bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics and Mechanism of the Oxidation Reactions of Dialkyldithiocarbamatocopper(I) Tetramer and -silver(I) Hexamer with Tetraalkylthiuram Disulfide
Authors: Kita Hidetoshi , Miyake Shin-ichi , Tanaka Koji , Tanaka Toshio
Published: July 2006

Kinetics of the oxidations of dialkyldithiocarbamatocopper(I), [{Cu(S2CNR2)}4] (R=Et, n-Pr), and -silver(I), [{Ag(S2CNR2)}6] (R=Et, n-Pr, i-Pr), with the corresponding tetraalkylthiuram disulfide, [(R2NC(S)S) \llap–2], were investigated in dichloromethane employing a stopped-flow technique. The reactions are interpreted to proceed by a mechanism involving a rapid equilibration (i) (the multi-step equilibrium constant=K0) to form adduct,

(Remark: Graphics omitted.)

[M(S2CNR2){(R2NC(S)S) \llap–2}], which are decomposed in a rate-determining step (the rate constant=k) yielding the final products, [M(S2CNR2)2]. According to this mechanism, the rate law in the presence of excess [(R2NC(S)S) \llap–2] is expressed as v=K0k[[(R2NC(S)S) \llap–2]][[{M(S2CNR2)}x]]/(1+K0[[(R2NC(S)S) \llap–2]]), where K0k(25 °C)=1.17×104 (Et), 5.70×103 (n-Pr) M−1 s−1 (M=mol dm−3) for the copper system, and K0(25 °C)=28.2 (Et), 49.1 (n-Pr), 86.7 (i-Pr) M−1 and k(25 °C)=2.17 (Et), 1.50 (n-Pr), 6.56 (i-Pr) s−1 for the silver system. The activation parameters also were determined and the nature of transition states is discussed.
CNDO/2 Parametrizations and the Applications to Some Organosulfur Molecules: (CH2SH)2, (CH2SCH3)2, CH3SCH2SH, and CH3SCH2SCH3
Authors: Ohsaku Masaru , Bingo Norihisa , Sugikawa Wataru , Murata Hiromu
Published: July 2006

The CNDO/2 spd′ parametrizations of Kd, βc, ζs, and βs have been performed. Some of the valence and torsional angles of 1,2-ethanedithiol (CH2SH)2, 1,2-bis(methylthio)ethane (CH2SCH3)3, methanethiol, ethanethiol, (methylthio)methanethiol CH3SCH2SH, and bis(methylthio)methane CH3SCH2SCH3 have been optimized. In order to obtain further information on the rotational isomerism, CNDO/2 spd′ and sp calculations have been conducted for the molecules with variations in torsional angle.
Spectrophotometric Determination of Cadmium(II) with Dithizone and 1,10-Phenanthroline
Authors: Akaiwa Hideo , Kawamoto Hiroshi , Yoshimatsu Eiji
Published: July 2006

Cadmium(II) has been quantitatively separated from zinc(II) by an ion-pair extraction system. An ion-pair consisting of cadmium(II) and 1,10-phenanthroline (phen) was found to be preferentially extracted into chloroform from an aqueous chloride solution containing zinc(II). The extracted species in chloroform reacted with dithizone (H2Dz) to give the reddish mixed complex Cd(HDz)2(phen) having an absorption maximum at approximately 505 nm. The resulting calibration curve obeys Beer’s law, the Sandell sensitivity being 0.0013 μg cm−2. The effect of diverse ions has been examined, and a new highly selective method for the spectrophotometric determination of trace amounts of cadmium in metallic zinc established.
Reaction of Dimethyl Phosphonate with Ketene Dimethyl Dithioacetal Derivatives. An Alternative Method to Prepare s-Alkylphosphonates
Authors: Yamashita Mitsuji , Miyano Tadaaki , Watabe Takashi , Inokawa Hiromi , Yoshida Hiroshi , Ogata Tsuyoshi , Inokawa Saburo
Published: July 2006

Reaction of dimethyl phosphonate with phenylketene dimethyl dithioacetal derivatives have been investigated to prepare s-alkylphosphonates. The addition reactions of phosphonate were accelerated in dithioacetal derivatives in the following order: –SMe<–SOMe<<–SO2Me. The reaction of β,β-bis(methylsulfonyl)styrene (7) with dimethyl phosphonate followed by the catalytic reduction afforded dimethyl α-methylbenzylphosphonate in 74% yield from compound 7. The reaction of 1-methylsulfinyl-1-methylthio-4-phenyl-1-butene with dimethyl phosphonate gave dimethyl (2-methylthio-1-phenethylvinyl) phosphonate in 21% yield.
Crystal Structure of 5-Bromocytosine
Authors: Kato Masuhiro , Takenaka Akio , Sasada Yoshio
Published: July 2006

The crystal structure of 5-bromocytosfne has been determined by X-ray analysis to investigate the bromination effect on the cytosine moiety. The space group is P21/a, with dimensions a=16.943(2), b=9.155(1), c=3.846(1) Å, β=99.89(1)°, and Z=4, The structure was solved by the heavy-atom method and refined by the full-matrix least-squares method. A comparison with the cytosine structure indicates some large deviations in bond lengths and angles, which are attributed to the steric and electronic effects caused by bromination. After the VSEPR theory, the slight increase of C(2)–N(3)–C(4) angle (0.8°) is interpreted as the decrease of the effective charge of the lone pair on N(3), and this is related to the difference of pKa values between 5-bromocytosine and cytosine.
Reactions of 2′-Hydroxyisoflavone and 2′-Hydroxy-2-methylisoflavones with Metal Salts
Authors: Kurosawa Kazu , Araki Fukuo
Published: July 2006

Reactions of four 2′-hydroxy-2-methylisoflavones with lead(IV) acetate gave the corresponding l0b-acetoxy-5a-methyl-5a,10b-dihydrobenzofuro[2,3-b][1]benzopyran-11-ones in 21–25% yields and 2-(2-methyl-4-oxo-4H-chromen-3-yl)-p-benzoquinones in 27–46% yields. Reactions of the isoflavones with manganese(III) acetate gave the ketones in 1–25% yields. Reaction of 2′-hydroxy-4′,7-dimethoxyisoflavone with lead(IV) acetate gave 10b-acetoxy-3,8-dimethoxy-5a,10b-dihydrobenzofuro[2,3-b][1]benzopyran-11-one, and 3,8-dimethoxybenzofuro[2,3-b][1] benzopyran-11-one.
Preparation and Isomerization of Isomers of the l- or d-Aspartato(l-histidinato)cobalt(III) Complex
Authors: Watabe Masatoshi , Yano Hisao , Yoshikawa Sadao
Published: July 2006

The six isomers of the [Co(l- or d-asp)(l-his)] complex (asp=aspartate ion and his=histidinate ion) have been prepared and the isomerization studied in the absence of any catalyst. The equilibrium mole fractions of these isomers in water has been found for l-transO5cisN5, l-cisO5transN5, l-fac, to be 0.53, 0.06, and 0.41, respectively, those for d-cisObcisN5, d-transO5transN5, and d-fac to be 0.48, 0.01, and 0.51 respectively. The indication is that the relative positions of the six coordinated atoms around a cobalt atom cause these unequal isomer concentration ratios. The isomerisms are dealt with by means of a network of first order reversible reactions and the absolute values of the rate constants at 80 °C have been determined.
A Broad-line NMR Study on Some Pyrene Complexes: Molecular Motion and Isomorphism in the High-temperature Forms
Authors: Inabe Tamotsu , Matsunaga Yoshio , Yoshida Yuji
Published: July 2006

The pyrene complexes with six polynitro aromatic compounds are isomorphous to each other above the transition temperatures. The onset of a large degree of molecular motion has been shown from broad-line NMR measurements to occur at the transition temperature of all the six complexes.
The Structure of Yahazunol, a New Sesquiterpene-substituted Hydroquinone from the Brown Seaweed Dictyopteris undulata Okamura
Authors: Ochi Masamitsu , Kotsuki Hiyoshizo , Muraoka Kiyoshi , Tokoroyama Takashi
Published: July 2006

The structure of yahazunol, an antimicrobial substance isolated from the brown seaweed D. undulata Okamura, was established on the basis of spectral and chemical evidence.
The Photochemical Reaction of Benzo[c]cinnoline. III. Mechanism of Carbazole Formation
Authors: Inoue Hiroyasu , Hiroshima Yukimi , Miyazaki Kiyoto
Published: July 2006

5,6-Dihydrobenzo[c]cinnoline is an intermediate in the photochemical formation of carbazole from benzole[c]cinnoline. The mechanism of the photo-induced carbazole formation from 5,6-dihydrobenzo[c]cinnoline has been studied in acidic aqueous 2-propanol of the reactant previously produced by the photo-reduction of benzo[c]cinnoline. It has been established that only the protonated species of the reactant undergoes photoreaction. The results of quenching experiments on quantum yields for the reaction and on the fluorescence of the reactant have shown that the reactive state is the first excited singlet state of protonated 5,6-dihydrobenzo[c]cinnoline. The initial step in the reaction is the hydrogen atom abstraction followed by elimination of the amino radical.
Transport of Picrate Anion against Its Concentration Gradient through a Dichloroethane Membrane
Authors: Sugiura Masaaki , Shinbo Toshio
Published: July 2006

The rate of picrate transport coupled to a diffusion of potassium ions through a bulk 1,2-dichloroethane membrane has been measured. The membrane, containing a potassium ionophore separated two aqueous phases, one containing picrate and potassium salt and the other containing picrate and lithium salt. The picrate anion was accumulated against the concentration gradient in the aqueous phase containing the lithium salt. The rate of picrate transport incrased with increasing ionophore concentration and in the absence of the ionophore, the transfer of picrate did not occur. The effect of potassium and lithium counter-ions such as chloride, nitrate and sulfate on the transport of picrate has been examined. The combination of potassium sulfate and lithium nitrate showed the highest rate of transport. In the potassium nitrate-lithium nitrate system, the transport of picrate was appreciably depressed by the transfer of nitrate ions across the membrane. The decrease in concentration of potassium ion in the aqueous phase brought about a lowering of the rate of picrate transport. The rate of picrate transport rose according to the following order of ionophore : dicyclohexyl-18-crown-6>dicyclohexyl-24-crown-8>dibenzo-18-crown-6>dibenzo-24-crown-8>valinomycin.
The Rates of the Hydrogenation of the Coordinated Styrene and Acrylonitrile in a Rhodium-Olefin Complex [RhClH2(ol)(PPh3)2]
Authors: Ohtani Yoshimi , Yamagishi Akihiko , Fujimoto Masatoshi
Published: July 2006

Kinetics of the hydrogenation of coordinated styrene and acrylonitrile in a rhodium-olefin complex RhClH2(ol)(PPh3)2 (ol=styrene or acrylonitrile) was studied by stopped-flow method and by the direct measurements of hydrogen-gas uptake. The equilibrium constant of the reaction RhCl(ol)(PPh3)2+H2\ightleftharpoonsRhClH2(ol)(PPh3)2, K34, and the rate of the hydrogenation of the olefin in the complex RhClH2(ol)(PPh3)2, k45, were determined to be 3.2×103 mol−1 dm3 and 2.7 s−1 for styrene, and 3.5×102 mol−1 dm3 and 0.50 s−1 for acrylonitrile, respectively. The differences in the values for these two olefins were discussed. The data for cyclohexene were also briefly mentioned.
Molecular Structure and Internal Rotation of Trimethylamine-Boron Trifluoride. A Combination of Electron Diffraction and Spectroscopic Data
Authors: Iijima Kinya , Shibata Shuzo
Published: July 2006

The molecular structure of trimethylamine-boron trifluoride (CH3)3N·BF3 was determined from gas electron-diffraction data with vibrational and rotational spectroscopic data. The geometric parameters of the molecule were found to be very close to those inferred from the preliminary analysis of the diffraction data alone. The structural parameters and uncertainties were rg(N–B)=1.674(4) Å, rg(B–F)=1.374(2) Å, rg(C–N)=1.485(2) Å, rg(C–H)=1.100(3) Å, rg(F…F)=2.288(2) Å, and rg(C…C)=2.420(4) Å. The potential barrier about the N–B axis was estimated to be 4.3±0.3 kcal/mol in the gas phase; this value is much larger than that from NMR spectra.
Glucosidation of Tetra-O-benzyl-α-d-glucose with Chlorosilane and Silver Sulfonate
Authors: Koto Shinkiti , Morishima Naohiko , Zen Shonosuke
Published: July 2006

Glucosidation of 2,3,4,6-tetra-O-benzyl-α-d-glucopyranose with methanol or cyclohexanol in the presence of chlorosilane and silver sulfonate is described. As by-products, octa-O-benzyl-α,α- and -α,β-trehaloses are also formed. Possible reaction pathways are discussed.
Photolysis of Organic Azides. IV. Formation of o-Xylylene Derivatives from 2,3-Diazidonaphthalenes. Direct Observation by Low-temperature and Flash Photolysis
Authors: Yabe Akira
Published: July 2006

The photolysis of 2,3-diazidonaphthalene (3a) in a rigid matrix at 77 K gave the product having absorption bands in the 400–500 nm region, which has been assigned as α,ω-dicyano-o-xylylene (2a) by use of another precursor 1,2-dicyano-1,2-dihydrobenzocyclobutene. 2a has been also observed by the flash photolysis of 3a in fluid solution at room temperature, and the lifetime in methanol at 20 °C was 62 s. The dominating factor in the lability of 2a was the rigidity of the medium rather than the temperature. The reaction mechanism for the formation of 2a from 3a has been proposed as a monophotonic process involving the attack of the nitreno group on the azido group at the ortho position. Similarly, direct observations of α,ω-dimethoxy- and α,ω-diacetoxy-α,ω-dicyano-o-xylylenes have been given from 1,4-dimethoxy- and 1,4-diacetoxy-2,3-diazidonaphthalenes respectively.
The Structure and Configuration of (+)-Glutionosone and (+)-Oxyglutinosone
Authors: Murai Akio , Taketsuru Hirofumi , Yagihashi Fujio , Katsui Nobukatsu , Masamune Tadashi
Published: July 2006

The structure elucidation of (+)-glutinosone and (+)-oxyglutinosone, antifungal norsesquiterpenes qualified as phytoalexins in diseased tobacco leaves and in diseased potato tubers, respectively, is described.
Modification of (S)-N,N-Dimethyl-1-[(R)-1′,2-bis(diphenylphosphino)ferrocenyl]ethylamine (BPPFA) as a Ligand for Asymmetric Hydrogenation of Olefins Catalyzed by a Chiral Rhodium(I) Complex
Authors: Yamamoto Keiji , Wakatsuki Junya , Sugimoto Ryuichi
Published: July 2006

Asymmetric homogeneous hydrogenation of prochiral olefins catalyzed by chiral rhodium(I) complexes was carried out by using several ferrocenylphosphines as ligands which play a key role of the chiral recognition. Modifications of BPPFA were made in order to examine a steric effect of the given substutient at the asymmetric center on the efficiency of the chiral ligands, indicating the parent BPPFA to be superior to the others examined for the asymmetric hydrogenation of highly functionalized olefins.
Cyclotrimerization of Phenylacetylene Catalyzed by Halides of Niobium and Tantalum
Authors: Masuda Toshio , Mouri Taizo , Higashimura Toshinobu
Published: July 2006

Halides of niobium and tantalum (NbX5, TaX5; X=Cl, Br, F) catalyzed the cyclotrimerization of phenylacetylene in hydrocarbon and chlorinated hydrocarbon solvents at 0–90 °C. When NbCl5 and TaCl5 were used as catalysts, two cyclic trimers, 1,2,4- and 1,3,5-triphenylbenzenes were exclusively formed, and their ratio varied from 17:83 to 94:6 depending on reaction conditions. The cyclotrimerization was more selective than those by other known catalysts. The cyclotrimerization by NbBr5 and TaBr5 occurred in a similar manner, but the reaction was less selective than that catalyzed by NbCl5 and TaCl5. Not only cyclotrimerization but also linear oligomerization proceeded by NbF5 and TaF5 as catalysts. The results obtained were discussed together with the linear polymerization of phenylacetylene catalyzed by MoCl5 and WCl6.
Exact Relationship between Resonance Energies and Ring Currents of Aromatic Annulenes
Authors: Aihara Jun-ichi
Published: July 2006

Haddon’s analytical relationship between the resonance energies and the ring currents of (4n+2)π-electron annulenes was decidedly improved by means of the graph theory of aromaticity.
Surface Composition of SnO2–ZrO2 Binary Oxide Catalyst and Its Selectivity for C3H6–NO Reaction
Authors: Imanaka Toshinobu , Hashimoto Takeshi , Sakurai Katsumi , Okamoto Yasuaki , Teranishi Shiichiro
Published: July 2006

The relation between the composition of outermost surface layer on SnO2–ZrO2 binary oxide catalyst and catalytic selectivity in the C3H6–NO reaction has been investigated by XPS technique. The composition of outermost surface layer was estimated from a comparison of the intensity ratios of X-ray induced Auger peak or XPS peak of Sn to XPS peak of Zr. A superficial enrichment of Zr was observed in these catalysts calcined at 600 °C in the air, while surface enrichment of Sn took place during the course of evacuation at 450 °C. The catalytic selectivity for formation of acrylonitrile showed a maximum with the catalyst containing Sn and Zr in the same concentration at the outermost surface layer of catalyst.
Topological Index and Thermodynamic Properties. II. Analysis of the Topological Factors on the Absolute Entropy of Acyclic Saturated Hydrocarbons
Authors: Narumi Hideyuki , Hosoya Haruo
Published: July 2006

The absolute entropy of acyclic saturated hydrocarbons is found to be well correlated linearly with the logarithm of the topological index (ZG) of the graph of the carbon atom skeleton as, S°=alogZG+b, excpet for sterically overcrowded and highly symmetrical molecules. This relation is improved by taking the symmetry factor σ into account as, S°=alogZG+b+clogσ. The physical meaning of these relations is clarified by analyzing the mathematical properties of ZG and the rotational partition function proposed by Pitzer.
The Collection of Uranium from Sea Water with Hydrous Metal Oxide. III. The Effects of Diverse Ions in Sea Water on Uranium Adsorption by Hydrous Titanium(IV) Oxide
Authors: Yamashita Hisao , Ozawa Yoshihiro , Nakajima Fumito , Murata Toshifumi
Published: July 2006

The effect of diverse ions present in sea water on the uranium adsorption is elucidated in the present paper. The uranium-adsorption experiments were conducted using sea water and a solution containing 0.72 mol dm−3 NaCl and 2.3×10−3 mol dm−3 NaHCO3. The uranium uptake was about ten times larger from the NaCl–NaHCO3 solution than from sea water. The ions which depressed the uranium uptake were the calcium, magnesium, and fluoride present in sea water. Among these ions, calcium had the largest effect on the uranium uptake. The analysis of calcium and carbonate in the adsorbent after the adsorption experiment has revealed that the molar ratio between calcium and carbonate was about one. It was considered that calcium carbonate was deposited on the adsorbent during the uranium adsorption. The specific surface area and the pore volume decreased after the deposition of calcium carbonate. It was supposed that the decrease in the uranium uptake was caused by the coverage of the surface of hydrous titanium(IV) oxide with calcium carbonate. Magnesium ions depressed the uranium uptake in the same manner as calcium ions. The effect of the magnesium ions, however, was relatively small compared with that of the calcium ions.
Aldol Condensations with Metal(II) Complex Catalysts
Authors: Irie Kazuo , Watanabe Ken-ichi
Published: July 2006

Aldol condensations of aldehydes with ketones catalyzed by the first-row transition metal(II) complexes have been widely studied. Complexes of Co(II), Ni(II), Cu(II), and Zn(II) acetates with 2,2′-bipyridine were effective catalysts to afford cross-aldol condensation products, α,β,-unsaturated ketones, in high yields without any self-condensation products. The reaction of 2-butanone, unsymmetrical aliphatic ketone, with benzaldehyde took place regioselectively to give base-catalyzed-type products.
Preparation and 1H-NMR Spectra of Dialkyl{tetrakis(1-pyrazolyl)borato}thallium(III) Complexes
Authors: Onishi Masayoshi , Hiraki Katsuma , Nakagawa Shigeki
Published: July 2006

Diethyl- and dibuthyl{tetrakis(1-pyrazolyl)borato}thallium(III) complexes were prepared and characterized. The 1H-NMR spectra of pyrazolyl protons of the BPz4 ligand as well as the coupling constants between thallium and alkyl protons are discussed.
New Applications of Crown Ethers. II. Synthesis of 4′-Formylbenzocrown Ethers
Authors: Wada Fumio , Hirayama Hiroshi , Namiki Hiroshi , Kikukawa Kiyoshi , Matsuda Tsutomu
Published: July 2006

4′-Formylbenzo-15-crown-5, -18-crown-6, and bis(4′-formylbenzo)-18-crown-6 were conveniently synthesized in excellent yields by Smith modification of Duff reaction: formylation with hexamethylenetetramine and trifluoroacetic acid or methanesulfonic acid.
Oxidation of Nitrotoluenes with Electro-generated Superoxide Ion
Authors: Sagae Hiromitsu , Fujihira Masamichi , Lund Henning , Osa Tetsuo
Published: July 2006

The oxidation of o-, m-, and p-nitrotoluenes with electro-generated superoxide ion in dimethylformamide was studied using cyclic voltammetry and controlled potential macro-electrolysis. The electrochemical reduction of oxygen in the presence of o- and p-nitrotoluenes yielded the corresponding carboxylic acids because the methyl groups in these derivatives are activated by the nitro group. An intermediate in these oxidations should be the corresponding nitrobenzaldehyde. The reaction mechanism is discussed.
Solvent Effects on the Photoamination of 1-Amino-2,4-dibromoanthraquinone. II. Dual Mode of the Photoamination in Ethanol via the S1(1CT) and T1(3CT) States
Authors: Inoue Haruo , Shinoda Tsutomu , Hida Mitsuhiko
Published: July 2006

The photoamination of 1-amino-2,4-dibromoanthraquinone (1) by butylamine in ethanol was investigated. The reaction was accelerated under an air atmosphere (Φair=1.7×10−3, ΦN2=2.3×104, where [butylamine]=5.00×10−2 mol/dm3). A detailed kinetic study indicated that, under nitrogen, the photoamination proceeded via the T1(3CT) state populated by the intersystem crossing from the S1(1CT) state, while under air it proceeded via both the T1(3CT) and the S1(1CT) states. The latter pathway under air included an interaction between the S1(1CT) state and oxygen to form an exciplex or a collisional complex such as [AQδ+···O2δ−]. The deactivation constant from the T1(3CT) of 1 in ethanol was revealed to be one order of magnitude smaller than that in benzene and one order magnitude larger than that of 1-aminoanthraquinone in benzene. These results were discuessd in relation to the energy diagram in the excited state and the intramolecular heavy-atom effect of bromine in 1.
Metal Complexes in Acetic Acid. I. Kinetics and Mechanism of Reactions of Tetra-μ-acetato-dicopper(II) with Lithium Chloride and Hydrogen Chloride
Authors: Funahashi Shigenobu , Nishimoto Tetsuo , Banerjee Pradyot , Sawada Kiyoshi , Tanaka Motoharu
Published: July 2006

Kinetics of reactions of tetra-μ-acetato-dicopper(II) (copper(II) acetate dimer: Cu2(OAc)4) with lithium chloride and hydrogen chloride (XCl where X denotes Li or H) in acetic acid have been studied spectrophotometrically by using a stopped-flow technique with a computer-assisted averaging device. The rate of decomposition of copper(II) acetate dimer to the monomeric chloro complex is expressed as −d[Cu2(OAc)4]/dt=kXCl[Cu2(OAc)4][XCl]. At 25 °C kLiCl=(3.5±0.6)×105 mol−1 kg s−1 (ΔH\eweq=50±10 kJ mol−1 and ΔS\eweq=30±20 J mol−1 K−1) and kHCl=(4.8±1.0)×105 mol−1 kg s−1 (ΔH\eweq=23±10 kJ mol−1 and ΔS\eweq=−60±20 J mol−1 K−1). Mechanisms are proposed for the decomposition of copper(II) acetate dimer and some discussions are made on the difference in reactivities of LiCl and HCl.
Wittig-type Reaction of Dimetallated Carbodianion Species as Produced by Zinc Reduction of gem-Polyhalogen Compounds in the Presence of Lewis Acids
Authors: Takai Kazuhiko , Hotta Yuji , Oshima Koichiro , Nozaki Hitosi
Published: July 2006

Treatment of R1COR2 with a suspension prepared from diiodomethane, trimethylaluminum and excess zinc in tetrahydrofuran at room temperature affords olefins R1R2C=CH2 in fair (R1,R2=alkyl) to good (R1=alkyl, R2=H) yields. The ketone methylenation is better carried with another system consisting of CH2Br2–Zn–TiCl4. Ketones and aldehydes are transformed into α-chloro α,β-unsaturated esters or α,β-unsaturated esters in good yields on treatment with methyl trichloroacetate or t-butyl dichloroacetate (ethyl dibromoacetate) in the presence of diethylaluminum chloride and zinc.
A Re-investigation of the Conformational Interconversion in the 1,2,3,6,7,8-Hexahydropyrene Anion Radical by ENDOR
Authors: Iwaizumi Masamoto , Kita Shouichi , Kohno Masahiro , Isobe Taro
Published: July 2006

The ENDOR spectra of the 1,2,3,6,7,8-hexahydropyrene anion radical were measured at −94–−60 °C. Based on the computer simulation of the temperature-dependent ENDOR spectra, the thermodynamic constants of the conformational interconversion of the anion radical were determined and compared with those previously obtained by ESR spectroscopy.
The Glucosylation of Several Alcohols with Tetra-O-benzyl-α-d-glucopyranose and a Mixture of p-Nitrobenzenesulfonyl Chloride, Silver Trifluoromethanesulfonate, and Triethylamine
Authors: Koto Shinkiti , Sato Tadaaki , Morishima Naohiko , Zen Shonosuke
Published: July 2006

A novel glucosylation of several alcohols using 2,3,4,6-tetra-O-benzyl-α-d-glucopyranose and a ternary mixture of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine is presented.
The Formation of Two Kinds of Thiophene Derivatives by the Reaction of the 4H-Pyran-4-thione Derivative with Dimethyloxosulfonium Methylide in a One-pot Process
Authors: Yamaoka Hiroshi , Mishima Ikuhiro , Hanafusa Terukiyo
Published: July 2006

The reaction of 2,6-dimethyl-3,5-diphenyl-4H-pyran-4-thione with dimethyloxosulfonium methylide occurred facilely to give two kinds of 2-thienylacetones, accompanied by a five-membered α,β-unsaturated thione, a naphtho-[2,1-b]thiophene derivative, and a hemithioacetal.
The Absorption Spectra of Monolayers of Fat-soluble Vitamins and the Orientations of Their Chromophores
Authors: Matsuki Kazunori , Nagahira Yukio , Fukutome Hideo
Published: July 2006

The UV absorption spectra at normal incidence and the polarized spectra at 45° incidence of monolayers of vitamin K1, α-tocopherylquinone, vitamin E, ergosterol, and vitamin D2 were measured. The absorption peaks of the monolayers of vitamin K1, α-tocopherylquinone, and vitamin D2 shifted to wavelengths longer than those in a hexane solution, while vitamin E and ergosterol showed little shift. The orientations of their chromophores in the monolayers were investigated by means of the dichroic ratios obtained from their polarized spectra. The molecular axes of vitamin K1, α-tocopherylquinone, and vitamin E were found to be oriented in the range from 0° to about 30° against the normals of their monolayer planes. The molecular axis of ergosterol was found to tilt about 24° against the normal of the monolayer plane. For vitamin D2, no reliable conclusion could be obtained as to its orientation.
Interaction of Water with the Surface of Calcite
Authors: Morimoto Tetsuo , Kishi Jiro , Okada Osamu , Kadota Toshie
Published: July 2006

The interaction of water with the surface of ground calcite was investigated by measuring the water adsorption isotherm and the amount of thermally desorbed molecules in vacuo. The results showed that the surface of ground calcite has chemisorbed water at room temperature which can be completely desorbed by evacuation up to 600 °C, and on which water can be physisorbed in a H2O:OH ratio between 1:2 and 1:1, depending on the conditions of the pretreatment. The isosteric heat of the physisorption of water on the hydroxyls showed that the activity of the adsorption sites for water is reduced by treating the sample at higher temperatures or by washing with water. Moreover, it was found that the surface of the calcite sample starts to release CO2 molecules by heat treatment at relatively low temperatures below 300 °C in vacuo, and that the amount of CO2 increases exponentially with an increase in the temperature.
Copper(I) and Copper(II) Complexes of Tripod Ligands, Tris(2-alkylthioethyl)amine
Authors: Suzuki Masatatsu , Kanatomi Hajime , Koyama Hiroyuki , Murase Ichiro
Published: July 2006

A series of five-coordinate copper(II) complexes with tripod ligands, tris(2-alkylthioethyl)amines (NS3–R, R=CH3, C2H5, n-C3H7, i-C3H7, and t-C4H9), [Cu(NS3–R)L](ClO4)n, where L represents Cl−, Br−, I−, NCS−, im(imidazole), py(pyridine) and H2O, n=1 or 2 were prepared and characterized. The electronic, infrared and ESR spectral data suggest that [Cu(NS3–Me)im](ClO4)2 and [Cu(NS3–Me)OH2](ClO4)2 have a five-coordinate square pyramidal geometry, the other complexes having distorted trigonal bipyramidal or trigonal bipyramidal geometry. The copper(I) complexes with NS3–Me, [Cu(NS3–Me)]ClO4 and [Cu(NS3–Me)NCS] were also prepared and characterized.
Electronic Structures and Conformations of N-Benzylideneanilines. II. Photoelectron Spectral Study
Authors: Akaba Ryoichi , Tokumaru Katsumi , Kobayashi Tsunetoshi , Utsunomiya Chikatoshi
Published: July 2006

Electronic structures and molecular conformations have been studied for N-benzylideneaniline and its 2-methyl, 2,6-dimethyl, and their 4-nitro derivatives by photoelectron spectroscopy. The lower energy bands are analyzed in detail, and the twist angles θN of the anilino benzene rings (ring A) about the carbon-nitrogen bonds are estimated by examining the effect caused by a methyl substitution. It is concluded that N-benzylidene-4-nitroaniline takes a more twisted conformation than N-benzylideneaniline.
The Asymmetric Homogeneous Hydrogenation of Olefins with the Rhodium Complexes of (1S,2S)-1,2-Bis(diphenylphosphinamino)cyclohexane and (2S,3S)-2,3-Bis(diphenylphosphinamino)butane
Authors: Onuma Ken-ichi , Ito Tomiyasu , Nakamura Asao
Published: July 2006

The effect of triethylamine on asymmetric hydrogenation has been studied using the cationic rhodium complex of (1S,2S)-1,2-bis(diphenylphosphinamino)cyclohexane or (2S,3S)-2,3-bis(diphenylphosphinamino)butane as a catalyst. By the addition of triethylamine, higher optical yields are achieved in the hydrogenation of (Z)-α-acetamidocinnamic acid and itaconic acid and higher conversion rates are obtained in the hydrogenation of (E)-2-methylcinnamic acid, mesaconic acid, and citraconic acid. The specific effect of triethylamine on the substrates with a carboxyl group may be explained by the ionization of the carboxyl group, which coordinates the catalytic rhodium complex firmly.
A New Bromophenol from the Red Alga Polysiphonia urceolata
Authors: Kurata Kazuya , Amiya Takashi
Published: July 2006

The investigation of the red alga Polysiphonia  urceolata afforded a new bromophenol, 3,3′-dibromo-4,4′,5,5′-tetrahydroxybibenzyl. The structure was elucidated by a combination of spectroscopic methods and chemical transformations. Besides this compound, seven known bromophenols were isolated.
The Substituent Effect. 15. The LSFE Treatment of Substituent Effects on Basicities of Pyridines
Authors: Sawada Masami , Ichihara Masaharu , Yukawa Yasuhide , Nakachi Takeshi , Tsuno Yuho
Published: July 2006

The relative dissociation constants of meta and para substituted pyridinium ions in H2O at 25 °C were collected from a number of sources. To understand the actual substituent effects with a combination of inductive (I) and pi-electronic (Pi) effect components, the LSFE equation has been employed statistically for each of the meta and para series.

ΔpK_a=ρ_iσ_i+ρ_π^+σ_π^++ρ_π^-σ_π^-

The results illustrate (1) the I effect from the meta position is 1.2 times more effective than that from the para position, (2) the Pi effects from the para position have clearly different sensitivities for pi-donor (−R) and pi-acceptor (+R) classes of substituents; more exalted and more reduced Pi effects than that involved in a σp° constants for −R and +R groups, respectively. Compared with earlier results from the Taft’s DSP and relevant treatments, the soundness of the dual ρπ approach and, further, the superiority of the LSFE treatment have been demonstrated for the description of substituent effects on basicity changes in pyridines.
Negative Azeotropic Transformation in Mixed Monolayers of Octadecylammonium Chloride and Tetradecanoic Acid
Authors: Motomura Kinsi , Ikematsu Masaki , Hayami Yoshiteru , Matuo Hirosi , Matuura Ryohei
Published: July 2006

The surface pressure of mixed monolayers of octadecylammonium chloride and tetradecanoic acid has been measured as a function of mean area per film molecule at various compositions and temperatures. It has been observed that the transition pressure from expanded to condensed state of either constituent decreases with the addition of the other one. This behavior has been called a negative azeotropy in the two-dimensional state in contrast to the positive azeotropy observed for the ethyl heptadecanoate–tetradecanoic acid system. By applying the thermodynamic treatment, the phase diagram has been constructed and the apparent molar entropy and energy associated with the phase transition have been calculated. The results support the view that the negative azeotropic transformation in the mixed monolayer is brought about by the mutual interaction between octadecylammonium chloride and tetradecanoic acid molecules which is stronger than that between the same kind of molecules.
A Thermodynamic Study on Hydrolytic Reactions of Lead(II) Ion in an Aqueous Solution and Dioxane–Water Mixtures. I. A Potentiometric Study
Authors: Kawai Takayoshi , Ishiguro Shin-ichi , Ohtaki Hitoshi
Published: July 2006

The hydrolytic reactions of lead(II) ions were studied at 25 °C by means of potentiometric titrations by using a glass electrode in water and dioxane–water mixture (dioxane contents: 0.1 and 0.2 mol fractions) containing 3 mol dm−3 LiClO4 as a constant ionic medium. Four complexes, Pb3(OH)33+, Pb4(OH)44+, Pb3(OH)42+, and Pb6(OH)84+ were found in the solvent systems examined at pH\lesssim8, and the formation constant *βpq for the reaction, qPb2++pH2O=Pbq(OH)p(2q−p)++pH+, was determined. The autoprotolysis constants Ki in the same solvent systems were also obtained by use of a hydrogen electrode. The formation constant βpq(=*βpq/Kip) for the reaction, qPb2++pOH−=Pbq(OH)p(2q−p)+ was evaluated by combining the formation constants *βpq and the autoprotolysis constants obtained. The free energy change of transfer from water to a dioxane-water mixture for the reaction could be estimates as ΔGpqt=−RTln{βpq(mix)⁄βpq(aq)}. The values (1/p)ΔGpqt of hydroxo complexes of various metal ions such as lead(II), copper(II), nickel(II), beryllium(II), and cadmium(II) ions were approximately independent of the complexes at a given concentration of dioxane. This result suggested that the formal charge per metal ion of the complex, z′ (=z−p/q; z: charge of a metal ion), rather than the total charge of the complex, zq–p, is essential for the interactions between the hydroxo complexes and solvent molecules.
Mechanism of Base Catalyzed Oxidation of 2-(1-Hydroxyalkyl)thiazolium Ion with 3-Methyllumiflavin
Authors: Yano Yumihiko , Tamura Yoshiharu , Hoshino Yutaka , Tagaki Waichiro
Published: July 2006

The oxidation of 2-(α-hydroxybenzyl)- and 2-(1-hydroxyethyl)thiazolium ions with 3-methyllumiflavin was studied kinetically in an aqueous buffer solution. The results indicate that the rate-determining step is carbanion formation followed by rapid oxidation. The carbanion formation was subjected to general base catalysis.
The Effect of Sugars on the Thermal Denaturation of Lysozyme
Authors: Uedaira Hatsuho , Uedaira Hisashi
Published: July 2006

Thermal denaturation of lysozyme (hen egg-white) in aqueous sugar solution was studied by DSC measurements at pH 5 and by CD measurements at pH 2.12. All of the sugars investigated show a stabilizing influence on the native conformation. The effect of sugars on the transition temperature of lysozyme almost linearly increased with the increase of the numbers of equatorial hydroxyl groups per molecule of sugars. The ellipticity of the solutions at 294 nm of lysozyme and glucose or arabinose was additive in the value of each component at pH 5. The effect of sugars in stabilizing the protein structure may be due to the intensification of the hydrophobic interactions inside the protein molecule.
Fluctuation of Local Field and Depolarization Degree of the ν1 Line of Carbon Tetrachloride
Authors: Hyodo Shi-aki , Fujiyama Tsunetake
Published: July 2006

The depolarization degree of a molecule having a Td symmetry was expressed in terms of the mean square fluctuation of the local field which is felt by a molecule in the condensed phase. By the use of the mean square amplitude values observed by the X-ray diffraction method, the depolarization degree of liquid carbon tetrachloride was calculated to be 0.0021, which agrees well with the observed value of 0.0039±0.0002.
Study of Triplet-Triplet Energy Transfer between Like Molecules in a Rigid Glass Solution by Means of Optical Detection of Magnetic Resonance
Authors: Inoue Akinori , Nishi Nobuyuki , Kinoshita Minoru , Ebara Nozomu
Published: July 2006

The triplet-triplet energy transfer between like molecules was investigated for the system of quinoxaline in ethanol by using the method of optical detection of zero-field magnetic resonance at 1.4 K. The concentration dependence of the spin state population indicates that the energy transfer between quinoxaline molecules takes place at concentrations higher than about 2×10−2 mol/dm3.
Electronic Structure of Transition Metal Complexes II. Trans Influence in Ammine Complexes of the First Transition Metals
Authors: Kai Eiko , Misawa Tomoko , Nishimoto Kichisuke
Published: July 2006

CNDO/2 calculations of pentaammine complexes, [M(NH3)5X] (both low and high spin states), where M=Co2+, Co3+, Fe2+, and Fe3+, and X=FH, OH2, CO, NH3, pyridine, OH−, F−, and CN−, have been carried out in order to investigate the mutual influence between ligands. The present calculation shows that the σ-type mutual influence is remarkably affected by the oxidation number and the spin state of the metal ion and scarecely affected by the number of d electron (d electron configuration). Furthermore, the calculated results show the metal-ligand bond distance of a complex in the low spin state should be shorter than that in the high spin state.
Liquid Crystalline Properties of N-(4-Alkoxybenzylidene)-4-halogenoanilines
Authors: Sakagami Sakumitsu , Nakamizo Minoru
Published: July 2006

N-(4-Alkoxybenzylidene)-4-halogenoanilines have been synthesized, and the phase transitions determined using a differential scanning calorimeter and a polarizing microscope. Smectic and nematic phases have been observed for fluoro and chloro derivatives whereas bromo and iodo derivatives exhibit only a smectic phase.
Synthetic Photochemistry. XVIII. A Sensitizer Dependence in the Photooxidation of Indene and Acenaphthylene. The Occurrence of cis-1,2-Glycol Formation in a Rose Bengal-sensitized Reaction
Authors: Hatsui Toshihide , Takeshita Hitoshi
Published: July 2006

Upon Rose Bengal-sensitized photooxygenation, indene and acenaphthylene afforded substantial amounts of the expected cis-glycols by means of the reduction of the intermediate dioxetanes. The formerly proposed structure of one of the isomeric methoxy hydroperoxides was revised on the basis of the chemical and spectral evidence.
Background Atmospheric Concentrations of Halogenated Hydrocarbons in Japan
Authors: Makide Yoshihiro , Kanai Yutaka , Tominaga Takeshi
Published: July 2006

The atmospheric concentrations of CCl2F2, CCl3F, CH3CCl3, CCl4 CCl2FCClF2, CHCl=CCl3, CCl4, CHCl=CCl2, and CCl2=CCl2 in remote areas in Japan arid over the Japan Sea were measured in the summer of 1979. The averaged observed concentrations (in 10−12 v/v) for the compounds were 301±12, 175±7, 23±2, 117±11, 107±6, 14±10, and 19±10 respectively.
Induced Circular Dichroism Spectra of Some Racemic cis-Bis(ethylenediamine)cobalt(III) Complexes in Aqueous (R,R)-Tartrate and (R,R)-Tartratoantimonate(III) Solutions and Their Optical Resolution by Ion-exchange Chromatography
Authors: Nakazawa Hiroshi , Oh Chang Eon , Miyoshi Katsuhiko , Yoneda Hayami
Published: July 2006

Induced circular dichroism (induced CD) was measured for some racemic cobalt(III) complexes in aqueous (R,R)-tartrate and (R,R)-tartratoantimonate(III) solutions, and correlation was examined between the sign of their induced CD spectra and their elution order in ion-exchange chromatography.
Thermal Decomposition of Graphite Fluoride. I. Decomposition Products of Graphite Fluoride, (CF)n in a Vacuum
Authors: Watanabe Nobuatsu , Koyama Satoshi , Imoto Hiroki
Published: July 2006

The mechanism of thermal decomposition of graphite fluoride, (CF)n in a vacuum was studied by means of chemical and gas analyses, and the measurement of crystallinity. The crystallinity of (CF)n was slightly improved in the step of initial decomposition. The fluorine/carbon atomic ratio of initial gaseous product evolved by decomposition was about 2. The product is CF2 or C2F4, and then it gives several compounds by secondary reaction. Every second layers of (CF)n are decomposed, and the evolved molecules or radicals abstract fluorine atoms which are bonded to the neighboring two layers.
Intrinsic Quantum Efficiencies of Semiconductor Photoelectrodes Obtained by Temperature Measurement
Authors: Fujishima Akira , Maeda Yasuhisa , Honda Kenichi
Published: July 2006

Quantum efficiencies of photoelectrochemical reactions on n-type and p-type semiconductor electrodes can easily be determined by the measurement of temperature changes of the surface of semiconductor electrodes by use of thermistors. The quantum efficiencies are intrinsic, since only the absorbed light quanta contribute to temperature change. The merits of the method, simplicity and applicability to the semiconductor of large surface reflectance, are discussed. The intrinsic quantum efficiencies were compared with those obtained by the usual chemical actinometric method.
Liposomal Membranes. IV. Fusion of Liposomal Membranes Induced by Several Lipophilic Agents
Authors: Sunamoto Junzo , Hamada Tomiko , Murase Hiroki
Published: July 2006

It was found that several lipophilic agents, such as cis-, trans-ethyl decaprenoate and their structural analogues, significantly induce the liposome-liposome fusion when incubated together a set of two different liposomes, the A-liposome containing a marker and the B-liposome involving a lipophilic agent. The rate and extent of fusion were followed spectrophotometrically by monitoring the leakage of an amphiphilic marker, Bromothymol Blue, from the fused liposomes. Fusion was also visualized directly by electronmicrographic technique. When only A-liposome was incubated or when a blank liposome containing no lipophilic agents was added to the A-liposome after the preincubation, neither the fusion nor the marker release was observed at least in periods of several hours. Also, neither fusion nor the marker release was observed when either A- or Bliposome or both were multicompart-ment liposome. Removing cholesterol from liposome significantly depressed the fusion. The effect of cholesterol was more prominent on the A-liposome side. trans-Ethyl decaprenoate was more effective about three-fold to induce the fusion than the cis-isomer. Interestingly, the effect was parallel to the antihypertensive activity of the agent.
The Structure of the Cyclodextrin Complex. IX. The Crystal Structure of α-Cyclodextrin–m-Nitroaniline (1:1) Hexahydrate Complex
Authors: Harata Kazuaki
Published: July 2006

The crystal structure of α-cyclodextrin–m-nitroaniline hexahydrate complex was determined by X-ray analysis. The crystal is monoclinic and the space group is P21 with Z=2. The cell dimensions are: a=8.054(1), b=13.508(1), c=25.331(2) Å, and β=103.90(1)°. The structure was solved by an inspection of a Patterson map and by a trialand-error method. The refinement was done by the block-diagonal least-squares method to the final R-value of 0.11 for 2351 reflections (sinθ⁄λ<0.49). α-Cyclodextrin molecules are stacked along the a axis in the head-to-tail fashion to form a channel-type structure. Most of the primary hydroxyl groups of α-cyclodextrin are in a gauche-gauche conformation and linked by hydrogen bonds directly or through water molecules to the secondary hydroxyl groups of the next α-cyclodextrin molecule along the channel. The guest m-nitroaniline molecules are linearly arranged in the channel. The α-cyclodextrin ring includes the nitrophenyl group, while the amino group protrudes outside from the secondary hydroxyl side of α-cyclodextrin and is hydrogen-bonded to a primary hydroxyl group of the next α-cyclodextrin molecule. Along the channel, m-nitroaniline molecules are linked to each other by a weak N–H···O hydrogen bond between the amino group and the nitro group. Columns formed by the stack of α-cyclodextrin are closely packed in the crystal, and intermolecular spaces are filled with water molecules which form many hydrogen bonds with each other and with α-cyclodextrin.
X-Ray Diffraction Study of Liquid Water
Authors: Nishikawa Keiko , Kitagawa Nobuko
Published: July 2006

The energy-dispersive X-ray diffractometer has been applied to the structural study of liquid water. The intensity data are in good agreement with those obtained by the use of an angle-dispersive method. Water has a structural correlation up to only 8 Å at 25 °C.
The Electrochemical Studies of Tetrasulfur Tetranitride in Acetonitrile
Authors: Hojo Masashi
Published: July 2006

S4(NH)4 has been prepared in a good yield (80% or more) by the electrolytic reduction (4-electrons) of S4N4 in the presence of a proton donor in acetonitrile. In the proton donor, a fairly high acidity (acetic acid or a stronger acid) and a much higher concentration than would be expected from the stoichiometry was needed. With a low acidity (e.g., phenol) or a low concentration of the proton donor, a side reaction occurred with the formation of H2S and NH3. Under these conditions, a blue species was produced in the course of the electrolysis; this species was confirmed to be S3−. The re-oxidation of S4(NH)4, the oxidation of S4N4, and the reduction of S4(NH)4 were also examined in this connection.
Layered Compounds. LXIV. Syntheses and Charge Transfer Spectra of Multilayered Paracyclophanequinones
Authors: Machida Hideki , Tatemitsu Hitoshi , Otsubo Tetsuo , Sakata Yoshiteru , Misumi Soichi
Published: July 2006

Three isomeric triple-layered and two isomeric quadruple-layered charge transfer cyclophanes containing benzoquinone and dimethoxybenzene moieties have been synthesized together with two triple-layered and two quadruple-layered paracyclophanequinones. The structures of the isomers were determined by 1H- and 13C-NMR spectra and/or alternative syntheses. By comparing the CT bands of a series of dimethoxycyclophanequinones with those of the corresponding cyclophanequinones, it is concluded that the CT stabilization of multilayered dimethoxyquinones should be attributed mainly to the π-basicity of the durene ring which faces the acceptor quinone ring and partly to the decreasing π-basicity of dimethoxybenzene ring as the layer number increases. No orientational dependence of quinone and dimethoxybenzene moieties on GT transition was observed in the multilayered series.
Structure of α Form of l-Glutamic Acid. α-β Transition
Authors: Hirayama Noriaki , Shirahata Kunikatsu , Ohashi Yuji , Sasada Yoshio
Published: July 2006

An X-ray analysis of the α form of l-glutamic acid, C5H9NO4, has been carried out. The space group is P212121 with a=7.068(1), b=10.277(1), c=8.755(1) Å and Z=4. The structure was solved by the direct method, and least-squares refinement using 855 reflexions led to the final R value of 0.034. The molecule is in a zwitter ion form, and there is a strong OH···O intermolecular hydrogen bond with the O···O distance of 2.578(2) Å. The conformation of l-glutamic acid in the α form is quite different from that in the β form. The occurence frequency in various crystal structures containing glutamic acid residues shows that the conformation in the β crystal is more stable and favourable than that in the α crystal. The transition of the α form to the β form of l-glutamic acid in the mother liquor and the conditions for obtaining the α crystals are discussed based on the crystal and molecular structures of the two polymorphs.
A Study of the Ligand Exchange of Bromo(o-tolyl)bis(triphenylphosphine)nickel(II) with Amine by Means of 31P-and 13C-NMR Spectroscopy
Authors: Nakamura Yoshiyuki , Maruya Ken-ichi , Mizoroki Tsutomu
Published: July 2006

The amine substitution of bromo(o-tolyl)bis(triphenylphosphine)nickel(II) was investigated by the use of 31P- and 13C-NMR. The triphenylphosphine ligands are readily replaced by sterically less crowded amines, such as primary amines, secondary amines, pyridine, and γ-picoline, at room temperature in chlorobenzene, while no replacement at all takes place with tertiary amines. The equilibrium constants with γ-picoline, pyridine, or dibutylamine, as defined by Eq. 2, show that the entropy change contributes predominantly to the constant. The substitution with pyrrolidine, as monitored by means of 13C-NMR, indicates that the amine coordinates to the nickel(II) atom.