bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Characterization of Mixed-Metal Sulfido Clusters with the Cubane-Type PtMo3S4 Core
Authors: Masui Dai , Ishii Youichi , Hidai Masanobu 
Published: September 2002

Abstract
The reaction of the incomplete cubane-type cluster [Mo3(μ3-S)(μ-S)3(H2O)9]Cl4 (1) and [Pt(dba)2] (dba = 1,5-diphenyl-1,4-pentadien-3-one) in MeOH gave a brown precipitate (4) that contains platinum and molybdenum in the atomic ratio of 1 : 3. Further treatment of 4 with 3 equiv of dppe (dppe = 1,2-bis(diphenylphosphino)ethane) gave the cubane-type cluster [PtMo3(μ3-S)4Cl4(dppe)3] (5) in 37% yield, whose molecular structure was unambiguously characterized by X-ray diffraction study of 5·2CH2ClCH2Cl·2H2O. A similar reaction of 4 with 4 equiv of dppe afforded the cationic cluster [PtMo3(μ3-S)4Cl3(dppe)4]Cl (6) in 29% yield, which was characterized spectroscopically. The Pd-Mo and Ni-Mo analogues of the above Pt-Mo clusters, [PdMo3(μ3-S)4Cl3(dppe)4]Cl·CH2Cl2 (7) and [NiMo3(μ3-S)4Cl4(dppe)3] (8), were also synthesized by the reactions of the corresponding aqua clusters with dppe.
Kinetic Study on the Oxidation of Trichlorophenol Using Hydrogen Peroxide and an Iron(III) Complex of Tetrasulfonatophthalocyanine Catalyst
Authors: Kasuga Kuninobu , Mori Kentaro , Sugimori Tamotsu , Handa Makoto 
Published: September 2002

Abstract
An oxidative decomposition of TCP, catalyzed by the title complex in the presence of hydrogen peroxide, was studied kinetically. The decrease in the initial reaction rate in an acidic solution resulted from a depression of the proton dissociation of hydrogen peroxide.
Molecular Structures of Methyl 5,6-Diaryl-1,2,4-trimethyl-7-oxobicyclo[2.2.1]hept-5-en-2-
endo
-carboxylates (aryl = phenyl or
o
-methoxyphenyl)
Authors: Balasubrahmanyam SNatarajan , Rao Sunkada P , Bhadbhade Mohan M , Sudarsanakumar C , Joseph Bubbly K 
Published: September 2002

Abstract
Structural assignments based on a reconstruction from the 1H NMR dynamic behavior of the three 5,6-bis(substituted aryl)-7-oxo-5-norbornene-2-carboxylic esters named in the title have received confirmation from X-ray crystallographic studies. The specific structural features of these systems are compared among themselves and with those of 7-oxo-5,6-diphenyl-5-norbornene-2-carboxylic esters, analogues systems without substitution on the phenyl groups, which were studied earlier.
Iodination of Both Deactivated and Activated Arenes with Sodium Periodate or Sodium Iodate as the Oxidants
Authors: Lulinski Piotr , Skulski Lech 
Published: September 2002

Abstract
Five easy, relatively inexpensive, and environmentally-safe aromatic oxidative iodination procedures are presented; three of them are particularly suitable for deactivated arenes. Nine deactivated arenes, four halobenzenes, benzene, toluene, and N,N-dimethylaniline were reacted upon with the following anhydrous systems: diiodine/NaIO4 or (in four cases) NaIO3/acetic anhydride/glacial acetic acid, acidified with varying amounts of concd (98%) sulfuric acid; the following workups are explained. The aromatic oxidative iodination reactions proceeded mostly at room temperature and within 1—8 h to give fifteen mono- and two diiodinated purified products (sometimes obtained in 2—3 different ways) in 51—95% yields.
Study of the Mechanism for the Hydrolysis of Alkoxy(aryl)(phenyl)-λ6-sulfanenitriles, ArPhS(OR)(N)
Authors: Yoshimura Toshiaki , Dong Tiaoling , Fujii Takayoshi , Ohkubo Masanori , Sakuta Mikiko , Wakai Youko , Ono Shin , Morita Hiroyuki , Shimasaki Choichiro 
Published: September 2002

Abstract
The hydrolysis of alkoxy(aryl)(phenyl)-λ6-sulfanenitriles in several buffer solutions was found to follow a good pseudo-first-order kinetic equation, giving the corresponding sulfoximides and alcohols (for the case of the hydrolysis of neopentyloxy-λ6-sulfanenitrile, giving a rearranged product, 2-methyl-2-butanol). The dependence of the rate of hydrolysis on the structure of the alkyl group showed the opposite trend to the usual SN2 character, i.e. Me &lt; Pr &lt; Bu ≈ Et &lt; i–Pr, except for neopentyl. The pH-rate profiles indicated that the rate of hydrolysis is also first order in [H+] at pH more than 6.08, and trends to saturate at low pH. According to these kinetic results, a two-step reaction mechanism was proposed which involves a pre-equilibrium protonation on the nitrogen atom of the alkoxy-λ6-sulfanenitriles, followed by a rate-determining C-O bond cleavage via an SN2 or SN1 mechanism on the alkyl carbon atom depending on the structure of the alkyl group. From a double-reciprocal plot of 1/kobs vs. 1/[H+], the pKa value and the rate constant of the second reaction of neopentyloxy(diphenyl)-λ6-sulfanenitrile were estimated to be 5.02 and 7.02×10-3 s-1, respectively. The substituent effects on the phenyl group of neopentyloxy(diphenyl)-λ6-sulfanenitrile afforded a large negative ρ-value (-1.88) for pKa and positive one (+1.66) for the second reaction at 25.2 °C. The small negative ρ-values observed at pH 6.27 for diphenyl(propoxy)-λ6-sulfanenitrile (-0.42) and neopentyloxy(diphenyl)-λ6-sulfanenitrile (-0.26) were found to be the results of a cancellation of those for the opposite trend of the reactions of the pre-equilibrium and the second step. The activation parameters for both the pre-equilibrium and the subsequent reactions were also estimated based on the parameters for the hydrolysis of neopentyloxy(diphenyl)-λ6-sulfanenitrile at pH 6.22 and 2.99. The buffer effect is due to a nucleophilic attack of the buffer base to the alkyl carbon atom of the protonated alkoxy-λ6-sulfanenitriles. The sulfoximide moiety in the protonated λ6-sulfanenitrile is revealed to be a very good leaving group.
In situ Activating Glycosylation of 6-Deoxysugars: Synthesis of O-α-D-Fucosyl-(1→4)-O-α-D-fucosyl-(1→4)-O-α-D-quinovosyl-(1→4)-D-quinovose
Authors: Koto Shinkiti , Kusunoki Ami , Hirooka Motoko 
Published: September 2002

Abstract
The linear tetrasaccharide, α-D-fucopyranosyl-(1→4)-α-D-fucopyranosyl-(1→4)-α-D-quinovopyranosyl-(1→4)-D-quinovopyranose, the sugar cluster of asterosaponin A from the starfish, Asterias amurensis, was synthesized in a convergent manner. We employed an in situ activating glycosylation using 1-OH sugar derivatives and a system of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine as well as a related system.
Intramolecular Stacking of Two Aromatic Rings in the Platinum(II) Coordination Sphere: Preparation, Crystal Structures, and 1H NMR Spectra of Bipyridine(N-arylmethyl-1,2-ethanediamine)platinum(II) Nitrate
Authors: Goto Masafumi , Matsumoto Takashi , Sumimoto Masamitsu , Kurosaki Hiromasa 
Published: September 2002

Abstract
Square-planar complexes with the formula [Pt(L1)(L2)](NO3)2·nH2O, where L1 is bipyridine (bpy) and L2 is N-benzyl-1,2-ethanediamine (Been) (1) (n = 0), N-(1-naphthyl)methyl-1,2-ethanediamine (Npen) (2) (n = 2), and N-(9-anthryl)methyl-1,2-ethanediamine (Aten) (3) (n = 2), were prepared and X-ray crystal-structure determinations were carried out. The molecular structures of the complex cations revealed that the N-arylmethyl groups are forced to take pseudo axial dispositions due to an intramolecular repulsion from hydrogen atoms of bpy. The aromatic-aromatic interaction between the aromatic rings of ethanediamine derivatives and coordinated bpy caused 2 and 3 to take a conformation where the aromatic ring and bpy stack face-to-face to each other intramolecularly. An intermolecular aromatic-aromatic face-to-face interaction was also observed for 1, 2, and 3 in the crystals. The latter interaction occurs between bpy and the aryl substituent, except for 1. For D2O solutions of 1 through 3, significant upfield shifts due to the intramolecular stacking were observed in the 1H NMR spectra for the protons on the half ring of bipyridine, depending on the size of the aromatic ring. The crystal data of 1: monoclinic, P21/c, a = 9.884(2), b = 24.717(2), c = 9.560(5) Å, β = 113.83(3)°, Z = 4, and R = 0.029. 2: monoclinic, Ia, a = 17.030(5), b = 10.461(4), c = 14.727(4) Å, β = 94.72°, Z = 4, and R = 0.023. 3: monoclinic, Pn, a = 10.471(2), b = 8.844(5), c = 15.332(3) Å, β = 98.61(2)°, Z = 2, and R = 0.034.
Effects of Anions in Subphases on a Langmuir Monolayer of N,N-Dimethyl-1-octadecanamine
Authors: Negi Shigeru , Futami Eri , Tsukube Hiroshi , Kano Koji 
Published: September 2002

Abstract
The surface pressure-area (π-A) and surface potential-area (ΔV-A) isotherms of N,N-dimethyl-1-octadecanamine (C18NMe2) were measured on water subsolutions containing various sodium halides (NaX). The amine monolayer showed an expanded liquid (LE) to a condensed liquid (LC) phase transition on water at pH 7 containing 0.01 mol dm-3 NaF, while only the LE phase existed on a subsolution with NaI. The Langmuir monolayer (LM) regularly expanded and the A value at π = 30 mN m-1 increased in the order F- &lt; Cl- &lt; Br- &lt; I-, while the ΔV value decreased in the order F- &gt; Cl- &gt; Br- &gt; I-. The X--dependent π-A isotherm of the C18NMe2 LM is interpreted in terms of deprotonation from the protonated amine molecules at the LM surface upon compression. Similarly, the C18NMe2 LM expanded regularly in the presence of AMP, ADP, and ATP. Such a phenomenon is understandable by assuming that a high-valent anion in subphase is bound to protonated amine molecules more strongly than a low-valent anion.
Homo-Coupling Reactions of Alkenyl- and Arylfluorosilanes Mediated by a Copper(I) Salt
Authors: Nishihara Yasushi , Ikegashira Kazutaka , Toriyama Fumihiko , Mori Atsunori , Hiyama Tamejiro 
Published: September 2002

Abstract
Homo-coupling reactions of an alkenyl- or arylsilane readily occur with a copper(I) salt in an aprotic polar solvent such as N, N-dimethylformamide or dimethyl sulfoxide under an aerobic condition to give the corresponding conjugated dienes or biaryls, respectively. Optimization of a copper salt and a solvent for the homo-coupling reaction is discussed. The formation of the organocopper intermediates is evidenced by trapping experiments with iodine and by a conjugate addition to methyl vinyl ketone.
A Chiral Tweezers-Type Dicarboxylic Acid: Studies on Its Complexation with Amines Utilizing CD Spectrum
Authors: Matsui Hiroyuki , Kushi Sayuri , Matsumoto Shoji , Akazome Motohiro , Ogura Katsuyuki 
Published: September 2002

Abstract
Complexation of a tweezers-type dicarboxylic acid (1) having an optically active π-system at its center with tertiary amines (triethylamine and DABCO) and secondary amines (piperidine and 4,4′-bipiperidine) was investigated under highly dilute conditions (about 6×10-5 mol dm-3) in CHCl3. The complex formation could be pursued with the CD spectrum of 1 which is markedly varied due to the titration of amines. The complexation process is discussed.
1,4-Addition of Diorganozincs to α,β-Unsaturated Ketones Catalyzed by a Copper(I)-Sulfonamide Combined System
Authors: Kitamura Masato , Miki Takashi , Nakano Keiji , Noyori Ryoji 
Published: September 2002

Abstract
A mixture of CuCN and N-benzylbenzenesulfonamide catalyzes the 1,4-addition of dialkylzincs or diarylzincs (Cu : Zn = 1 : 200 to 1 : 10000) to α,β-unsaturated ketones to give, after aqueous workup, the corresponding β-substituted ketones in nearly quantitative yields. A range of cyclic enones having s-cis or s-trans geometries as well as conformationally flexible acyclic enones are usable as substrates. The ethyl group migrates more readily than the methyl and phenyl groups. CuOTf, CuO-t-C4H9, and mesitylcopper can be used in place of CuCN. The in situ-formed alkylzinc enolate, prior to aqueous workup, further undergoes an aldol reaction with aldehydes or Pd(0)-assisted coupling with allyl acetate, resulting in regio-controlled, vicinal carbacondensation products. A catalytic cycle is proposed on the basis of a kinetic study and a structural analysis of the zinc enolate product by NMR and molecular weight measurements.
Two-Dimensional Correlation Spectroscopy: Principle and Recent Theoretical Development
Authors: Ozaki Yukihiro , Šašic Slobodan , Tanaka Takeyuki , Noda Isao 
Published: September 2002

Abstract
This review paper aims at examining the recent developments in optical two-dimensional (2D) correlation spectroscopy. Particular emphasis is put on progress in the theory and calculation methods in 2D correlation spectroscopy. A historical review of 2D correlation spectroscopy is described first, and the mathematical treatment of generalized 2D correlation spectroscopy is explained next. Then a recently proposed efficient route to calculating 2D correlation spectra is reviewed in detail. Examples of applications of 2D correlation spectroscopy are also reported. In the last part of this article, a new possibility of the generalized 2D correlation spectroscopy, sample-sample correlation spectroscopy, is to be discussed.
Solvation Structure of Lithium Bromide in Concentrated Acetone Solutions
Authors: Kameda Yasuo , Kudoh Naomi , Suzuki Shun , Usuki Takeshi , Uemura Osamu 
Published: September 2002

Abstract
Polarized Raman scattering and neutron diffraction measurements have been carried out for concentrated LiBr acetone solutions, in order to deduce detailed information on the solvation structure of Li+ in non-aqueous solutions. Isotropic Raman spectra observed for (LiBr)x[(CH3)2C=O]1−x with x = 0.02–0.06 exhibited a polarized peak at ν ≈ 370 cm−1 which is attributable to the interionic vibration of Li+···Br− ion pair which is formed in the solutions. The neutron distribution function around Li+, GLi(r), derived from the first-order difference function between 6Li/7Li isotopically substituted 6 mol% LiBr acetone-d6 solutions indicated the presence of a well-defined first solvation shell around Li+ in the solution. The nearest neighbor Li+···O(acetone) distance, rLiO, and coordination number, nLiO, were respectively determined to be 2.24(1) Å and 3.2(1), from the least squares fitting analysis for the observed difference interference function, ΔLi(Q). Structure parameters for the nearest neighbor Li+···Br− interaction were determined to be rLiBr = 2.86(2) Å and nLiBr = 0.8(1), respectively.
Synthesis and Structural Characterization of Tetranuclear Zinc(II) Complexes with a Linear Array
Authors: Mikuriya Masahiro , Ikenoue Shuichi , Nukada Ryoji , Lim Jong-Wan 
Published: September 2002

Abstract
1,3-Bis(salicylideneamino)-2-propanol (H3salpro) and 1,3-bis(salicylideneamino)propane (H2salpn) react with Zn(ClO4)2•6H2O and pyrazole (Hpz) to give tetranuclear complexes with a linear Zn4 array, [Zn4(Hsalpro)2(pz)2-(Hpz)2](ClO4)2 (1) and [Zn4(salpn)2(pz)2(Hpz)2] (ClO4)2 (2), which were characterized by infrared spectra and X-ray crystallography.
Desymmetrization of Achiral Skeletons by Mono-Substitution. Its Characterization by Subduction of Coset Representations
Authors: Fujita Shinsaku 
Published: September 2002

Abstract
A set of equivalent positions in an achiral skeleton is regarded as an orbit as-signed to a coset representation G(/Gi), where the subgroup Gi is Cnv or Cn. Desymmetrization of the achiral skeleton by substituting a single ligand is examined by virtue of the subduction of the coset representation G(/Gi) ↓ Gi, which is determined to be αGi(/Gi) + βGi(/Gk(i)). The multiplicities (α and β) of the resulting coset representations are calculated from the data of the participating groups and the normalizer of Gi.
Electric Field Effects on the Adsorption, Charge Transfer and Vibrational State at Metal Electrodes: A DFT Study on H2O/Pt(111), H2O/Pt(100) and (H2O)2/Pt(111)
Authors: Ohwaki Tsukuru , Kamegai Kazuhisa , Yamashita Koichi 
Published: September 2002

Abstract
Electric field (EF) effects on an adsorbed H2O and (H2O)2 on Pt(111) and (100) surfaces have been studied using density functional theory (DFT) at the B3LYP/LanL2DZ level. For the interactions between the H2O and the Pt surface (modeled as a cluster), natural bond orbital (NBO) analysis was performed. This showed that the H2O interacts strongly with the Pt surface through the higher energy level lone pair of the H2O in a parallel orientation. Geometry optimizations of the adsorbed water molecule on the Pt(111) surface were carried out, and the changes in the orientation and geometry induced by the EF are discussed. In the cases of EF = 0 and EF &gt; 0, the charge transfer interaction between the H2O and the Pt surface dominates and the H2O is adsorbed at the top site. For EF &lt; 0, the interaction between the dipole moment of the H2O and EF dominates over the charge transfer interaction. Based on the optimized geometries, we have analyzed the vibrational structure and the EF effects on the vibration of the adsorbed H2O. For the (H2O)2 adsorbed on the Pt(111) surface, partial-optimization calculations have been carried out and the hydrogen bonding in the dimer has been analyzed.
Pressure and Viscosity Effects on Thermal Geometrical Isomerization of Oxacarbocyanine Cations
Authors: Kim Jong Chul , Ohga Yasushi , Asano Tsutomu , Weinberg Noham N , George Adrian V 
Published: September 2002

Abstract
Pressure and viscosity effects on the rate of thermal Z/Eisomerization of two carbocyanine dyes, 3,3′-diethyloxacarbocyanine iodide (DOCI) and 3,3′-diethyloxadicarbocyanine iodide, (DODCI) were measured in 2-methylpentane-2,4-diol. From the results, the following conclusions are obtained. 1. The medium and the chemical coordinates have to be treated separately, as in the reactions of uncharged species. 2. A positive charge on the reactant seems to induce an earlier deviation from the transition state theory. 3. The most important factors controlling a deviation from the transition state theory are the anisotropy of the characteristic times of reaction and solvent fluctuations, and the strength of the solute-solvent interactions.
Isotope Effects of Hafnium in Solvent Extraction Using Crown Ethers
Authors: Fujii Toshiyuki , Moriyama Hirotake , Hirata Takafumi , Nishizawa Kazushige 
Published: September 2002

Abstract
Hafnium isotopes were fractionated in a liquid–liquid extraction system by using seven types of crown ethers, tributyl phosphate, or o-diethoxybenzene. The largest isotope effect was observed in the isotope pair of 177Hf–179Hf with dibenzo-24-crown-8; the isotope enrichment factor was observed to be 0.0129 ± 0.0032.
Conformations of 1,2-Dicyano-1,1,2,2-tetraphenylethane and Cyanodiphenylmethyl Peroxide
Authors: Lam Yulin , Lee Gene-Hsiang , Liang Eping 
Published: September 2002

Abstract
The solid-state structures of 1,2-dicyano-1,1,2,2-tetraphenylethane and cyanodiphenylmethyl peroxide are determined by X-ray crystallography. Both molecules adopt the trans conformation in the solid-state. Experimentally derived values of the energy difference between the gauche and trans rotamers and their population quotient are compared with values predicted by semiempirical MO calculations.
Site-Selective Recognition of Amino Acids by Co(III) Complexes Containing a (N)(O)3-Type Tripodal Tetradentate Ligand
Authors: Kumita Hideyuki , Morioka Taiju , Ozawa Tomohiro , Jitsukawa Koichiro , Einaga Hisahiko , Masuda Hideki 
Published: September 2002

Abstract
The bis-N,N-carboxymethy-(S)-phenylalaninato carbonato cobalt(III) complex, [Co(bcmpa)(CO3)]2−, has been prepared as a simple model that enables the recognition of an amino acid (Haa) whose coordination behaviours in solution have been characterized by electronic absorption (AB), circular dichroism (CD) and 1H NMR spectroscopies. The reaction of the K2[Co(bcmpa)(CO3)] complex with amino acids (Haa) has predominantly afforded the [Co(bcmpa)(aa)] complex in the trans(N)-configuration mode, rather than in the cis(N)-form. By using amino acid derivatives with bulky substituents at their amino or carboxylate sites under a neutral condition, the reactions have been demonstrated to be initiated by coordination of the amino nitrogen site. Interestingly, the cis(N)-complex, which is isolated as a minor product, isomerizes to the trans(N)-form in the presence of active charcoal under pH 7 in an aqueous solution. The site-selective coordination of Haa to the [Co(bcmpa)(CO3)]2− complex and the stereoselective isomerization of the [Co(bcmpa)(aa)]− complex have been explained to be regulated by weak non-covalent interactions within the ligands, whose origin has been discussed based on a detailed examination of the crystal structures of the trans(N)- and cis(N)-K[Co(bcmpa)(aa)] complexes.
Enhanced Reactivity in the Quinolinium Fluorochromate Cooxidation of Some Cycloalkanones and Oxalic Acid
Authors: Meenakshisundaram Subbiah , Sockalingam Ramanathan 
Published: September 2002

Abstract
Under identical experimental conditions, the kinetics of the oxidation of oxalic acid and cycloalkanones with quinolinium fluorochromate (QFC) was examined separately and the rate coefficients evaluated. Oxalic acid reacts ca. 70-times faster than cyclohexanone. It seems that the enol form of the cycloalkanone is the active substrate. π-Complex formation has been envisaged to explain the oxidation of cycloalkanones. The formation of a 2 : 1 oxalic acid–QFC complex has been assumed to be the slow rate-limiting step in the oxalic acid–QFC oxidation system. The cooxidation process has been characterized by the rate equation,
k obs = k′[Oxalic acid]2 + k′′[Oxalic][Ket][H+].
The presence of oxalic acid results in the suppression of a ring-cleavage reaction, yielding cyclohexane-1,2-dione as the main product. Cr(II) involvement in the reaction sequence is ruled out. Mn(II) catalyzes the cooxidation process at its higher concentrations. The order of reactivity C6 &gt; C8 &gt; C5 &gt; C7, is explained.
197Au Mössbauer Spectroscopy Studies of Some Cyclometalated Gold Dimers
Authors: Bhargava Suresh K , Mohr Fabian , Takahashi Masashi , Takeda Masuo 
Published: September 2002

Abstract
The oxidation states and structures of a series of cyclometalated gold complexes derived from oxidative addition reactions of the digold(I) complex [Au2(μ-C6H3-2-PPh2-6-Me)2] have been determined by 197Au Mössbauer spectroscopy. The spectra for the binuclear gold(I)/gold(I) and gold(II)/gold(II) complexes indicate the presence of equivalent gold atoms, whereas the gold(I)/gold(III) and gold(III)/gold(III) spectra show signals due to two inequivalent metal centers. The coordination spheres of metal centers in the complexes have been determined from isomer shift and quadrupole splitting data.