bluuebunny/crossref_metadata_2025 huggingface dataset:
A Pair of Trans and Cis Isomers of Platinum(II) Schiff Base Complex with N, S Chelate Containing Ferrocenyl Pendant Groups
Authors: Nagasawa Isoroku , Kawamoto Tatsuya , Kuma Hiro , Kushi Yoshihiko
Published: February 2006

The reaction of bis(hexafluoroacetylacetonato)platinum(II) with 2-(ferrocenyl)benzothiazoline affords trans and cis isomers of platinum(II) Schiff base complex, trans-[Pt(fabt)2] (1) and cis-[Pt(fabt)2] (2) (fabt = 2-(ferrocenylmethyleneamino)benzenethiolato). The structures of 1 and 2 have been determined by the single crystal X-ray diffraction method. Crystal data for complex 1 are triclinic with space group ; a = 15.283(15), b = 13.180(8), c = 9.847(12) Å; α = 72.91(6), β = 98.02(9), γ = 94.95(6)°; V = 1875.2(30) Å3; Z = 2. Crystal data for complex 2 are orthorhombic with space group P212121; a = 20.593(7), b = 12.300(5), c = 11.754(4) Å; V = 2977.0(18) Å3; Z = 4. The complex 1 has a trans-planar N2S2 configuration and two fabt groups take an unique umbrella conformation. On the other hand, the complex 2 has a cis-planar N2S2 configuration and two fabt groups take a helical geometry with a stepped conformation. The space group P212121, Z = 4 for 2 indicates that 2 is spontaneously resolved.
A New Active Intermediate in Monooxygenations Catalyzed by Iron Porphyrin Complexes
Authors: Murakami Tatsuya , Yamaguchi Kazuya , Watanabe Yoshihito , Morishima Isao
Published: February 2006

A new type of high-valent oxoiron porphyrin (3b) has been prepared by the reaction of FeIII(tdcpp) (1b) [tdcpp: 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin] with an oxidant such as p-nitroperbenzoic acid and pentafluoroiodosylbenzene at −90 °C in CH2Cl2  in the presence of a small amount of methanol. The UV-vis spectrum of 3b (λmax at 418 and around 550 nm) is similar to that of O=FeIV(tdcpp) (4b, λmax 419, 543 nm). However, titration of 3b by iodide ion indicates that the oxidation state of 3b is two-electron oxidized from the iron(III) state. Further, 3b catalyzes oxygenation of olefins such as styrene even at −90 °C. Possible formulation of 3b as a π-cation radical is readily ruled out by deuterium NMR observation. The solution magnetic susceptibility (μeff = 4.0 ± 0.2 μB) of 3b indicates that 3b has three unpaired electrons. These results indicate the formal description of 3b as being a high spin complex of either an O=Fe(V) porphyrin or ·O–Fe(IV) porphyrin. The same oxidation of 1b  in the absence of methanol gave O=FeIV(tdcpp) π-cation radical (2b). We think the ligation of methanol causes the destabilization of iron d orbitals and eventually turns upside down the energy levels between the iron dxz, dyz orbitals and the porphyrin HOMO orbital (a2u) since the a2u orbital is stabilized by the introduction of electron-withdrawing groups on the porphyrin ring.
Studies of Organotin(IV) Derivatives of Dl-Methionine and l-Asparagine
Authors: Nath Mala , Yadav Rakesh
Published: February 2006

New organotin(IV) complexes of the general formula R3SnL [where R = Me, Bu, and Ph], Ph2SnL2 and Bu2SnL2 [where L = monoanion of Dl-methionine (HL-1) and l-asparagine (HL-2)] were synthesized and characterized by elemental analyses as well as molar conductance, electronic, infrared, far-infrared, 1H and 13C NMR, and 119Sn Mössbauer spectral studies. Probable structures are suggested for the complexes. Thermal studies of a few complexes have been carried out in the temperature range 25—1000 °C using the TG, DTG, and DTA techniques, indicating the formation of SnO as a residue. The complexes were tested in vitro against a wide spectrum of bacteria and fungi and found to be active. Only two complexes, Ph3SnL-1 and Ph3SnL-2, have been found to be slightly active in vivo against a multiinfection fungal model in mice.
Synthesis, Crystal Structures, and Properties of S-Bridged Pt(II)-Ni(II) Dinuclear Complexes: Conversion of Square-Planar [Ni(aet)2] to Octahedral Geometry by Forming an S-Bridged Structure with Pt(II) (aet = 2-Aminoethanethiolate)
Authors: Okamoto Ken-ichi , Yoshinari Yukie , Yamada Yasunori , Sakagami Narumi , Konno Takumi
Published: February 2006

The reactions of [Ni(aet)2] with [PtCl2(L)] gave a new type of S-bridged dinuclear complexes [Pt(L){Ni(aet)2(H2O)2}]2+ (aet = aminoethanethiolate; L = bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline (5), dmbpy = 4,4′-dimethyl-2,2′-bipyridine). These complexes readily react with L′ to form [M(L){Ni(aet)2(L′)}]2+ (L = bpy, L′ = bpy (3), phen; L = phen, L′ = phen, bpy; L = L′ = dmbpy). A similar reaction of [Ni(aet)2] with [PtCl2(phen)] and phen gave only [Pt(phen){Ni(aet)2(phen)}]2+. The crystal structures of 3 and 5 were determined by X-ray crystallography. The Ni atoms are surrounded by two aet and a bpy or two water molecules to have an approximately octahedral geometry, forming the C2-cis(S)-[Ni(aet)2{bpy or (H2O)2}] unit. The Pt atoms have a square-planar geometry, in which two Cl atoms of the starting [PtCl2(L)] (L = bpy or phen) have been substituted by the two S atoms from the Ni(II) unit. The Pt(II) plane and the Ni(II) equatorial plane are almost coplanar, and the Pt–Ni distance is 3.4987(8) Å (3) and 3.476(4) Å (5). All of the complexes were characterized on the basis of the electronic absorption and infrared spectra and the cyclic voltammetry. The conversion of a square-planar [Ni(aet)2] to an octahedral [Ni(aet)2{(H2O)2 or (L′)}] units was also considered. In the solid state, the water molecule in [Pt(L){Ni(aet)2(H2O)2}]2+ could be readily exchanged by nitrate.
Observation of a Cobalt as a Chemical Modifier for Lead in Electrothermal Atomic Absorption Spectrometry Using a Tungsten Furnace by Means of a Surface Analysis
Authors: Narukawa Tomohiro , Yoshimura Wataru , Uzawa Atsushi
Published: February 2006

The behavior and effect of cobalt as a chemical modifier for lead were studied by electrothermal atomic absorption spectrometry using a tungsten furnace. The characterization of materials formed on the tungsten surface at the charring stage was performed using of a scanning electron microscope and X-ray photoelectron spectrometer. The experimental results indicate that the effect of a cobalt modifier is related to the formation of granular cobalt crystals during a pre-heating stage. Under the coexistence of lead, however, the cobalt crystals became irregularly shaped, probably forming an intermetallic compound between cobalt and lead. By an examination using sample materials containing chloride, nitrate, and sulfate salts, it was found that a cobalt modifier is effective for suppressing the interference of chloride and nitrate. All of the sulfate salts gave negative interference; the cobalt crystal, which acted as a chemical modifier, was included inside a large crystal which originated from the sulfate at the charring stage. The thermal stability of lead is difficult to maintain with increasing sulfate salts. The cobalt modifier was applied to the determination of lead in several water samples.
Synthesis of a Fragment A Derivative of an Antibiotic, Nosiheptide
Authors: Umemura Kazuyuki , Noda Hirofumi , Yoshimura Juji , Konn Akihito , Yonezawa Yasuchika , Shin Chung-gi
Published: February 2006

Two 4-ethoxycarbonyl thiazolyl groups were introduced into 2- and 5-positions of 3-hydroxypyridine in 8 steps using 5-cyano-3-hydroxypyridine (2) as the starting material. The pyridine derivative obtained in the last step was converted to a fragment A derivative (21) by stepwise introduction of the 2-substituted 4-thiazolyl group into the 6-position. The total yield for the formation of 21 via 14 steps was 7.6%.
Tetrachlorocyclopentadienone O-Oxide, a Facile Oxygen-Atom-Transfer Reagent: The Disproportionation of Cycloalkyldioxyl Radicals
Authors: Dunkin Ian R , McCluskey Adam
Published: February 2006

Photolysis of tetrachlorodiazocyclopentadiene (1) in oxygen-saturated hydrocarbon solvents results in the transient formation of tetrachlorocyclopentadienone O-oxide (3). This rapidly decomposes, giving rise to products derived from oxidation of the hydrocarbons. Cyclopentane, cyclopentene, cycloheptane, cycloheptene, cycloheptatriene, and indene have been studied. Cycloheptatriene and indene gave only low yields of tractable products, but the others gave the corresponding ketones and secondary alcohols as the major products. Although yields varied considerably, the ketone and alcohol products were always obtained, within experimental error, in a 1 : 1 molar ratio. This observed product ratio supports the disproportionation of cycloalkyldioxyl radicals as a crucial step.
Thermodynamic Stabilities of Phenonium Ions Based on Bromide-Transfer Equilibria in the Gas Phase
Authors: Mustanir  , Mishima Masaaki , Fujio Mizue , Tsuno Yuho
Published: February 2006

The thermodynamic stabilities of the phenonium (ethylenebenzenium) ion and ring-substituted derivatives were determined based on the bromide-transfer equilibria in the gas phase. It has been shown that the phenonium ion is 2.4 kcal mol−1 more stable than the t-butyl cation, and that the substituent effect on its stability can be correlated with the Yukawa–Tsuno equation with a ρ value of −12.6 and an r+ of 0.62. An r+ value smaller than unity of the α-cumyl(1-methyl-1-phenylethyl) cation suggested that π-delocalization in the phenonium ion is essentially less effective than through a benzylic π-interaction. On the other hand, the ρ value of −12.6 is distinctly larger than that for the ordinary benzylic carbocation systems, but is comparable to that of the benzenium ion. In addition, it has been found that the r+ value of the phenonium ions in the gas phase is in complete agreement with that for the aryl-assisted process in the acetolysis of 2-arylethyl toluenesulfonates. This suggests that the degree of π-delocalization of the positive charge is the same in the transition state and the intermediate cation. It is concluded that an r+ value of 0.6, which is ranked at a unique position in the continuous spectrum of the resonance demand, is characteristic of the bridged structure of the phenonium ion intermediate and the transition state.
Tail-to-Tail Dimerization of Acrylonitrile Catalyzed by Low-Valent Ruthenium Complexes
Authors: Fukuoka Atsushi , Nagano Takeyuki , Furuta Shuichi , Yoshizawa Michito , Hirano Masafumi , Komiya Sanshiro
Published: February 2006

Zero-valent ruthenium complexes, [Ru(cod)(cot)] and [Ru(cod)(benzene)], are effective catalyst precursors for the tail-to-tail dimerization of acrylonitrile. Hydrogen pressure is necessary for the catalytic reaction, and the turnover number for dimers is greatly improved in neat acrylonitrile. Under the conditions of 150 °C and 25 atm of H2 (initial pressure at room temperature), the conversion of acrylonitrile is 61% and the yield of tail-to-tail dimers is 42% (selectivity 69%) in 3 h. The turnover number for the dimers is 2060, which is much higher than those reported so far. From the results of a catalytic reaction under D2 pressure, a reaction mechanism is proposed, in which two successive insertions of acrylonitrile into dihydridoruthenium complex are involved. A fast and reversible insertion of the third acrylonitrile is responsible for the H–D exchange of acrylonitrile in the deuterium labeling experiment.
Synthetic Studies on Biscembranoids. Asymmetric Total Synthesis of the 14-Membered Diene Unit of Methyl Sarcophytoate
Authors: Yasuda Minoru , Ide Mitsuaki , Matsumoto Yuka , Nakata Masaya
Published: February 2006

An asymmetric total synthesis of the 14-membered diene unit, (1S,2S,4E,6E,10S,11Z,14R)-10,14-epoxy-4-isopropenyl-1,7,11-trimethyl-4,6,11-cyclotetradecatriene-1,2-diol (3), of methyl sarcophytoate (1) has been achieved. Methyl ketone, (3S,4S)-3,4-(isopropylidenedioxy)-3,7-dimethyl-6-octen-2-one (6), was enantioselectively prepared from geraniol via Sharpless asymmetric epoxidation and a regioselective epoxide-opening reaction. The aldol coupling between the lithium enolate of 6 and aldehyde, (2E,6E)-2,6-dimethyl-8-(2,2-dimethylpropanoyloxy)-2,6-octadienal (7), which was also prepared from geraniol, gave a 1 : 1 separable mixture of the adducts (17 and 18). Reduction of the carbonyl group in 17 and 18, followed by regioselective oxidation of the allylic hydroxy group, afforded α,β-unsaturated ketone, (2E,6E,10R,11R,12S)-1-(2,2-dimethylpropanoyloxy)-10-hydroxy-11,12-(isopropylidenedioxy)-3,7,11,15-tetramethyl-2,6,14-hexadecatrien-8-one (5). The intramolecular oxy-Michael addition of 5 followed by regioselective enol triflation and deoxygenation gave dihydropyran, (2E,6S,7Z,10R,11R,12S)-1-(2,2-dimethylpropanoyloxy)-6,10-epoxy-11,12-(isopropylidenedioxy)-3,7,11,15-tetramethyl-2,7,14-hexadecatriene (31). The regioselective epoxidation of 31 and a subsequent functional-group transformation gave (2E,6S,7Z,10R,11R,12S,14RS)-6,10 : 14,15-diepoxy-11,12-(isopropylidenedioxy)-3,7,11,15-tetramethyl-1-(phenylthio)-2,7-hexadecadiene (4). The 14-membered ring formation was achieved by the treatment of 4 with the n-BuLi–Bu2Mg complex to give (1Z,3S,6E,8RS,9RS,11S,12R,13R)-3,13-epoxy-9-(1-hydroxy-1-methylethyl)-11,12-(isopropylidenedioxy)-2,6,12-trimethyl-8-(phenylthio)-1,6-cyclotetradecadiene (33), which was transformed to 3 through triene construction and deacetonidation.
Syntheses and Properties of 11,11,12,12-Tetracyano-2,6-anthraquinodimethane (TANT) and Its 9,10-Dichloro Derivative as Novel Extensive Electron Acceptors
Authors: Takimiya Kazuo , Yanagimoto Tetsuya , Yamashiro Takashi , Ogura Fumio , Otsubo Tetsuo
Published: February 2006

The title compound (TANT) and its 9,10-dichloro derivative (TANT-Cl) have been prepared as higher homologues in an extended electron-acceptor series of TCNQ and TNAP. On the basis of cyclic voltammetry, the accepting ability of TANT is nearly comparable to those of TCNQ and TNAP, and that of TANT-Cl is further enhanced by the chloro substitutuent groups. In addition, TANT and TANT-Cl show an effective reduction of on-site coulombic repulsion, due to their extensive anthraquinone quinonoid system. They thus behave as superior electron acceptors for forming electrically conductive charge-transfer complexes with various electron donors, mostly of the TTT type.
Generation of Radical Species from Cyclohexane-1,2-dione and the Reaction with Olefins: Preparation of 4,5-Dihydro-7(6H)-benzofuranone Derivatives
Authors: Miura Masanori , Arai Noriyoshi , Narasaka Koichi
Published: February 2006

Oxidation of cyclohexane-1,2-dione with ammonium hexanitratocerate(IV) (CAN) generates 2,3-dioxocyclohexyl radical, which reacts with electron-rich olefins to afford the corresponding addition products. The adducts thus generated are converted to 4,5-dihydro-7(6H)-benzofuranone by acid treatment. In addition to cyclohexane-1,2-dione, radical species are also generated from cyclopentane-1,2-dione and cycloheptane-1,2-dione.
Norbornadiene-Fused Heterocycles: Synthesis and Bromination Reaction of 5,8-Dihydro-5,8-methanoquinoxaline Derivatives
Authors: Kobayashi Tomoshige , Miki Kiyomi
Published: February 2006

A norbornadiene-fused pyrazine was prepared by the condensation reaction of bicyclo[2.2.1]hept-5-ene-2,3-dione with ethylenediamine followed by oxidation. Treatments of the norbornadiene-fused pyrazine and its benzo derivative with bromine in carbon tetrachloride or in dioxane afforded trans-adducts as major products, accompanied by the formations of cis-adducts and dibromo derivatives derived from Wagner–Meerwein type skeletal rearrangement, while bromination of a fused dicyanopyrazine in carbon tetrachloride gave only a trans-adduct. In contrast, a fused pyrazine with an electron-donating N-oxide group gave a 7,9-dibromo derivative as the main component. The possibility of the intervention of a 2H-pyrazinium ion for the formation of the skeletally rearranged products is discussed together with the results of ab-initio (3-21G*) calculations.
Selective PdZn Alloy Formation in the Reduction of Pd/ZnO Catalysts
Authors: Iwasa Nobuhiro , Ogawa Noriaki , Masuda Satoshi , Takezawa Nobutsune
Published: February 2006

Temperature programmed reduction (TPR) experiments were carried out over Pd/ZnO with different Pd loadings. Combined results with an X-ray diffraction method and X-ray photoelectron spectroscopy showed that a Pd–Zn alloy with a structure of PdZn was selectively produced in the course of TPR of Pd/ZnO. It was suggested that hydrogen retained in Pd spilled over to ZnO. The ZnO was reduced to metallic Zn, being converted to PdZn. The molar amounts of the ZnO reduced were practically the same as the those of Pd loaded. Hence, all the Pd loaded was completely transformed to the PdZn alloys upon reduction.
Thermal and Rheological Properties of Physical Gels Formed from Benzylidene-d-sorbitol Derivatives
Authors: Watase Mineo , Itagaki Hideyuki
Published: February 2006

The thermal and rheological properties of gels formed from 2,4-(mono)-O-benzylidene-d-sorbitol (MBS), 1,3 : 2,4-di-O-benzylidene-d-sorbitol (DBS), and 1,3 : 2,4 : 5,6-tri-O-benzylidene-d-sorbitol (TBS) in ethylene glycol (EG) and from DBS in glycerol (GL) were investigated. In all the gels studied, the values of the enthalpy of melting for the gel obtained from the Eldridge–Ferry plot agreed well with those obtained from the peak area of the DSC curves. This agreement has not been demonstrated clearly for biopolymeric systems thus far but can now be successfully shown by first using small molecule systems. In conclusion, the transitions of the gel formation and gel melting proceed via a second order or higher order process. The experimental results show that the ease by which formation and stabilization of gels takes place for the sorbitol derivatives in EG is in the following order: DBS > TBS > MBS. Accordingly, the main reason for the stabilization of sorbitol gels in alcoholic solvents is concluded to be not simply due to hydrogen bonding or hydrophobic interactions among benzylidene groups but rather it is due to a delicate balance of chemical structure that facilitates the formation of crystals. In particular, the symmetric structure of a DBS molecule, which has a rigid and chiral ten-member ring symmetrically connected with two benzylidene groups in equatorial positions, is considered to be the most crucial reason to form most stable gels studied in this work.
Adsorption Behavior of Methyl Orange on the Monolayer and Langmuir–Blodgett Films of Octadecylamine
Authors: Takahashi Masashi , Kobayashi Koichi , Takaoka Kyo , Tajima Kazuo
Published: February 2006

The monolayer properties of octadecylamine (ODA) on both distilled water and aqueous Methyl Orange (MO) solution were studied from the measurements of surface pressure–area (π–A) isotherms. From the π–A isotherms at various pHs, hydroxide ions, and MO anions in the subphase were confirmed to interact competitively with the ODA monolayer. Furthermore, Langmuir–Blodgett (LB) film of ODA was fabricated from the surface of an alkaline subphase, and the adsorption characteristics of the ODA LB film were investigated by using MO as an adsorbate. As a result, the ODA LB film exhibited specific adsorbability for the MO anion, similar to that of the LB film of long-chain quaternary alkylammonium salt, but the adsorption rate of the MO on the ODA LB film was slower than that on the LB film of long-chain quaternary alkylammonium salt. In addition, adsorbability of the ODA LB film showed pH dependence.
Antioxidative Dopant for Thermal-Resisting Polypyrrole and Its Mechanism
Authors: Takeoka Shinji , Hara Tomitaro , Fukushima Kazuaki , Yamamoto Kimihisa , Tsuchida Eishun
Published: February 2006

In order to improve the thermal stability of the electric conductivity of polypyrrole (PPy), a series of aromatic sulfonate derivatives having acid-type substitute groups, such as –COOH, –OH, and –SO3H, were used as dopants. The PPy doped with these dopants showed excellent thermal stability of their electric conductivity, even at 150 °C in air. Especially, 2-hydroxy-5-sulfobenzoic acid, having one –COOH and one –OH, provided the highest thermal stability; the doped PPy maintained 95% of its initial conductivity, even after heating for 8 h at 150 °C in air. Furthermore, the PPy showed 20-times higher stability against long-term heating at 125 °C for 1000 h in comparison with PPy doped with p-methylbenzenesulfonic acid, which is conventionally used to provide high thermal stability. The thermal-stabilization mechanism has suggested that dopants having acidic substituents should suppress proton dissociation from the N-position of the PPy main chain and keep the π-conjugation structure by supplying a proton from the acidic groups. Such a proton supplement was confirmed by the IR spectroscopy of deuterized PPy.
Preparation of α,ω-Diols of Long Carbon Chains and Their Use in Polyurethane Synthesis
Authors: Osakada Kohtaro , Takenaka Yasumasa , Yamaguchi Isao , Yamamoto Takakazu
Published: February 2006

NaH promoted coupling reaction of HO(CH2)12O–TBDMS (1, TBDMS=SiMe2(t-Bu)) and Br(CH2)12O–TBDMS (2) followed by deprotection of the organosilyl groups affords HO(CH2)12O(CH2)12OH (5). 1,12-Dodecanediol reacts with an excess amount of 2 in the presence of NaH to give TBDMS–O(CH2)12O(CH2)12O(CH2)12O–TBDMS (6) which is turned into HO(CH2)12O(CH2)12O(CH2)12OH (7) by removal of the protecting groups. Similar 1 : 2 condensation of hydroquinone with 2 and with Br(CH2)6O–TBDMS (3) leads to formation of the corresponding α,ω-diols, HO(CH2)12OC6H4O(CH2)12OH (9) and HO(CH2)6OC6H4O(CH2)6OH (11), respectively. The four new long α,ω-diols are isolated and characterized by means of IR and NMR spectroscopy as well as elemental analyses. Polyaddition reactions of 5, 7, 9, and 11 to 1,3-bis(isocyanatomethyl)benzene and 1,1′-methylenebis[4-isocyanatobenzene] give the corresponding poly(urethane)s in high yields. The obtained polymers, which were characterized by IR and NMR spectroscopy, have molecular weights over 20000 as determined from gel permeation chromatography using polystyrene standards.
Alkene and Alkyne Complexes of Zirconocene. Their Preparation, Structure, and Novel Transformations
Authors: Negishi Ei-ichi , Takahashi Tamotsu
Published: February 2006

Dialkylzirconocenes in situ generated such as Cp2Zr(n-Bu)2, Cp2ZrEt2, and Cp2Zr(t-Bu)(i-Bu) are thermolyzed to afford zirconocene-alkene complexes. In the cases of Cp2Zr(n-Bu)2 and Cp2Zr(t-Bu)(i-Bu), Cp2Zr-alkene complexes generated from them tend to act as a “Cp2Zr” equivalent, since the initially generated alkene is often replaced by another π-bond containing compound. In the presence of alkynes, for example, alkyne complexes may be generated. On the other hand, Cp2Zr(ethylene) tends to serve as an intermediate since the ethylene moiety is often incorporated in the final organic products. Ring expansion and contraction, ligand substitution, transmetallation, migratory insertion, stereoisomerization, regioisomerization, oxidative addition involving these Cp2Zr-alkene and Cp2Zr-alkyne complexes as well as their structures are reviewed.
Studies on Polyketide Metabolites of a Symbiotic Dinoflagellate, Symbiodinium sp.: A New C30 Marine Alkaloid, Zooxanthellamine, a Plausible Precursor for Zoanthid Alkaloids
Authors: Nakamura Hideshi , Kawase Yuko , Maruyama Kyoko , Murai Akio
Published: February 2006

In studies on the biogenesis of vasocontrictive macrolides, zooxanthellatoxins isolated from a symbiotic dinoflagellate Symbiodinium sp., we have investigated metabolites of the dinoflagellate cultured under different conditions. Four new compounds were isolated from 70% EtOH extract of the cells cultured in f/2 medium. Two betaines (zooxanthellabetaine-A and -B) were obtained from a neutral fraction of n-BuOH soluble portion and the structure of zooxanthellabetaine-A was determined as 4-(4-hydroxybenzoyloxy)-3-(trimethylammonio)butyrate. The EtOAc soluble portion afforded a new C-30 alkaloid, zooxanthellamine, and a new ceramide, symbioramide-C16. The structural similarity of zooxanthellamine to zoanthid alkaloids, zoanthamines, suggested an algal origin of these zoanthamines. Zooxanthellamine might be derived biogenetically from a polyketide chain presumably started from a glycine unit, like other marine toxins such as zooxanthellatoxin and palytoxin.
Adsorption of Metal Ions to Surface-Template Resins Prepared with Amphiphilic Styrene Monomers Bearing Amino Carboxylic Acid
Authors: Koide Yoshifumi , Tsujimoto Keigo , Shosenji Hideto , Maeda Mizuo , Takagi Makoto
Published: February 2006

Monomer-type functional surfactants, 2-(p-vinylbenzylamino)alkanoic acid (RnNAc) and N,N-dialkyl derivatives (RRnNAc), have been used as both a ligand and an emulsifier for the preparation of surface-template resins. The surfactants adsorbed at the toluene–water interface and emulsified divinylbenzene–styrene in a Cu2+ or Zn2+ solution. Emulsion polymerization using a K2S2O8 initiator (80 °C) or by irradiation with γ-rays gave fine particles of 200—800 nm in diameter. Metal-imprinted resins prepared with RnNAc and RRnNAc showed a high adsorptive capacity for the metal ion (surface-template effect). Cu-imprinted resins prepared with R8NAc were 2.69-times as effective for Cu2+ in competitive sorption from a Cu2+–Zn2+ mixture and Zn-imprinted resins were 1.84-times as effective for Zn2+, compared with unimprinted resins. Because of the great emulsifying power, metal-imprinted resins prepared with R8NAc showed the most metal-selective adsorption and the largest capacity among resins prepared with RnNAc and RRnNAc.
Crystal Structure and Physical Properties of M = Rb and Tl Salts of (BEDT-TTF)2MM′(SCN)4 [M′ = Co, Zn]
Authors: Mori Hatsumi , Tanaka Shoji , Mori Takehiko , Kobayashi Akiko , Kobayashi Hayao
Published: February 2006

Crystal structure analyses, band calculations, and electrical resistivity and magnetic susceptibility measurements have been carried out for new θ-type BEDT-TTF [bis(ethylenedithio)tetrathiafulvalene; abbreviated as ET] salts, θ-(BEDT-TTF)2TlCo(SCN)4 and θ-(BEDT-TTF)2TlZn(SCN)4 [abbreviated as θ-TlCo and θ-TlZn], as well as crystal structure analyses of θ-(BEDT-TTF)2RbM′(SCN)4 [M′ = Co, Zn; abbreviated as θ-RbM′]. θ-TlCo and θ-RbM′ [M′ = Co, Zn] are isostructural to the previously reported θ-CsM′, and the metal-insulator transition temperature increases from 20 K (θ-CsM′ [M′ = Co, Zn]), 190 K (θ-RbM′) to 250 K (θ-TlCo) with decreasing the unit cell volume, namely, the inverse chemical pressure effect. A structural investigation for θ-RbM′ [M′ = Co, Zn] indicates a lattice a modulation at the metal-insulator transition temperature (190 K). For the other salt, θ-TlZn, a semiconductor–semiconductor transition has been observed at 165 K, where the behavior of the magnetic susceptibility, following the two-dimensional Heisenberg model, changes from J = −30 K to −57 K under a slow cooling condition.
EPR Studies at High-Pressures. V. Spin-Exchange Reactions of Nitroxide Radicals with Cobalt and Nickel Complexes
Authors: Sueishi Yoshimi , Inoue Hajime , Oka Tetsuhito , Tsukube Hiroshi , Yamamoto Shunzo
Published: February 2006

The rate constants kex for the spin exchange of nitroxides with various kinds of cobalt(II) and nickel(II) complexes were determined from the EPR line-broadening of nitroxides. The rate constants estimated were in the range of 108—109 M−1 s−1 and this reaction was found to be diffusion-controlled. In order to distinguish cases of strong and weak spin exchange, we examined the pressure dependence of the spin exchange between nitroxide and the complexes. It was found that the ligand in the first coordination sphere of the complexes plays an important role for the efficiency of spin exchange. The presence of the coordinated halide ion provides strong exchange, regardless of any screening of the complex’s internal atoms by organic molecules. From the pressure dependence of kex, the J2fs values (the exchange integral J and the steric factor fs) for the spin exchange of nitroxides with cobalt and nickel complexes were estimated to be about 1020 s−2. Based on the results, the steric hindrance for the reaction of spin exchange is discussed.
Luminous Characteristics and 89Y-Static NMR in Red Phosphor, Eu-Doped Y2O3
Authors: Harazono Toshie , Yokota Etsuzo , Uchida Hiroshi , Watanabe Tokuko
Published: February 2006

Luminous properties of a red phosphor, Eu–Y2O3 (Eu-doped Y2O3) have been studied by 89Y (nuclear spin 1/2)-static NMR. Pure Y2O3 showed an anisotropic pattern with the peak centered at 299 ppm assigned to the Y atom in the site, where none of the 12 nearest neighbouring Y atoms are substituted by an Eu atom. The signal became broader with increasing doped Eu content. Additionally, a shoulder peak assigned to the Y atom in the site where one of the 12 nearest neighbouring Y atoms was replaced by one Eu atom appeared around 100—110 ppm in the samples with more than 1 mol/% Eu content.

The spin–spin relaxation of the centered signal was mainly dominated by the dipole–dipole interaction mechanism between the 89Y nucleus and the paramagnetic electrons of Eu3+ with 4f6 electron configuration which substituted at the second nearest and further neighbouring Y. In conclusion, the line-broadening of 89Y signal at constant Eu content was correlated with the Eu distribution on the basis of the facts that the phosphor sample with higher brightness showed broader linewidth and the intensity of the ESR signal corresponding to the lattice defects has no relation to the brightness.
Structural and Electronic Properties of Adsorbed Thiophene on Cu(111) Studied by S K-Edge X-Ray Absorption Spectroscopy
Authors: Imanishi Akihito , Yokoyama Toshihiko , Kitajima Yoshinori , Ohta Toshiaki
Published: February 2006

The surface structure and electronic properties of 0.07 ML thiophene (C4H4S) adsorbed on Cu(111) have been investigated by means of S K-edge X-ray-absorption fine structure measurements. The results are comparatively discussed with the previously studied C4H4S/Cu(100) case. It is found that C4H4S molecules are adsorbed with the molecular plane parallel to the surface, as in the Cu(100) substrate. The S–Cu distance is 2.50 ± 0.02 Å, which is significantly longer than that of Cu(100) (2.42 ± 0.02 Å), while the S–C bond distance is 1.71 ± 0.04 Å, somewhat shorter than the Cu(100) one (1.74 ± 0.04 Å). Correspondingly, a smaller amount of charge transfer of (0.5 ± 0.2) electron from the substrate to the C4H4S π* orbital is estimated compared to the Cu(100) case of (1.0 ± 0.2) electron. These findings indicate a considerably weaker interaction of thiophene with Cu(111) than with Cu(100), due to a more closely packed surface of Cu(111).
Light-Induced Mixed-Valence State of FeII[Fe(CN)5NO]·xH2O
Authors: Morioka Yoshiyuki , Hisamitsu Taka-aki , Inoue Hidenari , Yoshioka Naoki , Tomizawa Hiroshi , Miki Ei-ichi
Published: February 2006

A long-living metastable state is produced in FeII[Fe(CN)5NO]·xH2O by an irradiation of 488 nm light at 200 K. A strong near-infrared band of about 10000 cm−1 and a ν(CN) band at 2070 cm−1 that newly appear in the metastable state point to development of the mixed-valence state analogous to Prussian blue. An iron-to-nitrosyl charge transfer in pentacyanonitrosylferrate(2−), [Fe(CN)5NO]2−, explains the formation of the mixed-valence state, because the charge transfer causes a pair of iron(II) and iron(III) atoms bridged by CN− that has the same local structure as Prussian blue. In addition to the formation of the metastable state, the prolonged irradiation causes an irreversible change of FeII[Fe(CN)5NO]·xH2O and leads to the formation of a photoproduct. The photoproduct also has infrared spectra characteristic of the mixed-valence state. Mössbauer spectra of the photoproduct show that a low-spin iron ion in pentacyanonitrosylferrate(2−) is divalent and a high-spin iron outside of pentacyanonitrosylferrate(2−) is trivalent. Therefore, the charge-transfer between the two non-equivalent iron ions is thought to follow the intra-molecular charge transfer in pentacyanonitrosylferrate(2−).
Negative Second Hyperpolarizability of the Nitronyl Nitroxide Radical
Authors: Nakano Masayoshi , Yamada Satoru , Yamaguchi Kizashi
Published: February 2006

The static second hyperpolarizability (γ) for a symmetric open-shell system including nitroxide radical groups, nitronyl nitroxide radical, has been studied using ab initio molecular-orbital methods, including various electron-correlation effects. This system is predicted to exhibit a negative γ by our classification rule of γ based on symmetric resonance structures with inversible polarization (SRIP). A remarkable electron correlation dependence has been observed in the magnitude and sign of γ, which has been found to be negative by using high-order electron correlation methods. This tendency has also been investigated in terms of the second hyperpolarizability density, which is defined as the third-derivative of the charge density with respect to the applied electric field.
Effects of Hydrogen Bonding and Hydrophobic Interactions on the Ultraviolet Resonance Raman Intensities of Indole Ring Vibrations
Authors: Matsuno Motonori , Takeuchi Hideo
Published: February 2006

UV resonance Raman intensities of indole ring vibrations were examined in solutions of different solvent properties to establish the correlation between the intensity and the environment of the indole ring, the main side-chain component of amino acid tryptophan. Each of the Raman bands that are enhanced through resonance with the Bb electronic transition gives the highest intensity when the indole NH site is hydrogen-bonded with a proton acceptor in hydrophobic environments. On the other hand, the Raman bands that gain intensity through resonance with the La transition are most enhanced when the indole ring is not hydrogen-bonded. Although these changes in Raman intensity result from small red and blue shifts of the Bb and La absorptions, respectively, the Raman intensity changes are much greater than the changes in UV absorption spectra. UV resonance Raman intensities are thus expected to be useful markers of hydrogen bonding and hydrophobic interactions of tryptophan residues in proteins.
Extraction, Separation, and Spectrophotometric Determination of Tellurium(IV) with 1-(4-Bromophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol
Authors: Kolekar G B , Anuse M A
Published: February 2006

A method is proposed for the extraction, separation and spectrophotometric determination of trace levels of tellurium(IV) from hydrochloric acid media with 1-(4-bromophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol (4-bromoPTPT) in chloroform. The yellow-colored complex absorbs at 440 nm and the system obeys Beer’s law in the 1—15 ppm concentration range. The molar absorptivity and Sandell’s sensitivity are 8.1 × 103 dm3 mol−1 cm−1 and 16 ng cm−2, respectively. The probable composition of the extracted species is TeL2. The interference of various ions was studied. Various parameters, such as the effects of the acidity, reagent concentration, equilibration time etc., have been established for the extractive spectrophotometric determination of tellurium(IV). The method has been applied for the determination of tellurium(IV) in various synthetic samples corresponding to alloys, and provides for the binary separation of tellurium(IV) from lead, bismuth, copper, gold, and antimony. It is also applicable for the simultaneous determination of selenium(IV) and tellurium(IV). The method is accurate, simple, rapid, and selective, and the overall process of extraction and determination takes about 15 to 20 min.
Synthesis and Characterization of Ruthenium Terpyridine Dioxolene Complexes: Resonance Equilibrium between RuIII–Catechol and RuII–Semiquinone Forms
Authors: Kurihara Masato , Daniele Stephane , Tsuge Kiyoshi , Sugimoto Hideki , Tanaka Koji
Published: February 2006

A series of [RuX(dioxolene)(terpy)] (terpy = terpyridine; X = Cl, OAc) and one-electron oxidized complexes were prepared. The molecular structures of [RuCl(O2C6H2-3,5-Bu2)(terpy)] (1) and [Ru(OAc)(O2C6H4)(terpy)] (3) were determined by X-ray crystallography. Crystal data for 1: monoclinic, space group P21/c, Z = 8, a = 11.548(1), b = 18.224(5), c = 30.002(8) Å, β = 96.51(2)°, and R = 0.077 (Rw = 0.068). Crystal data for 3: monoclinic, space group C2/c, Z = 8, a = 13.355(5), b = 12.131(4), c = 26.645(4) Å, β = 92.46(2)°, and R = 0.041 (Rw = 0.041). Although the binding mode of O2C6H2-3,5-Bu2 to Ru was not determined by the molecular structure of 1, the carbon–oxygen and carbon–carbon bond lengths of O2C6H4 in 3 were consistent with those of catecholato ligands. Electronic absorption spectra of [RuX(dioxolene)(terpy)] were explained by the electronic structure of [RuIIX(semiquinone)(terpy)] rather than [RuIIIX(catecholato)(terpy)], while the reverse assignment was deduced from the IR spectra. Moreover, ESR spectra showed hyper-fine structures due to the contribution of semiquinone superimposed on an axial pattern of the Ru(III) center, indicating a resonance equilibrium between [RuIIX(semiquinone)(terpy)] and [RuX(dioxolene)(terpy)].
Substitution of Cl Atom in (2-Chloromethylallyl)palladium Complexes with Soft and Hard Nucleophiles
Authors: Watanabe Saisuke , Hiraike Hiroshi , Kurosawa Hideo
Published: February 2006

[Pd{η3-CH2C(CH2Cl)CH2}(μ-SPh)]2 is spontaneously transformed, in MeCN, into [Pd{η3-CH2C(CH2SPh)CH2}(Cl)]2, which has a novel thioether-bridged dimeric structure. This transformation is suggested to proceed by an attack of the thiolate anion at the methylene carbon bearing a Cl substituent of an ionic intermediate, [Pd{η3-CH2C(CH2Cl)CH2}(MeCN)2]+. [Pd{η3-CH2C(CR2Cl)CH2}(μ-SPh)]2 (R = H, Me) reacts with PPh3 to give [Pd{η3-CH2C(CH2SPh)CR2}(Cl)(PPh3)]. This transformation proceeds via an attack of the thiolate anion at the terminal allyl carbon of an ionic intermediate, [Pd{η3-CH2C(CH2Cl)CH2}(PPh3)2]+, to give 2-phenylthiomethylallyl chloride, which undergoes an oxidative addition to the resulting Pd(0) complexes. [Pd{η3-CH2C(CR2Cl)CH2}(Cl)(PPh3)] (R = H, Me) reacts with Bu3SnCH=CH2 to give [Pd{η3-CH2C(CH2CH=CH2)CR2}(Cl)(PPh3)] through a reductive elimination–oxidative addition sequence, starting from an intermediate, [Pd{η3-CH2C(CR2Cl)CH2}(CH=CH2)(PPh3)].
Kinetics and Mechanism of the Copper(II)-Catalyzed Oxidation of the Iodide Ion by Chromate(VI) Ion in an Aqueous Solution
Authors: Kimura Masaru , Ikawa Rie , Shiota Yuko , Tsukahara Keiichi
Published: February 2006

Although the chromate(VI) ions, CrO42− and HCrO4−, which are described as CrVI herein, could hardly oxidize the iodide ion to iodine above pH 3.0, it was catalytically oxidized by adding traces of copper(II) ion. When a copper(II) solution of 10−7—10−5 mol dm−3 was mixed with an iodide solution, after a fast formation of iodine, the iodine concentration remained constant. After such an iodine formation had occurred, if a chromate solution was added into the reacting mixture, the iodine began to form again in accordance with a rate law of 2/3(d[I2]/dt) = −d[CrVI]/dt = k[CuI][CuVI], in which [CuI] is the steady-state concentration in the chain cycle CuI+/CuI. The rate of the chain reaction was independent of the time to add chromate, and the formation of iodine I2 (or triiodide ion I3−) stopped at the time when all of the chromate was consumed by the chain reaction. The stoichiometry was 3I− + CrVI → 1.5I2 + CrIII. The iodine formation was extremely inhibited by the presence of either radical scavengers or complex-forming reagents as well as by increasing pH. Although addition of alcohols to the reaction mixture extremely accelerated the iodine formation before adding chromate, it hardly affected on this process after the addition of chromate. The reaction mechanisms are presented in order to account for the observed results.
Use of a Sacrificial Aluminum Anode in the Acylation of Some Olefins
Authors: Vukicevic Rastko D , Joksovic Ljubinka , Konstantinovic Stanimir , Markovic Zoran , Mihailovic Mihailo Lj
Published: February 2006

The acylation of some alicyclic and aliphatic alkenes by the electrochemical generation of a catalyst using a sacrificial aluminum anode was investigated. Substrates were electrolyzed in a dichloromethane solution of an appropriate electrolyte (tetraalkylammonium salts) in the presence of an acylating agent (acetyl chloride or anhydride). Thus, unsubstituted cycloalkenes, namely cyclohexene and cycloheptene, gave by that reaction conjugated ketones, i.e. the corresponding 1-acetylcycloalkenes, as the only unsaturated carbonyl compounds in moderate-to-good yields. Under the same reaction conditions their 1-methyl derivatives gave mixtures of the corresponding conjugated and β,γ-unsaturated isomeric ketones in which unconjugated compounds predominate. In both cases unsaturated ketones were accompanied by different amounts of side products. Terminal aliphatic alkenes (1-hexene, 1-heptene, and 1-dodecene) afforded only conjugated a ketone with a normal skeleton, but in lower yields. The acylation of cyclohexene was studied in more detail, altering the reaction conditions by changing the reaction temperature, the supporting electrolyte, the acylating agent and the electrochemical cell. Mechanistic considerations were made on the basis of the products distribution and some theoretical calculations being made by the MOPAC program package (version 7.0).
Dinitrogen Tetraoxide Complexes of Iron(III) and Copper(II) as Efficient and Mild Reagents for Oxidation of Hydroxy Compounds
Authors: Iranpoor Nasser , Firouzabadi Habib , Zolfigol Mohammad Ali
Published: February 2006

Fe(NO3)3·1.5N2O4 is a highly efficient reagent for the oxidation of various classes of hydroxy compounds in dichloromethane at room temperature, or in the absence of solvent. Cu(NO3)2·N2O4 oxidizes different hydroxy compounds in refluxing carbon tetrachloride and is a highly selective reagent for oxidation of primary benzylic alcohols in refluxing EtOAc.
Photodimerization of trans-Cinnamic Acid in a Bilayer of Dimethyldioctadecylammonium Bromide
Authors: Nakamura Tomotaka , Takagi Katsuhiko , Sawaki Yasuhiko
Published: February 2006

The photochemistry of trans-cinnamic acid (trans-1) was studied in a cast film of dimethyldioctadecylammonium bromide (2), deposited from aqueous dispersions as a crystalline solid by the spontaneous vaporization of water. UV irradiation of the cast film resulted in a highly selective formation of the syn-Head-to-Head dimer, suggesting a parallel orientation of trans-1 within a bilayer film. Analyses with X-ray diffraction, differential scanning calorimetry, and IR spectra revealed the formation of a bilayer structure of 2 in which the molecules of trans-1 are dissolved to interact with 2 of the polar head groups. The photoreactivity of trans-1 in the cast film was found to be dramatically suppressed by heating at 40—60 °C, which is attributed to an improvement in the crystallinity of the bilayer.
Dimensiosolvatic Effects. IV. Topomerization in Alkyl α-Chlorobenzyl Ethers and Insights into Mechanisms of Their Thermolyses
Authors: Oki Michinori , Ikeda Hiroshi , Miyake Hiromichi , Mishima Hirohito , Toyota Shinji
Published: February 2006

Rates of topomerization in α-chlorobenzyl ethyl ether and its p-methyl as well as p-methoxy derivatives were determined in various solvents by the dynamic NMR method. The topomerization process was deduced to be ionic because the rates are enhanced in polar solvents as well as by electron-donating substituents. Concentration dependence study of the topomerization in carbon tetrachloride revealed that the observed process is unimolecular; the rates are not affected by concentration of the substrate if the concentration is lower than 0.2 mol L−1. The rates of topomerization are smaller for solutions in bulky solvents than in small solvents, the effects being clear for compounds with electron-donating substituents. The key feature of the kinetic parameters is that the entropy of activation is large and negative for all the solvents examined. The reaction mechanisms are discussed on the basis of these data. The effects of the molecular size of the solvent, dimensiosolvatic effects, are attributed to the effectiveness of the solvation in the formation of ion pairs. The results show that thermolyses of alkyl α-chlorobenzyl ethers are much slower reactions than the ionization. The nature of the reaction is discussed.
Synthesis of the Hexagonal Form of Tungsten Trioxide from Peroxopolytungstate via Ammonium Paratungstate Decahydrate
Authors: Han Wonchull , Hibino Mitsuhiro , Kudo Tetsuichi
Published: February 2006

Two types of crystalline (NH4)10[H2W12O42]·10H2O were precipitated in sequence when an ammonia solution of peroxopolytungstate was neutralized with hydrochloric acid. It was found by X-ray diffraction that one of them is an unknown phase of ammonium paratungstate, and the other is the reported one. Heating the former, it turned directly to common triclinic WO3. On the other hand, the latter yielded the hexagonal form of WO3 (h-WO3) in the temperature range 350—370 °C. This is a new synthetic method of h-WO3, though the final precursor is a known compound. The color of h-WO3 thus formed was pale yellow and contained a small amount of residual ammonia (N/W = 0.017 in molar ratio). Its crystallographic c-axis (7.689 Å) was shorter than than the reported value (7.798 Å) for the same WO3 phase synthesized from 3WO3·H2O.
Comparison of Catalytic Decomposition of Dinitrogen Oxide and Nitrogen Monoxide over Cu/ZSM-5 and Cu/Y Zeolites
Authors: Wang Jie , Mizuno Noritaka , Misono Makoto
Published: February 2006

A comparative study of NO and N2O decomposition over Cu/ZSM-5 and Cu/Y zeolites with various Cu loading levels has been carried out at 523—823 K. The Arrenhius plot of NO decomposition tended to level off above 773 K, as reported in the literature, while that of N2O decomposition was linear. It was noted that the reactivity of N2O decomposition rose much more sharply than that of NO decomposition with an increase in the level of the copper-ion exchange. The implications of these results on the reaction mechanism were discussed. In addition, the adsorption of NO on Cu/ZSM-5 and Cu/Y was measured by IR at 173—373 K and the results were compared with the catalytic decomposition results.
Reaction of Nitrides of Molybdenum and Tungsten with Hydrogen Peroxide to Form Inorganic Proton Conductors
Authors: Nakajima Hitoshi , Tanaka Hitoshi , Hibino Mitsuhiro , Kudo Tetsuichi , Mizuno Noritaka
Published: February 2006

Reactions of nitrides of Mo, W, V, and Ti with hydrogen peroxide, especially Mo and W, were investigated. The reactions were characterized by elemental analysis, NMR, IR, Raman, XPS, TOF mass, and TG/DTA spectroscopy and titration of ammonia and peroxo group. The major oxometalate species in reaction solution for Mo and W were [MoO(O2)2(OOH)]22− and [W2O3(O2)4(H2O)2]2−, respectively. As for the nitrogen-containing species, ammonium ions were initially formed, followed by the nitrate ions. Protons formed by the reaction take part in the formation of ammonia. The removal of unreacted hydrogen peroxide and the evaporation to dryness resulted in the formation of isopolymetalates. The peroxooctamolybdate, peroxododecatungstate, and decavanadate were suggested to be formed. Among them, the peroxopolytungstate was the most thermally stable and provided homogeneous thin films. The films showed protonic conductivity and the logarithm of conductivity changed linearly with the relative humidity or the inverse of the temperature.