bluuebunny/crossref_metadata_2025_split huggingface dataset:
Internal Reference Compounds Available for the Determination of Binding Constants for Cyclodextrin Complexes by 1H NMR Spectrometry
Authors: Matsui Yoshihisa , Tokunaga Shuichi 
Published: June 2006

Abstract
The 1H NMR chemical shifts (δ’s) of the tetramethylammonium ion (TMA), methanol, and HDO, measured by using sodium 2,2-dimethyl-2-silapentane-5-sulfonate as an external reference, showed upfield shift with increasing concentration (c) of carbohydrates such as cyclodextrins (CD’s) and methyl glucopyranoside. The plots of δ vs. c gave straight lines with slopes proportional to the number of glucopyranoside residues involved in the carbohydrates, indicating that the upfield shifts are not due to inclusion phenomena but to a change in water structure with the formation of hydrogen bonds between carbohydrates and D2O. When an internal reference, TMA, was used instead, the 1H NMR signals of such organic molecules as acetonitrile, ethanol, 1-propanol, and 1-butanol showed uniform downfield shifts upon adding α-CD. The curve-fitting analysis of the plots of δ vs. c gave binding constants in agreement with those determined by other methods. It is concluded that the internal reference method is more reliable than the external one.
X-Ray Structures and Spectroscopic Studies of Diaqua- and Dichlorocopper(II) Complexes of 15-Crown-5 and 4′-Substituted Benzo-15-Crown-5 with a 3dz2 Ground-State Doublet
Authors: Li Yong 
Published: June 2006

Abstract
Crystallographic and spectroscopic investigations were carried out for Cu(II) complexes of 15-crown-5 (15C5) and 4′-substituted benzo-15-crown-5 (B15C5) derivatives. X-Ray diffraction measurements were performed for two single crystals of [Cu(15C5)(H2O)2](ClO4)2 and [Cu(B15C5)(H2O)2](ClO4)2, obtained from 60% HClO4 solutions. The results of the X-ray analysis demonstrated that these complexes take a seven-coordinate pentagonal bipyramidal geometry, in which the copper ion is located in the center of the crown ether cavity with two water molecules at the axial positions. The ESR spectra observed for these complexes in 60% HClO4 exhibited the characteristic g-anisotropy (gz &lt; gx, gy), leading to an electronic configuration of a 3dz2 ground-state doublet. ESR and electronic absorption measurements were made for Cu(II) complexes of 4′-substituted B15C5 in systems of BF3–ether–water and of dry CHCl3 in which complexes having two chloride ions at the axial positions were produced. Although these systems showed the same remarkable substituent effects, clear differences were detected between them, attributable to the different axial ligands. The results of an extended Hückel MO calculation performed for the models of these complexes provide qualitative explanations for the experimental results.
Preparation and Characterization of Nickel(II), Palladium(II), and Platinum(II) Complexes Containing (2-Aminoethyl)dimethylphosphine or the Related Didentate Phosphine Ligands
Authors: Suzuki Takayoshi , Morikawa Akira , Kashiwabara Kazuo 
Published: June 2006

Abstract
Here are described several new nickel(II), palladium(II), and platinum(II) complexes of bis(chelate)-type with didentate phosphine ligands having an amino or thioether donor group: Me2PCH2CH2NH2 (edmp), Ph2PCH2CH2NH2 (edpp), Me2PCH2CH2NMe2 (dmedmp), or Me2PCH2CH2SMe (mtdmp). Bis(tetrafluoroborate) salts of [M(P–N or S)2]2+ (M = Ni, Pd, and Pt; (P–N or S) = the ligands above) have been prepared and the geometrical structures determined by NMR spectroscopy. All the palladium(II) complexes prepared in this study are cis-isomers, in contrast to the analogous Me2PCH2CH2S− (dmsp) complex (trans-[Pd(dmsp)2]), which indicates that the anionic phosphine-thiolate ligand prefers the trans geometry more than the neutral phosphine-amine or -thioether ligand does. The dichloride salts of the bis(edmp) complexes, cis-[M(edmp)2]Cl2 (M = Ni (4a), Pd(5a), and Pt(6a)), and those of the bis(edpp) complexes have been obtained as crystals, while the corresponding salts of dmedmp, mtdmp, and 8-(dimethylphosphino)quinoline complexes can not be isolated due to their oily properties. Further, addition of LiBF4 to a methanolic solution of 4a, 5a, or 6a gives exclusively a precipitate of the chloride tetrafluoroborate salt, cis-[M(edmp)2]Cl(BF4) (M = Ni (4c), Pd(5c), or Pt(6c)). The crystal structures of 4a, 5c, and 6a determined by X-ray analyses indicate a weak (not strong enough to form a five-coordinated complex) interaction between cis-[M(edmp)2]2+ and Cl− anion. The average M–N bond lengths in 4a, 5c, and 6a are considerably longer than those in the corresponding 1,2-ethanediamine complexes, owing to the strong trans influence of the –PMe2 group in edmp. The order of strength of the trans influence among NiII, PdII, and PtII triad metal series is non-periodical: NiII &lt; PtII &lt; PdII. This order is similar to the order among CoIII, RhIII, and IrIII triad metal series found in our previous study on fac-[M′(edmp)3]3+ (M′ = CoIII, RhIII, and IrIII) complexes.
Stereochemistry and Electrochemistry of Cobalt(II) and Cobalt(III) Complexes Containing Optically Active Tetradentate Schiff Base Ligands
Authors: Hirotsu Masakazu , Kojima Masaaki , Nakajima Kiyohiko , Kashino Setsuo , Yoshikawa Yuzo 
Published: June 2006

Abstract
Cobalt(II) complexes containing tetradentate Schiff base ligands with phenyl substituents, [Co(Schiff base)], have been prepared and the electrochemical properties are reported. The crystal structure of [Co{7-Phsal-(rac)-stien}], where the Schiff base ligand was derived from 2-hydroxybenzophenone and (rac)-1,2-diphenylethylenediamine, has been determined by X-ray structure analysis. Crystal data: monoclinic, P21/n, a = 13.956(2), b = 14.703(2), c = 17.808(3) Å, β = 112.21(1)°, V = 3383.0(9) Å3, Z = 4, and R = 0.052 and Rw = 0.039 for 3976 unique reflections with I &gt; 3σ(I). The two phenyl groups in the N–N chelate moiety are in the axial positions and block the apical sites. In this complex, the redox potential of the Co(III)/Co(II) couple is 0.20 V vs. Ag/Ag+ in acetonitrile and becomes more positive by ca. 300 mV than that for [Co(salen)]. This large positive shift is attributed to the steric effect of the two axially disposed phenyl groups. The redox potentials of the analogous cobalt(II) Schiff base complexes, where (meso)-1,2-diphenylethylenediamine and (R)-1-phenylethylenediamine were used as a diamine, are also explained in terms of the steric effect of the phenyl substituents. The corresponding cobalt(III) Schiff base complexes with two additional axial ligands, [Co(Schiff base)(L)2]ClO4 (L = imidazole (im), 1-methylimidazole (Meim)), have been prepared. The steric interaction between the phenyl groups on the N–N chelate moiety and the axial ligands is discussed based on the X-ray structure, the circular dichroism (CD) spectra, and the 1H NMR spectra. The crystal structure determination of [Co{sal-(meso)-stien}(Meim)2]ClO4 has been performed. Crystal data: monoclinic, P21/c, a = 10.789(2), b = 20.512(3), c = 15.330(2) Å, β = 99.88(1)°, V = 3342.3(8) Å3, Z = 4, and R = 0.051 and Rw = 0.049 for 3414 unique reflections with I &gt; 3σ(I). In order to study the steric effect of the phenyl substituents, the [Co(Schiff base)(L)2]ClO4 complexes have been prepared using (R)-1,2-propanediamine as a diamine. The different behavior shows that the interaction between the phenyl groups is sensitive to the orientation.
Structure and Some Properties of (Alkoxo)(subphthalocyaninato)boron(III)
Authors: Kasuga Kuninobu , Idehara Tsutomu , Handa Makoto , Ueda Yoichi , Fujiwara Takaji , Isa Kimio 
Published: June 2006

Abstract
A few (alkoxo)(subphthalocyaninato)boron(III) complexes, [BX(subpc)] (X = OMe, OEt, OBut, and OPh), were prepared and characterized. The molecular structure of [B(OEt)(subpc)] was determined by an X-ray structure analysis; the boron atom is situated 0.642 Å upward from the triangle plane of three isoindoline nitrogen atoms. The geometry of the boron atom is distorted tetrahedral, and the complex shows a wine-glass shape. The mass spectra showed that a part of the hydrogen atoms of the subphthalocyanine ring are displaced by the halogen atoms of boron trihalide or solvents. The complexes showed strong absorption bands at around 560 (Q band) and 300 nm (B band) in chloroform, respectively. The complexes decomposed in solution under irradiation with visible light. The first oxidative or reductive half-wave potential of [B(OEt)(subpc)] was observed at 1.06 V (vs. SCE) or −1.11 V, respectively.
Specific Salt Effect on the Solubility of fac-Tris(α-amino acidato)cobalt(III)
Authors: Yoshimura Yasuki 
Published: June 2006

Abstract
The salt effect on fac-tris(aniono)cobalt(III) of α-amino acids (fac-[Co(amino acidato)3]), such as d-proline and glycine, was examined by determining its solubility in various aqueous salt solutions. For a comparison, the solubilities of tris(2,4-pentanedionato)cobalt(III) ([Co(acac)3]) and l-phenylalanine (l-phalaH) were also determined. The enthalpy (ΔHs) and entropy of dissolution (ΔSs) were estimated from the temperature dependence of the solubility. While NaCl and Na2SO4 cause a decrease in the solubilities (salting-out effect) of [Co(acac)3] and l-phalaH, these salts result in an increase in the solubility (salting-in effect) of fac-[Co(amino acidato)3]. The salting-out of [Co(acac)3] is caused by an increase in ΔHs, while the salting-out of l-phalaH results from a decrease in TΔSs. On the other hand, the salting-in of fac-[Co(amino acidato)3] is caused by a decrease in ΔHs. These results suggest that the origin of the salt effect on fac-[Co(amino acidato)3] and l-phalaH differs from that of the salt effect on [Co(acac)3].
Ion Pair Charge-Transfer Complexes of Dithiolatocobaltates with Cationic Copper or Nickel Macrocycles: Crystal Structure and Magnetic Properties
Authors: Schmauch Georg , Chihara Teiji , Wakatsuki Yasuo , Hagiwara Masayuki , Kisch Horst 
Published: June 2006

Abstract
The complexes {[M(tim)]2+[Co(mnt)2]2−}, (M = Ni (NiCo), Cu (CuCo), tim = 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene, mnt2− = cis-1,2-dicyano-1,2-ethylenedithiolato) have been isolated. NiCo and CuCo have isomorphous crystal structures (P1-), the basic feature of which is the presence of mixed donor–acceptor chains induced by short intrachain distances of 3.15 and 3.03 Å, respectively. For both NiCo and CuCo, an ion pair charge-transfer band is observed at 707 and 843 nm; application of the Hush model affords reorganization energies for electron transfer from the dianion to the dication of 89 and 104 kJ mol−1, respectively. The magnetic properties of the powder samples have been studied in the temperature range of 2 K to 300 K. In NiCo the diamagnetic [Ni(tim)]2+ acceptor induces antiferromagnetic coupling of the spin a half system [Co(mnt)2]2− along the a-axis over a distance of 6.3 Å. From the exchange coupling constant of J = −37 cm−1 a Weiss temperature of 26 K is calculated. Contrary to that, the magnetic orbitals of [Cu(tim)]2+ and [Co(mnt)2]2− remain uncoupled in CuCo.
Synthesis of a Bis(boronate) Compound Having s-Indacene Framework and Its Property as a Host Molecule for Dimethylaminopyridine
Authors: Sakurai Hidehiro , Iwasawa Nobuharu , Narasaka Koichi 
Published: June 2006

Abstract
A bis(boronate) compound (1) in which boronate components are situated on the same side of the planar s-indacene framework is synthesized from 1,5-dihydro-1,1,5,5-tetramethyl-s-indacene by OsO4-catalyzed dihydroxylation in the presence of dihydroxyphenylborane. The property of 1 as a host molecule has been examined with various compounds. The host 1 forms a 1 : 1 complex with 4-dimethylaminopyridine (DMAP) when an equimolar amount of DMAP is added; more concave-type complexes (2) are formed than convex-type complexes (3). When excess amounts of DMAP are present, a 1 : DMAP = 1 : 2 complex (4) can be isolated as a single crystal. This complex can be characterized by NMR measurements and X-ray analyses. These analyses indicate that the concave-type complex 2 does not have a bidentate coordination between the two boron–nitrogen atoms as proposed previously, but has a monodentate coordination form.
Synthesis of Chiral Crown Ethers Having Bromoarylene Moieties on Their Rim. Anomalous Behavior of Racemic Substrates in Cyclization to Crown Ethers
Authors: Kiyooka Syun-ichi , Tada Mitsuhiro , Kan Sachie , Fujio Mizue 
Published: June 2006

Abstract
Bis(binaphtho)-22-crown-5 and bis(binaphtho)-22-crown-4, having bromoarylene moities on their rim, were prepared from (R)- and (S)-2,2′-dihydroxy-1,1′-binaphthyl. An acyclic diol, bridged by two (R)-binaphthyl moieties, underwent cyclization reaction with diethylene glycol ditosylate to afford the corresponding (R,R)-bis(binaphtho)-22-crown-5 in a good yield (69%). A one-pot cyclization reaction of (R)-2,2′-dihydroxy-1,1′-binaphthyl with 2,6-bis(bromomethyl)bromobenzene resulted in a good yield (45%) of (R,R)-bis(binaphtho)-22-crown-4, having two symmetrical bromoarylene units. In contrast to the cases started with (R)- and (S)-2,2′ -dihydroxy-1,1′-binaphthyl, the racemate in cyclization reactions did not give the corresponding crown products in the expected proportion.
Self-Sensitized Photolysis of N-(1-Naphthoyl)-N-phenyl-O-(benzoyl-substituted benzoyl)hydroxylamines
Authors: Nagakubo Hiroshi , Kubota Gou , Kubo Kanji , Kaneko Tsuyoshi , Sakurai Tadamitsu , Inoue Hiroyasu 
Published: June 2006

Abstract
The mechanism of intramolecular triplet–triplet (T–T) energy transfer and subsequent reaction in N,O-diacylhydroxylamines was investigated using the model compounds N-(1-naphthoyl)-N-phenyl-O-(benzoyl-substituted benzoyl)hydroxylamines (NPB) with self-sensitization abilities. An examination of the UV absorption and phosphorescence behavior as well as of energy-minimized conformations of these relatively flexible model compounds established that T–T energy transfer from the benzophenone chromophore to the naphthoyl chromophore occurs in a nearly unit efficiency exhibiting only phosphorescence derived from the latter chromophore in both methanol–ethanol (1 : 1 v/v) and 2-chlorobutane at 77 K and is more likely to proceed by a “through-space” mechanism than by a “through-bond” mechanism. The self-sensitized photolysis of NPB with 366 nm light in methanol at room temperature was found to give the fragmentation products, N-phenyl-1-naphthalenecarboxamide (PNA), benzophenone (BP), and benzoyl-substituted benzoic acids (BBA), whereas no BBA was detected in the photolysis in 1,2-dichloroethane and acetonitrile. The finding that the reaction of NPB is efficiently quenched by trans-stilbene according to the Stern–Volmer equation in both methanol and 1,2-dichloroethane indicates that all the products come from the first excited triplet state of the naphthoyl chromophore. On the other hand, the enhanced hydrogen bonding ability of the medium resulted in an increase in the quantum yield for the formation of BBA (ΦBBA) accompanied by a decrease in ΦBA holding the magnitude of ΦBBA + ΦBA nearly constant. But neither ΦPNA nor the quantum yield for the disappearance of NPB was subject to such a hydrogen-bonding effect. This intriguing result was explained in terms of a mechanism in which the N–O bond cleavage in triplet NPB gives a vibrationally excited triplet radical pair whose relaxation is very slow compared to decarboxylation of the caged benzoyl-substituted benzoyloxyl radical in 1,2-dichloroethane. Solvation of this vibrationally hot radical pair through hydrogen bonding substantially promotes its relaxation eventually affording BBA.
Molecular Design of Boronic Acid-Based Dye Receptors for Nucleosides
Authors: Takeuchi Masayuki , Taguchi Masahiro , Shinmori Hideyuki , Shinkai Seiji 
Published: June 2006

Abstract
Chromophric receptors for nucleosides were designed utilizing the boronic acid–diol interaction which effectively operates in aqueous solution. Receptors consist of a boronic acid moiety and a dimethylaminophenylazo moiety. The boronic acid moiety forms a covalently-bonded ester linkage with the 2,3-diol group in nucleosides in a reversible manner and the anionic charge generated on the boron atom is stabilized intramolecularly by the pyridinium cation. The azo moiety can overlap with the heteroaromatic ring moiety in nucleosides to stabilize the complex. The complexation constants could be conveniently determined by the absorption spectral change. Comparison of the complexation constants with those of 2-deoxyadenosine without 2-OH and 1,4-anhydroerythritol without the heteroaromatic ring established that the complex formation is primarily due to the boronic acid–diol (2,3-diol) interaction and secondarily facilitated by the hydrophobic and/or π–π stacking interactions.
Asymmetric Synthesis of SM-9164, a Biologically Active Enantiomer of Antifungal Agent SM-8668
Authors: Miyauchi Hiroshi , Nakamura Toshio , Ohashi Naohito 
Published: June 2006

Abstract
SM-9164, a biologically active enantiomer of antifungal agent SM-8668, was prepared by asymmetric synthesis in 10 steps in 13% overall yield from commercially available 2-chloro-1-(2,4-difluorophenyl)ethanone. The crucial steps were Katsuki-Sharpless asymmetric epoxidation of the (E)-allylic alcohol and epimerization of the erythro-sulfone to the desired threo-isomer under basic conditions.
Ring-Opening Reactions of Cyclic Sufinate Esters with a Phenolic Leaving Group
Authors: Okuyama Tadashi , Takano Hideki , Senda Koji 
Published: June 2006

Abstract
The reactions of dibenzo[1,2]oxathiin 6-oxide (1a) and 3,4-dihydro-1,2-benzoxathiin 2-oxide (1b) with a phenolic leaving group were examined in acid and buffer solutions. The substrate 1b undergoes a ring opening in acid and at a higher pH, while 1a is stable in acid with a reverse ring closure predominating. The 18O-labeled 1a undergoes an isotope exchange in acid through a ring opening-closure. Although the ring opening of 1a and 1b is accelerated by buffer bases, owing to nucleophilic catalysis, a similar reaction of 3H-2,1-benzoxathiole 1-oxide with a benzylic alcohol leaving group is independent of the buffer concentration, or is decelerated by some amines. The results are accommodated by a mechanism involving a hypervalent addition intermediate with a varying rate-determining step.
An Efficient Synthesis of Unsymmetrical Dithioacetals from Sulfoxides and Thiols by the Magnesium Amide-Induced Pummerer-Type Reaction
Authors: Kobayashi Kazuhiro , Kawakita Masataka , Akamatsu Hideki , Morikawa Osamu , Konishi Hisatoshi 
Published: June 2006

Abstract
It has been found that the reactions of sulfoxides bearing hydrogen(s) at the α-position (R1SOCHR2R3: R1 = alkyl or Ph; R2 = H, alkyl, or Ph; R3 = H or Me) with thiols (R4SH: R4 = alkyl or aryl) in the presence of the (diisopropylamino)magnesium reagent, generated in situ from the reaction of ethylmagnesium bromide and diisopropylamine, in diethyl ether gave unsymmetrical dithioacetals (R1SCR2R3SR4) in isolated yields ranging from 44 to 91%.
Highly Stereocontrolled Access to 1,1,1-Trifluoro-2,3-epoxypropane via Lipase-Mediated Kinetic Resolution of 1,1,1-Trifluoro-3-(phenylthio)propan-2-ol and Its Application
Authors: Shimizu Makoto , Sugiyama Kouki , Fujisawa Tamotsu 
Published: June 2006

Abstract
1,1,1-Trifluoro-3-(phenylthio)propan-2-ol was prepared in high enantiomeric purity by lipase-mediated kinetic resolution of the corresponding esters. The resolved alcohol was successfully converted into 1,1,1-trifluoro-2,3-epoxypropane and/or used in the subsequent reactions as latent 1,1,1-trifluoro-2,3-epoxypropane via sulfonium salt formation.
Magnetic Field Effects on the Dopant-Exchange Process in Polypyrrole
Authors: Mogi Iwao 
Published: June 2006

Abstract
The electrochemical dopant-exchange (DE) process of p-toluenesulfonate-doped polypyrrole (PPy/TsO−) was studied in LiClO4 and LiBF4 aqueous solutions under high magnetic fields of up to 12 T. The application of magnetic fields to the redox process of the PPy/TsO− film or to the electropolymerization process shifts the undoping potential of the TsO− ion to a positive or negative side, respectively. As a result, the magnetic fields allow control of the plastic behavior in the DE process of the PPy/TsO− film. These results are discussed in connection with the effect of the diamagnetic orientation.
A New Aspect of Organobismuth Chemistry: Synthesis, Properties, and Reactions of Bismuthonium Compounds
Authors: Matano Yoshihiro , Suzuki Hitomi 
Published: June 2006

Abstract
This article is intended to describe recent progress in the chemistry of bismuthonium compounds, represented by onium salts, ylides, and imides, that have long been left untouched within the frame of heteroatom chemistry mainly because of limited access. However, the recent development of methodologies for the preparation of bismuthonium compounds has enabled us to unveil their properties as well as their chemistry. The article is comprised of three sections that mainly deal with: bismuthonium salts synthesized from triphenylbismuth difluoride and organo-silanes or -stannanes; stabilized and moderately stabilized bismuthonium ylides synthesized from triphenylbismuth(V) compounds and bismuthonium salts; and bismuthane imides prepared by oxidative imination of bismuthanes and by reaction between triphenylbismuth(V) dihalides and sulfonamides. Synthesis, X-ray structures, and typical reaction modes of these bismuthonium compounds are delineated in the order in which they appear.
Crystal and Molecular Structures of Novel Metal–Carbene Complexes IV. Effect of Carbonyl Groups and Formation Mechanism
Authors: Manabe Noriko , Yasui Masanori , Nishiyama Hideyuki , Shimamoto Souichi , Matsumura Noboru , Iwasaki Fujiko 
Published: June 2006

Abstract
X-Ray structure analyses were carried out for the metal complexes obtained from 2,3,4,5-tetrahydro-1,6-dialkyl-3,4-trimethylene-5-thioxo-6aλ4-thia-1,3,4,6-tetraazapentalene-2-ones (8) and 2,3,4,5-tetrahydro-1,6-diphenyl-3,4-trimethylene-6aλ4-thia-1,3,4,6-tetraazapentalene-2,5-dione (9), in order to investigate the effect of the carbonyl groups on the formation of the metal–carbene complexes instead of thiocarbonyl groups. The structure analyses revealed that the Pt complex 10, {[3-(methylcarbamoyl-κN) perhydropyrimidine-1-yl-κC2] (methyliminomethanethiolato-κS)}(triphenylphosphine)platinum (II), and the Rh complex 11, trans(P,P′)-(chloro) {[3-(ethylcarbamoyl-κN)perhydropyrimidine-1-yl-κC2] (ethyliminomethanethiolato-κS)}bis(triphenylphosphine)rhodium(III), were obtained from the mono-carbonyl derivative 8. They are metal–carbene complexes coordinated with S and N atoms; the oxygen atoms of the carbonyl groups remained without coordinating to a metal atom. Treating a bis-carbonyl derivative 9 with a Rh reagent, the resultant complex was a Rh complex, 12, trans(P,P′)-dichlorobis(triphenylphosphine) [1,4,5,6-tetrahydro-1-(phenylcarbamoyl)-2-pyrimidinethiolato-κN,κS]rhodium(III), which was not a metal–carbene complex. The formation of the metal–carbene complexes required at least one thiocarbonyl group; the central metal was coordinated by at least one S atom. The formation mechanism of the metal–carbene complexes was proposed from the results of the structures of carbene complexes and MO calculations.