bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of Electron Transfer from Cyclic Ketones to Ni(IV) Periodate Complex in Aqueous Alkaline Medium
Authors: Khan Jaffar Ali , Chandraiah U , Kumar B Kishore , Kandlikar Sushama
Published: July 2006

The kinetics of electron transfer from cyclic ketones (represented by (S)) to Ni(IV) periodate complexes has been studied in aqueous alkaline medium. The kinetics exhibit a pseudo-first-order disappearance of Ni(IV) periodate complexes when the [substrate] is present in excess. The pseudo-first-order rate constants, kobs, were linearly dependent on [S] and the order in [S] were found to be unity. The rate of the reaction increased with the increase in [OH−], however the rates were retarded with the increase in [periodate]. Salt and solvent effect studies indicate that the reaction is of ion-dipole type. A suitable mechanism involving slow adduct formation between enol and oxidant, and its decomposition in a fast step have been suggested. A rate law consistent with the proposed mechanism has also been derived. The products of oxidation were identified as corresponding decarboxylic acids.
4-(2-Quinolylazo)phenol as a Spectrophotometric Reagent for Palladium(II), Osmium(VIII), and Gold(III)
Authors: Singh Ishwar , Kadyan Pratap Singh , Garg B S , Barua Sudarsan
Published: July 2006

Reaction behavior of 4-(2-quinolylazo)phenol (p-QAP) is established with three noble metals, i.e. palladium(II), osmium(VIII), and gold(III), under various conditions. Palladium(II) forms a 1:1 greenish violet complex at pH 8–10 (absorption maximum at 580 nm), while osmium(VIII) forms a 1:1 violet compex at pH 8–9.5 (absorption maximum at 550 nm) with the ethanolic solution of p-QAP. Color reaction with gold(III) with ethanolic solution of p-QAP is instantaneous, but fades away with time. However, a 4:4:2 mixture of water, ethanol, and cyclohexanol stabilizes this color for 45 min. Thus a 1:1 red gold(III) complex formed at pH 8–9.5 absorbs maximum at 550 nm. The Sandell’s sensitivities (ng cm−2) of the color reactions are 2.7, 3.9, and 9.8 with palladium(II), osmium(VIII), and gold(III) respectively. Other physicochemical characteristics of the complexes are established. A number of foreign ions tested for their interferences and use of masking agents wherever necessaty it tabulated. Synthetic solutions identical in composition to some palladium(II) and gold(III) alloys are estimated to ascertain the suitability of the reagent.
Intrinsic Reaction Coordinates for the Dissociation and the Isomerization Reactions of Formaldehyde
Authors: Cho Seikichi
Published: July 2006

Static and dynamic intrinsic reaction coordinates are defined by using the eigenvectors of the force constant matrix, and the simultaneous eigenvectors of the relative kinetic energy and the force constant matrix, respectively. The theory was applied to the dissociation and the isomerization reactions of the formaldehyde molecule. It is shown that the intrinsic reaction coordinate of the dissociation reaction of formaldehyde left from the normal coordinate of the equilibrium formaldehyde with the second lowest wavenumber, the rocking mode of vibration, while that of the isomerization reaction departed from the scissoring mode having the third lowest wavenumber.
Nontemplate Synthesis of Macrocyclic Tetraimine Schiff Bases Incorporating Dithienylmethane Units
Authors: Sone Tyo , Ohba Yoshihiro , Watanabe Ryuji
Published: July 2006

Novel 26- and 28-membered macrocyclic tetraimine Schiff bases incorporating four thiophene units as ring constituents were synthesized by a nontemplate method starting from bis(5-formyl-2-thienyl)methane derivatives and aliphatic diamines under high-dilution conditions.
A Facile and Practical Synthesis of 1-Aryl-3,3,3-trifluoropropynes
Authors: Hiyama Tamejiro , Sato Ken-ichi , Fujita Makoto
Published: July 2006

A facile and practical method for the synthesis of ArC≡CCF3 is described which involves (1) conversion of aldehydes ArCHO into ArCH=CClCF3 with 1,1,1-trichloro-2,2,2-trifluoroethane, zinc powder, and acetic anhydride in one-pot and (2) dehydrochlorination with sodium t-butoxide or sodium amide/t-butyl alcohol.
Sodium Telluride-Mediated Sulfenylation of α-Halo Carbonyl Compounds with Diphenyl Disulfide
Authors: Padmanabhan Seetharamaiyer , Ogawa Takuji , Suzuki Hitomi
Published: July 2006

Under mild aprotic conditions α-halo carbonyl compounds react with diphenyl disulfide in the presence of sodium telluride to give the corresponding α-phenylthio derivatives in good to moderate yields. The reaction appears to proceed involving the sulfur–sulfur bond cleavage of diphenyl disulfide by sodium telluride.
Stereospecific Preparation of Chiral 1,5-Diketone by One-Methylene Incorporated Dimerization Reaction of d-Camphor Enolate and Reduction of the 1,5-Diketone
Authors: Kiyooka Syun-ichi , Yamashita Tsuneo , Yamamoto Akihisa , Fujiyama Ryoji
Published: July 2006

The reaction of d-camphor with N,N-dimethylformamide (DMF) in the presence of potassium hydride stereoselectively gave bis[(1R,3S,4R)-2-oxo-3-bornyl]methane (1). This new condensation reaction is proposed to proceed by an attack of the d-camphor enolate to DMF and a subsequent reduction. Three chiral diols were obtained from the reduction of 1.
A 13C NMR Relaxation Study of Octyltrimethylammonium Salts in D2O
Authors: Uzu Yuhei , Saito Yasushi , Yokoi Masatoki
Published: July 2006

The concentration dependence of the 13C spin-lattice relaxation times (T1) of the alkyl carbons in octyltrimethylammonium salts was analyzed by means of applying the phase separation model. At higher concentration, the 1/T1 value deviates from a linear plot and depends on the magnetic field strength. The molecular motions in monomer and micellar states are discussed, along with the overall motions of the molecule and its internal motion.
Molecular Complexes of Cyclophanes. XV. Charge-Transfer Complexes of Sterically Hindered[2.2]metapara- and [2.2]paracyclophanes with π-Acceptors
Authors: Mourad Aboul-fetouh E , Hassan Alaa El-Din A , Dannheim Jörg
Published: July 2006

The charge-transfer (CT) complexes of some sterically hindered [2.2]metapara- and [2.2]paracyclophanes as π-donors with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tetracyanoethylene (TCNE) as π-acceptors have been investigated by electronic as well as infrared spectroscopy. Electronic, steric, and transannular effects governing the formation and stability of the CT complexes studied are discussed.
Theoretical Investigation of the Interaction Potential of Helium Trimer
Authors: Ichihara Akira , Itoh Reikichi
Published: July 2006

Using the help of an ab initio calculation along with a configuration interaction treatment, the interaction potential of a He trimer has been calculated. The basis set superposition error in the He trimer system could be avoided using a reference calculation approximated by a simple formula.
Detection of Photoinduced Intramolecular Electron Transfer in 4-(1-Pyrenyl)butyl 9-Anthracenecarboxylate by Transient Absorption and Resonance CARS Spectra
Authors: Kamisuki Toshio , Akamatsu Naotoshi , Adachi Yukio , Hirose Chiaki , Yamamoto Noritaka , Takuma Keiichi , Iwamura Michiko
Published: July 2006

Transient absorption and resonance CARS spectra of title molecule have been observed in acetonitrile solution to show the presence of cationic pyrenyl group and anionic 9-anthryl group (or 9-anthracenecarbonyloxy group). The 337 nm UV pulse was used for the excitation. The result was combined with the linear dependence of the signals on the intensity of UV pulse to prove that the ionic radicals were produced by the intramolecular electron transfer from the locally excited pyrenyl group to the 9-anthryl group (or 9-anthracenecarbonyloxy group).
Electrical and Magnetic Properties of (BEDT-TTF)4Ni(CN)4 Complex
Authors: Tanaka Masashi , Takeuchi Hideo , Sano Mitsuru , Enoki Toshiaki , Suzuki Kazuya , Imaeda Kenichi
Published: July 2006

The electrical conductivity and the ESR spectra of the single crystal of (BEDT-TTF)4Ni(CN)4 complex were measured. This crystal exhibits a metal–insulator transition at 160 K. The ESR signals show the presence of the [NiIII(CN)4]− anion in addition to the BEDT-TTF cation radical. The spin concentration of Ni(III) ion was estimated to be 0.01 of the total Ni ions from the temperature dependence of the spin susceptibility of these components. The X-ray photoelectron spectra were also taken.
Aromatic Hydroxylation with an Iron(III)–Catechol–H2O2 System. Mechanistic Implication of the Role of Catechol
Authors: Tamagaki Seizo , Suzuki Kenji , Tagaki Waichiro
Published: July 2006

The role of catechol in benzene hydroxylation with Fe3+/catechol/H2O2 system, the so-called Hamilton system, has been mechanistically investigated by using tiron as a substitute for pyrocatechol. The yield of phenol progresses linearly with reaction time. The phenol yield is dependent on the mole ratio of Fe3+ relative to tiron, and the ratio of more than unity is particularly important for the effective functioning of the catalyst system. The o-, m-, and p-product isomer distributions for a few aromatic hydrocarbons are nearly identical with those of the Fenton reaction. These and the separate experimental results are consistent with the mechanism involving the rate-limiting redox reaction between tiron and Fe3+ and then the follow-up radical chain sequence as in the Fenton reaction.
Dispersion Behavior of Solutes in an Ideal Laminar Flow with Small-Bore Glass Tubes
Authors: Korenaga Takashi , Shen Fenghua , Yoshida Hirofumi , Takahashi Teruo
Published: July 2006

The dispersion behavior of solute molecules injected as a sample plug into an ideal laminar capillary flow was experimentally analyzed by means of microscopic and microphotometric methods. The flow pattern in small-bore glass tubes was directly observed by the microscopic method using a camera. The peak responses obtained for the colored solutes by means of the microphotometric method consist of double-humped peak features which resulted from both laminar flow convection and the molecular diffusion of solute molecules at the parabolic interface between the sample plug and the carrier fluid. The influences of the diffusion coefficient of the solute, the flow rate, the tube length, the tube diameter, etc. were mainly investigated in order to guide the design and optimization of the flow systems of capillary liquid chromatography (CLC), capillary electrophoresis (CEP), flow-injection analysis (FIA), etc. The experimental results obtained here are in good agreement with the theoretical results obtained by the numerical solution for the diffusion-convection equation.
The Determination of a Small Amount of a Biological Constituent by the Use of Chemiluminescence. XV. A Zeolite Column-Chemiluminescence Detection System for the Separation and the Determination of a Protein Mixture
Authors: Hara Tadashi , Tsukagoshi Kazuhiko , Kurita Yuichiro
Published: July 2006

To make use of zeolite as the packing material for the separation of proteins by means of adsorption chromatography, the adsorption behavior of protein onto the Na-X type of zeolite (Molecular Sieve 13X) in an aqueous solution or onto a column (3 mm i.d.×50 mm) packed with the same zeolite as above was examined using a ultraviolet absorption detector and model proteins, such as human-serum albumin and human-serum γ-globulin. The following results were obtained: 1) Human-serum γ-globulin was much more adsorbed onto the zeolite than was human-serum albumin and 2) in general, more protein was adsorbed in an acidic solution than in an alkaline solution. Moreover, a chemiluminescence detector using a 1,10-phenanthroline–hydrogen peroxide–copper(II) system, which has been developed by the present authors, was modified to improve its sensitivity for the determination of protein. Both the carrier solution and the eluting solution which were used in combination with a zeolite column with a chemiluminescence detector were optimized so as to give a smooth baseline on a recorder. A microbore zeolite column (1 mm i.d.×250 mm)-chemiluminescence detection system suitable for the separation and the determination of a small amount of a protein mixture was established on the basis of these experimental results. Since human-serum albumin passed through a microbore zeolite column, while human-serum γ-globulin was retained on the column, when a model sample containing human-serum albumin and human-serum γ-globulin was injected into the column, human-serum albumin was first determined, followed by the determination of human-serum γ-globulin after its desorption. Both human-serum albumin and human-serum γ-globulin in the concentration range of 2×10−5–5×10−3 g dm−3 could be determined economically and conveniently, with a detection limit of about 1 ng (injected sample volume: 50 mm3; S/N=2). The present method was, therefore, applicable to the separation and the determination of albumin and globulin in a serum sample.
Dynamic NMR as a Nondestructive Method for the Determination of Rates of Dissociation. XVI. Mechanism of Sulfur Inversion in Platinum(II)–Thioether Complexes Revisited
Authors: Toyota Shinji , Yamada Yasuhisa , Kaneyoshi Masami , Oki Michinori
Published: July 2006

The mechanism of sulfur inversion in some platinum(II)–thioether complexes was reinvestigated with the use of the dynamic NMR technique. Activation parameters for the sulfur inversion in [(isopropylthio)acetato-O,S]bis(triphenylphosphine)platinum(II) perchlorate in CDCl3 were obtained by taking advantage of the line shape changes in its 1H NMR spectra at various temperatures as follows: ΔH\eweq 18.0±0.4 kcal mol−1, ΔS\eweq 4.0±1.4 cal mol−1 K−1. The kinetic parameters varied little, though the rates of inversion were determined in other solvents. The entropy of activation and the solvent effects together with the presence of coupling between the phosphine-31P and the methine-1H throughout the temperature range of investigation evidence the sulfur inversion without breaking the Pt–S bond. The sulfur inversion in dichlorobis(dialkyl sulfide)platinum(II) in nonpolar solvents was also concluded to take place without bond breakage.
EXAFS and XANES Spectra of Cobalt(III) EDTA Complexes in Solids and Solutions
Authors: Sakane Hideto , Watanabe Iwao , Ikeda Shigero
Published: July 2006

The Co K-edge XANES (X-ray Absorption Near-Edge Structure) of [Co(edta)]− (edta4−=ethylenediamine-N,N,N′,N′-tetraacetate) complex in crystal varies with the kind of counter cations and it also varies with the kind of solvents when it is dissolved. The amplitude of the oscillation in its EXAFS (Extended X-ray Absorption Fine Structure), or the peak height in its Fourier transform, also varies as much as threefold depending on the kind of counter cations or solvents. The most plausible cause for the variations is the difference in the thermal disorder of the bonds which is enhanced by the formation of hydrogen bonding between carboxylato groups in the complex and the water molecules in crystal or the solvent molecules in solution.
Preparation and Characterization of Cobalt(III) Complexes Containing (2-Aminoethyl)dimethylarsine (edma). Resolution and Racemization of fac-[Co(edma)3]3+
Authors: Nemoto Kazuhiro , Kita Masakazu , Kojima Masaaki , Fujita Junnosuke
Published: July 2006

(2-Aminoethyl)dimethylarsine (edma) and its cobalt(III) complexes, trans(X,X),cis(As,As)-[CoX2(edma)2]+ (X=Cl, Br, and I), trans(As,As)- and trans(As,N)-[Co(acac)(edma)2]2+ (acac=acetylacetonate ion), trans(As,N)-[Co(CO3)(edma)2]+, [Co(acac)2(edma)]+, and fac-[Co(edma)3]3+ were prepared and characterized. From a comparison of the first d–d absorption bands of analogous diamine and (2-aminoethyl)dimethylphosphine (edmp) complexes, the spectrochemical series of Group 5B elements was found to be P>As>N. The fac-[Co(edma)3]3+ complex was resolved and the absolute configuration of the (+)490CD-isomer was assigned to Λ on the basis of the CD spectrum. Racemization of fac-[Co(edma)3]3+ was studied in aqueous solutions in the pH and temperature ranges of 7.88–9.32 and 35.0–50.0 °C, respectively. The racemization obeyed a rate law of the form, R=k[OH−][complex]. The activation enthalpy and entropy values were found to be ΔH\eweq=132±4 kJ mol−1 and ΔS\eweq=171±11 J K−1 mol−1, respectively.
A New Method for the Preparation of α-Methylene-γ-butyrolactones Using 3-Ethoxycarbonyl-3-(phenylsulfonyl)cyclobutanone
Authors: Fujiwara Tooru , Morita Koichi , Takeda Takeshi
Published: July 2006

The reaction of 3-ethoxycarbonyl-3-(phenylsulfonyl)cyclobutanone with Grignard reagent or aryllithium gave 1-(alkyl or aryl)-3-ethoxycarbonyl-3-(phenylsulfonyl)cyclobutanol which was treated with potassium hydride, reduced with LiBH4 in the presence of ZnCl2, and treated with p-TsOH or aluminum triisopropoxide successively to give α-methylene-γ-butyrolactone in good yield.
Topochemical Photopolymerization and Photo-Copolymerization of the Crystals of Unsymmetrically Substituted Diolefin Compounds Having Pyrimidine Ring
Authors: Hasegawa Masaki , Endo Yasuhiro , Aoyama Masato , Saigo Kazuhiko
Published: July 2006

Several new diolefin compounds, methyl and ethyl 4-[2-(4-pyrimidyl)ethenyl]cinnamates (1a and 1b), and methyl, ethyl, and propyl α-cyano-4-[2-(4-pyrimidyl)ethenyl]cinnamates (1c, 1d, and 1e) were synthesized, and their photoreactivity in the crystalline state was investigated. The crystals of 1c, 1d, and 1e gave amorphous oligomers having cyclobutane skeletons (average degree of polymerization was approximately 10) through the [2+2] photocycloaddition. The dimers (2c, 2d, and 2e) were formed in high yields by the exclusive photoexcitation of the monomers. The dimers were isolated by column chromatography. The cyclobutane structure of 2c and 2d was β-type homo adduct whereas that of 2e was β-type hetero adduct. As only one type of adduct was detected for each crystal, photodimerization was interpreted as being of a crystal lattice controlled process. The conversions of these reactions were not as high as that of the reaction in α-type of 2,5-distyrylpyrazine (DSP). The lower conversion was interpreted as being due to alternative reacting sites which inevitably result from the β-type molecular packing and to the drastic displacement of molecules which causes the distortion of crystal lattice. The mixed crystals (1f) of 1d and 1e (molar ratio 1.3/1), of which the X-ray diffraction pattern is similar to that of 1e, photopolymerized to give amorphous cooligomers (average degree of polymerization was approximately 5). The reaction went through an intermediate similar to dimer 2e.
Synthetic Photochemistry. XLIX. Synthesis and Photoisomerization of 2-Acetyl-2-azatricyclo[6.2.2.01,5]dodeca-4,6,9,11-tetraen-3-one. An MO Explanation of the Cycloaddition of Cyclohepta[b]pyrrol-2(1H)-ones
Authors: Tian Guan Rong , Mori Akira , Takeshita Hitoshi , Higashi Miwako , Yamaguchi Hiroyuki
Published: July 2006

Thermal cycloaddition reactions of 2,3-bis(methoxycarbonyl)-7-oxabicycloheptadiene with cyclohepta[b]pyrrol-2(1H)-ones gave the [4+2]adducts and products derived from the [8+2]adducts. Among [4+2]adducts, a new adduct was isolated. Cyclohepta[b]pyrrol-2(1H)-ones, having a substituent at the C-3 position exclusively, gave [4+2]adducts. The photolysis of 2-azatricyclo[6.2.2.01,5]dodeca-4,6,9,11-tetraen-3-one afforded substituted 9-methylenebarbaralane, 5-methylenetricyclo[4.3.0.02,9]nonadiene, and 1-methylenedihydroindene derivatives.
Phosphonylation of Biomolecules with Inorganic Diphosphonate. III. Formation of an H-phosphonate Analogue of Adenosine 5′-Triphosphate by Phosphonylation of Adenosine 5′-Diphosphate
Authors: Baba Yoshinobu , Sumiyama Tomoko , Tsuhako Mitsutomo , Yoza Norimasa
Published: July 2006

Phosphonylation of adenosine 5′-diphosphate (ADP) with inorganic diphosphonate was investigated by use of 31P NMR spectroscopy and the coupled system of high-performance liquid chromatography and flow injection analysis. ADP was phosphonylated by inorganic diphosphonate to form an H-phosphonate analogue of adenosine 5′-triphosphate (ATP) in aqueous solutions. The yield of the H-phosphonate analogue of ATP varied strongly depending on reaction conditions: pH and initial concentration of inorganic diphosphonate. The maximum yield of the H-phosphonate analogue of ATP was 56% under the following conditions: initial concentration of inorganic diphosphonate and ADP were 1.8 and 0.1 mol dm−3, respectively; 50 °C; pH 5; 90 min. In basic solutions, 2′ or 3′-hydroxyl group on ADP was predominantly phosphonylated.
The Catalytic Role of a Flavin Analogue for Aromatic Hydroxylation with the Udenfriend System
Authors: Tamagaki Seizo , Sasaki Masaaki , Tagaki Waichiro
Published: July 2006

A new combination of the Udenfriend reagent and a flavin analogue was found to hydroxylate benzene to phenol. Effects of temperature and concentrations of reaction components, i.e., iron(II), flavin, and ascorbate, on the phenol yield were examined. In particular, decreasing ascorbate concentration increased the yield of phenol. Thus, 68% of the yield was obtained under better conditions. The mechanism of action of ascorbic acid and the flavin was discussed.
A Spectroscopic Characterization of Metal Ion-Complexed NADH Models and Their Kinetic Behavior in Nitrosobenzene Reduction
Authors: Tamagaki Seizo , Simojo Yoshitaka , Mimura Takasi , Tagaki Waichiro
Published: July 2006

The structures of metal ion complexes of a series of NADH models were spectrophotometrically investigated. The electronic spectra were sensitive to variation of both the 1,4-dihydropyridines and the metals; particularly, 1-benzyl-3,5-bis(1-pyrrolidylcarbonyl)-1,4-dihydropyridine (BPDH) was recognized to produce two types of complexes with zinc and lead perchlorates, whereas 1-benzyl-1,4-dihydronicotinamides (BNAH) complexed metal ion only at the amide oxygen. In order to elucidate these structures, the effect of changing perchlorate ion concentrations was examined. In addition, reduction of nitrosobenzene in the presence of bivalent metal cations was kinetically investigated.
Synthesis of 2-Alkyl-Substituted 1,3-Diketones via the 1,4-Addition of the Grignard Reagents to α,β-Unsaturated Imidates
Authors: Inoue Seiichi , Suzuki Osamu , Sato Kikumasa
Published: July 2006

4-Propyl-3,5-nonanedione was selectively formed by the reaction of methyl N-phenylacrylimidate with ethylmagnesium bromide in 80% yield. Similar diketones were obtained from methyl N-phenylcrotonimidate and N-phenylcinnamimidate with the Grignard reagents. The coupling of N-magnesio α-methoxy enamine and ketenimine, both of which are formed through the initial 1,4-addition of the Grignard reagent to α,β-unsaturated imidate, is the most plausible pathway for the formation of the diketones.
Synthesis of a Functionalized Carbocyclic Skeleton of Ptaquilosin, the Aglycone of a Bracken Carcinogen Ptaquiloside Based on an Intramolecular Diels–Alder Reaction
Authors: Kigoshi Hideo , Sawada Akihiko , Niwa Haruki , Yamada Kiyoyuki
Published: July 2006

A tricyclic compound 13 possessing the carbocyclic skeleton of ptaquilosin (2), the aglycone of a bracken carcinogen ptaquiloside (1) has been synthesized by the intramolecular Diels–Alder reaction of trienes 12a and 12b.
Oxidation of Methoxy- and/or Methyl-Substituted Benzenes and Naphthalenes to Quinones and Phenols by H2O2 in HCOOH
Authors: Orita Hideo , Shimizu Masao , Hayakawa Takashi , Takehira Katsuomi
Published: July 2006

The oxidation of a number of arenes (methoxybenzenes, methylbenzenes, and naphthalenes) to quinones and phenols by H2O2 in HCOOH has been examined. Methoxybenzenes were much more easily oxidized to p-benzoquinones than methylbenzenes (e.g., 1,3,5-trimethoxybenzene was oxidized to 2,6-dimethoxy-p-benzoquinone in a 75% yield and 1,2,4-trimethylbenzene to 2,3,5-trimethyl-p-benzoquinone in a 16% yield). Electronwithdrawing substituents, such as nitro, cyano, and chloro groups, lowered the conversion of reactants and changed the product selectivity from quinones to phenols. Methoxybenzonitriles were oxidized to corresponding phenols in a moderate yield (e.g., 2,6-dimethoxybenzonitrile to 3-hydroxy-2,6-dimethoxybenzonitrile in a 39% yield and a 64% selectivity).
Synthetic Photochemistry. L. Isolation and the X-Ray Structure Determination of Photocyclodimers Formed by UV-Light Irradiation of Alkyl 2,4-Dioxopentanoates
Authors: Mori Akira , Nishiyama Nobuaki , Kohguchi Yukiko , Shinka Hisayo , Takeshita Hitoshi
Published: July 2006

Upon UV-light irradiation with a high-pressure mercury lamp, methyl 2,4-dioxopentanoate in a mixture of benzene and cyclohexane afforded a crystalline head-to-head[2+2]cyclodimer. Its structure was elucidated by a single-crystal X-ray analysis, as well as 1H and 13C NMR spectroscopy. Ethyl 2,4-dioxopentanoate also gave a cyclodimer.
A Convenient Synthesis of Diketones via Alkylation of Alkyl Methyl Ketone Dimethylhydrazones
Authors: Yamashita Masakazu , Matsumiya Kaoru , Morimoto Hiroko , Suemitsu Rikisaku
Published: July 2006

Symmetrical diketones were prepared by the reaction of the lithium salts of alkyl methyl ketone dimethylhydrazones with dibromoalkanes.
Reactions of Metal Benzoylacetonates and Acetylacetonates with Formaldehyde
Authors: Takeichi Tsutomu , Okumura Hiroaki , Sakurada Yoshihiro , Takayama Yuzi
Published: July 2006

The reaction of cobalt benzoylacetonate with formaldehyde in water or methanol gave benzoic acid along with 4-hydroxy-3,3-bis(hydroxymethyl)-2-butanone or 4-methoxy-3,3-bis(hydroxymethyl)-2-butanone, respectively. The result suggests the formation of acetic acid in the reaction of metal acetylacetonate.
Basicity of Water in Hydrogen-Bonded Networks of Methanol–1,2-Dichloroethane Mixtures Using the [(1R,4S,8R,11S)-1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane]nickel(II) Cation as a Probe of Electron-Pair Acceptance
Authors: Iwamoto Etsuro , Yamasaki Shoji , Kumamaru Takahiro
Published: July 2006

The basicity of water in methanol (MeOH) and MeOH–1,2-dichloroethane (DCE) mixtures was examined by using spectral data of the title square planar chelate cation ([Ni(tmc)]2+). Although MeOH molecules are hardly coordinated to the chelate, the water molecules hydrogen-bonded with MeOH are easily coordinated to the cation, depending on the degree of hydrogen-bonded networks of MeOH. A fitting method showed that in the MeOH-rich mixtures the dimerization of water occured and only the terminal monomeric water molecule in the MeOH oligomer could be coordinated. The equilibrium constant KNiW1=[Ni(tmc)(H2O)2+]/[Ni(tmc)2+][H2O] was 3.2 in the 0.1 MeOH mole fraction mixture, 3.0 in 0.3, 3.2 in 0.5, 6.2 in 0.7, 9.5 in 0.9, 10.0 in 1.0. Linear relationships of 1H chemical shift of the OH group for MeOH in various solvents with the KNiW1 values and Gutmann’s donor number (DN) were found and DN values were estimated for the DCE–MeOH mixtures. The enhancement of basicity of the water molecules was discussed from the viewpoints of the charge transfer effect through hydrogen bonding and the development of hydrogen-bonded networks.
The IR Photochemistry of Organic Compounds. II. The IR Photochemistry of Ethers: The Decomposition Patterns
Authors: Majima Tetsuro , Ishii Tadahiro , Arai Shigeyoshi
Published: July 2006

The infrared multiple-photon decomposition (IRMPD) of saturated open-chain ethers has been systematically investigated with the intention of establishing their decomposition patterns. The main products in the IRMPD of ethers (1a–f, 2) are H2CO, CO, H2, and lower hydrocarbons. Acetaldehyde is additionally formed in the IRMPD of 1b and 1d, while acetone is formed in the IRMPD of 1d. The observed results are explained on the basis of the decomposition of the highly vibrationally excited ethers produced in the IRMP excitation. The initial process is the homolytic cleavage of a C–O bond to yield the corresponding alkyl and alkoxyl radicals. The alkyl radicals are trapped by Br2. Sequential splitting and addition reactions of the radicals yield primary products with a high internal energy. The primary products also decompose sequentially into stable products, in part. The sequential processes compete with collisional deactivation. Therefore, the branching ratio depends on the internal energy of the radicals and the primary products.
Relationships between Mesophase Behavior and Crystal Structures of Chiral Smectogenic 4-[(S)-2-Methylbutyl]phenyl 4′-Alkoxybiphenyl-4-carboxylates
Authors: Hori Kayako , Takamatsu Miho , Ohashi Yuji
Published: July 2006

Interlayer distances of Sm*C and Sm A phases of the title series were measured as functions of temperature by X-ray diffraction. With increase in temperature, molecular tilt angles in Sm*C decrease from 22–25 to 0°. Crystal structures of the heptyl (1) and octyl (2) homologues have been determined by X-ray analysis. (1): 4-[(S)-2-Methylbutyl]phenyl 4′-heptyloxybiphenyl-4-carboxylate, monoclinic, P21, a=26.929(4), b=5.4249(5), c=9.2607(9) Å, β=96.78(1)°, Z=2. (2): 4-[(S)-2-Methylbutyl]phenyl 4′-octyloxybiphenyl-4-carboxylate, orthorhombic, P212121, a=9.249(1), b=56.259(9), c=5.412(1) Å, Z=4. Final R were 0.076 and 0.121, respectively. Both crystals have distinct layer structures similar to those of Sm*C. In the former crystal, the molecules tilt to one direction uniformly throughout layers, while in the latter, they take two opposite directions alternately from layer to layer. However, structures within a layer are very similar to each other. Each molecule has a coplanar biphenyl moiety and a twisted paraffin chain. Mesophase behavior was interpreted very well by the molecular interaction revealed in the crystal structures.
Preparation and Properties of the σ-Picolyl Complexes of Palladium(II), [{PdCl(C5H4N-2-CH2)PPh3–nMen}2] (n=0, 1, and 2)
Authors: Isobe Kiyoshi , Nakamura Yukio , Kawaguchi Shinichi
Published: July 2006

The oxidative addition of 2-(chloromethyl)pyridine to tetrakis(triphenylphosphine)palladium(0) in toluene at 100 °C gave [{PdCl(C5H4N-2-CH2)PPh3}2] (1a), which was characterized by analytical, molecular-weight, and IR data as well as 1H, 31P, and 13C NMR spectroscopy. The chloride ligand was readily replaced by other halides, whereas tertiary phosphines such as diphenylmethyl-, phenyldimethyl-, and triethylphosphines cleaved the bridge after substitution of triphenylphosphine to result in the monomeric trans-[PdCl(C5H4N-2-CH2)(PR3)2] complexes. Reactions of 1a with carbon monoxide and other reagents are also reported. The corresponding 3-picolyl complex [{PdCl(C5H4N-3-CH2)PPh3}n] was also prepared, but could not be well characterized because of lower stability and solubility.
Single Crystal X-Ray and Optical Studies on Bis(1,5-diazacyclooctane)copper(II) Nitrate, a Thermochromic Copper(II) Complex Involving Hydrogen Bonds between the Ligand and the Counter Ion
Authors: Hoshino Naomi , Fukuda Yutaka , Sone Kozo , Tanaka Kiyoaki , Marumo Fumiyuki
Published: July 2006

A thermochromic copper(II) complex of 1,5-diazacyclooctane (daco), [Cu(daco)2](NO3)2, has been subjected to single-crystal X-ray and optical studies. This complex is orange as isolated, but it turns violet discontinuously when heated above 90 °C and returns to orange on cooling. Crystal structure of the low-temperature form has been determined at room temperature; the complex crystallizes in the monoclinic space group P21⁄n with a=7.9040(7), b=15.694(1), c=7.0886(7) Å, β=95.36(1)°; V=875.5(1) Å3, and Z=2. The CuN4 chelate plane is planar and Cu–N coordination bonds are rather short. The structure has revealed the presence of weak hydrogen bonds bridging imino groups of the ligands with the nitrate ions and forming a macrocycle-like ring system, which results in enhancement of the ligand field strength. Single-crystal visible and infrared spectra for both low- and high-temperature forms have heen obtained and compared. A high-energy d–d transition band(s) causing the orange color at room temperature is in contrast to an extremely flattened broad band(s) for the violet form. The IR spectra of the two forms clearly differ in the intensity of νNH stretching peak, implying that the thermochromic phase transition involves a change in the nature of the hydrogen bonds of the imine ligands. On the basis of these observations and comparison to reported studies on a similarly thermochromic copper(II) complex, a mechanism is suggested involving dynamic fluctuation of the ligand field and geometry due to thermal motion of the anion/ligand hydrogen bond system.
Synthesis and Properties of Copper(II) Perchlorate Complexes with Imino Oximes
Authors: Wan Songping , Mori Wasuke , Yamada Shoichiro , Murahashi Shun-Ichi
Published: July 2006

Three types of imino oxime copper(II) complexes were obtained by the reactions of copper(II) perchlorate with imino oximes (3-[2-[(alkylamino)ethyl]imino]-2-butanone oximes or 3-[2-[(dialkylamino)ethyl]imino]-2-butanone oximes, abbreviated as Hdox-enRR′). One type contains the dinuclear complexes [Cu2(dox-enRR′)2]2+ and uncoordinated perchlorate anions. The magnetic susceptibilities measured over the temperature range 77–320 K indicate that there exists a strong antiferromagnetic spin coupling interaction through the N–O bridge in these complexes. The magnetic behavior can be explained by using the Bleaney–Bowers equation. Complexes of the second type probably contain a square-tetranuclear complex. The copper(II) ions assume a penta-coordinated configuration with perchlorate anion coordinated at the axial coordination site. It is assumed that the dinuclear and mononuclear magnetic units coexist in the complexes of the third type. The plot of the magnetic susceptibilities versus temperature is linear in the two temperature ranges (T>250 K, <100 K).
Microbiosensing Device for Real Time Determination
Authors: Ikariyama Yoshihito , Shimada Naoki , Yukiashi Tomoaki , Aizawa Masuo , Yamauchi Shigeru
Published: July 2006

A microbiosensing device fabricated by assembling an enzyme-embodied microelectrode with a counter electrode and a reference electrode was applied to the real time determination of trace droplet of glucose sample. The microdevice demonstrated unique properties such as real time response, independence of sample volume, unnecessity of sample mixing by the rendezvous of microfabricated biosensing device with pulse voltammetry. A linear relationship between sensor output and glucose concentration was obtained in the concentration range from 10−3 to 10−1 mol L−1. The sensing device responded to every glucose sample of different concentration in 2 ms, and the coefficient of variation for 10 mM glucose determination was within 5%.
Micro-Enzyme Electrode as a High-Performance Detector of Flow Injection Analysis
Authors: Ikariyama Yoshihito , Yamauchi Shigeru , Yukiashi Tomoaki , Ushioda Hiroo , Aizawa Masuo
Published: July 2006

The advantages of miniaturized enzyme electrode have been applied to flow injection analysis for the development of a rapid and selective method for the continuous determination of glucose. By assembling a micro-enzyme electrode having a diameter of 10 μm for an amperometric flow-through detector, at least 600 glucose samples can be determined in one hour. And micro-enzyme electrodes are satisfactorily stable for over 4 weeks even after 1000 glucose injections.
Oxidation of Lipids. XVI. Inhibition of Autoxidation of Methyl Linoleate by Diarylamines
Authors: Takahashi Mareyuki , Tsuchiya Jyunichi , Niki Etsuo
Published: July 2006

The inhibition of oxidation of methyl linoleate in homogeneous solution and in aqueous dispersions by diarylamines has been studied. Diphenylamines with electron-donating substituents exhibited antioxidant activities, while those having electron-withdrawing substituents such as niflumic acid and flufenamic acid did not suppress the oxidation appreciably. When both 4,4′-dimethoxydiphenylamine and α-tocopherol were present as antioxidants, only α-tocopherol was consumed at first and when α-tocopherol was almost completely depleted, 4,4′-dimethoxydiphenylamine began to be consumed to give nitroxide radical, which further acted as antioxidant.
Oxidation of Lipids. XVII. Crossover Effect of Tocopherols in the Spontaneous Oxidation of Methyl Linoleate
Authors: Takahashi Mareyuki , Yoshikawa Yasuyuki , Niki Etsuo
Published: July 2006

Tocopherols suppressed the spontaneous, thermal oxidation of methyl linoleate and produced a clear induction period. During the induction period, small amounts of cis,trans-hydroperoxides were formed but the formation of trans,trans-hydroperoxides was almost completely inhibited. Tocopherols were consumed and when they were depleted, the induction period was over and a fast oxidation proceeded to give more trans,trans-hydroperoxides than cis,trans-hydroperoxides. However, tocopherols, especially α-tocopherol, acted as prooxidants when their concentrations were extraordinarily high and the rate of initial radical formation was low. The reducing agent such as ascorbic acid diminished the prooxidant action of α-tocopherol. This prooxidant effect of tocopherols was ascribed to the spontaneous formation of tocopheroxyl radical followed by the hydrogen atom abstraction by the tocopheroxyl radical from the hydroperoxide to give a peroxyl radical.
Synthesis of a Protected Sperm Whale Myoglobin-(77–96)-Eicosapeptide and Circular Dichroism Spectra of the Related Peptides
Authors: Hashimoto Chikao , Muramatsu Ichiro
Published: July 2006

A protected sperm whale myoglobin-(77–96)-eicosapeptide (23) was synthesized by a solution method. The protected peptide 23 could be effectively purified by silica-gel column chromatography with 1-butanol–acetic acid–water as the eluate. The CD spectra of protected fragment peptides were measured in a solution of 2,2,2-trifluoroethanol. A protected sperm whale myoglobin-(85–96)-dodecapeptide and 23 showed CD profiles characteristic of a helical structure.
Replacement of an 11-Carbonyl Group of 11-Oxo Steroid by an Oxygen Atom. A New Partial Synthesis of 11-Oxaprogesterone
Authors: Suginome Hiroshi , Wang J B
Published: July 2006

We describe the transformation of commercially available 3α-hydroxy-5β-pregnane-11,20-dione acetate (1) into 11-oxaprogesterone (15) in 11 steps including the regioselective β-scission of an alkoxyl radical as a key step.
The Formation Pathway of 3,5-Bis(methoxymethyl)perhydro-1,3,5-oxadiazin-4-one
Authors: Shiba Ryuichi , Takahashi Miyuki , Ebisuno Toichi , Takimoto Michiaki
Published: July 2006

The investigation of the reactions of urea and its methyl derivatives with formaldehyde elucidated the formation pathway of 3,5-bis(methoxymethyl)perhydro-1,3,5-oxadiazin-4-one. 1) The addition of formaldehyde to urea became increasingly difficult according to the increase of the number of added formaldehyde molecules, probably because of the steric hindrance of the hydroxymethyl groups. 2) 3,5-Bis(methoxymethyl)perhydro-1,3,5-oxadiazin-4-one was concluded to be derived from urea via tris(hydroxymethyl)urea and 3-(hydroxymethyl)perhydro-1,3,5-oxadiazin-4-one but not via tetrakis(hydroxymethyl)urea or perhydro-1,3,5-oxadiazin-4-one.
Stereochemistry of a Chiral Germyl Radical in the Reaction of Carbon Tetrachloride
Authors: Mochida Kunio , Yamauchi Takato , Sakurai Hideki
Published: July 2006

A chiral germyl radical produced from an optically active hydrogermane, 1-NpPhMeGe*H, abstracted a chlorine atom from CCl4 to give the corresponding chlorogermane with retention of configuration. Progressive dilution of CCl4 with cyclohexane demonstrated that the chiral germyl radical could also undergo inversion. A mechanism in which inversion of the chiral germyl radical competed with chlorine abstraction was proposed and the relative rate of chlorine abstraction to inversion (kCl⁄kinv) of the chiral germyl radical was found to be (0.52±0.13) mol−1 dm3 at 80 °C. The rate constant for the chlorine abstraction (kCl) by germyl radicals with CCl4 was determined to be (6.6±1.0)×108 s−1 mol−1 dm3 by laser-photolysis experiments. By using this rate constant, the kinv value for the chiral germyl radical was estimated to be ca. 2×109 s−1.
Synthesis of Nonadeca- and Octadecaribonucleotides Using the Solid-Phase Phosphotriester with Tetrahydropyranyl Groups as the 2′-Hydroxyl-Protecting Group
Authors: Hirao Ichiro , Ishikawa Masahide , Hori Hiroyuki , Watanabe Kimitsuna , Miura Kin-ichiro
Published: July 2006

Nonadeca- and octadecaribonucleotides corresponding to the D-loop of tRNAPhe from yeast and the leader sequence of phage f1 coat protein mRNA were synthesized by the activated phosphotriester method. Coupling yield in the synthesis of oligoribonucleotides depended on the extent of nucleosides loaded on controlled pore glass beads (CPG). N-Acyl-5′-O-dimethoxytrityl-2′-O-tetrahydropyranyl derivatives were used as fully protected ribonucleotide monomer units. The 18mer and 19mer corresponding to the D-loop did not serve as substrates for tRNA (guanosine-2′-)methyltransferase from T. thermophilus, but inhibited methylation of the 5′-half fragment of tRNAPhe. This indicates that both fragments possess some affinity with the enzyme.
Uranyl Ion as a Highly Effective Catalyst for Internucleotide Bond Formation
Authors: Sawai Hiroaki , Kuroda Kensei , Hojo Takashi
Published: July 2006

Uranyl ion catalyzes the polymerization of adenosine-5′-phosphorimidazolide very efficiently in aqueous solution. Up to 95% of the input adenosine-5′-phosphorimidazolide is converted to oligoadenylates from dimer to hexadecamer when 1 mM of UO22+ is used as a catalyst. The oligomeric products are predominantly 2′–5′ linked. The chain length and the regioselectivity of the resulting oligoadenylates varies greatly with the concentration of the UO22+ ion catalyst and the pH of the reaction medium. A high total yield of oligouridylates up to dodecamer is also obtained by UO22+ ion catalyst with high 2′–5′ regioselectivity. The oligonucleotide formation is mediated by UO22+-nucleotide complex.
Ring-Opening Fluorination and Ring-Expansion Fluorination of Cyclopropanemethanols with Amine/Metal Fluoride/Poly(hydrogen fluoride)–Pyridine Complex
Authors: Kanemoto Shigekazu , Shimizu Makoto , Yoshioka Hirosuke
Published: July 2006

Treatment of cyclopropanemethanols with pyridinium poly(hydrogen fluoride) in the presence of diisopropylamine and KHF2 gave selectively homoallylic fluorides or fluorocyclobutanes according to the mode of substitution of the starting cyclopropanemethanols. Cyclopropanemethanols with no substitution at 1-position of the cyclopropane ring gave homoallylic fluorides in a stereoselective manner. While, 1-methylcyclopropanemethanol gave the fluorocyclobutane in high stereoselectivity. Fluorocyclobutanes containing hydroxy methyl group were also prepared from 2-(1-methylcyclopropyl)oxiranes. The amine and the metal fluoride were necessary as additives for the best results. Influencing factors involving solvents and temperature for the reactions are also described.
Substrate Selectivity of Artificial Transaminase Constituted with Functionalized Bilayer Membrane
Authors: Murakami Yukito , Kikuchi Jun-ichi , Shiratori Nobuyuki
Published: July 2006

The transamination reactions of α-amino acid derivatives with α-keto acids as catalyzed by an artificial transaminase were examined in aqueous media under mild conditions. The present artificial holoenzyme was constituted with a combination of a cationic peptide lipid having a l-histidyl residue, a hydrophobic pyridoxamine derivative, and copper(II) ions, and found to exercise marked substrate selectivity which came from the molecular recognition in the course of formation of the aldimine Schiff-base chelates composed of the hydrophobic pyridoxal derivative, α-amino acids, and copper(II) ions. The transamination reaction of the hydrophobic β-benzyl l-aspartate with the hydrophilic pyruvate was most effectively catalyzed among 18 combinations of substrate species employed here. Enantioselectivity was observed for the catalytic transamination of phenylalanine with pyruvate.
The Electrolytic Reduction of p-Substituted α-(Methylsulfinyl)-α-(methylthio)acetophenones in Acetonitrile
Authors: Kunugi Akira , Takahashi Norimasa , Abe Kyo , Hirai Taketsugu
Published: July 2006

p-Substituted α-(methylsulfinyl)-α-(methylthio)acetophenones (1) exhibit, on polarographic reduction, three waves. The two last waves correspond to the reductions of p-substituted α-(methylthio)acetophenones (2) and p-substituted acetophenones respectively. The macroelectrolysis at the first wave potential results in the formation of 2 in good yields in the presence of benzoic acid. The electrolytic reduction of 1 is characterized by the elimination of the methylsulfinyl group rather than by the deoxygenative reduction of the sulfoxide to the sulfide or the reduction of the carbonyl group.
Photooxidation of Bis[1,2-diphenylethanedithione]nickel(0)tetrabutylamine with α-Tocopherol
Authors: Enmanji Koe
Published: July 2006

The photooxidation of a nickel dithiolate complex by α-tocopherol was found for the development of a recording medium which can be used to read by a laser diode. The mechanism was analyzed. As a result, it was found that α-tocopherol produced oxygen adducts by light; the oxygen adducts oxidized bis[1,2-diphenylethanedithione]nickel(0)tetrabutylamine.
Metastable Dissociations of CH3NO2+ and CD3NO2+ Ions. Isotope Effects of the Loss of a Hydroxyl Radical
Authors: Arakawa Ryuichi
Published: July 2006

A large kinetic isotope effect has been observed for the metastable transitions of CX3NO2+→CX2NO++OX (X=H, D). The large effect was explained by assuming a rate-determining isomerization to an aci-nitromethane ion and the quantum mechanical tunneling of a hydrogen atom.
A Molecular Orbital Study of Cyclodextrin Inclusion Complexes, II. The Structural Analysis of α-Cyclodextrin Inclusion Complex with m-Nitrophenol in Aqueous Solution Based on the Quantum-Chemical Solvation Theory
Authors: Sakurai Minoru , Kitagawa Masaki , Hoshi Hajime , Inoue Yoshio , Chûjô Richirô
Published: July 2006

The host–guest orientation and the position of the guest m-nitrophenol (MNP) in the α-cyclodextrin(α-CD)–MNP complex in aqueous solution have been determined by comparing the complexation-induced 13C NMR chemical shifts of MNP with those predicted by quantum chemical calculation. The results are consistent with the X-ray data of this complex.
Effects of Pressure on Hydrolysis of p-Nitrophenyl Acetate in Aerosol OT Reversed Micelles
Authors: Tamura Katsuhiro , Yoshinari Mami
Published: July 2006

Kinetic studies were made on imidazole-catalyzed hydrolysis of p-nitrophenyl acetate in Aerosol OT (AOT) reversed micelles (AOT/H2O/heptane) at high pressure. The rate of the reaction was found to increase with increase in the size of the aqueous core in the reversed micelles and with increase in pressure. Micellar effects on the hydrolysis are discussed in relation with the activation parameters of the reaction.
Optical Resolution of Di-2-pyridylamine Complexes of Ruthenium(II)
Authors: Fukuchi Takashi , Nagao Noriharu , Miki Eiichi , Mizumachi Kunihiko , Ishimori Tatsujiro
Published: July 2006

Through SP-Sephadex ion exchange chromatography [Ru(Hdpa)3]2+ and [Ru(bpy)2(Hdpa)]2+ (Hdpa=di-2-pyridylamine) were resolved by the use of an aqueous sodium d-tartrate solution as the eluting agent. Λ-[Ru(Hdpa)3]2+ and Δ-[Ru(bpy)2(Hdpa)]2+ were eluted in the early fractions. The precipitation of diastereomers with dibenzoyl-d-tartrate was also successful in the resolution of [Ru(Hdpa)3]2+ and [Ru(bpy)(Hdpa)2]2+. The absolute configurations of the complexes were assigned by referring to the signs of CD spectra at around 3.2–3.8 μm−1.
The Crystal and Molecular Structures of Tetraethylammonium [Heptakis(isothiocyanato)lanthanate(III) and -praseodymate(III)]·Benzene, [(C2H5)4N]4[M(SCN)7]·C6H6 (M=La, Pr), in a Unicapped Trigonal Prism Geometry
Authors: Matsumoto Fumiko , Takeuchi Toshio , Ouchi Akira
Published: July 2006

The crystals of the title new lanthanum(III) complex, LaC45H86N11S7, F.W. 1144.59 are orthorhombic space group Bm21b, a=17.438(7), b=21.507(9), c=16.616(6) Å, U=6232(4) Å3, Dm=1.21(3), Dx=1.22 g cm−3, and μ(Mo Kα)=9.63 cm−1. The central lanthanum(III) atom has a unicapped trigonal-prism 7N-hepta-coordination geometry: seven thiocyanato nitrogen atom are ligated. There are no bridgings between the complexes and/or counter cations. Each benzene molecule is surrounded by the thiocynate ions and ethyl groups of the cations. Although these crystals lose benzene at about 60 °C, they are stable for more than several weeks ambient temperature, and can be regarded as a kind of inclusion compound. The isomorphous praseodymium(III) complex was also obtained.