bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidation Behavior of Ni in Molten Carbonate
Authors: Motohira Naobumi , Takai Takahiro , Kamiya Nobuyuki , Ota Ken-ichiro 
Published: May 2004

Abstract
The oxidation behavior of Ni in molten carbonate was evaluated by chronopotentiometry. The oxidation of Ni in molten carbonate proceeded in a two-step reaction. The first step of oxidation was independent of the specimens’ nature and depended on PCO2. On the other hand, the second step of oxidation depended on the batch of the specimens, and was independent of PCO2. The corrosion product in both oxidation processes was divalent Ni oxide, namely NiO.
Synthesis of Enantiomerically Pure (R,R)- and (S,S)-1,2-Bis(pentafluorophenyl)ethane-1,2-diamine and Evaluation of the pKa Value by Ab Initio Calculations
Authors: Sakai Takashi , Korenaga Toshinobu , Washio Noriyuki , Nishio Yuji , Minami Shinichi , Ema Tadashi 
Published: May 2004

Abstract
1,2-Bis(pentafluorophenyl)ethane-1,2-diamine (1) was synthesized by the imino pinacol coupling of 4-methoxy-N-(pentafluorobenzylidene)benzylamine using a Zn–Cu couple and p-TsOH·H2O. The optical resolution of (±)-1 by means of chiral HPLC gave enantiomerically pure (R,R)- and (S,S)-1. The pKa value of 1 was estimated by a titration experiment and ab initio calculations, showing that 1 has a basicity comparable to aniline derivatives.
The Cyanation of Aromatic Halides Catalyzed by Nickel(0) Complexes Generated In Situ. III. Kinetic and Mechanistic Aspects
Authors: Sakakibara Yasumasa , Sasaki Ken , Okuda Fumio , Hokimoto Akihiro , Ueda Takuji , Sakai Mutsuji , Takagi Kentaro 
Published: May 2004

Abstract
The cyanation of chlorobenzene catalyzed by [Ni(PPh3)n], which was generated in situ from [NiBr2(PPh3)2]–Zn–PPh3 (Ni:Zn:P = 1:3:2 molar ratio), was carried out at 60 °C using KCN or NaCN in hexamethyl phosphoric triamide (HMPA). Kinetic analyses revealed that the reaction rates in the KCN–HMPA system were zero order for both of chlorobenzene and nickel concentrations, and two-thirds order for KCN. The determination of the kinetic order for NaCN was difficult due to its high solubility in HMPA since excess cyanide ion inhibited the reaction. Zinc bromide which was formed with [Ni(PPh3)n] from [NiBr2(PPh3)2]–Zn–PPh3, acted as an important cocatalyst for the successful cyanation by comparison with [Ni(cod)2] (cod = 1,5-cyclooctadiene)–PPh3 system. Based on these experimental results, a reaction mechanism was proposed and discussed.
Development of New Reagents Containing Silicon and Related Metals and Application to Practical Organic Syntheses
Authors: Hosomi Akira , Miura Katsukiyo 
Published: May 2004

Abstract
Our research works in the last few decades are summarized. We have studied the synthetic use of organometallics, especially organosilicon compounds, and have developed a number of new reagents and reactions useful for efficient organic synthesis. In the first section, the allylation of carbon electrophiles with allylsilanes, the so-called Hosomi–Sakurai reaction, is described. We have demonstrated that the allylation reaction is valuable not only for highly regio- and stereoselective carbon–carbon bond formation but also for introduction of a variety of functionalities. The second section deals with synthetic reactions using highly coordinated organosilanes and other organometallics, including Cr, Mn, Fe, and Cu. Higher coordination by one or more extra anionic ligands brings about unique reactivities that enable synthetically useful transformations. As shown in the third section, we developed stable 1,3-dipole equivalents protected by a silyl group and their cycloadditions, leading to N, S, or O-containing heterocycles. The following section describes the stereoselective synthesis of cyclic ethers and amines by acid-catalyzed cyclizations of vinylsilanes bearing a hydroxy or amino group. These silicon-directed cyclizations have disclosed the synthetic utility of β-silylcarbenium ion species generated from vinylsilanes by protonation. The copper-catalyzed reactions of organosilanes via silicon–copper exchange are described in the fifth section. In the final section, our studies on homolytic carbometalation reactions are presented.
Novel π-Conjugated Nano-Supramolecules Having Fine-Controlled Metal-Assembling Functions
Authors: Higuchi Masayoshi , Yamamoto Kimihisa 
Published: May 2004

Abstract
Dendritic and cyclic polyphenylazomethines (DPA and CPA) were exploited as π-conjugated polymer ligands having novel topological structures. DPAs were synthesized by the convergent method via dehydration in the presence of TiCl4. DPA G4 molecules have a sphere-like structure with a 2.3-nm diameter, and they are regularly assembled without deformation of the molecule on a plate, as observed by means of GPC, molecular modeling, TEM, AFM, and π–A measurements. The stepwise radial complexation in DPAs with SnCl2 was observed as a stepwise shift in the isosbestic point in the UV–vis spectra; this conclusion was further supported by TEM, NMR, and shell-selective reduction (SSR) of the imines. The order of complexation among the shells permits control by the introduction of electron-withdrawing groups to the DPA structure. CPAn-ab and CPAn-aabb (designated as CPAX-Y where X and Y are the degree of polymerization and whether the polymerization was AB- or AABB-type, respectively) was synthesized via dehydration in the presence of TiCl4, TiCl4(THF)2 or p-toluenesulfonic acid (PTS). The unique structures of CPAn-ab and CPAn-aabb: triangle, square, or oblong, and their regular molecular-packing were revealed by NMR, MD calculations, and X-ray crystal analysis. CPAn-aabb shows reversible redox functions by protic acid doping, unlike conventional polyphenylazomethine (PPA).
Exterior Characteristics of Molecular Orbitals and Molecular Surfaces as Studied by Atomic Probes
Authors: Ohno Koichi 
Published: May 2004

Abstract
This is a brief survey of studies on exterior characteristics of molecules conducted by means of atomic probes, mostly by metastable states of rare gas atoms in collisional ionization experiments and partly by atoms from H to Ar in quantum chemical calculations. Spatial distributions of molecular orbitals (MO) outside the molecular surfaces have been studied to determine stereoelectronic properties related with partial ionization cross sections of molecules due to electrophilic attacks of metastable atoms. A newly developed collision-energy/electron-energy resolved two-dimensional electron spectroscopy has disclosed anisotropic and dynamic characteristics of molecular surfaces (MS) via collision-energy dependence of partial ionization cross sections. Starting from a simple theoretical model of exterior electron densities (EED), researchers have developed quantum chemical treatments of the ionization reactions to a level of trajectory calculations based on potential energy surfaces of both entrance and exit reaction channels together with electronic transition rates between the surfaces. The present stage of techniques can elucidate one of the two aspects, MO or MS, assuming knowledge of the other. Since experimental aspects may contain various features of MO and MS, a simultaneous determination of both MO and MS by experiments will allow further developments in experimental techniques.
X-ray Analysis of Excited-State Structures of the Diplatinum Complex Anions in Five Crystals with Different Cations
Authors: Yasuda Nobuhiro , Uekusa Hidehiro , Ohashi Yuji 
Published: May 2004

Abstract
The photo-excited structures of [Pt2(pop)4]4− and [Pt2(pop)2(popH)2]2−, (pop = diphosphite) in five kinds of complexes were analyzed by X-rays. For the complex with tetrabutylammonium (Bu), tetrapentylammonium (Pn), benzyltriethylammonium (Bzte), or benzyltributylammonium (Bztbu) as a counter cation, the Pt complex anion is attached by two protons and is represented as [Pt2(pop)2(popH)2]2−, whereas the anion is [Pt2(pop)4]4− for the complex with benzyldimethylphenylammonium (Bzdmp) as a cation. Since the Bu, Pn, and Bzte complexes have two crystal forms, the structures of eight crystals, Bu1, Bu2, Pn1, Pn2, Bzte1, Bzte2, Bztbu, and Bzdmp, were determined by X-ray analysis before irradiation. The five crystals of Bu1, Pn1, Bzte1, Bztbu, and Bzdmp were irradiated with a xenon lamp. The intensity data were collected at the light-on and light-off stages at 173 K for Bu1, Pn1, and Bzdmp crystals and at 103 K for Bzte1 and Bztbu crystals. Each crystal showed the contraction of the unit-cell volume significantly at light-on stage and returns to the original one at light-off stage. The analyzed structures at light-on and light-off stages clearly indicated that the Pt–Pt and Pt–P bond distances became significantly shorter at light-on stage than the corresponding distances at light-off stage. The decreased values for the Pt–Pt and Pt–P distances at the light-on stage are 0.0038(3) and 0.0069(10) Å for Bu1, 0.0081(3) and 0.0053(11) Å for Pn1, 0.0127(5) and 0.0085(14) Å for Bzte1, 0.0031(3) and 0.0019(12) Å for Bztbu, and 0.0019(2) and 0.0033(8) Å for Bzdmp, respectively. The other bond distances in anions and cations are not significantly changed. These structural changes indicate that the excited- and ground-state molecules reach the equilibrium state at the light-on stage; the values are in good agreement with the results observed by spectroscopic methods and theoretical calculation.
One Novel Racemic Cu–Co Cyano-Bridged Complex: Synthesis, Characterization, Crystal Structure, and Magnetic Properties
Authors: Choudhury Chirantan Roy , Dey Subrata Kumar , Mitra Samiran , Mondal Nijhuma , Ribas Joan , Abdul Malik K M 
Published: May 2004

Abstract
One novel racemic Cu–Co cyano-bridged complex [C38H38CoCu2N14O]+[C22H18CoCuN10]−·7H2O where [L = N,N′-bis(2-pyridylmethylene)butane-1,4-diamine] has been prepared and characterized by elemental analyses, spectroscopic study, single crystal X-ray crystallography, and variable temperature magnetic susceptibility measurements. The compound crystallises as a 57/43 racemic twin and contains two different, one binuclear and one trinuclear, complex species. A low temperature magnetic susceptibility measurement showed the existence of very weak antiferromagnetic interactions.
New Bioactive Zinc(II) Complexes with Peptides and Their Derivatives: Synthesis, Structure, and In Vitro Insulinomimetic Activity
Authors: Ueda Eriko , Yoshikawa Yutaka , Kishimoto Noriko , Tadokoro Makoto , Sakurai Hiromu , Kajiwara Naemi , Kojima Yoshitane 
Published: May 2004

Abstract
Four Zn(II) complexes with dipeptides and three new Zn(II) complexes with pseudo-tripeptides were prepared and a complex, [Zn(glythr)2]n, was revealed to have a polymeric structure by X-ray structure analysis. The ligand, glythr−, acts as a bridging ligand completely, a monodentate oxygen atom of the terminal carboxyl group of threonine residue and a didentate ligand containing the nitrogen and oxygen atoms of glycine one. Because the Zn2+ ion has a distorted six-coordinated octahedral geometry, it binds with two terminal carboxyl groups and two didentate ligands. Also, all Zn(II) complexes were found to have high in vitro insulinomimetic activity compared with that of zinc sulfate, as estimated by the inhibition of free fatty acid release in isolated rat adipocytes that had been treated with epinephrine (adrenalin).
A New Method for 18F-Labeling of Biochemical Molecules Using [18F]Perfluoronitrobenzene and Its Application to 18F-Labeling of Angiotensin II
Authors: Hashizume Kazunari , Tamakawa Hiroyoshi , Hashimoto Naoto , Miyake Yoshihiro 
Published: May 2004

Abstract
We propose a new method for labeling biochemical molecules with fluorine-18 (positron emitters) using [G-18F]polyfluoronitrobenzene as the reagent. Perfluoronitrobenzene was easily labeled with 18F− by the 18F- for-19F exchange reaction giving [G-18F]pentafluoronitrobenzene (PFNB, radiochemical yield 30-41 %) and the [G-18F]PFNB was applied successfully for 18F-labeling of angiotensin II.
Chelate-Ring Formation in Cr(CO)5(phen) Studied by Laser Flash Photolysis with Visible and Infrared Detection
Authors: Oishi Shigero , Inui Hiroshi , Kuriyama Yasunao 
Published: May 2004

Abstract
Kinetic parameters were obtained for the formation of chelate ring in transient Cr(CO)5(phen) and 0.17 s−1 (20 °C), ΔH‡ = 85.0 kJ·mol−1, and ΔS‡ =29.8 J·mol−1·K−1, indicating the concerted extrusion of CO by an uncoordinated nitrogen rather than the simple dissociation of CO. In comparison with other bidentate ligands, it was revealed that the structural advantage of phen, which gave significant enhancement in the rate of chelation, was due to entropy term.
Enantioselective Synthesis of Octalactin A
Authors: Kodama Mitsuaki , Matsushita Masayuki , Terada Yuuko , Takeuchi Atsuko , Yoshio Suzuyo , Fukuyama Yoshiyasu 
Published: May 2004

Abstract
An efficient enantioselective synthesis of the C1-C9 fragment 2 of octalactin A (1) has been achieved starting from (−)-citronellol (3).
An Efficient Method for Catalytic and Stereoselective Glycosylation with Thioglycosides Promoted by Trityl Tetrakis(pentafluorophenyl)borate and Sodium Periodate
Authors: Uchiro Hiromi , Mukaiyama Teruaki 
Published: May 2004

Abstract
A new and efficient method for catalytic stereoselecive synthesis of several glycosides from thioglycosides is successfully performed by the combined use of trityl salt and sodium periodate. Several β-d-gluco- and galactopyranosides are prepared in good yields with high stereoselectivities.
A Carbene•Phosphinidene Adduct: “Phosphaalkene”
Authors: Arduengo Anthony J , Dias H V Rasika , Calabrese Joseph C 
Published: May 2004

Abstract
The synthesis, characterization and X-ray crystallographic structure determination are described for a “phosphaalkene” formally derived from 1,3,4,5-tetramethylimidazol-2-ylidene and phenylphosphinidene. This carbene•phosphinidene adduct has a central P-C bond length of 179.4 pm and a dihedral twist of 46° which indicates a very weak C-P pπ-pπ interaction. The valence angle at phosphorus in 102.3°.
Preparation and Characterization of Macrocyclic Tetraamine Dimethylthiolate Copper(II) Complex
Authors: Choi Ki-Young , Oh Mi-Ran , Suh Il-Hwan 
Published: May 2004

Abstract
A novel compound, [Cu(L)(SCH3)2]· 2H2O 1 (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07,12]docosane), bridged by two thiolate sulfur atoms, has been prepared and characterized. The copper(II) ion adopts a tetragonally elongated octahedral geometry with two axial thiolate sulfur atoms.
13C-NMR Evidence for Hydrogen Supply by Water for Polymer Cracking in Supercritical Water
Authors: Nakahara Masaru , Tennoh Toshinari , Wakai Chihiro , Fujita Emi , Enomoto Heiji 
Published: May 2004

Abstract
A rubber polymer (EPDM, ethylene-propylene-diene-terpolymer) vulcanized was cracked to paraffinic oil (PO) in NaOH-containing supercritical water (SCW) at 420 °C and 30 MPa. The SCW polymer cracking in not oxidative but reductive. The 13C-NMR analysis of PO obtained by SCW D2O cracking demonstrates that the terminal methyl carbons are deuterated as a clear indication of hydrogen supply by SCW in the cracking.
Stereoselective Synthesis of trans-2,5-Disubstituted Tetrahydrofurans via the Lewis Acid Mediated Reduction of Cyclic Hemiketals with Triphenylsilane
Authors: Nishiyama Yutaka , Tujino Takashi , Yamano Tadamichi , Hayashishita Masayoshi , Itoh Kazuyoshi 
Published: May 2004

Abstract
An efficient method for the synthesis of trans-2,5-disubstituted tetrahydrofuran derivatives has been developed. Dithioacetal-functionalized cyclic hemiketals are reduced by triphenylsilane (Ph3SiH) in the presence of TiCl4 to afford the corresponding trans-2,5-disubstituted tetrahydrofuran derivatives in good yield and high stereoselectivity. Asymmetrical synthesis of (2S,5S) disubstituted tetrahydrofuran was also achieved by using this reduction method.
Carbon Molecular Sieve Membrane Prepared from Phenolic Resin
Authors: Kita Hidetoshi , Maeda Hiroshi , Tanaka Kazuhiro , Okamoto Ken-ichi 
Published: May 2004

Abstract
Carbon membranes are prepared by coating thin layers of phenolic resin on the outer surface of a porous alumina substrate and then carbonizing the polymer under nitrogen atmosphere at 600 °C. The membranes have excellent separation performances of alkene/alkane and CO2/N2.
Linear Trinuclear Copper(II) Complexes Bridged by Oximato and Azido or Hydroxo Groups
Authors: Akagi Fumio , Nakao Yasuo , Matsumoto Keiji , Takamizawa Satoshi , Mori Wasuke , Suzuki Shinnichiro 
Published: May 2004

Abstract
The linear trinuclear copper(II) complexes Cu3(L1)2(N3)2(NO3)2·2H2O·2CH3OH 1 and Cu3(L1)2(OH)2(ClO4)2 2 containing 3-[{2-(2-pyridinyl)ethyl}imino]-2-butanone oximato ligand (L1) were prepared; the crystal structure of 1 was determined by X-ray crystallography. Magnetic susceptibility measurements from liquid helium temperature to room temperature showed a vary strong antiferromagnetic exchange coupling between copper(II) ions(J = −266 cm−1 and −245 cm−1 for 1 and 2, respectively, H=−2JS1·S2).
Regioselective distal-Dibromination of Calix[4]resorcinarene
Authors: Konishi Hisatoshi , Nakamaru Hidekazu , Nakatani Hideki , Ueyama Tsuyoshi , Kobayashi Kazuhiro , Morikawa Osamu 
Published: May 2004

Abstract
The partial bromination of calix[4]resorcinarene with a limited amount of N-bromosuccinimide was examined. The ratio of the two dibromo derivatives, distal- and proximal-isomers, was 10:1, which is much different from the statistical value of 1:2. The simple procedure for the preparation of the distal-dibromo derivative is described.
A Novel Type of Amidato Coordination: The Metallocycle Rh-Rh-NH-C(Me)=O
Authors: Kukushkin Vadim Yu , Nishioka Takanori , Nakamura Shigeyuki , Kinoshita Isamu , Isobe Kiyoshi 
Published: May 2004

Abstract
Treatment of [Rh2Cp*2(μ-CH2)2(μ-O2CO)] (Cp* = η5-C5Me5) with acetonitrile in aqueous solution followd by addition of KPF6 affords the Rh–Rh complex [Rh2Cp*2(μ-CH2)2(μ-NHC(=O)Me)][PF6], which has been characterized by elemental analysis, FAB-MS, 1H and 13C{1H} NMR spectroscopy, and X-ray crystallography. [Rh2Cp*2(μ-CH2)2(μ-η1:η1-NHC(=O)Me)][PF6] is the first example of an amidato complex where the ligand [NHC(=O)Me]− links the metal–metal site forming a novel type of metallocycle.
Femtosecond Visible Pump Mid-IR Probe Study on the Effects of Surface Treatments on Ultrafast Photogenerated Carrier Dynamics in n-GaAs (100) Crystals
Authors: Ebina Kojiro , Yagi Ichizo , Noguchi Hidenori , Uosaki Kohei 
Published: May 2004

Abstract
The femtosecond visible pump mid-IR probe technique was employed to investigate photogenerated carrier dynamics in n-GaAs (100) crystals subjected to various surface treatments in a time domain of picoseconds–several tens of picoseconds. Pt- or Ru-treatment significantly accelerated the carrier recombination as a result of the introduction of surface states. The recombination rate was also increased by Au-treatment but less significantly than that by the Pt- or Ru-treatment. The effect of sulfide treatment on the recombination dynamics seemed to be rather small, although it has been reported that the density of surface states is decreased by the sulfide treatment.
A Practice Perspective on Technology-Mediated Network Relations: The Use of Internet-Based Self-Serve Technologies
Authors: Schultze Ulrike , Orlikowski Wanda J. 
Published: May 2004

Embedded relationships with customers have been key in generating repeat business and economic advantage, especially in business-to-business settings. Such relationships are typically maintained through interpersonal interactions between customers and their providers. Lately, however, firms have been seeking to make their service operations more scalable by offering customers access to Internet-based, self-serve technology. This raises questions about the implications of inserting self-serve technology into embedded relationships. Recent research on the role of information technology (IT) within interfirm network relations suggests that relationships and the use of IT are complementary. However, most of this research focuses on the organizational level and fails to consider the instantiation of these interfirm relations by the actions and interactions of individual actors (e.g., customers and salespeople) representing their respective firms. In this paper, we explore the implications of using IT within interfirm relations through an analysis of customers’ and sales representatives’ (reps) work activities and interpersonal relationships. We apply a practice perspective that highlights how macrolevel phenomena such as interfirm relations are created and recreated through the microlevel actions taken by firm members. This analysis reveals that managing the complementarity between relationships and IT in practice is fraught with considerable tension. This study of WebGA, a bricks-and-clicks dotcom, highlights how the use of the self-serve technology made it more difficult for sales reps to build and maintain embedded relationships with their customers. The use of IT altered the nature and quality of information shared by the participants, undermined the ability of sales reps to provide consulting services to customers, reduced the frequency of their interaction, and prompted sales reps to expend social capital to promote customers’ technology adoption. These changes produced intended and unintended shifts in the network relations enacted by WebGA and its customers, and raised serious challenges to the viability of WebGA’s business model.
Building Effective Online Marketplaces with Institution-Based Trust
Authors: Pavlou Paul A. , Gefen David 
Published: May 2004

Institution-based trust is a buyer’s perception that effective third-party institutional mechanisms are in place to facilitate transaction success. This paper integrates sociological and economic theories about institution-based trust to propose that the perceived effectiveness of three IT-enabled institutional mechanisms–specifically feedback mechanisms, third-party escrow services, and credit card guarantees–engender buyer trust in the community of online auction sellers. Trust in the marketplace intermediary that provides the overarching institutional context also builds buyer’s trust in the community of sellers. In addition, buyers’ trust in the community of sellers (as a group) facilitates online transactions by reducing perceived risk. Data collected from 274 buyers in Amazon’s online auction marketplace provide support for the proposed structural model. Longitudinal data collected a year later show that transaction intentions are correlated with actual and self-reported buyer behavior. The study shows that the perceived effectiveness of institutional mechanisms encompasses both “weak” (market-driven) and “strong” (legally binding) mechanisms. These mechanisms engender trust, not only in a few reputable sellers, but also in the entire community of sellers, which contributes to an effective online marketplace. The results thus help explain why, despite the inherent uncertainty that arises when buyers and sellers are separated in time and in space, online marketplaces are proliferating. Implications for theory are discussed, and suggestions for future research on improving IT-enabled trust-building mechanisms are suggested.