bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inositol Derivatives. 8. Azidolysis of Tri- and Tetra-sulfonates of myo-Inositol
Authors: Suami Tetsuo , Ogawa Seiichiro , Oki Shuichi , Kunitomo Hideo 
Published: July 2006

Abstract
Reactions of the azide ion with four trisulfonates (1,4,5-, 1,4,6-, 1,5,6-, and 4,5,6-) and one tetrasulfonate (1,4,5,6-) of myo-inositol were studied. The structures of the new azido compounds were established by PMR spectroscopy and reaction sequences. The mechanism of neighboring-group participation reactions were discussed.
Kinetic Studies of the Reaction between Sodium Dodecyl Sulfate and Pinacyanol Chloride
Authors: Tatsumoto Nobuhide , Takeda Kunio , Isshiki Shunji , Yasunaga Tatsuya 
Published: July 2006

Abstract
Below the critical micelle concentration, a kinetic study of the aggregate formation reaction of sodium dodecyl sulfate and pinacyanol chloride was made by means of a stopped-flow system combined with a rapid scanning spectrophotometer. The process involves the following four steps and a precipitate whose composition ratio was dodecyl sulfate : pinacyanol= 1 : 1 was obtained as the final product:
(Remark: Graphics omitted.)
where D and S are the dye and detergent molecules respectively. The forward rate constants have been calculated to be 6×105 (M s)−1 for [S]0=0.05–0.1 mM in the second step and 1.2×102–3.9×10−3 s−1 for [S]0=0.05–1.0 mM in the third step.
Semi-empirical SCF-MO Studies of Pd(II)- and Hg(II)-Ethylene Complexes, the Oxymercuration and the Wacker Reaction
Authors: Sakaki Shigeyoshi , Kato Hiroshi , Kanai Hiroyoshi , Tarama Kimio 
Published: July 2006

Abstract
Using the modified CNDO MO method, the electronic structures of Pd(II)- and Hg(II)-ethylene complexes have been studied successfully. Our MO calculations have shown that the nucleophilic attack of OH− on ethylene was accelerated by Pd(II) and Hg(II), and that the acceleration by Hg(II) was larger than that by Pd(II), these results agree well with those of the experiments. The cis-attack of OH− in the oxymercuration has also been discussed by the use of the results obtained by the MO calculations. The mechanism of the cis-type four-center addition of OH− to ethylene in the Wacker reaction, which was supposed by Henry and Jira et al. in spite of any direct evidence, has been supported by the MO calculations. Our calculations have been able to explain the Markovnikoff rule in the Wacker reaction and in the oxymercuration of propylene.
The Thermal [2+2] Cycloaddition of 1-Halo-2-(9-fluorenylidene)ethylene to Afford Fluorene-9-spiro-1′-[2′-halo-3′-(9-fluorenylidene)-4′-halomethylene]cyclobutane
Authors: Toda Fumio , Motomura Hiroharu , Oshima Hirofumi 
Published: July 2006

Abstract
The thermal [2+2]cycloaddition products of 1-chloro-(II) and 1-bromo-2-(9-fluorenylidene)ethylene (X) were found to be two head-to-tail dimers, fluorene-9-spiro-1′-[2′-chloro-3′-(9-fluorenylidene)-4′-chloromethylene]cyclobutane (VI) and its bromo-analog (XI) respectively.
Preferential Precipitation of Δ-[Co(en)3]2(d-C4H4O6)3 by Alcohol Addition to the [Co(en)3]3+–d-C4H4O62− Aqueous Systems
Authors: Yoneda Hayami , Takemoto Gen , Sakaguchi Ushio 
Published: July 2006

Abstract
Alcohol addition to the aqueous [Co(en)3]3+–d-tart systems causes the preferential precipitation of Δ-[Co(en)3]2(d-tart)3. The yield lies in between 54–55% under experimental conditions employed.
A Novel Type of Penta-Coordinated Iron(III) Complex FeCl[SSeCNR2]2 (R=CH3, C2H5)
Authors: Nakajima Shunji , Tanaka Toshio 
Published: July 2006

Abstract
The titled compounds were prepared, and the magnetic susceptibility and electronic spectrum were measured; the two weak bands observed in the near-infrared region are assigned as spin-forbidden d-d bands.
Normalization of Potentials in Propylene Carbonate, Ethylene Carbonate, N,N′-Dimethylformamide, and Dimethyl Sulfoxide to the Water Scale Studied by Polarographic Method
Authors: Matsuura Niro , Umemoto Kisaburo , Waki Masako , Takeughi Zen’ichi , Omoto Mariko 
Published: July 2006

Abstract
The polarographic behavior of alkali metal ions were studied in propylene carbonate (PC), ethylene carbonate (EC), water, N,N′-dimethylformamide(DMF), and dimethyl sulfoxide(DMSO). The polarographic half-wave potentials measured in these solvents against an aqueous saturated calomel electrode(SCE) were normalized to the potential of SCE in aqueous system by making corrections of potential required for transfer of rubidium ion from water to these solvents. The free energies of transfer of rubidium ion from water to other solvents were calculated by the application of the modified Born equation. The potential series on the normalized potential scale were given in the order DMSO&lt;DMF&lt;water&lt;PC&lt;EC, indicating that the metal ion-solvent interaction increases with increasing the electron donor property of the solvent. The solvent shifts in potential calculated by the application of the modified Born equation disagreed with the experimental results. In order to fit well the calculated solvent shifts in potential with the experimental results, following values of liquid junction potential must be assumed for these solvents; +0.090 V for DMSO, +0.085 V for DMF, +0.004 V for PC, and −0.064 V for EC against the aqueous phase.
PECULIARITY IN THE FORMATION OF THE NITRILE-ESTERS OF DICARBOXY-GLUTACONIC ACID
Authors: Urushibara Yoshiyuki 
Published: July 2006

Abstract
From the results of eight reactions it was deduced that the four compounds,
XYC=CH–CNaX′Y′,
X′Y′C=CH–CNaXY,
X′Y′C=CH–CNaX′Y′,
XYC=CH–CNaXY,
can be produced in the condensation of the ethoxymethylene compound XYC=CHOC2H5 with the sodio-methylene compound CHNaX′Y′, where each of X, X′, Y, and Y′ represents either –CN or –COOC2H5.
STUDIES ON THE ENZYMES OF SILKWORM. I
Authors: Mori Motohichi 
Published: July 2006

Abstract
1. The optimal temperatures for the action of amylase obtained from the middle intestine of silkworm have been determined.
2. The optimal hydrogen ion concentration for the amylase action has been determined to be PH=9.4–11.3 at 30–40°C.
3. The amylase charges positively in alkaline reaction, and negatively in acid reaction, the isoelectric point being at about PH=5.7.
SORPTION OF GAS BY MINERAL. II. LAUMONTITE
Authors: Sameshima Jitsusaburo 
Published: July 2006

Abstract
Dehydrated Iaumontite sorbs ammonia but not carbon dioxide. The sorption amount of ammonia varies markedly by the conditions of the dehydration. Same amount of ammonia is sorbed at 25°C. and at 0°C. by a sample. The ammonia combines chemically with dehydrated mineral.
Solvent Effects and Hyrogen-bonding Interactions on Absorption and Fluorescence Spectra of 1-Methyl-2-pyridone
Authors: Fujimoto Akira , Inuzuka Kozo 
Published: July 2006

Abstract
The electrostatic solvent effects and hydrogen-bonding interactions on IR and UV absorption and fluorescence spectra of 1-methyl-2-pyridone has been investigated. It was found that the UV absorption and fluorescence bands of 1-methyl-2-pyridone shifted towards the shorter-wavelength region with increasing solvent polarity and that these bands exhibited a blue shift on hydrogen bond formation with alcohols and chloroform. The excited-state dipole moment of 1-methyl-2-pyridone, and the equilibrium constants in the ground and excited states and enthalpy change in the ground state for hydrogen-bond formation between 1-methyl-2-pyridone and ethanol have been determined from the spectroscopic studies.
The Crystal Structure of the 1 : 2 Tetrapropylammonium Guanidinium Bromide Complex
Authors: Taga Tooru , Ohashi Makoto , Osaki Kenji , Miyajima Koichiro , Yoshida Hiromitsu 
Published: July 2006

Abstract
The crystal of the title complex is monoclinic, P21/a with these unit cell dimensions: a=16.16, b=19.18, c=15.46 Å, and β=98°. The crystal structure has layers of hydrogen-bond networks formed by the guanidinium and bromide ions. Two different conformers of the tetrapropylammonium ions are packed between the networks.
Secondary Deuterium Isotope Effects in the Intramolecularly-competing Methoxymercuration of Ethylene-1,1-d2 and cis-2-Butene-2-d1
Authors: Shinoda Sumio , Isemura Masashi , Saito Yasukazu 
Published: July 2006

Abstract
Secondary deuterium isotope effects in the intramolecularly-competing methoxymercuration of ethylene-1,1-d2 and cis-butene-2-d1, determined from the rate ratio (k(β-deuteriomercurial)/k(α-deuteriomercurial)=1.12, 1.06), indicate that the transition state for the methoxymercuration of ethylene and cis-2-butene does not have a symmetrical structure such as a mercurinium ion, but is accompanied by considerable C–O bond formation.
Friedel-Crafts Reaction of Anisole with 2-t-Butyloxirane
Authors: Inoue Masashi , Harada Masatsune , Umaki Nobuyuki , Ichikawa Katsuhiko 
Published: July 2006

Abstract
The title reaction in excess anisole gave a mixture composed of 3-(methoxyphenyl)-2,3-dimethyl-1-butanols (2) (a mixture of ortho and para isomers), 2-p-methoxyphenyl)-2-methybutane (3), and oligomer of 2-t-butyloxirane, while the same reaction in nitromethane gave a product composed of 2 (only the para isomer) and hexylanisoles, but not 3. The reaction sequences to give the products are discussed in terms of step-by-step and concerted alkylation mechanisms.
The Reactions of 2-(Trimethylsiloxy)furans with Orthocarboxylic Esters, Acetals, and Acylal in the Presence of Lewis Acids
Authors: Asaoka Morio , Sugimura Naoyuki , Takei Hisashi 
Published: July 2006

Abstract
The reaction of 2-(trimethylsiloxy)furan (1) with orthocarboxylic esters, acetals, and acylal in the presence of Lewis acids afforded the corresponding 4-substituted 2-buten-4-olides. The reaction of 5-methyl-2-(trimethyl-siloxy)furan with orthocarboxylic esters gave unstable 2-substituted 3-penten-4-olides as major products; these gave 2,5-alkanediones upon hydrolysis. The furan (1) also reacted with 1,1-diacetoxy-2-butene to give a mixture of 5-acetoxy-2,6-octadien-4-olide and 7-acetoxy-5-methyl-2,6-heptadien-4-olide. From the former compound, nigrosporalactone was synthesized.
The Transformations of Terpene Ketones by Oxygen. I. The Autoxidation of Fukinone
Authors: Horinaka Akio , Naya Keizo 
Published: July 2006

Abstract
Fukinone, possessing a cisoid enone system, is susceptible to air oxidation. The oxidation products have been extensively examined and have been established as including diastereomeric epoxides, a hydroxy ketone (petasitolone), a lactol (8β-hydroxyeremophilenolide), and a peroxy hemiacetal. Also, the products were compared with those derived from the autoxidation of pulegone, a monoterpenic analogue of fukinone.
Chemistry of N-Thiosulfinylanilines. I. Reactions of Sterically Hindered Anilines with Sulfur Chlorides. Preparation of N-Thiosulfinylanilines
Authors: Inagaki Yoshio , Okazaki Renji , Inamoto Naoki 
Published: July 2006

Abstract
Reaction of 2,4-di-t-butyl-6-methylaniline (3) with disulfur dichloride afforded 2,4-di-t-butyl-6-methyl-N-thiosulfinylaniline (4) as a stable compound in 80% yield. Reaction of 2,4,6-tri-t-butylaniline (1) with disulfur dichloride gave in 70% yield 2,4,6-tri-t-butyl-7,8-dithia-9-azabicyclo[4.3.0]nona-2,4,9-triene, which in solution, exists as a tautomeric mixture with 2,4,6-tri-t-butyl-N-thiosulnnylaniline (2b) as a minor component. In the reactions with 2,4-di-t-butyl-6-isopropyl- or 2,4,6-trimethylaniline, N-thiosulfinylanilines obtained were unstable at ambient temperature. Aniline 1 reacted with sulfur dichloride to give 2 and the corresponding sulfur diimide and N-sulfinylaniline. The reaction of 4 with the dichloride afforded 4 and the corresponding sulfur diimide.
Chemistry of N-Thiosulfinylanilines. III. Thiosulfinylamine—5H-1,2,3-Dithiazole Equilibrium as Studied by NMR Spectroscopy
Authors: Inagaki Yoshio , Okazaki Renji , Inamoto Naoki , Yamada Koh-ichi , Kawazura Hiroshi 
Published: July 2006

Abstract
Thermodynamic parameters (ΔH=−4.9 kcal mol−1, ΔS=−11.3 cal mol−1 deg−1) were determined for cyclization of 2,4,6-tri-t-butyl-N-thiosulfinylaniline (1b) (the minor component) into 2,4,6-tri-t-butyl-7,8-dithia-9-azabicyclo[4.3.0]nona-2,4,9-triene (1a) (the major component) by means of NMR spectroscopy. Using these values, π-bond of thiosulfinylamino group (–N=S=S) was estimated to be weaker than that of sulfinylamino group (–N=S=O) by, at least, 25 kcal mol−1. The equilibrium ratio [1a]/[1b] is subject to considerable solvent effect, polar solvents favoring the cyclic form (1a). Similarity of the thiosulfinylamine-dithiazole equilibrium to that of azidoimine-tetrazole has been pointed out.
A New Synthesis of Arylacetic Esters Starting from Aromatic Aldehyde by the Use of Methyl (Methylthio)methyl Sulfoxide
Authors: Ogura Katsuyuki , Ito Yoko , Tsughihashi Gen-ichi 
Published: July 2006

Abstract
Methyl (methylthio) methyl sulfoxide was found to react with benzaldehyde in the presence of benzyl tri-methylammonium hydroxide (Triton B), sodium hydroxide, or potassium hydroxide, affording 1-(methylsulfinyl)1-(methylthio)-2-phenylethylene. Treatment of this product with hydrogen chloride in an alcohol gave the corresponding alkyl phenylacetate in high yield. The whole reaction sequence provides a new method for synthesizing phenylacetic esters starting from benzaldehyde. In a similar manner, (alkoxy-, halogen-, or alkyl-substituted phenyl)acetic esters could be synthesized from the corresponding aromatic aldehydes. The present method was shown to be also applicable to the production of (2-thienyl)acetic esters.
Chemistry of Dienyl Anions. I. Crystalline Dienyl Anions by Direct Reaction of Conjugated and Non-conjugated Dienes with Alkali Metals in the Presence of Et3N
Authors: Yasuda Hajime , Ohnuma Yasuo , Yamauchi Michihide , Tani Hisaya , Nakamura Akira 
Published: July 2006

Abstract
Series of acyclic and cyclic dienyl anions were prepared from both conjugated and non-conjugated dienes by direct metalation with alkali metals (Li, Na, K, Rb, and Cs) in tetrahydrofuran in the presence of triethylamine or N,N,N′,N′-tetramethylethylenediamine. Eight different dienyl anions of open chain or cyclic structures were isolated as crystals. All the acyclic potassium dienides of pentadienes, 2-methylpentadienes, 3-methylpentadienes, hexadienes and 2,4-dimethylpentadienes gave the corresponding 1,3-dienes upon hydrolysis, while the potassium cyclic dienide of cycloheptadienes and cyclooctadienes gave 1,4-dienes exclusively. The result of methylation of dienyl anions with methyl iodide agreed with that of hydrolysis. The reaction path for formation of these dienyl anions was studied based on the carbon skeleton and the molar ratio of the reduced diene dimers produced together with the dienyl anions. Selective oxidative coupling of the dienyl anions occurred with CuX or CuX2 to give linear tetraenes in good yield.
The Characterization of the Hydroxyl Surface of Silica Gel
Authors: Kondo Seiichi , Tomoi Kazuo , Pak Chynryon 
Published: July 2006

Abstract
The properties of silica gel were studied as a function of the hydrothermal treatment of hydrogel by means of the nitrogen-adsorption isotherm, the mechanical strength, thermodilatometry, and infrared spectroscopy. As a result, the number of contact points between primary particles of silica was found to decrease, and closed pores were found to be produced, by this treatment. The analysis of the infrared absorption spectra of the OH groups of this material showed that there are three kinds of OH groups in silica gel; (1) free OH groups on the outer surface of primary particles, which can adsorb molecules easily, (2) weakly perturbed OH groups inside closed pores, and (3) strongly hydrogen-bonded OH groups on the surface around the contact points. The relative concentration of these OH groups changes drastically upon the hydrothermal treatment; this is in accord with the change in the macroscopic properties mentioned above.
Diffusion Thermoeffect in Gases (The Dufour Effect)
Authors: Boushehri Ali , Abbaspour A 
Published: July 2006

Abstract
A study of the Dufour effect was made for four different gas mixtures: SF6–N2O, SF6–N2, SF6–CO2, and He–CO2. Measurements were made at 300 K under 700 Torr. The values of the thermal diffusion factor were calculated for the above mixtures from experimental data on the basis of the thermodynamics of irreversible processes. A theoretical study was made also to calculate the thermal diffusion factor from kinetic theory.
Magnetic and Spectral Properties of Binuclear Nickel(II) Nitrato and Acetato Complexes of Tridentate Schiff Bases Derived from Salicylaldehydes and N-Substituted Trimethylenediamines
Authors: Tokii Tadashi , Emori Shuji , Muto Yoneichiro 
Published: July 2006

Abstract
A new series of binuclear Ni(II) complexes with the empirical formula Ni(5-Y-sal·pr·NRR′)X has been prepared by the reaction of the parent complexes, Ni(5-Y-sal·pr·NRR′)2 with metal salts NiX2, where 5-Y-sal·pr·NRR′= Schiff base ligand derived from 5-substituted salicylaldehyde and N-substituted trimethylenediamine, R=H or CH3, R′=CH3, Y=H or Cl and X=NO3 or CH3COO. The nature of the complexes has been confirmed to be dimeric on the basis of the results of molecular weight, magnetic and spectral measurements. The values of exchange integral, J=−10–−15 cm−1, have been evaluated for the Ni(II) complexes from their temperature dependences of magnetic susceptibilities. The antiferromagnetic property has been discussed in terms of structural considerations. For comparison, the corresponding Cu(II) complexes Cu(5-Y-sal·pr·NRR′)X have been prepared and investigated.
The Thermal Decompositions of Dialkyl Peroxides
Authors: Uetake Kazuya , Ueda Kenji , Sakikawa Noriyuki 
Published: July 2006

Abstract
With the purpose of obtaining information needed for hazard prevention, pure liquid dialkyl peroxides (di-t-butyl peroxide (1), bis(1-methyl-1-phenylethyl) peroxide (2), t-butyl 1-methyl-1-phenylethyl peroxide (3), 2,5-bis(t-butyldioxy)-2,5-dimethylhexane (4)) were subjected to thermal-decomposition experiments, in which thermal analyses were conducted by the use of a thermogravimetry (TG)-differential scanning calorimetry (DSC) apparatus equipped with a pinholed pan with a minute pinhole. From the DSC curves recorded, we obtained the decomposition temperature of Samples 2, 3, and 4, as a constant value for each sample, and the maximum exothermic peaks at the optimum pinhole diameters (0.07–0.2 mm). The heats of decomposition obtained could be considered appropriate, as they roughly agreed with the estimated value, on the other hand, 1 shows no exothermic peak under these condition. Plotting by the Goats-Redfern method based on the TG-curve data (2, 3, and 4) gave reaction orders of more than unity, activation energies of 33–37 kcalth/mol, and frequency factors of 1016–1018 s−1. It is conceivable that these results could be derived by virtue of the TG–DSC curves that were suitable in obtaining thermochemical parameters. In other words, the analysis method introduced in this paper was found to be an efficient one for liquid peroxides that are difficult to analyze by a conventional TG–DSC method.
Adduct Formation of the Mixed Copper(II) 2-Thenoyltrifluoroacetonate-3-isopropyltropolonate Chelate with Tributyl Phosphate in Solvent-extraction Systems Containing These Ligands
Authors: Sekine Tatsuya , Tosaka Teruyuki 
Published: July 2006

Abstract
From the extraction data of copper(II) in a perchlorate solution into carbon tetrachloride containing 2-thenoyltrifluoroacetone (Htta), 3-isopropyltropolone (Hipt), and tributyl phosphate (tbp), the formation of an adduct mixed chelate, Cu(tta)(ipt)(tbp), together with the Cu(tta)2, Cu(tta)2(tbp), Cu(tta)(ipt), and Cu(ipt)2 species, was concluded, and the formation constant of this adduct mixed chelate was calculated.
Synthesis of (S,S)-2-Amino-3-phenylbutyric Acid
Authors: Tsuchihashi Gen-ichi , Mitamura Shuichi , Ogura Katsuyuki 
Published: July 2006

Abstract
(S,S)-2-Amino-3-phenylbutyric acid was synthesized starting from diethyl (R)-(1-phenylethyl)malonate which was obtained by desulfurization of the adduct in the stereoselective Michael reaction of (R)-styryl p-tolyl sulfoxide with diethyl malonate. This synthetic amino acid was identical with the 2-amino-3-phenylbutyric acid obtained by degradation of bottromycin and thus the absolute configuration of the naturally occurring amino acid was proved to be (S,S).
Kinetics of the Aminolysis of α-Chloropropionic Acid. Reactivity of Aliphatic Amines
Authors: Ogata Yoshiro , Yamauchi Yuya 
Published: July 2006

Abstract
The kinetics for the reaction of α-chloropropionic acid with some amines (methylamine, dimethylamine, trimethylamine, ethylamine, and diethylamine) and ammonia have been studied in an aqueous solution. The reactivity of amines is discussed on the basis of the Swain-Scott and Taft equations.
Interaction of Excited Lithium Atom with Molecular Hydrogen. I. Preliminary Potential Energy Surfaces in an OVC MCSCF Approximation
Authors: Mizutani Kimiko , Kuribara Yoshihiro , Hayashi Kazuko , Matsumoto Shiro 
Published: July 2006

Abstract
Potential energy surfaces were computed for the Li–H2 system of C2V symmetry, which dissociates to a normal hydrogen molecule and a lithium atom either in its ground state or in the 2P excited state, in order to get an idea of the quenching process of the atom by the molecule. The potential surfaces crossed in a line and two shallow minima appeared on the 2B2 surface. Natural orbital analysis and electron density maps gave information on the charge transfer character of the interaction of the excited atom with the molecule.
Singlet Excitation Energy Migration in the Glassy Organics Blended with Polymer
Authors: Sano Yumiko , Shirota Yasuhiko , Mikawa Hiroshi 
Published: July 2006

Abstract
Studies have been made of the singlet excitation energy migration of 1,3-diphenyl-5-(p-chlorophenyl)-2-pyrazoline in a glassy state blended with an ethylene-vinyl acetate copolymer by the fluorescence quenching method. The results are discussed in terms of the simple random energy migration model, showing that the efficiency of the singlet excitation energy migration does not differ between the glassy state and the polymer blend system.
Ultraviolet Photoelectron Spectra of Crown Ethers
Authors: Kajitani Masatsugu , Sugimori Akira , Sato Naoki , Seki Kazuhiko , Inokuchi Hiroo , Harada Yoshiya 
Published: July 2006

Abstract
The He I spectra of 12-crown-4, 15-crown-5, 18-crown-6, dicyclohexyl-18-crown-6, and dibenzo-18-crown-6 have been measured. The features of the spectra are similar except for the case of dibenzo-18-crown-6, where two lower IP bands correlated with the highest occupied π-orbitals of benzene are observed together with the bands due to the polyether ring. By the aid of the CNDO/2 calculation, the lower IP bands of the spectra have been assigned to the MO’s mainly due to the equatorial or axial type non-bonding orbitals of the oxygen atoms of the polyether rings.
A Study on Electronic Excited States of Iridium(III) Complexes Containing Bipyridine and Phenanthroline Ligands. Solvent Effect on Triplet-Triplet Absorption Spectra
Authors: Ohashi Yukako , Kobayashi Takayoshi 
Published: July 2006

Abstract
In order to study the solvent effect on the lowest excited state of of cis-[IrCl2L2]Cl (L=2,2′-bipyridine, 1,10-phenanthroline, and 4,7-dimethyl-1,10-phenanthroline), the triplet-triplet absorption spectra (15000 cm−1—27000 cm−1) were measured by the use of N,N-dimethylformamide–water mixed solvents. For the triplet-triplet spectra of the three iridium complexes, remarkable spectral changes were observed with the change of the solvent polarity. An SCF calculation of the triplet-triplet transitions was carried out for free bipyridine and free phenanthroline. By comparing the calculated results and the observed spectra, the solvent effect can be interpreted in terms of a model invoking dπ*-ππ* interaction, as proposed by Crosby. The lowest triplet state of [IrCl2(phen)2]Cl is predominantly a dπ* state in 95% v/v DMF–water, but in water, by the reversal of the state ordering, the lowest state becomes a ππ* state. Furthermore, a quite similar solvent effect which was observed on the lowest triplet state of [IrCl2(bpy)2]Cl is discussed; this state is not expected to have a dπ*-ππ* interaction.