bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Photochemical Debromination of Bromocyclopropane in the Presence of Amine
Authors: Tomioka Hideo , Inoue Osamu 
Published: July 2006

Abstract
The irradiation of bromoarylcyclopropanes (1) in the presence of tertiary amine resulted in the formation of the debrominated cyclopropanes as a mixture of geometrical isomers, whose ratios were essentially similar regardless of the stereochemistry of the bromide. The reactions were not, however, observed in the absence of amine. The results are interpreted as indicating that the reactions proceed through an initial single-electron transfer to the excited 1, followed by debromination and hydrogen-abstraction.
A Michael Reaction Product of Cyclohexylidenemalononitrile
Authors: Nakano Yoshiharu , Yokota Hiroaki , Igarashi Minoru , Sato Shoichi 
Published: July 2006

Abstract
Cyclohexylidenemalononitriles dimerize and cyclize to give 3-amino-2,4-dicyano-2-[imino(methoxy)methyl]spiro[bicyclo[4,4,0]deca-3,5-diene-1,1′-cyclohexane] (3). The crystal structure of 3 was determined by an X-ray diffraction method.
Fries Rearrangement in Calixarene Esters: A New Entry for the Synthesis of p-Substituted Calixarenes
Authors: Arimura Takashi , Shinkai Seiji , Matsuda Tsutomu , Hirata Yoshimi , Satoh Hiroshi , Manabe Osamu 
Published: July 2006

Abstract
The Fries rearrangement was found to be a convenient method to synthesize p-acylcalixarenes from O-acylcalixarenes, the yields being relatively good (29–34%) as a synthetic method for p-substituted calixarenes.
Electronic and ESR Spectral Studies of a Series of Phosphine and Phosphite Adducts with Cobaloxime Analog
Authors: Mita Keisuke , Hotta Kazuhiko , Takui Takeji 
Published: July 2006

Abstract
Electronic and ESR spectra were measured for solutions of Co(dmgBF2)2 in the presence of PX3, where Co(dmgBF2)2 is a BF2 capped species of bis(dimethylglyoximato)cobalt(II) (Co(Hdmg)2) and PX3 is PBu3, PPh3, P(OEt)3, or P(OPh3)3. 31P hyperfine splittings of their ESR spectra demonstrated that Co(dmgBF2)2 forms only 1 : 1 adducts with PX3. The visible absorption spectrum of the dichloromethane solution of Co(dmgBF2)2 showed an absorption band at 444 nm at 20°C. Upon PX3 being added to the solution, the band shifted to a longer wavelength; the band shift increased with increasing the electron-donating ability of PX3.
Configurational Stability of Optically Active Selenoxides; Racemization via Achiral Hydrate
Authors: Shimizu Toshio , Kobayashi Michio , Kamigata Nobumasa 
Published: July 2006

Abstract
Configurational stabilities of optically active diaryl selenoxides are examined under several conditions such as acidic, basic, or in the presence of water. It is found that the diaryl selenoxide which has two hindered t-butyl groups on the ortho positions is relatively stable toward racemization even under acidic conditions. Mechanism of racemization is ascertained to be via formation of the achiral hydrate (R–Se(OH)2–R′) by the observation of oxygen exchange on the selenium atom.
A Short-Step Synthetic Approach to Eudesmane Skeleton. A Synthesis of (±)-β-Eudesmol and Related Eudesmane Sesquiterpenes
Authors: Kawamata Takeshi , Harimaya Kenzo , Inayama Seiichi 
Published: July 2006

Abstract
The formal total syntheses of (±)-β-eudesmol and its related sesquiterpenes such as cryptomeridiol and neointermediol were accomplished by an efficient method using aldol cyclization as the key step starting from the known 3-vinyl-2-cyclohexen-1-one.
A New and Simple Route to 3-Arylthiophenes
Authors: Sone Tyo , Inoue Manabu , Sato Kazuaki 
Published: July 2006

Abstract
3-Arylthiophenes were prepared from 2,5-dichlorothiophene in two steps. 2,5-Dichlorothiophene reacted regioselectively with various aromatic compounds in the presence of AlCl3 under mild conditions to give 4-aryl-2-chlorothiophenes. The latter compounds were easily converted to the corresponding 3-arylthiophenes by catalytic dechlorination in good yields.
A Reinvestigation of a Sensitized Photochemical Cycloaddition of Coumarin with Cyclopentene
Authors: Suginome Hiroshi , Kobayashi Kazuhiro 
Published: July 2006

Abstract
A reinvestigation of a sensitized photochemical cycloaddition of coumarin with cyclopentene reported by Hanifin and Cohen indicated that the cycloaddition gives a sterically disfavored cis-cisoid-cis adduct (18%) together with a cis-transoid-cis adduct (25%) and a head-to-head coumarin dimer with a cis-transoid-cis disposition. The two adducts behaved differently in hydrolysis and recyclization.
New Applications of Crown Ethers. IX. Crystal Structure of KSCN Complex of N-Heptylmonoaza-18-crown-6, and Conformational Features of the Pivot Nitrogen
Authors: He Gong-Xin , Kikukawa Kiyoshi , Nishiyama Nobuaki , Ohe Hiroshi , Matsuda Tsutomu 
Published: July 2006

Abstract
Vertical arrangement of the alkyl side arm in the crystal structure of KSCN complex of N-heptylmonoaza-18-crown-6 is well-consonant with the effective side-arm participation in N-pivot lariat ether complexes and supports the lack of ‘biscrown effect’ for bis(monoaza-18-crown-6)s.
The Thermal Decomposition and Hydrolysis of Calcium Carbamoyl Phosphate
Authors: Shimasaki Choichiro , Suzuki Hiroki 
Published: July 2006

Abstract
Calcium carbamoyl phosphate (1) was prepared by adding an aqueous calcium chloride solution to a reaction solution of KH2PO4 with KOCN. 1 was unstable at room temprature. 1 was dehydrated to make anhydrous salt and thermally decomposed to liberate ammonia, cyanic acid, and carbon dioxide, finally resulting in the formation of calcium pyrophosphate in air. The apparent activation energies for the three endothermic peaks of the DTA curve were estimated to be 50.0, 83.9, and 148.3 kJ mol−1 respectively. The hydrolysis of 1 in an aqueous solution apparently obeyed the first-order kinetics. The activation parameters for the hydrolysis of 1 were evaluated by using the 31P NMR spectra of 1 with the lapse of the reaction time. The activation energy was 92.2 kJ mol−1; the activation enthalpy, 89.7 kJ mol−1, and the activation entropy, −6.3 e.u.
New Thiazolo[5,4-d]pyrimidines with Molluscicidal Properties
Authors: El-Bayouki Khairy A M , Basyouni W M 
Published: July 2006

Abstract
Ethyl chloroformate/DMF mixture is used as a reagent for the facile ring closure of 5-amino-2-(ethylthio)thiazole-4-carboxamide (1a) to afford an excellent yield of 2-ethylthiothiazolo[5,4-d]pyrimidin-7(6H)-one (3). The action of phosphoryl chloride on the latter product gave its 7-chloro derivative (4). The corresponding 7-(dicyanomethyl) (5a), 7-[cyano(ethoxycarbonyl)methyl] (5b), and 7-(substituted amino)derivatives (6a–j) are synthesized from reactions of malononitrile, ethyl cyanoacetate, and primary amines, respectively, with compound 4. Most of the obtained products have been screened for activity against the intermediate host of schistosomiasis, B. alexandrina snails.
Theoretical Treatment of Solvent Effects on the Frequency Shifts of Fluorescence Spectra
Authors: Abe Takehiro 
Published: July 2006

Abstract
A theoretical expression for the solvent fluorescence spectral shifts of a neutral solute molecule has been developed by following the same treatment as in Abe’s expression for solvent absorption spectral shifts (Bull. Chem. Soc. Jpn., 54, 327 (1981); 58, 3415 (1985)). Compared with all previous applicable expressions being applied to only polar solute molecules, the present expression has the advantage that it can be applied to not only the polar solute molecules but also nonpolar solute molecules. The polarizabilities of the ground and excited states concerning fluorescence are treated as being different from the corresponding values concerning absorption. Applications to nonpolar solute molecules are successfully presented.
Crystal and Molecular Structure of Double Macrocyclic Inclusion Complexes, γ-Cyclodextrin·12-Crown-4·NaCl, a Model for the Transport of Ions through Membranes
Authors: Kamitori Shigehiro , Hirotsu Ken , Higuchi Taiichi 
Published: July 2006

Abstract
The crystal structure of a γ-cyclodextrin·12-crown-4·NaCl (3 : 3 : 1) inclusion complex was determined by an X-ray method to be space group P4212, a=b=23.816(3) Å, c=23.072(3) Å. The inclusion complex has a C4 symmetry, and the cation, Na+, is coordinated by two 12-crown-4 molecules in a hydrophobic channel formed by tail-to-tail oriented two γ-cyclodextrin molecules.
Pressure and Temperature Effects on Octahedral–Tetrahedral Equilibria in 4-Methylpyridine and 2-Methylpyridine Solutions of Some Cobalt(II) Halides
Authors: Kojima Kazuo 
Published: July 2006

Abstract
The visible absorption spectra of CoX2 (X=Cl, Br) in solutions of both 4-methylpyridine (4-Me-py) and 2-methylpyridine (2-Me-py) have been measured in the pressure range of 1 bar −3 kbar at room temperature, and in the temperature range of ≈6–≈75 °C at 1 bar. In the 4-Me-py solution system, the configuration equilibrium, [CoX2(4-Me-py)2] (tetrahedral) +2(4-Me-py)\ightleftarrows[CoX2(4-Me-py)4] (octahedral), was found to exist over the experimental pressure range. Increasing the pressure shifted the equilibrium toward the octahedral species side with volume changes of −26 cm3mol−1 for the chloro complex and −25 cm3mol−1 for the bromo complex at 1 bar. The above equilibrium held fairly well over the whole experimental temperature range for the chloro complex, but in the restricted temperature range for the bromo complex. Increasing the temperature tended to increase the formation of the tetrahedral species, the heats of reaction, being 53.3 kJ mol−1 and 62.6 kJ mol−1 for the chloro and bromo complexes, respectively. On the other hand, in the 2-Me-py solution system, increasing the pressure or temperature could hardly confirm the existence of the octahedral-tetrahedral configuration equilibrium. A charge-transfer band between the solvent molecule 2-Me-py and the free ion X− decreased in intensity with increasing temperature. The above results in the 4-Me-py and 2-Me-py systems were compared with those of the pyridine (py) and 3-methylpyridine (3-Me-py) systems mentioned in the literature.
Structure of Mixed Ligand Complex [Cu(pan)(phen)]BF4 with Special Reference to the Acceleration of the Ligand Substitution Reaction
Authors: Wada Hiroko , Shiro Motoo , Yuchi Akio , Nakagawa Genkichi 
Published: July 2006

Abstract
The crystal structures of [1-(2-pyridylazo)-2-naphtholato]copper(II) complexes, [Cu(pan)(phen)]BF4 as well as [Cu(pan)(H2O)]ClO4 and [Cu2(pan)2(H2O)3](BF4)2 have been determined. In these complexes pan− anion coordinates with copper(II) as a tridentate ligand and all complexes have square pyramidal geometry. In the mixed ligand complex [(Cu(pan)(phen)]BF4, 1,10-phenanthroline occupies the forth position in the basal plane and the apical site, thus the structure is fairly distorted. This distorted structure is responsible for the fast substitution of [Cu(pan)(phen)]+ complex with edta4−.
Synthesis, Properties, and Crystal Structure of Binuclear Nickel(II) and Palladium(II) Complexes of Tridentate Thiolic Ligands with NNS-Donor Set
Authors: Handa Makoto , Mikuriya Masahiro , Zhong Zhuang Jin , Okawa Hisashi , Kida Sigeo 
Published: July 2006

Abstract
Nickel(II) and palladium(II) complexes with tridentate thiolic ligands of the NNS-donor set have been prepared and characterized on the basis of elemental analyses, IR and electronic spectra, molar conductances, and magnetic susceptibilities. The crystal structure of the nickel(II) perchlorate of 3-[2-(2-pyridyl)ethylamino]-1-propanethiol was determined by single-crystal X-ray diffraction method. The structure consists of thiolatebridged binuclear units. Each metal ion is coordinated by the amino nitrogen, pyridine nitrogen, and two bridging sulfur atoms, forming an essentially planar coordination unit, and the two N2S2 planes are connected at the S1–S2 edge with a dihedral angle of 136.1°.
Calorimetric and Raman Spectroscopic Studies of Cadmium(II) Thiocyanato Complexes in N,N-Dimethylformamide
Authors: Ishiguro Shin-ichi , Takamuku Toshiyuki , Ohtaki Hitoshi 
Published: July 2006

Abstract
Formation of thiocyanato complexes of cadmium(II) ion has been calorimetrically studied in N,N-dimethylformamide (DMF) at 25 °C. Calorimetric data obtained were well explained in terms of the formation of a series of four mononuclear [CdXn](2−n)+ (n=1–4, X=SCN) complexes, and their formation constants, enthalpies, and entropies were determined. Raman band shifts for the C–S stretching vibration of SCN− ion indicated that SCN− ion binds to cadmium(II) ion only with the N end within the mono- or dithiocyanato complex, [Cd(NCS)]+ or [Cd(NCS)2]. Within the tri- and tetrathiocyanato complexes, thiocyanate ions binds with both the N and S ends, and the coordination modes, [Cd(NCS)2(SCN)]− and [Cd(NCS)3(SCN)]2−, were suggested. The coordination modes for the di- and tetrathiocyanato complexes in DMF, [Cd(NCS)2] and [Cd(NCS)3(SCN)]2−, are different from those in water, [Cd(NCS)(SCN)] and [Cd(NCS)2(SCN)2]2−. It is thus shown that the N-bonding becomes more favorable in DMF than in water. Such a result may mainly be ascribed to relatively weakened solvation of the SCN− ion in DMF, especially at the N atom site which is hydrogen-bonded with water molecules but not with DMF.
Rotational Isomerism in Fluorene Derivatives. XIII. Conformational Equilibria of 9-(2-Methylaminophenyl)fluorene and the Effect of Acid on It
Authors: Nishida Akiko , Takeshita Makoto , Fujisaki Shizuo , Kajigaeshi Shoji 
Published: July 2006

Abstract
The compound 9-(2-methylaminophenyl)fluorene (2) was obtained by treatment of 9-(2-dimethylaminophenyl)-9-fluorenol (1b) with dry hydrogen bromide in acetic acid. The conformational equilibrium (ap\ightleftarrowssp) of 2 was investigated on the basis of dynamic 1H NMR spectra in CDCl3. The stabilization of the ap-iorm could be ascribed to an N–H···π interaction between the methylamino group and the fluorene ring. The effect of trifluoroacetic acid on the equilibrium of 2 is also discussed.
Reduction of Sulfur Dioxide and Carbon Dioxide with Benzoin Carbanion. Oxygen Transfer from Products Formed by the Reduction of Sulfur Dioxide to 7,7,8,8-Tetracyanoquinodimethane
Authors: Akiyama Fuminori 
Published: July 2006

Abstract
A reaction of sulfur dioxide (SO2) with benzoin carbanion (the lithium salt of benzoin dianion, 1) in tetrahydrofuran (THF) gave a mixture of benzil (2) and benzoin (3) in yields of 83 and 17%, respectively, irrespective of the reaction temperature between −78 and 25 °C. The reaction of carbon dioxide (CO2) with 1 in THF gave a mixture of 2 and 3 accompanied by the formation of a small amount of lithium benzoate (4). The proportion of 2 in a mixture of 2 and 3 formed in the reaction of CO2 with 1 were 49, 30, and 20% at −78, −22, and 25 °C, respectively. The reaction of SO2 with 1 in the presence of 7,7,8,8-tetracyanoquinodimethane (TCNQ) gave oligomers of TCNQ with a yield of 60%, in which some parts of the cyano groups were transformed to carboxylato groups.
Facile Formations of o- and p-Tropoquinone Mono- and Bisacetals by Anodic Oxidations of 2,3-, 2,5-, 2,7-, and 4,5-Dimethoxytropones
Authors: Mori Akira , Kubota Tadahiko , Takeshita Hitoshi 
Published: July 2006

Abstract
o- and p-Tropoquinone mono- and bisacetals (tetramethoxycycloheptadienones) were prepared from 2,3-, 2,5-, 2,7-, and 4,5-dimethoxytropones by means of anodic oxidations in practical yields. Cerium(IV) salt oxidations of dimethoxytropones afforded a mixture of products i.e., a hydrolysis product and/or a methanol adduct of tropoquinone bisacetals. By treating with sulfuric acid in a mixture of acetic acid and acetic anhydride, 4,4,7,7- and 2,2,7,7-tetramethoxycycloheptadienones gave the Thiele-type reaction products with a high positional selectivity. Similarly, 2-bromo-7-methoxytropone was anodically oxidized to 4,4,7,7-tetramethoxycycloheptadienone and its 2-bromo derivative. The mechanism of the reaction is also discussed in detail.
Footprint Catalysis. I. A New Method for Designing “Tailor-Made” Catalysts with Substrate Specificity: Silica (Alumina) Catalysts for Butanolysis of Benzoic Anhydride
Authors: Morihara Kensaku , Kurihara Sachiyo , Suzuki Junko 
Published: July 2006

Abstract
The design of tailor-made specific catalysts for a given organic reaction was investigated. Dibenzamide or N-benzoylbenzenesulfonamide, transition state analogs of benzoic anhydride on transacylation, was found to act as a template upon aluminium ion-doped silica gel and to imprint specific adsorption sites, “footprints,” on the surface. The footprints were particular Lewis acid sites with a complementary structure to the template. They demonstrated an enzyme-like specific catalytic function on the butanolysis of benzoic anhydride through their specific affinities for substrate molecules in the transition state.
The Photochemistry of Steroidal 6-Membered Cyclic α-Nitro Ketones
Authors: Suginome Hiroshi , Kurokawa Yoshitaka , Orito Kazuhiko 
Published: July 2006

Abstract
The results of the photolysis of five steroidal 6-membered cyclic α-nitro ketones in ethanol are described. Irradiation with a Pyrex-filtered light of 2-nitro-5α-cholestan-3-one in ethanol, which exists exclusively in the enol form in the solvent, resulted in a new photorearrangement and gave 5α-cholestane-2,3-dione 3-oxime with the accompanying formation of the corresponding α-diketone. We propose a path involving a nitro–nitrite rearrangement for this anomalous formation of 5α-cholestane-2,3-dione 3-oxime. However, similar irradiation of 4,4-dimethyl-2-nitro-5α-choloestan-3-one, which exists exclusively as the enol form in ethanol, and 3-nitro-5α-cholestan-2-one, which is in an 1 : 1 equilibrium mixture of keto and enol forms in ethanol, gave the corresponding α-hydroxyimino ketone and α-diketone respectively. Irradiation of 4β-nitro-5β-cholestan-3-one and 6α-nitro-5α-cholestan-7-one, both of which exist as the keto form in ethanol, gave similarly the corresponding α-hydroxyimino ketone respectively, but without the accompanying formation of α-diketone. The α-hydroxyimino ketones from the above four 6-membered cyclic α-nitro ketones arise through the hydrogen abstraction by the n,π* excited nitro group of the keto forms of the α-nitro ketones followed by the elimination of the element of water, while α-diketones are formed via the nitro–nitrite rearrangement of the excited nitro group of the enol forms.
1H NMR Study of Intramolecular Hydrogen-Bonding Interaction in Cyclodextrins and Their Di-O-methylated Derivatives
Authors: Onda Mitsuhiko , Yamamoto Yasuhiko , Inoue Yoshio , Chûjô Riichirô 
Published: July 2006

Abstract
Intramolecular hydrogen bonding of α-, β-, and γ-cyclodextrins, and α- and β-dimethyl cyclodextrins has been investigated in dimethyl sulfoxide-d6 by 1H NMR spectroscopy. The temperature dependence of 1H chemical shifts of secondary hydroxyl protons of cyclodextrins and dimethyl cyclodextrins reveals the existence of the intramolecular hydrogen bond. The strength of hydrogen bond becomes stronger as the ring size becomes smaller and by methylation. The intramolecular hydrogen bond in which the OH(3) is proton donor is preferred in α-cyclodextrin as well as in α- and β-dimethyl cyclodextrins. The orientation of secondary hydroxyl groups was estimated with the Karplus-type equation and the orientation is found to be suitable for making intramolecular hydrogen bond.
A Highly Chemoselective Reduction of Conjugated Nitro Olefins with Hantzsch Ester in the Presence of Silica Gel
Authors: Fujii Masayuki 
Published: July 2006

Abstract
An effective system to reduce conjugated nitro olefins into the corresponding nitroalkanes is described. The system composed of Hantzsch ester (HEH) and silica gel in benzene exerts high yield and excellent chemoselectivity under almost neutral conditions. Facile applications of the system to the syntheses of natural products are also described.
Multinuclear NMR and the Rotational Barriers about the C–N Bonds of Several, N,N-Disubstituted Arenecarboxamides
Authors: Suezawa Hiroko , Tsuchiya Kin-ya , Tahara Eiji , Hirota Minoru 
Published: July 2006

Abstract
The 15N, 17O, and 13C NMR spectra of substituted N,N-dimethyl- and N,N-dibenzylbenzamides and N,N-dimethylnaphthamides were measured and correlated with the height of their rotational barriers. The 15N and 17O chemical shifts of the amides were shown to be controlled predominantly by the extent of the contribution of the polar mesomeric structure (II) and, especially in the case of 15N, could be used to estimate the rotational barrier.
Solvation and Ionic Association of Bis(β-diketonato)(diamine)cobalt(III) Perchlorates in Alcohols and Ketones
Authors: Ito Kazuaki , Isono Hiroyuki , Iwamoto Etsuro , Yamamoto Yuroku 
Published: July 2006

Abstract
The conductances of bis(2,4-pentanedionato)(diamine)cobalt(III) perchlorates, [Co(acac)2(diamine)]ClO4 (where acac:2,4-pentanedionato; diamine:en (ethylenediamine) and N,N,N′,N′-tmen (N,N,N′,N′-tetramethylethylenediamine)) in methanol (MeOH), ethanol (EtOH), 2-propanol (i-PrOH), methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) and of bis(β-diketonato)(ethylenediamine)cobalt(III) perchlorates, [Co(β-dik)2(en)]ClO4 (where β-dik: acacBr (3-bromo-2,4-pentanedionato) and acacNO2 (3-nitro-2,4-pentanedionato)) in EtOH, acetone (Me2CO), and MEK were measured at 25 °C. [Co(acac)2(en)]ClO4 in the alcohols was found to be more dissociated than [Co(acac)2(N,N,N′,N′-tmen)]ClO4. This behavior was explained as being due to the strong solvation of [Co(acac)2(en)]+ by the alcohols. [Co(acac)2(N,N,N′,N′-tmen)]+ seems to be solvated in ketones rather than alcohols. The sequence of the ionic association constant for [Co(β-dik)2(en)]ClO4, acac&lt;acacBr&lt;acacNO2, could be interpreted in terms of an enhanced polarity of the cations with the electron-withdrawing groups.
Extraction–Spectrophotometric Determination of Pd(II) with 4-(3,5-Dichloro-2-pyridylazo)-1,3-diaminobenzene and Trichloroacetate. I
Authors: Fontán C A , Marone C B , Olsina R 
Published: July 2006

Abstract
In acid acqueous ethanol solutions Pd(II) reacts with 4-(3,5-dichloro-2-pyridylazo)-1,3-diaminobenzene (3,5-C12PADAB=L) making up three colored complex species. The three complexes have a 1 : 1 metal–ligand molar ratio and they differ from each other only in their protonation degree. In solutions with H2SO4 or HClO4 concentrations higher than 10 or 8 M, respectively, the complex species is yellow, and in less acid solutions (pH 0.80 to 2 M H2SO4 or pH 0.8 to 3 M HClO4 range) it changes in a reversible way to a violet color while its intensity increases (molar absorptivity 8.2×104 dm3 mol−1 cm−1 at 588 nm and 5.2×104 dm3 mol−1 cm−1 at 545 nm). The red purple complex formed in the pH range 3–4 are insoluble in 10% (v/v) ethanol–water solutions. The complex species were given the formulation PdHnL(n+2)+ (n&gt;1)(H2SO4&gt;10 M, or HClO4&gt;8 M), PdHL3+ (pH 0.8 to 2 M H2SO4 or pH 0.8 to 3 M HClO4 range) and PdL2+ (pH 3–4), and the existence of one or another depends exclusively upon the acidity of the reaction medium. In 10% (v/v) ethanol–water solutions acidified with H2SO4 or HClO4, only the last two species are extracted into benzene as PdL2+·(TCA−)2 and PdHL3+(TCA−)3 (TCA−=trichloroacetate) ion-associations. The composition of the complexes formed in aqueous solutions was estimated by the composition of the ion-association complexes transferred to the organic phase.