 3 has been studied. The structural assignments of the aldol products 4a, 4b, and 4c were based on the spectroscopic analysis and the chiroptical properties.
Synthesis of a Series of Acodazole and Naphthothiophene-Deuterioporphyrins and Metalloporphyrins
Authors: Sondhi Sham M , Magan Archana , Lown J William
Published: July 2006

The design and synthesis of several hybrid intercalator-linked porphyrins and their corresponding metalloporphyrin derivatives designed as cellular DNA targetted anticancer agents is described. 9-Chloro-7-methylimidazo[4,5-f]quinoline was condensed with ethylenediamine, 1,4-phenylenediamine and 2,5-toluenediamine to give compounds Ia–c. Naphtho[2,1-b]thiophene-4-carboxylic acid was condensed with 1,6-hexanediamine, 1,10-decanediamine, and 1,12-dodecanediamine to give compounds IIa–c and IIIa–c. Compounds Ia–c and IIa-c were condensed with deuterioporphyrin monomethyl ester and deuterioporphyrin to yield compounds IVa–j. Compounds IVa–h were refluxed with MnCl2 or CoCl2 in DMF to give metalloporphyrins Va–j. Compounds Ia–c, IIa–c, IIIa–c, IVa–j, and Va–j were characterized by IR, NMR, and MS (FAB) spectral data. Kassoc value for intercalative binding of these porphyrin derivatives to calf thymus DNA is in the range 1.9−3.0 × 106 L M−1.
Photoinduced Electron Transfer between Zinc Protoporphyrin Reconstituted Myoglobin and Methylviologen
Authors: Aono Shigetoshi , Nemoto Shuzo , Okura Ichiro
Published: July 2006

Photoinduced electron transfer proceeded between zinc protoporphyrin reconstituted myoglobin and methylviologen. The reduced methylviologen formed by electron-transfer quenching was observed by means of laser flash photolysis. The quenching rate constants were affected by the change in the surface charges of myoglobin.
Electrochemical Studies of Poly(mercaptohydroquinone) and Poly(mercapto-p-benzoquinone) Films Prepared by Electrochemical Polymerization. VI.Electroreduction of l-Cystine on Thiolates Fixed in the Polymer Film
Authors: Arai Gorou , Sugaya Toshiaki , Sakamoto Mika , Yasumori Iwao
Published: July 2006

Electrocatalytic reduction of l-cystine (CySSCy) was examined on glassy carbon electrodes coated with the title conductive polymer in which Pt, Pd, Cu, Ag, and Hg thiolates were fixed. Pt and/or Pd thiolate fixed in the polymer behaved as excellent electrocatalytic active sites for reductive cleavage of the sulfur–sulfur bond in CySSCy.
Effects of Redox Reagents on ESR Line Shape of Synthetic Melanins
Authors: Oniki Takayuki , Takahama Umeo
Published: July 2006

Melanins were synthesized from pyrogallol or β-(3,4-dihydroxyphenyl)alanine (dopa) and their electron spin resonance (ESR) spectra were measured. The pyrogallol melanin had four kinds of ESR signal; main and broad signals under anaerobic conditions, and inner and outer signals under aerobic conditions. The main, inner and outer signals disappeared by the reduction of the melanin by NaBH4 or ascorbic acid but the broad signal did not. By the oxidation of the melanin by hexacyanoferrate(III), the intensity of the signals decreased, and the inner and outer signals were not observed under aerobic conditions. Hydrogen peroxide decreased these signals especially under aerobic conditions at high pH. Superoxide gave the signals similar to that under aerobic conditions, but decreased the signals of the hexacyanoferrate(III)-oxidized melanin. ESR signals of dopa melanin showed similar behavior to that of pyrogallol melanin against redox reagents. The chemical structure around radicals in melanins were proposed from these results.
Single-Excitation Configuration Interaction Calculations of Hyperfine Coupling Constants of Small π and σ Radicals
Authors: Nakano Tatsuya , Morihashi Kenji , Kikuchi Osamu
Published: July 2006

Ab initio ROHF SCI calculations with Chipman’s [5s2p/3†s] and [5s2p1d/3†s1p] basis sets, in which all singly-excited configurations are included, give hyperfine coupling constants of α-protons which are in satisfactory agreement with the experiment values.
Crystal and Molecular Structure of the Asymmetric Cobaloxime, trans-Bis(2,3-butanedione dioximato(1−)-N,N′)iodopyridinecobalt(III): [Co(Hdmg)2I(py)]
Authors: Megnamisi-Belombe Michel , Nane Nlend Gaspard , Nuber Bernhard
Published: July 2006

The three-dimensional structure of the asymmetric cobaloxime, trans-bis(2,3-butanedione dioximato)iodopyridinecobalt(III), [Co(Hdmg)2I(py)] (Hdmg− = dimethylglyoximate; py = pyridine), has been determined by X-ray diffraction at ambient temperature. The monoclinic structure (P21⁄n) was refined by full matrix least-squares to a final Rw = 0.037 for 3233 observed independent reflections. The structure consists of interesting nautral cobaloxime molecules in which the coordination getmetry around CoIII resembles very closely that observed in cyanocobalamine or vitamin B12.
Choice of Manganese(III) Complexes for the Synthesis of 4,4′-Biphenyldiols and 4,4′-Diphenoquiones
Authors: Nishino Hiroshi , Itoh Nobuyuki , Nagashima Makiko , Kurosawa Kazu
Published: July 2006

2,6-Disubstituted phenols are oxidized with tris(2,4-pentanedionato)manganese(III), [Mn(acac)3], in glacial acetic acid to give the corresponding 4,4′-biphenyldiols in high yields, whereas similar reactions using manganese(III) acetate, [Mn(OAc)3], insted of [Mn(acac)3] quantitatively yield the corresponding 4,4′-diphenoquinones. Cross-coupling reactions of 2,6-di-t-butylphenol and other substituted phenols afford the corresponding cross-coupled 4,4′-biphenyldiols and 4,4′-diphenoquinones together with oxidation products derived from the starting phenols themselves. The advantageous use of [Mn(acac)3] and [Mn(OAc)3] in the ubiqitous phenol coupling reaction is discussed.
Spontaneous Color Development Encountered for Diquaternary Salts of 1,10-Phenanthrolines in Various Media
Authors: Kamogawa Hiroyoshi , Kato Atsushi , Mizuno Junichi
Published: July 2006

Diquaternary salts of 1,10-phenanthroline or, 2,9-dimethyl-1,10-phenenthroline (viologen), prepared according to the Menshutkin rection, developed intense colors spontaneously, presumably due to high reduction potentials. The extent and λmax of the colors developed were dependent upon both the kind of viologen and the media such as solvents and polymer matrices.
Sodium Tellurite as a Mild and Selective Oxidizing Agent for Thiols: Its Use in the One-Pot Synthesis of Unsymmetrical Disulfides
Authors: Suzuki Hitomi , Kawato Sei-ichi , Nasu Akira
Published: July 2006

Sodium tellurite acts as a mild and highly selective oxidizing agent for thiols under phase-transfer conditions at room temperature. Aromatic and benzylic thiols are rapidly converted to disulfides. Short-chain primary thiols undergo oxidation in preference to long-chain thiols. Secondary thiols are sluggish in oxidation and tertiary thiols remain intact. No overoxidation of the sulfur atom is observed. Similar results are also obtained with sodium tellurate.
Photochromism of Hemithioindigo Derivatives. I. Preparation and Photochromic Properties in Organic Solvents
Authors: Yamaguchi Takeo , Seki Takahiro , Tamaki Takashi , Ichimura Kunihiro
Published: July 2006

Thirteen hemithioindigo (HT) derivatives bearing alkyl chains are newly synthesized and their photochromism and emission properties are investigated. The Z/E photoisomerisms of these compounds in organic solvents are essentially in agreement with data reported by Mostoslavskii and Izmail’skii (J. Gen. Chem. USSR, Engl Transl.), 31, 21 (1961), and subsequent papers). At 77 K both the E and Z isomers of HT chromophore emit fluoresscences of comparable intensities, whereas at room temperature very weak fluorescence is observed only from the Z isomer. Examination of repeatable numbers of Z/E photoisomerization reveals that the HT chromophore possesses remarkable inherent photofatigue resistance.
Photochromism of Hemithioindigo Derivatives. II. Photochromic Behaviors in Bilayer Membranes and Related Systems
Authors: Seki Takahiro , Tamaki Takashi , Yamaguchi Takeo , Ichimura Kunihiro
Published: July 2006

Photochromic behaviors of hemithioindigo (HT) derivatives in bilayer membrane matrices and related aqueous system are investigated. HT derivatives were incorporated into bilayer membrane matrices at a molar ratio to bilayer amphiphiles of 0.01. Under these conditions, HT amphiphiles having an ammonio group disperse molecularly in the array bilayer membranes, and show the simple photochromism as in the organic solutions. For a HT derivative having no hydrophilic group, on the other hand, irreversible photobleaching proceeds in addition to the photochromic reaction possibly as a result of cluster formation in the bilayer membranes. E-Form conversion at the photostationary state and the E to Z thermal isomerization rate is largely influenced by the crystal to liquid crystal phase transition of the bilayer matrices.
Allylation of Aldehydes by Allyl- and Crotyltributyltin in the Presence of Catalytic Amounts of Bu2SnCl2 Complex
Authors: Yano Katsunori , Baba Akio , Matsuda Haruo
Published: July 2006

In nearly neutral media, the reaction of allylic tributyltin with aldehydes is effectively catalyzed by Bu2SnCl2 complexes. The addition of coordinative reagents and benzoyl chloride as a quencher is required of the catalytic allylation, furnishing homoallyl benzoates in good to excellent yields, where a regioreversed coupling to conventional methods using crotyltributyltin is exclusively observed.
Reaction of 1,3-Oxathiolium Salts with Three Types of Ring Expansion Reagents on a Nitrogen Atom
Authors: Yonemoto Katsumi , Honda Kazumasa , Shibuya Isao , Taguchi Yoichi , Tsuchiya Tohru , Yasumoto Masahiko
Published: July 2006

The ring expansion reactions of 1,3-oxathiolium salts (1) using NaN3 and an I2–aq NH3 system resulted exclusively in the formation of 1,4,2-oxathiazines (3) by incorporation of a nitrogen atom into the C–O bond in 1. On the other hand, the reaction of 1 with dialkylamino(thioxo)methanesulfenamides, another type of N-expansion reagent, gave di-5-thiazolyl sulfide derivatives (4) in addition to 3. The structure of 4 was confirmed by X-ray crystallographic analysis. It was speculated that the formation of 4 goes via initially-formed 3. Furthermore, 1 reacted with another N-unsubstituted sulfenamides having a heterocyclic substituent such as a 2-pyridyl and 2-benzothiazolyl group to afford 2-pyridyl 5-thiazolyl sulfide and 2-benzothiazolyl 5-thiazolyl sulfide derivatives, respectively, together with 3. The stability and reactivity of oxathiazines 3, which comprise an electron-rich π-system, were also examined.
The Hydroboration of 3-Chloro-1-trimethylsilyl-1-propyne with Dialkylboranes and Its Application to the Syntheses of (E)-3-Trimethylsilyl-2-alkenes and 3-Trimethylsilyl-1-alkenes
Authors: Hoshi Masayuki , Masuda Yuzuru , Arase Akira
Published: July 2006

The reaction of 3-chloro-1-trimethylsilyl-1-propyne with a stoichiometric amount of dialkylborane proceeds to the monohydroboration stage, giving a mixture of regioisomers, (Z)-dialkyl(3-chloro-1-trimethylsilyl-1-propenyl)borane and (Z)-dialkyl[1-chloromethyl-2-(trimethylsilyl)vinyl]borane. The hydroboration mixture is protonolyzed with acetic acid to give (Z)-3-chloro-1-trimethylsilyl-1-propene in a quantitative yield. Treatment of the hydroboration mixture with aqueous sodium hydroxide gives a good yield of highly pure (E)-3-trimethylsilyl-2-alkene whose alkyl group migrates from the boron atom. On the other hand, successive treatment of the hydroboration mixture with methyllithium and acetic acid gives a good yield of 3-trimethylsilyl-1-alkene whose alkyl group migrates from the boron atom. The above procedures provide convenient syntheses of (E)-3-trimethylsilyl-2-alkenes and 3-trimethylsilyl-1-alkenes. It is proposed that both products are afforded through the corresponding allylboranes derived from (Z)-dialkyl(3-chloro-1-trimethylsilyl-1-propenyl)borane, respectively. Thus, the former is formed by hydrolysis of alkyl[1-alkyl-1-(trimethylsilyl)allyl]hydroxyborane, while the latter is formed by protonolysis of alkylmethyl[3-alkyl-3-(trimethylsilyl)allyl]borane.
Dimer Formation of 9-Cyanoanthracene in a Nonpolar Medium at Low Temperatures
Authors: Hoshi Toshihiko , Okubo Jun , Imaizumi Fumitoshi , Ono Isao , Kobayashi Michio , Inoue Hiroyasu
Published: July 2006

The polarized electronic absorption spectrum of 9-cyanoanthracene has been measured in a stretched poly(vinyl alcohol) (PVA) film at 101 K, and the polarizations of the electronic transitions determined. It was found that the longer-molecular-axis polarized bands are at 364.4, 262. 1, and 229 nm, and that the shorter-molecular-axis polarized ones are at 411.2 and 223 nm. The absorption spectra of 9-cyanoanthracene were measured in MP (a 1:1 mixed solvent of methylcyclohexane and isopentane) at room and lower temperatures. It was found that additional bands appear at the lower energy sides of the corresponding monomer bands at lower temperatures. These spectral changes may be interpreted as being due to dimer formation. The dimer may be stabilized mainly through dipole-dipole interactions between the two cyano groups taking on a C2h symmetry. The 412.5, 363.5 and 281.5 nm bands of the dimer are assigned to the calculated S1←S0 (Bu←Ag), S4←S0 (Au←Ag) and S8←S0 (Au←Ag) transitions, respectively; these transitions correspond to the S1←S0 (A1←A1), S2←S0 (B2←A1) and S3←S0 (B2←A1) transitions of the monomer.
Oxidation of Alcohols with Peracetic Acid in Ethyl Acetate in the Presence of Sodium Bromide
Authors: Morimoto Takashi , Hirano Masao , Hamaguchi Takayoshi , Shimoyama Masahide , Zhuang Xiumin
Published: July 2006

Aliphatic primary alcohols and 1,ω-diols were oxidized to the dimeric esters and lactones, respectively, by peracetic acid in ethyl acetate in the presence of sodium bromide under mild conditions. Aliphatic secondary and benzylic alcohols were converted smoothly to the corresponding carbonyl compounds by the same system.
Synthesis and Characterization of Mono-, Bis-, and Trissubstituted Pyridinium and Pyrylium Dyes
Authors: Matsui Masaki , Kawamura Shigeo , Shibata Katsuyoshi , Muramatsu Hiroshige
Published: July 2006

A series of mono-, bis-, and trissubstituted pyridinium and pyrylium dyes have been synthesized by the condensation of methylpyridinium and methylpyrylium salts with aldehydes or nitroso compound. Large bathochromic shifts were observed in the following order, both in substituted azomethine pyridinium and pyrylium dyes, mono < bis < tris. The magnitude of the shift appeared in the order of multiple bonds, –CH=CH– < –CH=CH–CH=CH– < –CH=N–.
Electron-Transfer Reactions from Hydroquinone Dianions to 10-Methylacridinium Ion and a Cobalt(III) Porphyrin
Authors: Fukuzumi Shunichi , Yorisue Tomohiro
Published: July 2006

Electron transfer from various hydroquinone dianions (X-Q2−) to 10-methylacridinium ion (AcrH+) and [Co(tpp)]+ (H2tpp = tetraphenylporphyrin) occurs efficiently in deaerated MeCN to yield 10,10′-dimethyl-9,9′-biacridine [(AcrH)2] and [Co(tpp)], respectively. The electron transfer results in the one-electron or two-electron oxidation of X-Q2−, depending on the one-electron oxidation potentials of X-Q2− and X-Q−.
Effect of γ-Ray Irradiation on the Recoil Tritium Reaction in Xenon–Hydrogen Mixtures at 77 and 4.2 K. Competition of the Tunneling Reaction with the Combination Reaction
Authors: Miyazaki Tetsuo , Fujitani Yoshiteru , Shibata Masao , Fueki Kenji , Masaki Nobuyuki M , Aratono Yasuyuki , Saeki Masakatsu , Tachikawa Enzo
Published: July 2006

Recoil T-atom reactions have been studied in Xe–H2–D2 mixtures at 77 and 4.2 K. When T atom reactions were caused at 77 K by neutron irradiation at an extremely low dose rate of γ-rays, a large isotope effect (kHT/kDT≈7) on the formation of HT and DT was observed. When T-atom reactions were caused at 77 K by neutron irradiation at a high dose rate of γ-rays, there was no isotope effect (kHT/kDT≈1) on the formation of HT and DT. The production of H and D atoms by γ-irradiation of the Xe–H2–D2 mixtures was studied by ESR spectroscopy at 4.2 K. The significant effect of the dose rate of γ-rays on the HT and DT formation was interpreted in terms of competition between a tunneling reaction of thermal T atoms with H2(D2) and a combination reaction of thermal T atoms with H(D) atoms produced by γ-radiolysis.
Crystallization of Silica Gel in Alkaline Solutions. Characterization of SiO2–X2 and Other Crystalline Silicates by Comparing with Kenyaite
Authors: Muraishi Haruto
Published: July 2006

Several hydrated alkali silicates, SiO2–Y, SiO2–X2, and another silicate, form as intermediate products of the transformation of amorphous silica to quartz in alkaline solutions containing sodium and/or potassium salts at a temperature below 170 °C. SiO2–X2 (M2Si20O41·xH2O, M = K, Na, x = 8–10) usually appears after the formation of SiO2–Y (Na2Si14O29·xH2O, x = 9–11), and can also be prepared directly from a solution with the pH adjusted to about 9.5 or from a solution containing potassium ion alone. The resulting SiO2–X2 materials are compounds of hydrated sodium-, potassium- and (sodium, potassium)-form silicates. Another silicate precipitates directly from the solutions with the pH adjusted to below 9.5 by use of sodium carbonate and sodium hydrogencarbonate, and the product is a hydrated sodium silicate, Na2Si22O45·xH2O (x = 7–11). The structure and properties of this silicate are the same as that of natural kenyaite which is supposed to be a precursor of chert forming in evaporative alkaline lakes. These synthesized silicates have a layered structure and the interlayer alkali metal ions are exchanged by protons.
Kinetic Studies of the Incorporation of the Zinc(II) Ion into Water-Soluble N-Phenyl-Substituted Porphyrins. Deformation Effect on the Metallation Rate
Authors: Shimizu Yasuko , Taniguchi Keiko , Inada Yasuhiro , Funahashi Shigenobu , Tsuda Yasuyuki , Ito Yoshio , Inamo Masahiko , Tanaka Motoharu
Published: July 2006

Kinetics of zinc(II) ion incorporation into water-soluble N-phenylporphyrins (N-phenyl-5,10,20-tris(4-sulfonatophenyl)-15-phenylporphine: N-PhTPPS3 and N-phenyl-5,10,15,20-tetrakis(4-sulfonatophenyl)porphine:N-PhTPPS4) have been studied spectrophotometrically. The reaction proceeded through two parallel paths; one involving Zn2+ with a rate constant, k, and the other involving ZnOH+ with a rate constant, kOH. The rate constants (25 °C) and activation parameters at I = 0.10 M (NaNO3) were as follows (1 M = 1 mol dm−3): for N-PhTPPS3  k = (2.8 ± 0.1) × 103 M−1 s−1, kOH = (2.1 ± 0.1) × 106 M−1 s−1, ΔH≠ = 54 ± 3 kJ mol−1, ΔHOH≠ = 26 ± 2 kJ mol−1, ΔS≠ = 1 ± 10 J K−1 mol−1, ΔSOH≠ = −37 ± 8 J K−1 mol−1; for N-PhTPPS4  k = (5.3 ± 0.3) × 103 M−1 s−1, kOH = (2.0 ± 0.2) × 106 M−1 s−1, ΔH≠ = 62 ± 4 kJ mol−1, ΔHOH≠ = 34 ± 8 kJ mol−1, ΔS≠ = 35 ± 14 J K−1 mol−1, ΔSOH≠ = −11 ± 28 J K−1 mol−1. The rate of complexation for N-phenyl-substituted porphyrin was slower than that for the open-chain ligands, but much faster than that for the non-N-substituted homologues. This was due to the steric deformation of the porphyrin ring because of the presence of the bulky phenyl group. The ZnOH+ species was much more reactive in comparison to the Zn2+ species. Such a bound-ligand effect could be partly attributed to the labilization of the coordinated water molecules by electron donation from the bound hydroxide.
Effect of Water Vapor on the Thermal Behavior of Manganese cyclo-Tetraphosphate
Authors: Nariai Hiroyuki , Motooka Itaru , Tsuhako Mitsutomo
Published: July 2006

As a part of an investigation on the effect of water vapor on the thermal behavior of cyclo-phosphates, Mn3H2(P4O12)2·9.5H2O Mn3H2(P4m)2·9.5H2O was examined by means of DTA-TG, X-ray analysis, and HPLC-FIA. Mn3H2(P4m)2·9.5H2O lost the water of crystallization at about 145 °C. In a temperature range 165–265 °C, Mn3H2(P4m)2 anhydride decomposed to form oligophosphates(Poligo). At temperatures below 200 °C, the amounts of Poligo were more abundant under humid conditions than under dry conditions. At 265–450 °C, Poligo changed partially into polyphosphates (Ppoly) and insoluble highpolyphosphates(Phigh poly). The dehydration and condensation reactions proceeded faster under dry conditions than under humid conditions, where gradual water evolution was noted over the temperature range of 265 to 450 °C. The stable crystalline Phigh poly, Mn(PO3)2, was produced at temperatures above 450 °C, where the product was not affected by the water vapor.
Synthesis and Characterization of Vanadium-Substituted Heteropoly Molybdosulfate(VI) Complexes
Authors: Himeno Sadayuki , Osakai Toshiyuki , Saito Atsuyoshi , Hori Toshitaka
Published: July 2006

Monovanadium derivatives of 12-molybdosulfate(VI) and 18-molybdodisulfate(VI), [S(VMo11)O40]3− and [S2(VMo17)O62]5−, have been prepared as tetrabutylammonium (n-Bu4N+) salts from a Mo(VI)–V(V)–H2SO4–CH3CN system. Both mixed molybdosulfate(VI) comlexes were characterized by their IR and UV spectra and their voltammetric behaviors. These mixed complexes are stable in nonaqueous solutions. In a 90% (v/v) CH3CN–0.1 M (M = mol dm−3) HClO4 system, the [S(VMo11)O40]3− anion transforms spontaneously into 12-molybdovanadate(V), whereas the [S2(VMo17)O62]5− anion is stable. In a 90% (v/v) CH3CN–0.5 M HClO4 system, on the other hand, both mixed complexes change into 18-molybdodisulfate(VI), [S2Mo18O62]4−.
Exchange-Storage of a Guest Molecule in an Inclusion Crystal of 2,11,20,29-Tetramethyl-2,11,20,29-tetraaza [3.3.3.3]paracyclophane
Authors: Nonoguchi Hiroshi , Yamamura Kazuo , Tabushi Iwao , Higuchi Tai-ichi , Hirotsu Ken
Published: July 2006

The CHCl3 guest molecules of the 2,11,20,29-Tetramethyl-2,11,20,29-tetraaza[3.3.3.3]paracyclophane (1) inclusion complex were completely replaced by CH2BrCl when [1·CHCl3] powder simply made contact with gaseous CH2BrCl molecules. This guest exchange in the crystalline phase was confirmed by 1H NMR, GLPC, and X-ray analysis. The guest exchange was found to proceed in a biphasic manner, viz., (a) a “slow” exchange approaching a guest composition of 65% CHCl3 / 35% CH2BrCl followed by (b) a “rapid” exchange. The latter abrupt increase of the exchange rate was most reasonably attributed to a change of in crystal structure, based on the X-ray diffraction pattern of a fully guest-exchanged crystal (Type I) which was found to be very similar to that of a Type II crystal of [1·CH2BrCl].
[8+2] Cycloadditions of 2,4,6-Cycloheptatriene-1-imines with Chloroketenes: Facile and High-Yield One-Pot Synthesis of 1-Azaazulen-2(1H)-ones
Authors: Ito Kazuaki , Saito Katsuhiro , Takahashi Kensuke
Published: July 2006

Simple heating of mixtures of N-arylcycloheptatriene-1-imines and acyl chlorides in the presence of an excess amount of triethylamine afforded 1-azaazulen-2(1H)-ones in high yields. The intermediacy of the [8+2] cycloadducts between the 2,4,6-cycloheptatriene-1-imines and ketenes were confirmed by their isolations. Analogous results were obtained with tropone hydrazones.
Studies Concerning the Factors Affecting the Formation of Cyclohexanone Intermediates in the Catalytic Hydrogenation of Phenols. I. Hydrogenation of p-Cresol over Various Pd–C Catalysts
Authors: Higashijima Michio , Nishimura Shigeo
Published: July 2006

The catalytic hydrogenation of p-cresol with commercial Pd on active carbon (Pd–C), water-washed Pd–C (Pd–C–N), acid-treated Pd–C (Pd–C–A), and base-treated Pd–C (Pd–C–B) has been kinetically studied in cyclohexane as a solvent under 0.15–8.0 MPa hydrogen pressure at 80°C. Under each reaction condition, the hydrogenation rate constants for the cresol and the ketone intermediate, k1+k3 and k2, respectively, the relative reactivity of the ketone to the cresol (K) and the ratio of the adsorption coefficient of the ketone to that of the cresol (b2/b1) were determined on the basis of a Langmuir–Hinshelwood model. Regardless of the difference in the nature of the catalysts, hydrogenations with these catalysts always gave high selectivities of 0.85–1.0 for the formation of the ketone intermediate, and small values of 0.014–0.62 for the relative reactivity (K). The small values of K over Pd–C and Pd–C–B were shown to be mostly due to the small values of k2/(k1+k3). In contrast, even smaller values of K over Pd–C–N and Pd–C–A were found due to a great difference in the strength of adsorption between the cresol and the ketone intermediate. In general, both the values of K and k2/(k1+k3) increase with increasing hydrogen pressure. All of the experimental results show that both the alkaline impurities associated with catalyst preparation and the hydrogen pressure are the most important factors affecting the formation of the ketone intermediate.
Oxidative Dehydrogenation of Ethylenediamine Coordinated to Ruthenium with Hexafluoroacetylacetonate, Induced by Electrochemical Oxidation of Ruthenium(II) to Ruthenium(III)
Authors: Hoshino Yoshimasa , Okuyama Fumiyo , Nanba Akimichi , Shimizu Kunio , Satô Gen P
Published: July 2006

Two mixed-ligand complexes, [Ru(hfac)2(en)] and [Ru(hfac)(en)2]PF6 (en = ethylenediamine and hfac− = hexafluoroacetylacetonate ion), were synthesized. The oxidative dehydrogenation of their en ligand was studied in acetonitrile solutions. Each complex underwent a Nernstian one-electron oxidation at platinum electrodes. The resultant ruthenium(III) species was converted through a series of slow homogeneous reactions into the corresponding 1,2-diiminoethane ruthenium(II) species. Voltammograms recorded during the course of the reactions suggested the presence of 2-amino-1-iminoethane ruthenium(II) intermediates.
Extraction-Spectrophotometric Determination of Average Valence of Copper in Superconductor Y–Ba–Cu–O
Authors: Watanabe Kunihiro , Takakuwa Atsushi , Fueki Kazuo
Published: July 2006

The determination method of the average valence of copper in a Y–Ba–Cu–O superconductor has been investigated. Spectrophotometry was introduced to the iodometry considered to be a conventional method in order to decrease the amount of sample used. The iodine liberated by the reaction between Cu2+ and/or Cu3+ and I− ions was extracted into chloroform with Zephiramine (Zeph+Cl−) as a Zeph+I3− ion pair complex. The extraction of I3− enhanced the reproducibility. The effect of the HCl concentration was significant. The sample was dissolved with 5 ml of a 0.1 M (M = mol dm−3) HCl solution by means of ultrasonic irradiation. The employed method decreased the amount of consumed sample down to 4 mg. The modified method, using cuproine, decreased the amount down to 2 mg.
Crystal Structures of N-Benzoyl Derivatives of 8-Oxa-6-azabicyclo[3.2.1]octan-7-one, ε-Caprolactam and 2-Pyrrolidone
Authors: Yamane Takashi , Ito Yoshiaki , Ashida Tamaichi , Hashimoto Kazuhiko , Sumitomo Hiroshi
Published: July 2006

The crystal structures of N-benzoyl-8-oxa-6-azabicyclo[3.2.1]octan-7-one (Bz-BOL), N-benzoyl-ε-caprolactam (Bz-CLA), and N-benzoyl-2-pyrrolidone (Bz-PYR) have been determined in order to clarify the relation between their structures and reactivities by N-benzoyl substitution. Bz-BOL belongs to monoclinic, P21/n, a = 10.372(1), b = 23.155(5), c = 9.737(4) Å, β = 100.92(2)°, Z = 8. Bz-CLA is monoclinic, P21/c, a = 9.234(2), b = 8.532(3), c = 15.097(3) Å, β = 92.42(2)°, Z = 4. Bz-PYR is monoclinic, P21/n, a = 10.801(3), b = 6.020(1), c = 15.082(3) Å, β = 97.95(2)°, Z = 4. The final R-values are 0.049 for 2867 reflections of Bz-BOL, 0.069 for 1634 reflections of Bz-CLA, and 0.053 for 1175 reflections of Bz-PYR. In these compounds the orientaion of the benzoyl moiety against the lactam moiety is essentially the same, and the phenyl group is nearly perpendicular to the lactam-amide plane. The C–N bond distance of the lactam moieties in benzoyl derivatives is significantly prolonged, as compared with that in the original lactams, though the C–N distance is apparently equal to that of acyl moieties in these benzoyl derivatives. This suggests that the C–N bond of the lactam moieties in the benzoyl derivatives is weakened by acylation and is easily broken by a nucleophilic attack, as compared with that of the original lactams.
Adsorption-Order Dependence of the Numbers of Spins of Coexisting Two Radical Species on an HY Type Zeolite
Authors: Kashiwagi Hiroshi
Published: July 2006

The number of spins of coexisting two-radical species on an HY-type zeolite (HY) in the absence of a solvent were independently determined with electron paramagnetic resonance spectroscopy. The coexistence of both donors and acceptor molecules on HY gave rise to the increasing numbers of both cations and anion radicals and to their adsorption-order dependence. The numbers of coexisting cations and anion radicals were independent of, while their maximal numbers of spins were dependent on, the spin-generating abilities of the donors and acceptors. Futhermore, a small enhancement of radicals and a remarkable adsorption-order dependence arose in a solvent-free ternary system comprising HY and either two donors or two acceptors.
1H NMR Study of 2,3-Dicyanobicyclo[2.2.2]octa-2,5,7-triene Partially Oriented in a Nematic Phase
Authors: Tomishima Atsuko , Takakura Yutaka , Yokoyama Yukihiro , Saito Katsuhiro , Takahashi Kensuke
Published: July 2006

The 1H NMR spectra of the title compound dissolved in a nematic phase of ZLI1167 have been analyzed, and the structure of the proton skelton has been determined.
Stabilization Energy of the 9,9′-Trimethylenedianthracene Radical Cation Estimated by the Charge Resonance Band
Authors: Tsuchida Akira , Takamura Hiroshi , Yamamoto Masahide , Lee Bong , Ikeda Tomiki , Tazuke Shigeo
Published: July 2006

The charge-resonance band of the 9,9′-trimethylenedianthracene radical cation (9An9An+) was observed at 1550 nm by laser photolysis in the near-IR region. Two anthracene chromophores of 9An9An+ were found to take a full-overlap conformation; a clear relationship between the dimer stabilizaiton energy and the aromatic ring size was shown.
Determination of Fluoride Ion by a Flow Injection Analysis Based on the Formation of a Fluorescent Aluminium-Schiff Base Complex
Authors: Aoki Izuo , Tuyuki Masahiko , Watanabe Kunihiro
Published: July 2006

In the presence of fluoride ions, aluminium reacts with N-salicylideneethylenediamine to form fluorescent Schiff base complexes. A flow-injection analysis system based on this reaction has been developed for a determination of the fluoride ions at the ppm level. By measuring the fluorescence intensities, the number of fluoride ions could be selectively determined over the range 0.15–10 ppm; 40 samples could be analyzed per hour. The proposed system was applied to an analysis of the fluoried ion in river water.
Properties of Acid Sites on TiO2–SiO2 and TiO2–Al2O3 Mixed Oxides Measured by Infrared Spectroscopy
Authors: Nakabayashi Hirotoshi
Published: July 2006

Both Lewis and Brönsted acid sites were found on the surface of TiO2–SiO2 mixed oxide, thouth no Brönsted acid sites were detected on the surface of pure TiO2 and SiO2. While on the surface of TiO2–Al2O3 mixed oxide, no Brönsted acid sites were generated. The rate of isomerization of 1-butene was found to be enhanced on the Brönsted acid sites formed on the TiO2–SiO2 mixed oxide.
Two Conformers and Aggregation of Cyclic Octapeptide, cyclo(G-eLL-G)2, in Chloroform
Authors: Miyake Hiroyuki , Kojima Yoshitane , Yamashita Tetsushi , Ohsuka Akio
Published: July 2006

In chloroform, cyclo(G-eLL-G)2 exists as an equilibrium of two conformers and aggregates from the monomer to the oligomer with an increase in the peptide concentration, owing to the intermolecular hydrogen bonds formed between the amide hydrogen and the oxygen.
Chiral Hydantoin; A New Dienophile for Diels–Alder Reaction
Authors: Sankhavasi Wongsiri , Kohmoto Shigeo , Yamamoto Makoto , Nishio Takehiko , Iida Ikuo , Yamada Kazutoshi
Published: July 2006

A chiral hydantoin derivative, 5-methylene-1,3-bis[(S)-1-phenylethyl]-2,4-imidazolidinedione, was synthesized and the scope of this compound in Diels–Alder reaction was investigated.
Anodically-Generated Br–Cl Composite Halogenating Reagents
Authors: Fukui Kouta , Nonaka Tsutomu
Published: July 2006

The halogenating power of Br–Cl composite species (termed “BC-reagent” in this article) generated anodically from mixtures of Br− and Cl− in CH2Cl2 was examined in an ex-cell manner toward some organic compounds. The BC-reagent brominated methoxybenzenes, and the brominating power could be precisely controlled by means of the amount of electricity charged and by varying the ratio of Cl−/Br−. The power of the reagent was less controllable during the bromination of aniline. The reaction of olefins with the BC-reagent led to dibromination and bromochlorination, the product-selectivity of which could be also controlled. The theoretically calculated chemical composition of the BC-reagent agreed fairly well with the experimentally confirmed value in some cases.
Silicon Effects. IV. Solvolysis of 1-(Pentamethyldisilanyl)-2-phenylcyclopropyl Bromide in 2,2,2-Trifluoroethanol via σ(CC)-Assisted and -Unassisted Ionization Processes
Authors: Shimizu Nobujiro , Hayakawa Fumie , Tsuno Yuho
Published: July 2006

The rates of solvolysis of 1-(pentamethyldisilanyl)-, 1-trimethylsilyl-, and 1-methyl-substituted 2- phenylcyclopropyl bromides (4a, 4b, and 4c) were measured in 2,2,2-trifluoroethanol at 100 °C: The relative rates for trans-4a, trans-4b, and trans-4c were 3.48 : 1.0 : 10.7, respectively; the trans/cis isomeric rate ratios (kt/kc), which were determined by competition experiments, were 2.99 for 4a and 1.70 for 4b. The solvolysis of trans-4b yielded only open allylic ethers, consistent with a σ-assisted mechanism (kΔ); the trans-4a predominantly, however, gave a cyclopropyl ring-retained compound, dimethyl[trans-2-phenyl-1-(trimethylsilyl)cyclopropyl](2,2,2-trifluoroethoxy)silane, indicative of σ-unassisted (kc) solvolysis.
Relaxation Phenomena of the Concentration Polarization in High Temperature Air Cathodes
Authors: Kenjo Tadao , Yamakoshi Yukiyasu
Published: July 2006

The transient depolarization curves of Pt/ZrO2 high temperature air cathodes have been measured and compared with theoretical curves calculated by assuming a diffusion mechanism of atomic oxygen. The decay equation used involves the limiting current density, time constant for the decay rate and effective reaction area, as parameters to be determined. These parameter values were obtained by curve fitting. The polarization loss was found to decrease with increasing O2 pressure at the rate expected from the diffusion mechanism. The performance of the electrodes was enhanced as the sintering temperature rose. This trend was reflected on an increase in the parameter of effective reaction area. The performance was improved by loading an excess current. This effect was explained as being due to an increase in the diffusivity of Oa.
Synthesis, Characterization, and Magnetic Property of a Novel Dimer-of-Di(μ-oxo)dimanganese-Dimers with Two Coordinated Water Molecules in (III,IV,III,IV) Oxidation State
Authors: Kawasaki Hisano , Kusunoki Masami , Hayashi Yoshihito , Suzuki Masatatsu , Munezawa Kazutoshi , Suenaga Machiko , Senda Hitoshi , Uehara Akira
Published: July 2006

A dimer-of-di(μ-oxo)manganese(III)manganese(IV)-dimers with two coordinated water molecules, [{Mn2(tmdp)(O)2(H2O)}2](CF3SO3)4·6H2O (1), was prepared, where Htmdp is 1,5-bis[bis(2-pyridylmethyl)amino]-3-pentanol. Crystal structure of 1 was determined by X-ray structure analysis. 1 crystallizes in triclinic space group, with a = 16.543(1), b = 19.097(2), c = 13.393(1) Å, α = 94.450(7)°, β = 90.698(6)°, γ = 84.997(7)°, V = 4202.4(6) Å3, and Z = 2. The complex cation consists of two di(μ-oxo)manganese(III)manganese(IV) dimers which are linked by two tmdps and hydrogen bonding network between two coordinated water molecules and two alkoxo groups to form a dimer-of-dimers with a bilayered structure with dimer-dimer separation of 5.9 Å. The Mn–Mn separations are 2.644(2)—2.651(2) Å. Magnetism of 1 was well interpreted in terms of the model based on two kinds of the exchange interactions between Mn(III) and Mn(IV); the intradimer interaction (J1 = −145 cm−1) through di(μ-oxo) bridges and the interdimer interaction (J2   −0.2 cm−1) through hydrogen bonding network. The interdimer exchange interaction (J2) results in a triplet ground state. The ESR spectrum of a frozen solution sample of 1 showed a relatively intense “ΔMs = 2” signal centered at g = 4.5, which is only 7.6 times weaker than a much broader “ΔMs = 1” signal at g = 2.0. The best computer simulation revealed near rhombic zero-field splittings with |D| 0.07 cm−1 and |E| 0.023 cm−1, and Mn-hyperfine broadening, which are appropriate for the triplet ground state of such a tetrameric dimer-of-di(μ-oxo)manganese(III)manganese(IV)-dimers with 5.9 Å separation. The observed zero-field splittings could be interpreted in terms of an incomplete quenching of the crystal field effect of each Mn(III) ion in the triplet ground state mixed with the excited-state spin configurations through the J2 interactions. Cyclic voltammogram exhibited a quasi reversible wave (E1/2 = 0.98 V vs. SCE) and an irreversible oxidation wave at 1.10 V vs. SCE in acetonitrile. Constant potential electrolysis at 1.00 V vs. SCE indicated that the quasi reversible wave is a one-electron transfer process and corresponds to Mn4(III, IV, IV, IV)/Mn4(III, IV, III, IV) redox couple. A one-electron oxidized species which was generated electrochemically showed a so called sixteen hyperfine pattern at g = 2.0, supporting the presence of di(μ-oxo)manganese(III)manganese(IV) and di(μ-oxo)dimanganese(IV) species in the tetramer. Constant potential electrolysis at 1.20 V vs. SCE resulted in a decomposition of the complex.
Reductive Cupration of Cyanoketene Dithioacetals. Generation of Functionalized (E)-Vinylcopper Reagents and Their Reactions with Electrophiles
Authors: Hojo Makoto , Harada Hajime , Watanabe Chika , Hosomi Akira
Published: July 2006

Functionalized (E)-vinylcopper species, selectively generated by the effective reduction of cyanoketene dithioacetals with two equimolar amounts of cuprates, react with electrophiles such as water, allyl bromide, and acid chlorides to give the corresponding substitution products in good yields.