bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron Transfer Reaction between Δ2,2′-Bi-1,3-dithiole (TTF) and 7,7,8,8-Tetracyanoquinodimethane (TCNQ). Electron Donating Property of TTF
Authors: Yamagishi Akihiko , Iida Yôichi 
Published: July 2006

Abstract
The reaction between Δ2,2′-bi-1,3-dithiole (TTF) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) in ace-tonitrile solution, TTF+TCNQ\ightleftharpoonsTTF+·+TCNQ\ewdot, was analyzed spectrophotometrically. The thermodynamical data of chemical equilibrium were determined to be K=(2.8±0.1)×10−3 at 11 °C, ΔH=−6.7±1.3 kJ mol−1 and ΔS=−72.8±17 J K−1 mol−1. The reaction-rate study of the equilibrium in several solvents was also made by temperature-jump technique. The difference in the electron-donating properties between TTF and N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) is discussed by comparing the results with those of the reaction between TMPD and TCNQ.
The Enantioface-differentiating Hydrogenation of the C=O Double Bond with Asymmetrically Modified Raney Nickel. XXXIII. The Preparation of (R)- and (S)-1,3-Butanediol from 4-Hydroxy-2-butanone
Authors: Murakami Shigeki , Harada Tadao , Tai Akira 
Published: July 2006

Abstract
The enantioface-differentiating hydrogenation of 4-hydroxy-2-butanone (I) to 1,3-butanediol(II) was conducted with asymmetrically modified metal catalysts. Among the modified catalysts examined, Raney nickel modified with a solution containing tartaric acid and NaBr (TA–NaBr–MRNi) gave the best results with respect to the optical and chemical yields. (R)-II, an optical purity of 69% was obtained in a quantitative chemical yield by the use of (R,R)-TA–NaBr–MRNi. (S)-II was also obtained by the use of (S,S)-TA–NaBr–MRNi. A simple method for the preparation of optically pure (S)-and (R)-II from the hydrogenation product was also developed.
The Reaction of Olefins with Chloroalkoxyalkanes and Formic Acid in Ether
Authors: Nishiura Kazuo , Tagano Tsutomu , Wada Yasuo , Tanimoto Shigeo , Okano Masaya 
Published: July 2006

Abstract
The reaction of olefins with chloromethoxymethane (CMM) and excess formic acid in ether, in the presence of ZnCl2 or HgCl2, afforded mainly four products, 1-chloro- and 1-formyloxy-2-(formyloxymethyl)alkanes, and 3,5-dialkyl-4-chloro- and 3,5-dialkyl-4-(formyloxy)tetrahydropyrans, in various yields. In the case of styrene, the chief products were limited to the former two. Similar products were obtained from 1-chloro-1-ethoxyethane (CEE), but their yields were quite low.
The Chloroiodination of Deactivated Olefins with Antimony(V) Chloride–Iodine and Iodine Monochloride
Authors: Uemura Sakae , Fukuzawa Shin-ichi , Okano Masaya , Sawada Seiji 
Published: July 2006

Abstract
By the reactions of olefins with an equimolar mixture of SbCl5 and I2 in carbon tetrachloride, various chloroiodoalkanes are obtained in fair to good yields. This method is applicable to various deactivated olefins, the reactions of which do not proceed by the reported method using a mixture of CuCl2 and I2. Iodine monochloride can aslo be used for this reaction, but in this case both the yield and the regiospecificity of the products are sometimes inferior.
Studies on Heterocyclic Analogs of Azulene. VI. Cycloadditions of Styryl-substituted Aza Analogs of Azulene with Dimethyl Acetylenedicarboxylate
Authors: Abe Noritaka , Nishiwaki Tarozaemon 
Published: July 2006

Abstract
8-[(E)-Styryl]-1-azaazulenes stereospecifically react with dimethyl acetylenedicarboxylate to form trans-7H-6a-azacyclobuta[j]cyclopent[cd]azulene (3), which undergoes thermal rearrangement into 3-[(E)-styryl]3H-2a-azacyclopent[cd]azulene and 3a,4-dihydro-3H-2a-azadicyclopent[cd, ij]azulene (7), or isomerization into 3H-2a-azacyclopenta[ef]heptalene by silica gel. Compound 7 is oxidized during the course of reaction to yield 11-oxo-2aH-7,10b-methano-2a-azacyclopenta[ab]cycloundecene, compound 3 forming 5a,6-dihydro-3H-2a-azadicyclopenta[ef, kl]heptalene upon reaction with acetylene. The formation of 3 could be accounted for in terms of a symmetry-allowed thermal [π2s+π2a+π6a] cycloaddition.
Efficient Regioselective Aldol Condensation of Methyl Ketones Promoted by Organoaluminium Compounds, and Its Application to Muscone Synthesis
Authors: Tsuji Jiro , Yamada Toshiro , Kaito Mitsumasa , Mandai Tadakatsu 
Published: July 2006

Abstract
Dialkylaluminium aryloxide in combination with a tertiary amine was found to be a good reagent for regioselective aldol condensation of methyl ketones at the methyl side. Regioselective aldol condensation of 2-octanone was carried out using diisobutylaluminium phenoxide–pyridine. The intramolecular aldol condensation of 2,15-hexadecanedione promoted by the same reagent gave a mixture of dehydromuscones in 65% yield. Its hydrogenation produced muscone.
The Total Syntheses of Chamaecynone, Isochamaecynone, and Dihydroisochamaecynone
Authors: Ando Masayoshi , Asao Toyonobu , Hiratsuka Norio , Takase Kahei , Nozoe Tetsuo 
Published: July 2006

Abstract
A novel acetylenic nor-sesquiterpene, chamaecynone, and its related natural products, isochamaecynone and dihydroisochamaecynone, have been synthesized starting from α-santonin. In the base-induced equilibration of three pairs of compounds, chamaecynone and isochamaecynone, 4βH,5β-13-noreudesm-11-yn-3-one and 4αH,5β-13-noreudesm-11-yn-3-one, and 4βH,5β-13-noreudesm-11-en-3-one and 4αH,5β-13-noreudesm-11-en-3-one, the ΔH values were determined to be +1.47 kcal/mol, +0.77 kcal/mol, and −2.28 kcal/mol respectively.
Correlation between Electron Capture Detector Response and Chemical Structure for 1,2,3,4,5,6-Hexachlorocyclohexane
Authors: Hattori Yukikazu , Kuge Yoshio , Asada Shingo 
Published: July 2006

Abstract
The relative sensitivities of an electron capture detector for four 1,2,3,4,5,6-hexachlorocyclohexane isomers were measured at different detector temperatures. The temperature dependence of the electron capture coefficients (K) for these compounds was determined. The K values of these compounds increased with a decrease in the detector temperature. These results show that the electron capture reactions of these compounds proceed non-dissociatively.
A Measurement of the Thermal Decomposition of CS2 behind Reflected Shock Waves
Authors: Saito Ko , Toriyama Yoko , Yokubo Teiji , Higashihara Tetsuo , Murakami Ichiro 
Published: July 2006

Abstract
The thermal decomposition of CS2 in Ar was investigated in the temperature range of 2000–2900 K by monitoring both the UV absorption and the visible emission of CS2. A typical induction zone was observed during the decomposition. It was found that the rate constant of the initiation reaction obtained from the induction zone was smaller than that reported by previous workers.
Reflectivity of Two-dimensional Cluster Compound, Nb3I8
Authors: Kawamura Haruki , Shirotani Ichimin , Tanaka Masashi , Tachikawa Kyoji , Tanaka Jiro 
Published: July 2006

Abstract
The reflectivity spectrum of two-dimensional cluster compounds, Nb3I8, is measured from 5×103 to 35×103 cm−1 and compared to that of Ag2F. The spectrum has four peaks, at 7.5, 11.8, 20.0, and 28.6×103 cm−1.
Mechanical Strength and Thermal Expansion of Sintered Rare Earth Orthophosphate(RPO)4
Authors: Hikichi Yasuo , Hukuo Ken-iti , Shiokawa Jiro 
Published: July 2006

Abstract
RPO4 powders, obtained by heating a hexagonal form RPO4·0.5H2O (R=La, Ce, Pr, Nd, or Sm) or a monoclinic form RPO4·2H2O (R=Y, Er, or Yb) at 800 °C for 3 h, were pressed into plates or spheres at 500 kgf/cm2 (1 kgf/cm2=98.0665 kPa) and sintered at 1500 °C for 60 min in the air, the sintered bulk density being above 90% of the theoretical. The mechanical strength and thermal expansion of the sintered RPO4 are : compressive strength 2300–3000 kgf/cm2, bending strength 320–500 kgf/cm2, and linear thermal expansion coefficients (30–900 °C) (5.75–10)×10−6.
Two-phase Darzens Condensation Reaction with Octopus Compounds as a Catalyst
Authors: Akabori Sadatoshi , Ohtomi Michiko , Yatabe Seiichi 
Published: July 2006

Abstract
The octopus compound, readily derived from hexakis(mercaptomethyl)benzene and 1-chloro-3,6,9-trioxadecane, was effectively employed as a catalyst in the two-phase Darzens condensation of carbonyl compounds with chloroacetonitrile to afford the corresponding oxiranes in good yields.
Comparison of Lewis Acids as Catalyst for the Alkylation of Benzene with s-Butyl Chloride
Authors: Segi Masahito , Nakajima Tadashi , Suga Sohei 
Published: July 2006

Abstract
The Friedel-Crafts alkylation of benzene with s-butyl chloride has been carried out in the presence of various Lewis acid catalysts. The relative order of catalyst activity is: AlBr3, AlCl3, MoCl5, SbCl5&gt;TaCl5&gt;NbCl5&gt;FeCl3&gt;ZrCl4&gt;TiCl4&gt;&gt;WCl6. The effect of addition of nitromethane on alkylation has been investigated.
Preparation and Properties of N-(Pentafluoropropionyl)amino Acid
Authors: Kawa Hajimu , Ishikawa Nobuo 
Published: July 2006

Abstract
N-(Pentafluoropropionyl)amino acids, which were prepared by treating amino acids with hexafluoro-1,2-epoxypropane in diglyme, were found to be a versatile derivative of amino acids in gas chromatographic analysis.
Catalytic Geometrical Isomerization of cis-Chrysanthemaldehyde and Related Ketones
Authors: Sasaki Tadashi , Eguchi Shoji , Ohno Masatomi 
Published: July 2006

Abstract
cis-Chrysanthemaldehyde isomerized cleanly to the trans-isomer catalyzed with methoxydimethylsulfonium iodide (8) at 25 °C. Zinc halides as well as silica gel were also demonstrated to be effective catalysts. Related aldehydes and ketones isomerized also with 8 at 80 °C but dihydrochrysanthemaldehyde did not isomerize at all.
An Application of Microwave Treatment to the Dehydration of Manganese Dioxide for Lithium Nonaqueous Cells
Authors: Hirai Taketsugu , Tari Isao , Ohzuku Tsutomu 
Published: July 2006

Abstract
A new dehydration technique of manganese dioxide using 2.45 GHz microwave is presented. The so-called γ and γ,β-MnO2, each containing less than 1 wt% water, which are not attainable by heat, treatment, are obtained under specified conditions by this dehydration technique.
Structural Studies of Asymmetric Hydrogenation. V. The Crystal Structures of [(S)-1-Cyanoethyl][(S)(−)-α-methylbenzylamine]bis(dimethylglyoximato)cobalt(III) at 293 K and 173 K
Authors: Ohashi Yuji , Sasada Yoshio , Takeuchi Seiji , Ohgo Yoshiaki 
Published: July 2006

Abstract
The structure of [(S)-1-cyanoethyl][(S)(−)-α-methylbenzylamine]bis(dimethylglyoximato)cobalt(III) has been determined by X-ray analysis at 293 K and 173 K. The crystal is monoclinic, the space group being P21, Z=2, with a=8.768(2), b=13.356(2), c=9.538(3) Å, and β=96.73(3)° at 293 K, and a=8.617(4), b=13.222(4), c=9.517(7) Å, and β=96.26(7)° at 173 K. The structure was deduced by the heavy-atom method and was refined by the block-diagonal least-squares method to the final R values of 0.051 and 0.060 for 1878 and 1848 observed reflections at 293 K and 173 K respectively. The bis(dimethylglyoximato)cobalt moiety is twisted in the opposite way from that of [(R)-1-cyanoethyl][(S)(−)-α-methylbenzylamine]bis(dimethylglyoximato)cobalt(III). This supports the proposal that the asymmetry of the optically active amine is transferred into the substrate through the twist of the bis(dimethylglyoximato) cobalt moiety in the step of the σ-bond formation.
Neutron Diffraction Study of Liquid Acetyl Chloride
Authors: Ohtomo Norio , Arakawa Kiyoshi 
Published: July 2006

Abstract
The structure factor Sm(Q) for liquid acetyl chloride at room temperature has been determined in the range Q, 0.9–27 Å−1, by means of the time-of-flight (TOF) neutron diffraction method using the electron linear accelerator (LINAC). The structural parameters of CD3COCl, bond distances, bond angles, and rms amplitudes, in liquid phase have been determined by a comparison of calculated curves with observed data, and it has been concluded that a molecule within the liquid takes an essentially identical conformation as a rotational isomer with that in gaseous phase, which was determined by microwave spectroscopy.
Studies on the Aqueous Solutions of Guanidinium Salts. XIV. Effect of Guanidinium Bromide on the Surface Tension of Aqueous Solutions of the Cationic Surfactants
Authors: Miyajima Koichiro , Yoshida Hiromitsu , Maetani Junko , Nakagaki Masayuki 
Published: July 2006

Abstract
The surface tensions of decyl-, tetradecyl-, and hexadecyl-trimethylammonium bromides were measured in the aqueous solutions of potassium bromide (KBr) and guanidinium bromide (GuBr). The critical micelle concentrations (CMC’s) of the above surfactants decreased with increase of the concentration of KBr, while the CMC’s showed minimum values in the aqueous GuBr solution, as the concentration of GuBr increased. The Langmuir coefficient, KC, increased with decrease of the CMC. The influence of the salts on the surface tension and the micellization were well described in terms of the activity of the surfactant calculated by combining the Debye-Hückel law and Setschenow’s equation.
Selective Ester-exchange Reactions of Dibenzyl-aspartate and -glutamate in the Coordination Sphere of Copper(II) Ion
Authors: Nakao Yasuo , Demichi Masaaki , Nakahara Akitsugu 
Published: July 2006

Abstract
Copper(II) complexes of the Schiff bases derived from salicylaldehyde and dibenzyl aspartate or glutamate have been prepared for the first time. Upon refluxing the solution of these complexes in methanol for 30 min, bis(α-methyl β-benzyl N-salicylideneaspartato)copper(II) and bis(α-methyl γ-benzyl N-salicylideneglutamato)copper(II) were obtained. The mechanism of these selective ester-exchange reactions in the metal-coordination sphere has been discussed. Several Schiff bases were obtained and characterized.
Diastereomers and Circular Dichroism Spectra of the Tris(trans-1,2-cyclopentanediamine)cobalt(III) Complex
Authors: Kunimatsu Mihoko , Kanno Hideaki , Kojima Masaaki , Kashiwabara Kazuo , Fujita Junnosuke 
Published: July 2006

Abstract
The (lel3), (lel2ob), and (lelob2) isomers of [Co(rac-cptn)3]3+ were obtained by the reaction of trans-[CoCl2(pyridine)4]+ with rac-cptn, where cptn denotes trans-1,2-cyclopentanediamine. No indication for the formation of the (ob3) isomer was found. The isomers were resolved into optical isomers by SP-Sephadex column chromatography. The circular dichroism spectra of these optical isomers were measured and the results compared with those of the related complexes. The anomalous circular dichroism pattern of the (lel3) isomer in the region of the first absorption band was found to result from the contribution of the strong vicinal effect of the chiral cptn chelate ligand as compared with that of the configurational effect.
Kinetics and Mechanism of the Reactions of Bis(acetylacetonato)-palladium(II) with Alkylamines
Authors: Matsumoto Shinichi , Kawaguchi Shinichi 
Published: July 2006

Abstract
The reactions of bis(acetylacetonato)palladium(II), Pd(acac)2, with alkylamines (L) such as butyl-, cyclohexyl-, diethyl-, and dipropylamines in methanol to afford [Pd(acac)L2](acac) obey the usual two-term rate law, rate=(k0+k1[L])[Pd(acac)2]. On the other hand, the rate of reaction of Pd(acac)2 with diethylamine in THF and benzene is expressed by rate=(k1+k2[L])[L][Pd(acac)2]. A mechanism is proposed which presumes the hydrogen-bonding interaction of Pd(acac)2 with methanol and amine. Intermediacy of Pd(acac)(acac-C3)L in these reactions was denied on the basis of the kinetic studies, and the carbon-bonded complex was concluded to be produced via [Pd(acac)L2](acac). The equilibrium constants for the reactions, Pd(acac)2+2Et2NH\ightleftarrows[Pd(acac)(Et2NH)2(acac) and Pd(acac)(acac-C3)(Et2NH)+Et2NH\ightleftarrows[Pd(acac)(Et2NH)2](acac) were determined in dichloromethane and methanol.
Stereoselective Association between Acetylacetonatobis(ethylenediamine)cobalt(III) and Malonate Ions as Studied by Nuclear Magnetic Resonance
Authors: Nakazawa Hiroshi , Sakaguchi Ushio , Yoneda Hayami 
Published: July 2006

Abstract
The effect of added malonate upon the chemical shift and the exchange rate of amine hydrogens of acetylacetonatobis(ethylenediamine)cobalt(III) ion, [Co(acac)(en)2]2+, have been investigated by 1H and 13C NMR spectroscopy. In the absence of malonate, the amine groups give rise to two signals in the 1H spectra and two rate constants of amine exchange due to trans and cis (to coordinated oxygen) amine groups. Upon addition of malonate, the trans NH2 undergoes a down-field shift, the cis NH2 resonance splitting into two peaks. In the presence of malonate, all of the four kinds of amine hydrogens of [Co(acac)(en)2]2+ exhibit different exchange rates. The following conclusion was obtained from the results coupled with 13C NMR data, (i) The malonate ion works in two ways in amine exchange, as a general base catalyst and to form an exchange-inert ion-pair, (ii) The two trans hydrogens that are directed approximately parallel to the two-fold axis of the complex ion hydrogen-bond simultaneously to the two carboxyl groups of malonate, leading to a retardation of amine exchange rates. (iii) The rates of the other trans hydrogens and cis hydrogens are determined by a compromise between acceleration due to general base catalysis and deceleration due to forming ion-associated species, (iv) The conformation of coordinated ethylenediamine is fixed as either (δδ) or (λλ) in the hydrogen-bonded species.
Thermal Square Planar-to-Octahedral Transformation of Nickel(II) Complexes Containing 2-Aminobenzimidazole in the Solid Phase
Authors: Ihara Yoshinori , Tsuchiya Ryokichi 
Published: July 2006

Abstract
Thermal reactions of the complexes, [Ni(abi)4]X2·nH2O (abi, 2-aminobenzimidazole; X, Cl, Br, I, NO3, ClO4, or 1/2SO4; n, 3 for chloride and bromide, 1 for nitrate, and 0 for others) were investigated. Distinct color changes from orange to green were observed in the three complexes of chloride, bromide, and nitrate upon heating. It was found from the changes in absorption and far-IR spectra and magnetic susceptibilities under the thermal reactions that the complexes undergo transformation from square planar to tetragonally distorted octahedral structures, involving an increase in the coordination number from four to six. No such transformation could be found in the corresponding iodide, perchlorate, and sulfate. The effect of the introduced amino group on the structural conversion reactions of the abi complexes is discussed as compared with the corresponding benzimidazole complexes, [Ni(bimd)4]X2, which underwent transformation from square planar to octahedral structure upon heating when X is I or NO3.
New Synthesis and Hydroboration of Vinylphosphonates
Authors: Yamashita Mitsuji , Kojima Mitsumasa , Yoshida Hiroshi , Ogata Tsuyoshi , Inokawa Saburo 
Published: July 2006

Abstract
The Arbuzov reaction of trimethyl and triethyl phosphites with acyl chlorides gave 1-oxoalkylphosphonates in 57–80% yields. The Wittig reaction of the phosphonates with methylenetriphenylphosphorane gave vinylphosphonates in 25–59% yields. Hydroboration of vinylphosphonates in oxolane gave 2-hydroxyethylphosphonates in 50–65% yields. The procedure seems to be a good synthetic method to afford 1-alkyl-substituted 2-hydroxyethylphosphonates which have one more carbon atom than the starting 1-oxoalkylphosphonates.
Studies of Polymeric Flocculants. XI. The Preparation and Properties of Polyampholytes
Authors: Nonaka Takamasa , Egawa Hiroaki 
Published: July 2006

Abstract
The polyampholytes were prepared by treating potassium polymethacrylate with (3-chloro-2-hydroxypropyl)trimethylammonium chloride. The solution viscosity behavior and the potentiometric titration of the polyampholytes were studied. The flocculating ability of the polyampholytes was also investigated by the use of kaolin suspensions. The amine/acid ratio could be varied as desired to some extent by means of changing the reaction temperature. However, the polyampholytes containing more amino groups than about 46% could not be obtained. The resulting polyampholytes showed characteristic viscosity behavior. The results of the flocculation of kaolin suspensions with the polyampholytes showed that the polyampholytes can be expected to become a new type of polymeric flocculants, in which the chain expansion and the charge sign can be varied by changing the pH values of the solutions.
The Reaction of 2-Chloroazulene Derivatives with Lithium Acetylide in Liquid Ammonia
Authors: Morita Tadayoshi , Fujita Taira , Takase Kahei 
Published: July 2006

Abstract
The reaction of diethyl 2-chloroazulene-1,3-dicarboxylate (1a) with lithium acetylide in liq ammonia gave diethyl 4- and 6-ethynylazulene-1,3-dicarboxylates by an abnormal substitution reaction. In a similar manner, some 2-chloroazulenes, possessing alkoxycarbonyl and/or cyano substituents at the 1- and 3-positions of azulene nucleus, gave the corresponding 4 (or 8)- and 6-ethynylazulenes. The same type reaction proceeded when lithium phenylacetylide, sodium indenide, and sodium fluorenide were used as the reagents, 1a giving diethyl 4- and 6-(phenylethynyl)-, 6-(3-indenyl)-, and 6-(9-fluorenyl)azulene-1,3-dicarboxylates, respectively.
Heterofulvalenes. II. Synthesis and Reaction of 2,3 : 7,8-Dibenzo-1,4-dithia-6-azafulvalene
Authors: Nakayama Juzo , Imura Mimiko , Hoshino Masamatsu 
Published: July 2006

Abstract
Reaction of 2-isopentyloxy-1,3-benzodithiole with indole in acetic acid gave a 93% yield of 3-(1,3-benzodithiol-2-yl)indole (4a) which was converted to 2-(3-indolyl)-1,3-benzodithiolylium tetrafluoroborate (5a) in a 77% yield by treatment with trityl tetrafluoroborate. 5a was also prepared by reaction of indole with 2 molar amounts of 1,3-benzodithiolylium tetrafluoroborate. Treatment of 5a with triethylamine afforded the title compound 6a in 93% yield. 6a was protonated, methylated, and benzoylated at its 6-position by tetrafluoroboric acid, methyl iodide, and benzoyl chloride, respectively. Reaction of 6a with dimethyl acetylenedicarboxylate gave a 1,6-dipolar intermediate which was trapped as an adduct with ethanol. 6a was smoothly reduced by sodium borohydride to give its 5,6-dihydro derivative.
Studies on 1-(Thiosulfinylaminothio)piperidines
Authors: Morimura Syoji , Horiuchi Hideo , Tamura Chihiro , Yoshioka Takao 
Published: July 2006

Abstract
Hindered piperidine derivatives with a new functional group (–S–N=S=S), 2,2,6,6-tetramethyl-1-(thiosulfinylaminothio)piperidines (4) were obtained from the corresponding piperidines 1, sulfur monochloride and ammonia. These compounds were also prepared from bis(2,2,6,6-tetramethylpiperidino) disulfides or bis(2,2,6,6-tetramethylpiperidino) trisulfides under similar reaction conditions. In much lower yields, unhindered 1-(thiosulfinylaminothio)piperidines (8) were also obtained. The photochemical and thermal stabilities of 4 and 8 were nearly the same. Reaction pathways were disucssed.
The Electronic Spectra of Intramolecular Charge-transfer Compounds and Their Marked Solvatochromism in a Strong Hydrogen-bonding Solvent: 2-(Arylmethylene)-1,3-indandiones and 2-(1-Naphthyl)-p-benzoquinone
Authors: Chiba Kazuhiko , Aihara Jun-ichi , Araya Kotaro , Matsunaga Yoshio 
Published: July 2006

Abstract
The first electronic absorption bands of the title compounds can all be assigned to the intramolecular charge-transfer transitions. The solvent effects on these bands are quite analogous to those on the absorption bands characteristic of binary charge-transfer complexes. Especially, when the title compounds are dissolved in trifluoroacetic acid, marked bathochromic shifts of the first bands are observed, in harmony with their charge-transfer character. Such solvatochromism is obviously due to the hydrogen-bond formation between the solute and the solvent molecules. When strong hydrogen bonding occurs, the electron affinity of the 2-methylene-1,3-indandione moiety increases by about 0.41 eV.