bluuebunny/crossref_metadata_2025 huggingface dataset:
A Convenient Synthesis of Ethyl 3-(2,2-Dihaloethenyl)-2,2-dimethylcyclopropanecarboxylates and Its Modifications for cis-Isomer Enrichment
Authors: Matsui Kiyohide , Negishi Akira , Takahatake Yuriko , Sugimoto Kikuo , Fujimoto Tamotsu , Takashima Toshiyuki , Kondo Kiyosi
Published: July 2006

A synthesis of the title compounds 5 involves the reaction between 3-methyl-2-buten-1-ol and triethyl orthoacetate to produce ethyl 3,3-dimethyl-4-pentenoate, which is followed by the addition of various carbon tetrahalides to the double bond. The reaction of resulting adducts with a base affords 5 in high yields. Stereoselective preparation of the cis-isomer was achieved by the following two methods: First one involves selective transformation of ethyl 4-bromo-6,6,6-trichloro-3,3-dimethylhexanoate to ethyl 6,6,6-trichloro-3,3-dimethyl-4-hexenoate (8a) with piperidine followed by the selective conversion of 8a to cis-2,2-dichloroethenyl compound (cis-5a). Second one is based on the stereoselective cyclization of ethyl 4,6,6,6-tetrachloro-3,3-dimethylhexanoate (t-BuONa/solvent/HMPA) to ethyl cis-2,2-dimethyl-3-(2,2,2-trichloroethyl)cyclopropanecarboxylate which is transformed into cis-5a without cis-trans isomerization.
Vertical Concentration Distributions of Arsenic in a Reservoir and Its Sediment
Authors: Tamari Yuzo , Nishimura Kimio , Tsuji Haruo , Kusaka Yuzuru
Published: July 2006

Vertical concentration distributions of arsenite and arsenate in a reservoir (depth, ≈31 m) and its bottom sediment (core depth, ≈18 cm) have been investigated. The concentrations of arsenite and arsenate in the water were determined by a spectrophotometric method, and those in the sediment were also determined by the same method after the following leaching-treatments of the sediment. The leaching of arsenic from the sediment was carried out by using three solutions; (1) 0.1 M hydrochloric acid (acid-soluble fraction), (2) 1 M sodium hydroxide solution (alkali-soluble fraction), and (3) hydrofluoric and perchloric acid mixture (silicate fraction). It was found that arsenic was rich in the surface layer of the sediment, and most of it existed as arsenite fixed with iron hydroxide. Based on the analytical and leaching results of arsenic, iron, manganese, zinc, copper, and others in the reservoir and in its sediment respectively, the sedimentation process of arsenic from the reservoir and its dissolution process from the sediment have been discussed.
Racemic Structures and Optical Resolutions by Preferential Crystallization of Organic Ammonium Salts of N-Formyl-Dl-phenylalanine
Authors: Shiraiwa Tadashi , Miyazaki Hideya , Sakamoto Yoshihiro , Kurokawa Hidemoto
Published: July 2006

Racemic structures of the butylammonium salt, pentylammonium salt, benzylammonium salt, dicyclohexylammonium salt(Dl-DCH salt), and 4-methylpiperidinium salt(Dl-4-MP salt) of N-formyl-Dl-phenylalanine were studied to explore the possibility of optical resolution by preferential crystallization. Free energies of formation of racemate (ΔGF) of the Dl-salts and data at eutectic points in binary phase diagrams of melting points indicate that the Dl-salts form racemic compounds in the vicinity of the melting points. However, according to ΔGF of Dl-DCH and 4-MP salts and infrared spectra and solubilities of the Dl- and l-salts, these Dl-salts transform into conglomerates around room temperature. It is possible to resolve Dl-DCH and 4-MP salts by preferential crystallization at 10 °C. Successive preferential crystallization of Dl-4-MP salt at 10 °C in 1-butanol gives the d- and l-salts with optical purities of 95–100%.
Preparation and Complexing Properties of Crown Ether Compounds Incorporating a Ferrocene Unit at 1,2- or 1,3-Positions
Authors: Izumi Taeko , Saitou Katsuo , Matsunaga Shigeki , Kasahara Akira
Published: July 2006

Ten new crown ethers incorporating a ferrocene unit at 1,2- or 1,3-positions are reported. These crown ethers were synthesized by the reaction of 1,2- or 1,3-bis(hydroxymethyl)ferrocene with oligoethylene glycol ditosylate (n=1–5) with potassium t-butoxide by a high-dilution method. These new types of ferrocene crown ethers were examined for complexation behavior with alkali, alkaline earth, and transition-metal cations by solvent extraction. It was found to extract thallium ions most effectively.
Thermal Racemization of Thiaheterohelicenes
Authors: Yamada Koh-ichi , Nakagawa Hiroko , Kawazura Hiroshi
Published: July 2006

Thermal racemizations of four thiaheterohelicenes (TH) with alternant thiophene and benzene rings were examined and compared with those of carbohelicenes (CH). The racemization rate of [5]TH was very fast at room temperature, and the rates of [7]TH and [9]TH were found to be 1/5 to 1/50 times slower than the corresponding CH having a similar internal angle. The ΔS\eweq values obtained by temperature-variable experiments showed a large difference between [7]TH (−103.9±4.8 JK−1 mol−1) and [9]TH (−66.3±4.0), suggesting different conformations in the transition state. CNDO calculations on the transitional conformations of [5]TH demonstrated that a geometry, such as that distorting the benzene rings, has a lower energy than a geometry such as that twisting the thiophene ring. Based upon these results, the conformations in the transition states for the THs are inferred.
Infrared Absorption Study of Human Proinsulin C-Peptide Fragments in the Solid State
Authors: Narita Mitsuaki , Ogura Toshihiko , Sato Kazuhiro , Honda Shinya
Published: July 2006

In order to evaluate the propriety of the solubility prediction method for peptide intermediates having polar side chains, IR absorption spectroscopic analysis of human proinsulin C-peptide fragments was performed in the solid state. The polar amino acid residues involved in the peptide fragments are in the following: Glu(OBzl), Asp(OBzl), Gin, and Ser(Bzl). All peptide fragments except for ones containing the Pro residue exhibit a high potential for the formation of a β-sheet structure, indicating that, even when the polar side chains of the Glu, Asp, and Ser residues are protected by the Bzl group, the coil conformation parameter Pc for each amino acid residue is useful for estimating the potential for the formation of a β-sheet structure of peptide fragments smaller than critical size for development of α-helical structure in the solid state. As in the case of hydrophobic peptides, the β-sheet aggregation clearly plays an important role in reducing solubility of the peptide fragments having polar side chains. The effect of the Pro residue on the disturbance of the β-sheet structure was also observed. The ability of the short-range (polar side chain-backbone) or intraresidue interactions due to the low flexibility of the pyrrolidine ring of the Pro residue to promote helical folding in peptide fragments in the solid state was not observed for the peptide fragments corresponding to helical regions of human proinsulin.
Stereospecific Desulfinylation of α,β-Epoxy Sulfoxides with Butyllithium. A New Synthesis of Epoxides and Allylic Alcohols from Carbonyl Compounds
Authors: Satoh Tsuyoshi , Kaneko Youhei , Yamakawa Koji
Published: July 2006

Desulfinylation of α,β-epoxy sulfoxides, easily prepared from carbonyl compounds and 1-chloroalkyl phenyl sulfoxide, with 1 equivalent of butyllithium at low temperature gave epoxides in good yields. The similar α,β-epoxy sulfoxides having an arylmethyl group at the α-position gave 3-aryl-allylic alcohols upon treatment with excess butyllithium at −70 °C. These reactions offer a simple and useful approach to the synthesis of epoxides and 3-aryl-allylic alcohols from a carbonyl compound.
Formation and Reaction of Carbonyl Ylides. Production of 2 : 1-Cydoadducts of 2-Benzopyrylium-4-olates with Carbonyl Compounds
Authors: Ibata Toshikazu , Toyoda Jiro
Published: July 2006

The Cu(acac)2-catalyzed decomposition of o-(diazoacetyl)benzoates in the presence of carbonyl compounds such as benzaldehydes, acetophenones, acetone, fluorenone, and anthraquinone gave 2 : 1-adducts of the corresponding 2-benzopyrylium-4-olate (3) and the carbonyl compound, together with 1 : 1-adducts. The 2 : 1-adducts were confirmed to be produced by the cycloaddition of 3 toward the carbonyl group of the 1 : 1-adducts which have bulky aryl groups on exo-direction. The product ratios of the 2 : 1-adducts were explained according to the MNDO calculation.
The Synthesis of Macrocyclic Diaza n-n′-Fulvadiene Derivatives
Authors: Ojima J\={u}ro , Ejiri Emiko , Manaka Sumio , Morita Noboru , Asao Toyonobu
Published: July 2006

The diaza analogs of 7-13-, 7-15-, 7-17-, 13-13-, 13-15-, 15-15-, and 19-19-fulvadiene derivatives were synthesized through the reaction of 2,4,6-cycloheptatrienone and the corresponding bisdehydroannulenones with hydrazine dihydrochloride. The 1H NMR and electronic spectra of these compounds are discussed in connection with tropicity.
Bromochlorination of Alkenes with Dichlorobromate (1−) Ion. IV. Regiochemistry of Bromochlorinations of Alkenes with Molecular Bromine Chloride and Dichlorobromate (1−) Ion
Authors: Negoro Takeshi , Ikeda Yoshitsugu
Published: July 2006

The regioselectivity of the addition of molecular bromine chloride to alkenes is dependent on both the steric and electronic effects of the alkyl substituent. In contrast, the regioselectivity of the addition of dichlorobromate (1−) ion to alkenes is controlled mainly by the steric effect of the substituent.
Crystal and Molecular Structures of the Adduct of Fluoreno[9,1-bc]pyrylium-3-olate with Methyl Cinnamate and the Dimer of Fluoreno[9,1-bc]pyrylium-3-olate
Authors: Fukuyama Keiichi , Fujita Hideo , Tokushima Shigeru , Tsukihara Tomitake , Katsube Yukiteru , Motoyama Tadayuki
Published: July 2006

The molecular structures of the adduct of fluoreno[9,1-bc]pyrylium-3-olate with methyl cinnamate (1), C25H18O4, and the dimerized product of fluoreno[9,1-bc]pyrylium-3-olate (2), C30H16O4, have been determined by the X-ray diffraction method. In the adduct (1), the phenyl ring is situated above the fluorene ring with a dihedral angle of 64°. The product 2 has a dimeric structure with a head-to-head type anti-configuration, and a local two-fold symmetry. Both crystals belong to a triclinic system with a space group P\bar1. The cell constants for 1 are a=13.287(4), b=8.794(3), c=8.797(3) Å, α=109.78(3), β=82.17(3), γ=88.58(3)°, and those for 2 are a=10.401(2), b=12.425(3), c=8.564(2) Å, α=103.77(4), β=108.76(4), γ=95.06(4)°. The structure of 1 was refined to R=0.067 for 2141 reflections, and that of 2 to R=0.058 for 2301 reflections.
Carbon Monoxide Adsorbent Composed of Copper(I) Chloride and Polystyrene Resin Having Amino Groups
Authors: Hirai Hidefumi , Wada Keiichiro , Kurima Kazunori , Komiyama Makoto
Published: July 2006

A novel adsorbent of carbon monoxide (CO) is prepared by stirring copper(I) chloride and a macroreticular type polystyrene resin having amino groups in acetonitrile, followed by removal of the liquid phase at 5 mmHg, 80 °C. The adsorbent rapidly adsorbs carbon monoxide from 9 : 1 carbon monoxide–nitrogen mixture at 20 °C under 1 atm. The adsorbed carbon monoxide is readily desorbed by heating the adsorbent to 80 °C under 1 atm or by reducing the partial pressure of carbon monoxide to 5 mmHg at 20 °C. The CO adsorbing capacity (15.9 mmol) of the adsorbent composed of 10.0 g of the resin and 70 mmol of copper(I) chloride is 5.7 times as large as the carbon dioxide adsorbing capacity (2.8 mmol). The efficient adsorption of carbon monoxide by the present adsorbents is attributed to coordination of carbon monoxide to the copper(I) ions which coordinate the amino residues in the resin. The carbon dioxide adsorbing capacity (2.8 mmol) of the adsorbent is much smaller than that (8.3 mmol) of the resin without copper(I) chloride. The present adsorbent exhibits no measurable adsorptions of methane, nitrogen, and hydrogen at 20 °C under 1 atm, and thus is applicable to selective separation of carbon monoxide from gas mixtures containing these gases and carbon dioxide.
Synthesis of 2-Pyrrolidinylideneacetates by Means of a Reaction of Magnesium Ester Enolate with γ-Cyanoalkyl Tosylates
Authors: Kobayashi Kazuhiro , Suginome Hiroshi
Published: July 2006

We describe a new and efficient synthesis of t-butyl 2-pyrrolidinylideneacetate and its 3-substituted derivatives from a reaction of the magnesium enolate of t-butyl acetate with γ-cyanoalkyl tosylates.
Cyclic Peptides. XXIII. Synthesis of Retro-Enantio-AM-Toxin I
Authors: Mihara Hisakazu , Aoyagi Haruhiko , Ueno Tamio , Kato Tetsuo , Izumiya Nobuo
Published: July 2006

To characterize a receptive substance in an apple leaf of phytotoxic AM-toxin I, retro-enantiomer of the toxin was synthesized by the solution method. This analog showed no toxic activity, indicating that the specific backbone conformation of the toxin is essential for the activity.
Studies on the Valence State of Iron Atoms in the Mixed-Valence Binuclear Ferrocenes by X-Ray Absorption Near Edge Structure (XANES) and by X-Ray Photoelectron Spectroscopy (XPS)
Authors: Iwai Kumiko , Iwai Makoto , Suto Kyoko , Nakashima Satoru , Motoyama Izumi , Sano Hirotoshi , Ikemoto Isao , Kosugi Nobuhiro , Kuroda Haruo
Published: July 2006

In order to study the valence state in the mixed-valence binuclear ferrocenes, X-ray absorption spectra near the Fe K-edge were measured using synchrotron radiation. Well-resolved lines in the spectra obtained for ferrocene derivatives were assigned to the 1s→3d, 1s→Cp(π*), and 1s→4p transitions, respectively, based on the molecular orbitals. There is an apparent difference in the 1s→3d transitions between trapped-valence compounds and averaged-valence compounds in the I3− salts of the monocation of binuclear ferrocenes. The valence states of the mixed-valence binuclear ferrocenes were also studied by X-ray photoelectron spectroscopy.
Effect of Pressure on the Adsorption and Micelle Formation of Aqueous Dodecyltrimethylammonium Chloride–Cyclohexane System
Authors: Yamanaka Michio , Aratono Makoto , Motomura Kinsi
Published: July 2006

The interfacial tension of aqueous dodecyltrimethylammonium chloride (DTAC) solution–cyclohexane system was measured as a function of pressure at concentrations around the critical micelle concentration (cmc). The derivative of interfacial tension with respect to pressure was observed to change abruptly at the cmc. The volume changes associated with the adsorption of DTAC from its monomeric and micellar states and the volume of micelle formation were calculated and compared with the corresponding ones of the aqueous DTAC solution–hexane system. It was found that the molar interfacial excess volume of the adsorbed film is slightly larger than the molar volume of micelle in the case of the cyclohexane system, while in the case of the hexane system the former is approximately equal to the latter. Further, it was concluded that the micellar particles solubilize molecules of the oil coexisting in equilibrium with the aqueous solution. It was also proved in the case of the present system that the micelle formation can be treated thermodynamically as the appearance of a macroscopic bulk phase in the solution.
Photochemical Magnetic-Field Effects of Isoquinoline N-Oxide in Various Alcohols
Authors: Hata Norisuke
Published: July 2006

A pronounced solvent dependence of the magnetic-field effect due to the HFI-J mechanism was found for the first time in the case of a photochemical isomerization of isoquinoline N-oxide into lactam (1-isoquinolone). The chemical yield of the lactam showed a minimum at a higher magnetic field as one changes the reaction medium from t-butyl alcohol to 2-propanol (or ethanol) and then to methanol, which was the same order as the pKa value (t-butyl alcohol>2-propanole≈ethanol>methanol). Such a solvent dependence provides corroborating evidence that the photoisomerization proceeds via the S1-born singlet radical-ion-pair intermediate, which is linked by a hydrogen bond between the N→O group in the cation radical of N-oxide and the OH group in the anion radical of alcohol. Another interesting finding was that, in the case of the photochemical isomerization in t-butyl alcohol, the chemical yield of the lactam showed distinct maxima at approximately 0.9T and 1.35T in addition to a minimum at about 0.72T. The anomalous magnetic-field effect in a high field region (>0.8T) could reasonably be explained in terms of an HFI-J mechanism by assuming the T1-born triplet hydrogen-bonded radical-ion pair to have an electron-exchange interaction larger than that in the S1-born singlet hydrogen-bonded radical-ion pair.
Nuclear Magnetic Resonance Studies of Copper(I) Complexes of Imidazoles. I. Their Preparation, Characterization, Equilibria, and Reaction with Carbon Monoxide
Authors: Kitagawa Susumu , Munakata Megumu
Published: July 2006

Various copper(I) complexes with monodentate imidazole(im) have been prepared from [Cu(CH3CN)4]X (X=ClO4− and PF6−) in acetone. Their characterization has principally been made by 1H NMR spectroscopy. Binary copper(I) complexes are [Cu(im)2]+ (2) and [Cu(im)3]+ (3), while the monoimidazole complex is a ternary two- or four-coordinate complex (1). In contrast with 2 and 3, quantitative formation of [Cu(im)4]+ (4) does not occur in acetone. Even at [im]/[Cu]<2, 2 forms more preferentially than 1. This is due to the linear structure of 2. 2 and 3 provide stable CO adducts, both of which display complete reversibility. The affinity for CO of 3 is much stronger than that of 2. Pyrazole copper(I) complexes were also prepared and examined as a comparison with imidazole complexes. Monodentate pyrazole hardly gives two- and three-coordinate complexes. This is attributable to its low basicity in contrast with that of imidazole.
Preparation of Cubic HZr2(PO4)3 and Related Compounds
Authors: Ono Akira , Yajima Yoshiyuki
Published: July 2006

A single phase of cubic NH4Zr2(PO4)3 with a langbeinite-type structure was prepared at 235 °C by a hydrothermal method. A series of analogous compounds containing various monovalent cations or vacancies were made by starting with cubic NH4Zr2(PO4)3. They are polymorphs with respect to Nasicon-type compounds and have rigid skeleton structures with interstitial spaces partially occupied by monovalent ions and water molecules. Maximum water contents of the cubic compounds decrease with increasing sizes of the monovalent ions. Proton-bearing cubic compound exhibited ion exchange reactions with NaCl and LiCl solutions at 20 °C. This suggests the existence of bottlenecks large enough for permitting diffusion of Na+ and Li+ ions. Low thermal expansion of cubic NaZr2(PO4)3 was studied by high-temperature X-ray diffraction.
Green and Brown Isomers of the ((S)-1-Amino-2-propanethiolato-N,S)(1,4,7,10-tetraazacyclododecane)cobalt(III) Ion and Crystal Structure of the Green Isomer
Authors: Kojima Masaaki , Nakabayashi Kyoko , Ohba Shigeru , Okumoto Satoshi , Saito Yoshihiko , Fujita Junnosuke
Published: July 2006

The [Co(S-apS)(cyclen)]2+ (S-apS=(S)-1-amino-2-propanethiolate ion, cyclen=1,4,7,10-tetraazacyclododecane) complex was prepared and separated into two isomers (green and brown) by column chromatography. The crystal structure of the green isomer, [Co(S-apS)(cyclen)]ZnCl4·H2O was determined by X-ray analysis. Crystal data are as follows: monoclinic, space group P21, a=9.382(2), b=13.124(3), c=8.934(2) Å, β=91.08(3)°, and Z=2. The complex ion has a cis-octahedral geometry with the cyclen ligand coordinated in a folded, butterfly-like configuration and the bidentate S-apS ligand in a δ-gauche form. One of the two “planar” NH hydrogens of the macrocycle with respect to the S-apS ligand is directed opposite the S-apS chelate ring (exo), while the other “planar” and the remaining two “apical” NH hydrogens are directed to the S-apS ring (endo). The green isomer can be represented by endo(S,NH), where NH denotes the planar NH hydrogen cis to the sulfur atom. The other brown isomer was assigned as the exo(S,NH) configuration, where the S and NH2 coordination sites of S-apS in the green isomer are interchanged with each other, remaining the configuration of the macrocycle unchanged. Reversible isomerization between the two isomers occurred in aqueous solution and the kinetics was studied at 25.4 °C in the pH range of 5.98–6.97. The isomerization obeyed a rate law of the form, R=k[OH−]·[complex], and was suggested to take place with synchronous inversion at the two nitrogen atoms of the macrocycle. The relative abundance of the two isomers at equilibrium is 1.0, and the forward and reverse second-order rate constants at 25.4 °C are 6.5×103 mol−1 dm3 s−1.
Reaction of Carbocations Derived from Alkanes with Carbon Monoxide in HF–SbF5 Superacid
Authors: Yoneda Norihiko , Takahashi Yukio , Fukuhara Tsuyoshi , Suzuki Akira
Published: July 2006

Alkanes readily react with CO and H2O in HF–SbF5 at 30 °C under atmospheric pressure and give considerably different product distributions from those in the usual Koch–Haaf reaction. When using C5-or C6-alkanes with tertiary C–H bonds, a considerable amount of secondary carboxylic acids are produced by the reaction of CO with secondary alkyl cations. Such cations may appear as transient intermediates in the course of the carbon skeletal isomerization of initially formed tertiary cations. For the straight-chain alkanes, the protonolysis at C–C bonds initiated the reaction to give fragment alkyl cations. This resulted in the formation of carboxylic acids with a lower number of carbon atoms than the starting alkanes. Intermolecular hydride shift between the fragment cations and the starting alkanes occurred at the same time to form a large amount of carboxylic acids with the alkyl group of the same number of carbon atoms as the starting alkane. On the other hand, for alkanes with more than seven carbon atoms, β-scission occurs exclusively to produce C4–, C5–, and C6–carboxylic acids.
Synthesis of Vinylcyclopropanes, Cyclopropyl Vinyl Ketones, and 3-Pyrazolyl Vinyl Ketones from 1-Diazo-3-trimethylsilylpropanone
Authors: Tsuge Otohiko , Kanemasa Shuji , Suzuki Toshiro , Matsuda Koyo
Published: July 2006

Reaction of 1-diazo-3-trimethylsilylpropanone with olefins in the presence of cupric acetylacetonate (Cu(acac)2) affords cyclopropyl trimethylsilylmethyl ketones. One-flask procedure for the formation of these silylated ketones and subsequent treatment with organometallics or with lithium diisopropylamide (LDA) and then carbonyl compounds gives a variety of vinylcyclopropanes or cyclopropyl vinyl ketones in good yields, respectively. Cycloaddition of 1-diazo-3-trimethylsilylpropanone with acetylenes and similar carbon–carbon bond formation at the side chain of the cycloadducts lead to 3-pyrazolyl vinyl ketones.
The Stereochemistry of the Reduction of Carbon–Carbon Double Bond with the Cultured Cells of Nicotiana tabacum
Authors: Suga Takayuki , Hirata Toshifumi , Hamada Hiroki
Published: July 2006

The stereochemistry in the reduction of the C–C double bond adjacent to the carbonyl group with the cultured cells of Nicotiana tabacum was investigated by feeding (4R)-[6-2H]-(−)-carvone to the cultured cells. It was found that the hydrogen attack to the C–C double bond takes place stereospecifically from the si-face at C-1 and the re-face at C-6, being trans-addition.
Phenolic Solvent-Assisted Hydrogenolysis of trans-Stilbene
Authors: Mizuki Tatsuro , Futamura Shigeru , Kamiya Yoshio
Published: July 2006

Phenolic solvents such as phenol, 3,4-xylenol, 2-naphthol, and 5,6,7,8-tetrahydro-2-naphthol greatly promote toluene formation in the hydrogenolysis of trans-stilbene, compared with hydroaromatic hydrocarbon solvents. Toluene is afforded in the thermal decomposition of the phenolic solvent adduct to trans-stilbene, not via bibenzyl.
A 14N NMR Relaxation Study of Aqueous Alkyltrimethylammonium Salt Solutions
Authors: Uzu Yuhei , Nakagawa Jiro , Yokoi Masatoki
Published: July 2006

14N spin–lattice and spin–spin relaxation times were measured in a series of alkyltrimethylammonium salts at higher concentrations above the critical micell concentration. Octyltrimethylammonium bromide and dodecyltrimethylammonium chloride form spherical micelles at all concentrations, while decyl- and dodecyltrimethylammonium bromides form larger and rodlike micelles such as the hexadecyltrimethylammonium bromide suggested previously.
Optical Spectra of Tocopheroxyl Model Radicals
Authors: Mukai Kazuo , Watanabe Yoshiko , Ishizu Kazuhiko
Published: July 2006

Tocopheroxyl model radicals have been prepared by the reaction between tocopherol models and stable phenoxyl radical in ethanol under nitrogen atmosphere. Optical spectra were recorded, and wavelength of absorption peaks (λmax) and molar extinction coefficients (ε) were correctly determined.
Thermal Isomerization Equilibrium between 2′-Hydroxychalcones and Flavanones
Authors: Hoshino Yukio , Takeno Noboru
Published: July 2006

Nine substituted 2′-hydroxychalcones and the corresponding flavanones were heated separately at 230±0.2 °C in nitrogen atmosphere. Both materials were mutually isomerized under these reaction conditions and the equilibrium constants of this isomerization were measured by means of HPLC analyses. The substituent effect on the equilibrium is discussed and thermodynamic functions (ΔG, ΔH, and ΔS) are calculated.
Flow Injection Analysis of Cobalt(II) by Catalytic Oxidations of Stilbazo and Pyrocatechol Violet
Authors: Deguchi Toshio , Higashi Atsuya , Sanemasa Isao
Published: July 2006

Catalytic oxidations of ten organic dyes with an aromatic-hydroxyl or -amino functional group have been studied in the presence of metal ions such as cobalt(II), copper(II), and vanadium(V). Of these dyes, six were found to be effectively oxidized and decolorized specifically by one of these metals. 4,4′-Bis(3,4-dihydroxyphenylazo)stilbene-2,2′-disulfonic acid diammonium salt (Stilbazo) and 3,3′,4′-trihydroxyfuchsone-2″-sulfonic acid (Pyrocatechol Violet) were found to be promising for determining trace amounts of cobalt(II). The optimum analytical conditions have been studied for these two compounds with the aid of a flow injection analysis technique. The both reagents can be used to determine cobalt(II) down to 1 ppb.
Synthesis of 2,3-Dihydro-2-alkyl-3-(substituted amino)-1H-isoindol-1-ones. 2-Alkylation of 2,3-Dihydro-3-(substituted amino)-1H-isoindol-1-ones in a Phase-Transfer Catalyst System
Authors: Sato Ryu , Senzaki Toshihide , Goto Takehiko , Saito Minoru
Published: July 2006

A variety of 2,3-dihydro-2-alkyl-3-(substituted amino)-1H-isoindol-1-ones were conveniently synthesized by selective 2-alkylation of 2,3-dihydro-3-(substituted amino)-1H-isoindol-1-ones, which were derived from 2-cyanobenzaldehyde, with some alkyl halides in a phase-transfer catalyst system.
The Crystal and Molecular Structures of Bis(ethylenedithio)tetrathiafulvalene
Authors: Kobayashi Hayao , Kobayashi Akiko , Sasaki Yukiyoshi , Saito Gunzi , Inokuchi Hiroo
Published: July 2006

The X-ray crystal structure analysis of a sulfur containing π-donor molecule, bis(ethylenedithio)tetrathiafulvalene, (BEDT-TTF) shows that the BEDT-TTF molecule is nonplanar and that the crystal is composed of pairs of BEDT-TTF.
Reaction of Hydroxide Ion with Electron Acceptors in Dimethyl Sulfoxide
Authors: Umemoto Kisaburo , Okamura Nobuyuki
Published: July 2006

In dimethyl sulfoxide, the reaction of hydroxide ion with several electron acceptors—iodine, tetracyanoquinodimethan, Nitro Blue Tetrazolium chloride, 2,3,5-triphenyltetrazolium chloride, anthraquinone, and benzophenone—gave reaction products identical to those obtained by the reaction of these electron acceptors with electron donors. The reaction pathways of these electron acceptors were found to be composed of successive one-electron reactions similar to the electrochemical reduction of these electron acceptors. These results indicate that hydroxide ion acts as a reductant in dimethyl sulfoxide.
Ylide–Metal Complexes. XI. The Preparation and Properties of VIA Group Metal (Te) Complexes of Alkylidenetriphenylphosphoranes and the Corresponding Selenium Compounds
Authors: Yamamoto Yoshihisa
Published: July 2006

Reactions of (C6H5)3P=CH2 (L) with TeCl4 of mole ratios 2 : 1 and 3 : 1 yield new compounds: dichlorobis(methylenetriphenylphosphorane)tellurium dichloride, [L2TeCl2]Cl2 (1), and chlorotris(methylenetriphenylphosphorane)tellurium trichloride, [L3TeCl]Cl3 (2), respectively. The reaction of ylide L with compound 1 yields a new compound: tetrakis(methylenetriphenylphosphorane)tellurium tetrachloride, [L4Te]Cl4 (3). The structure of compounds 1–3 is a distorted tetrahedron. The color of 1–3 is yellow. The electronic absorption spectra of compounds 2 and 2 show six absorption bands in the region 200–500 nm in dry dichloromethane. The reactions of ylide L with (C6H5)2SeCl2 of mole ratios 1 : 1 and 2 : 1 yield new compounds: chloro(methylenetriphenylphosphorane)diphenylselenium chloride, [LSe(Cl)(C6H5)2]Cl (9), and bis(methylenetriphenylphosphorane)diphenylselenium dichloride, [L2Se(C6H5)2]Cl2 (11), respectively. The color of the selenium compounds is white. The tellurium and selenium compounds are thermally stable in the solid state.
The Crystal Structure of a Squarylium Dye, 2,4-Bis(1,3,3-trimethyl-2-indolinylidenemethyl)cyclobutenediylium-1,3-diolate
Authors: Kobayashi Yoshinori , Goto Midori , Kurahashi Masayasu
Published: July 2006

The crystal structure of 2,4-bis(1,3,3-trimethyl-2-indolinylidenemethyl)cyclobutenediylium-1,3-diolate has been determined. The space group is P21⁄c, with a=9.5115(4), b=15.712(1), c=15.174(1) Å, β=96.138(5)°, and Z=4. The molecule adopts the trans conformation.
Highly Enantioselective Reduction of Ethyl 2-Acyloxy-3-oxobutanoate with Immobilized Baker’s Yeast
Authors: Sakai Takashi , Nakamura Toshiki , Fukuda Katsuyoshi , Amano Eiichiro , Utaka Masanori , Takeda Akira
Published: July 2006

Reduction of ethyl 2-acetoxy-3-oxobutanoate (4a) with immobilized baker’s yeast in calcium alginate gel gave a 18 : 19 : 63 mixture of ethyl (2R,3S)- and (2S,3S)-2-acetoxy-3-hydroxybutanoates and ethyl (2S,3S)-2,3-dihydroxybutanoate each with >95% e.e. in 58% yield. A similar treatment of a 2-benzoyloxy analog of 4a afforded a 6 : 94 mixture of ethyl (2R,3S)- and (2S,3S)-2-benzoyloxy-3-hydroxybutanoates (>95% e.e.) in 70% yield. Their absolute configurations were determined by comparison with authentic (2R,3S)- and (2S,3S)-2,3-dihydroxybutanoic acids. Effects of the immobilization and the pH of culture solution on the product ratio are also discussed.
The High Pressure Diels–Alder Reactions of 5-Methoxy-2-methyl-4-(p-nitrophenyl)oxazole with Ethylenic Dienophiles
Authors: Ibata Toshikazu , Nakawa Hiroyuki , Isogami Yasushi , Matsumoto Kiyoshi
Published: July 2006

The high pressure Diels–Alder reactions of 5-methoxy-2-methyl-4-(p-nitrophenyl)oxazole with ethylenic dienophiles such as N-methylmaleimide, N-phenylmaleimide, dimethyl maleate and dimethyl fumarate gave the corresponding adducts in good to excellent yields. The effects of pressure, temperature, solvents on the yields were investigated. The high pressure also increased the formation of 3-hydroxypyridine derivatives via the elimination of methanol from the adducts. The stereospecificity of the reaction was confirmed for the reactions with maleate and fumarate.
Preparation of Optically Active Piperazines from Ethyl (S)-2-(2-Alkyl-1-aziridinyl)acetates
Authors: Yahiro Nobuhide , Ito Shigekazu
Published: July 2006

Reaction of ethyl (S)-2-(2-alkyl-1-aziridinyl) acetates with boron trifluoride etherate in a large excess of ethylamine or ammonia gives the corresponding optically active piperazines in good yields. These piperazines retain the configuration of the starting aziridines.
Kinetics and Mechanism of Anation of Pentaammineaquarhodium(III) Ion by Malonate in Weakly Acidic Media
Authors: Chatterjee Chinmay , Bali Aya Singh
Published: July 2006

Anation of pentaammineaquarhodium(III) ion by malonic acid, hydrogenmalonate, and malonate ions to form the hitherto unknown pentaamminemalonatorhodium(III) complex has been studied as a function of [H+] for the acidity range 1.4≤ pH ≤5.0, [total malonate], 0.3 mol dm−3 in the temperature range of 60 to 80 °C and at ionic strength 1.0 mol dm−3 adjusted with sodium perchlorate. Ion pairing is not significant between the complex and malonic acid but kinetically identifiable with hydrogenmalonate and malonate ions. Ion pair association constants for the hydrogenmalonate (Q1) and malonate ion (Q2) at 60 °C are 1.8 and 7.5 mol−1 dm3 respectively. The values of the rate constants at 60 °C for anation by malonic acid, hydrogenmalonate, and malonate ions are k0=3.04±0.2×10−5 mol−1 dm3 s−1, k1=1.73±0.2×10−4 s−1, and k2=3.46±0.4×10−4 s−1. The activation parameters, ΔH\eweq and ΔS\eweq corresponding to anation rate constants, k0, k1, and k2 are reported and the results discussed with reference to analogous reactions of Rh(III) and Co(III).
A 15N NMR Study of the Tautomeric Equilibria of Some 5-Substituted Tetrazoles
Authors: Bojarska-Olejnik Elzbieta , Stefaniak Lech , Witanowski Michal , Webb Graham A
Published: July 2006

15N NMR shielding data are presented for some 5-tetrazolones and some 5-tetrazolethiones. CNDO/S-SOS nitrogen shielding calculations are also performed for these compounds. The results obtained show that the compounds studied exist almost entirely in the oxo and thioxo forms, rather than the hydroxy or mercapto forms respectively, in DMSO solution.
The Structure of Bis(μ-thiocyanato)-bis[tris(benzylamine)(thiocyanato)nickel(II)], [Ni(SCN)2(C6H5CH2NH2)3]2
Authors: Taniguchi Masahiro , Ouchi Akira
Published: July 2006

The crystal and molecular structure of the title complex was determined by means of a single-crystal X-ray diffraction method. A crystal of Ni2C46H54N10S4, F. W. 992.67, is triclinic with a space group P\bar1, a=13.259(4), b=15.627(5), c=6.5150(16) Å, α=90.60(3), β=93.64(2), γ=112.601(19)°, U=1242.9(6) Å3, Z=1, Dm=1.32(3), Dx=1.33 Mg m−3, and μ(Mo Kα)=9.60 cm−1. The central metal atom is hexa-coordinated, being ligated with three benzylamine and two thiocyanato (SCN) nitrogen atoms as well as one SCN sulfur atom. Two metal atoms are bridged by two SCN ions; however, the Ni-S bond length is 2.639(3) Å, which is a little longer than the sum of the Shannon’s ionic radii. The distance Ni···Ni is 5.717(3) Å and the dimeric complexes are discrete in a crystal.
A Convenient Method for Conversion of Allylic Chlorides to α,β-Unsaturated Aldehydes
Authors: Suzuki Shigeaki , Onishi Takashi , Fujita Yoshiji , Misawa Hiromitsu , Otera Junzo
Published: July 2006

Tertiary amine N-oxides were found to be effective for converting allylic chlorides to α,β-unsaturated aldehydes.
Gas-Chromatographic Measurements of Atmospheric Sulfur Hexafluoride
Authors: Hirota Michio , Muramatsu Hisafumi
Published: July 2006

From air samplings on aircraft in February and December 1982 and in February 1983, and from gas-chrornatographic measurements, the background volume mixing ratio of sulfur hexafluoride(SF6) over Japan was found to be about (0.72±0.13) ppt, where ppt=10−12. Since the first observation by Lovelock in 1970 (0.03 ppt), SF6 seems to have been increasing steadily.
Synthesis of Phosphirane Oxide Derivatives Promoted by Introduced Phenylsulfinyl Groups and Their Pummerer Reaction
Authors: Oshikawa Tatsuo , Yamashita Mitsuji
Published: July 2006

Phosphirane oxide derivatives were first successfully synthesized in good yield under mild conditions wherein carbon–carbon bond formation was promoted by two phenylsulfinyl groups on the α and α′ carbons of the phosphorus atom. A structure determination of the formed phosphirane oxide derivatives as well as the stereochemistry of the Pummerer reaction product revealed a trans geometry for the phosphirane oxide.
Chromotropisms of Imidazole Derivatives. III. Crystal Structure of 4,5-Bis(4-methoxyphenyl)-2-(4-nitrophenyl)-1H-imidazole
Authors: Inouye Yoshinobu , Sakaino Yoshiko
Published: July 2006

The molecular and crystal structure of the title compound was determined by the single-crystal X-ray analysis. The crystal is orthorhombic with a space group Pbca, a=15.161 (9), b=25.805 (5), c=9.948 (1) Å, and Z=8. The 4-nitrophenyl ring is nearly on a same plane with the imidazole ring, while the other two benzene rings make angles of 26.5° and 47.7°.
A Convenient Synthesis of N-Substituted Formamidines by Desulfurization of the Corresponding Thioureas
Authors: Kashima Choji , Shimizu Masao , Eto Takeshi , Omote Yoshimori
Published: July 2006

N,N′-Di- and N,N,N′-trisubstituted thioureas were easily desulfurized by Raney nickel to yield the corresponding formamidines, while N-monosubstituted thioureas gave N,N′-disubstituted formamidines.
Asymmetric Reduction of Aromatic Ketone in a Continuous Flow System
Authors: Itsuno Shinichi , Ito Koichi , Maruyama Toshihiro , Kanda Naoki , Hirao Akira , Nakahama Seiichi
Published: July 2006

When THF–borane (1/1) and aromatic ketone were supplied continuously to the column containing polymer-supported (S)-(−)-2-amino-3-(p-hydroxyphenyl)-1,1-diphenyl-1-propanol, the chiral product, secondary benzylic alcohol, could be obtained successfully (>90% ee). Large quantities of highly optically pure alcohol could be produced by the continuous flow system by the use of only a small amount of polymeric auxiliary.
Electrocatalysis of the Heat-Treated (5,10,15,20-Tetraphenylporphyrinato)manganese(III) Halides for Cathodic Reduction of Oxygen
Authors: Ikeda Osamu , Kojima Toyosei , Tamura Hideo
Published: July 2006

Electrocatalysis of the heat-treated (5,10,15,20-tetraphenylporphyrinato)manganese(III) halides (MnIII(TPP)X, X:F−, Cl−, Br−, I−) for the O2 reduction in an alkaline solution has been studied by rotating ring-disc electrode technique, and the result was correlated with properties of the heat-treated MnIII(TPP)X, such as magnetic moment and electrical resistivity. The axial ligand X showed noticeable effect on the catalytic activity. The catalytic activity estimated from the overpotential changed in the following order: F−>Cl−>Br−>I−. The catalytic activity for reducing oxygen to OH− was low, but the same order of activity as the above applies. The order was interpreted by the σ-donating ability of halide ion X to dz2 orbital. The active site of the MnIII(TPP)X heat-treated at 700 °C for O2 reduction is ascribed to the metal ion, coordinated to slightly degraded or perfect N4 center, but not degradation products of the relevant compounds.
Stopped-Flow Kinetic Study of the Complex Formation between Pyridoxal 5′-Phosphate and Bovine Serum Albumin
Authors: Murakami Kiyofumi , Kubota Yukio , Fujisaki Yasuo , Sano Takayuki
Published: July 2006

The complex formation between pyridoxal 5′-phosphate (PLP) and bovine serum albumin at pH=7.0 and 25 °C was characterized by four relaxation processes. The dependence of the reciprocal relaxation times upon reactant concentrations was found to be consistent with a mechanism in which a rapid bimolecular binding step is followed by three sequential isomerization steps. The eight rate constants for this mechanism were determined and then combined to calculate an overall equilibrium constant which is in agreement with the literature value. Absorption spectra of the complexes formed by the two faster steps were determined from absorbance changes associated with them; the spectrum corresponding to the first complex has two bands at 330 nm and 360 nm and an additional 410 nm band, while the spectrum corresponding to the second complex has a large single band at 375 nm. Comparing these spectra with those reported for other PLP-enzyme systems, we speculate that four steps in the proposed mechanism may correspond to the rapid formation of a carbinolamine, which is in very rapid equilibrium with a Schiff base form, followed by the deprotonation of the ring nitrogen, the formation of an ionic hydrogen-bonded Schiff base, and the final formation of a nonionic hydrogen-bonded Schiff base.
High-Spin(5T2) \ightleftharpoons Low-Spin(1A1) Transition in Mixed Ligand Complex [Fe(2,2′-bipyridine)(1,10-phenanthroline)(NCS)2]
Authors: Inoue Hidenari , Nakajima Hiroko , Takahashi Takeshi , Uchida Hiroshi , Shirai Tsuneo , Fluck Ekkehard
Published: July 2006

A new type of the mixed ligand complex [Fe(bpy)(phen)(NCS)2] (bpy=2,2′-bipyridine and phen=1,10-phenanthroline) has been prepared by two different methods. The influence of the mixed ligand coordination of bpy and phen to a central iron(II) ion is studied by measurements of the temperature variation of magnetic moments and Mössbauer parameters. It has been demonstrated that the mixed coordination tends to make the 5T2(high-spin) \ightleftharpoons 1A1(low-spin) transition more gradual. The spin-crossover transition temperature depends on the electronic property as well as the structure of the ligand coordinated to the central iron(II) ion.
Structures of Yadanziosides K, M, N, and O, New Quassinoid Glycosides from Brucea javanica (L.) Merr
Authors: Sakaki Toshiro , Yoshimura Shin , Tsuyuki Takahiko , Takahashi Takeyoshi , Honda Tadashi , Nakanishi Toshihiro
Published: July 2006

Four new bitter quassinoid glycosides, yadanziosides K, M, N, and O were isolated from Brucea javanica (L.) Merr and their structures were determined by spectral measurement and chemical means. The aglycone of yadanzioside O was found to exhibit a significant antitumor activity against the murine P388 lymphocytic leukemia and this aglycone could be prepared from brusatol.
Syntheses of New Optically Active Organosilanes and Their Applications for the Optical-Purity-Determining Agents
Authors: Terunuma Daiyo , Kato Masato , Kamei Masanao , Uchida Hidekatsu , Ueno Satoshi , Nohira Hiroyuki
Published: July 2006

New optically active organosilicon compounds such as (benzylmethylphenylsilyl)acetic acid (1) and (ethylmethylphenylsilyl)acetic acid (2) were synthesized. Application of these acids as the optical purity determining agents for chiral amines and alcohols were successfully carried out. In addition, it was also revealed that optically active (benzylmethylphenylsilyl)methylamine (3) and [benzylmethyl(o-tolyl)silyl]methylamine (4) are able to be used as the optical purity determining agents for chiral carboxylic acids.
Effect of CH2Br2-Addition upon Direct Oxidative Dehydrogenation of Butane into 1,3-Butadiene over Fe–Sb–O Composite Catalyst
Authors: Saitoh Hitoshi , Satoh Satoshi , Sodesawa Toshiaki , Nozaki Fumio
Published: July 2006

Effect of CH2Br2-addition upon direct oxidative dehydrogenation of butane into 1,3-butadiene has been investigated in a conventional flow apparatus. The activity and selectivity of Fe–Sb–O catalyst were much improved by the addition of CH2Br2 to butane in the mole ratio, CH2Br2/n-C4H10, of 0.03 to 0.10 at temperatures near 450 °C.
Preparation of Polymer-Protected Colloidal Dispersions of Copper
Authors: Hirai Hidefumi , Wakabayashi Hidehiko , Komiyama Makoto
Published: July 2006

Colloidal copper dispersions are prepared by reducing copper(II) ions in water with sodium tetrahydroborate or hydrazine in the presence of various protective polymers. The polymers are poly(N-vinyl-2-pyrrolidone), poly(vinyl alcohol), poly(methyl vinyl ether), poly(potassium vinyl sulfate), dextrin, amylopectin, methylamylopectin, methylcellulose, ethylcellulose, and (2-hydroxyethyl)cellulose. The dispersions are black, reddish dark brown, or reddish brown homogeneous solutions, and are stable under nitrogen at room temperature for more than three months. Electron diffraction experiments indicate that copper atoms in the colloidal particles are arranged in an ordered way, which is almost identical with that in a crystal of bulk copper metal. At the charged molar ratio 40 of the monomeric residue of the protective polymer to copper(II) ion, the average diameters of the copper particles, prepared by use of sodium tetrahydroborate, range from 50 to 150 Å, depending on the polymer used. With the use of poly(N-vinyl-2-pyrrolidone) as protective polymer, the size of the copper particles monotonously increases with increase in the degree of polymerization of the polymer and also with decrease in the amount of the polymer.
Determination of a Small Amount of a Biological Constituent by Use of Chemiluminescence. IX. Effect of a Ligand on a Peak Shape
Authors: Hara Tadashi , Arai Akihiro , Iharada Takeshi
Published: July 2006

The chemiluminescence intensity of a 1,10-phenanthroline-hydrogen peroxide system was systematically examined in the presence of various types of copper(II) chelate-forming ligands. There was a good relation between the peak shape on a recorder chart and the types of ligands; they could be classified into four groups as follows: A) Both bidentate and tridentate ligands gave positive and negative peaks. B) The ligand having more than four donor atoms, as in a quadridentate ligand or protein, gave a single negative peak. C) A liberated porphine ring gave a single sharp negative peak. D) Some metal organic compounds such as vitamine B-12 and ferritin gave broader positive and negative peaks in comparison with those in A). These unique peak shapes were applicable to the estimation of the type of ligand. α-Fetoprotein as a tumor marker could be also easily detected with a detection limit of 250 pg and with a typical coefficient of variation of 3.8%.
Potentiometric Study of Copper(II) Complexes with β-Diketone in Micellar Solution Using a Copper(II) Ion-Selective Electrode
Authors: Aihara Makoto , Sugi Kyoko , Goya Yumiko
Published: July 2006

The distribution of copper(II) complexes with thenoyltrifluoroacetone, pivaloyltrifluoroacetone and 3-phenyl-2,4-pentanedione between micellar and bulk phases in aqueous solution containing nonionic surfactant was investigated by potentiometry with a copper(II) ion-selective electrode. The apparent equilibrium constants for the copper(II) complexes in micellar solution were determined.
Dehydrooligopeptides. VI. Facile Transformation of α-Phosphoranylideneamino-α-alkenoates to Δ2-Dehydrodipeptide Derivatives
Authors: Yonezawa Yasuchika , Kisuno Atsushi , Shin Chung-gi
Published: July 2006

Arbusov reaction of alkyl α-phosphoranylideneamino-α-alkenoates with several halides gave the corresponding α-phosphinylamino-α-alkenoates and Δ2-dehydrodipeptide derivatives.
A Convenient Synthesis of Cholesta-1,5,7-trien-3β-ol
Authors: Tachibana Yoji
Published: July 2006

Cholesta-4,6-dien-3β-ol (4) was obtained selectively by the dehydrobromination of 7-bromocholesterol with a base in the presence of a catalytic amount of tetrabutylammonium bromide. The oxidation of 4 with 2,3-dichloro-5,6-dicyano-p-benzoquinone gave cholesta-1,4,6-trien-3-one (7). Treatment of 7 with isopropenyl acetate under acidic conditions afforded 3-acetoxy-1,3,5,7-cholestatetraene, which was reduced with calcium borohydride to yield cholesta-1,5,7-trien-3β-ol (2).
The Dynamical Structure of Normal Alcohols in Their Liquids as Determined by the Viscosity and Self-Diffusion Measurements
Authors: Iwahashi Makio , Ohbu Yoko , Kato Tadashi , Suzuki Yumi , Yamauchi Kazuhiro , Yamaguchi Yoshimi , Muramatsu Mitsuo
Published: July 2006

The conformation of molecules of normal alcohols in their pure liquids is estimated through an analysis of their self-diffusion coefficients, viscosities, and molar volumes. The conformation of molecules of shorter chained alcohols (C1–C3) is approximately of sphere, while that for longer chains is of rodlike shape. In pure liquids of alcohols, rigid rod molecules whose free rotating motions along their rod axes seem to be restricted, are randomly orientated and entangled with one another. The self-diffusion of long-chain alcohols involves a longitudinal translation of rodlike molecules. Large apparent hydrodynamic radii suggest that the transport unit of normal alcohol is a dimer (on an average) of alcohol molecules.
Relations between Diatomic Constants and the Features of the Potential Energy Surfaces
Authors: Tanaka Noboru
Published: July 2006

The semiempirical method is used to calculate potential energy surfaces. The linear H3 and rectangular H4 systems have been chosen as standard surfaces in order to compare the surface features. Relationships between diatomic constants and topological features along a minimum energy path, and the height and location of the barrier, are demonstrated.