bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Adsorption and Desorption of Nitrogen Oxide by the Aqueous Dispersion of the Chelate Resin-Immobilized Iron(II) Complex
Authors: Toshima Naoki , Asanuma Hiroyuki , Yamaguchi Kazuaki , Hirai Hidefumi 
Published: July 2006

Abstract
Aqueous dispersions of the chelate resin–iron(II) complex were prepared by ion-exchange in water from iron(II) sulfate and a chelate resin containing iminodiacetic acid moieties. The resulting dispersions in water (50 cm3) can adsorb 78% of the nitrogen oxide (NO) from 6 dm3 of nitrogen gas containing 1000 ppm of nitrogen oxide at 25 °C. The adsorption rate of NO by the dispersions depends greatly on both the particle size of the chelate resin used and the concentration of iron(II) in the supernatant. A fast adsorption of nitrogen oxide can be achieved by using small particles of the chelate resin and by dissolving a large amount of iron(II) ions in the aqueous part of the dispersions. The adsorption and desorption of nitrogen oxide can be understood in terms of a 1:1 reversible coordination of NO to the iron(II) ion immobilized on the chelate resin. The equilibrium constant, enthalpy change, and entropy change for the above adsorbing reaction were 3.11×104 dm3 mol−1, −45.6 kJ mol−1, and −68.2 J K−1 mol−1 respectively. Since the adsorbing reaction of NO in this system is reversible, the adsorbed NO can be released by heating the dispersions which have already adsorbed NO. The amount of the released NO can be predicted from the equilibrium constant at the releasing temperature. Moreover, a concentrated recovery of the NO can be achieved by the present aqueous dispersions system.
Synthesis of Both the Enantiomers of Phoracantholide I, A Defensive Secretion of the Eucarypt Longicorn (Phoracantha synonyma), Employing Microbial Asymmetric Reduction with Immobilized Baker’s Yeast
Authors: Naoshima Yoshinobu , Hasegawa Hidenobu , Nishiyama Tadashi , Nakamura Akihiro 
Published: July 2006

Abstract
Highly optically pure (R)- and (S)-phoracantholide I were synthesized in relatively short steps starting from diethyl 3-oxoglutarate by means of a microbial asymmetric reduction of the intermediate keto acid with immobilized baker’s yeast entrapped in gels of κ-carrageenan.
Mössbauer Spectroscopic Study of Superconducting Y–Ba–Cu(Fe)–O Ceramics and Gamma-Ray Irradiation Effect
Authors: Nishida Tetsuaki , Ide Hiroshi , Maeda Yonezo , Nasu Hiroyuki , Yagi Toshirou , Sakai Akira , Takashima Yoshimasa 
Published: July 2006

Abstract
Mössbauer spectra of YBa2(Cu1−xFex)3O7−δ ceramics (x=0.003, 0.008, and 0.017) measured at room temperature show a superposition of three quadrupole doublets. An outermost doublet (δ=0–0.04 mm s−1, Δ=1.94–1.98 mm s−1) is ascribed to high-spin Fe4+ ions present at substitutional sites of Cu2+ ions (Cu(2) site). An intermediate doublet (δ=−0.03–0.02 mm s−1, Δ=1.12–1.17 mm s−1) is ascribed to intermediate-spin Fe3+ ions present at substitutional sites of Cu3+ ions (Cu(1) site). An innermost doublet is ascribed to Fe3+ ions (high spin) with tetrahedral symmetry, present along the b-axis. A decrease in Tc from 72 to 60 K, observed when iron content (x) is increased from 0.008 to 0.017, is explained by a lowered layer structure composed of “dimpled” CuCO4 planes, owing to a displacement of O(4) oxygen atoms sharing CuO5 tetragonal pyramids and CuO4 square planars. One-dimensional chains composed of CuO4 square planars proved to be primarily affected by γ-ray irradiation, whereas no change of Tc was observed. Low-temperature Mössbauer measurements revealed that “partial Debye temperatures” are 330 and 740 K for the chains and layer structure, respectively.
Synthetic Photochemistry. XLVII. Formation and Degenerate Cope Rearrangement of 9-Dicyanomethylenebarbaralane
Authors: Tian Guan Rong , Sugiyama Shigeru , Mori Akira , Takeshita Hitoshi 
Published: July 2006

Abstract
Photolysis of 2-dicyanomethylenehomobarrelene gave 9-dicyanomethylenebarbaralane, 5-dicyanomethylenetricyclo[4.3.0.02,9]nonadiene, and 1-dicyanomethyleneindan. Dicyanomethylenebarbaralane showed time-averaged NMR signals.
A Mild, High-Yield Conversion of Thiols into Disulfides Using Disulfide Dication Salt: A New Redox System
Authors: Fujihara Hisashi , Akaishi Ryouichi , Furukawa Naomichi 
Published: July 2006

Abstract
A new redox reaction of thiols with disulfide dication salt, 1,5-dithioniabicyclo[3.3.0]octane bis(trifluoromethanesulfonate), under mild conditions gave the corresponding disulfides in good yields together with 1,5-dithiacyclooctane.
Ab Initio Calculation for the Interaction Energy of He–He+
Authors: Ichihara Akira , Itoh Reikichi 
Published: July 2006

Abstract
Using an ab initio calculation with a configuration interaction (CI) treatment, the interaction energy of a He–He+ system in the ground (X2Σu+) electronic state was calculated. For X2Σu+He2+ calculations, the Gaussian-type [6s3pld] basis set of Khan and Jordan was employed, and the effect of the basis set superposition error was estimated.
γ-Radiolysis of 1-Substituted 5-Fluorouracil Derivatives
Authors: Kuroda Tokuyuki , Hisamura Koji , Matsukuma Ikuo , Nishikawa Hiroshi , Nakamizo Nobuhiro 
Published: July 2006

Abstract
A new concept, “Radiation-Induced Drug (RID)”, was proposed as a novel type of drugs for cancer therapy. To test the usefulness of this concept, 5-fluorouracil (5-FU) derivatives having various types of substituents at the 1-position were prepared and the γ-radiolyses of their aqueous solutions were studied. The compounds having sulfonyl and thioureido groups as the substituents produced efficiently 5-FU with high G values upon γ-irradiation. The medium effects on the radiolyses revealed that the above two substituents were removed mainly with HO· and hydrated electrons eeq−.
Facile Synthesis of (2S,3R,4R)-2-Hydroxymethyl-3,4-pyrrolidinediol and 4-Acetamido-1,2,3-tri-O-acetyl-4-deoxy-l-xylopyranose from the Photoproduct of d-Mannose
Authors: Hosaka Akira , Ichikawa Shuji , Shindo Hiroko , Sato Tadashi 
Published: July 2006

Abstract
(Synthesis of 2S,3R,4R)-2-hydroxymethyl-3,4-pyrrolidinediol and 4-acetamido-1,2,3-tri-O-acetyl-4-deoxy-l-xylopyranose were attained in four steps from d-mannose, using iron(III)-catalyzed photoreaction as a key reaction.
Stereoselective Synthesis of [1]Benzopyrano[4,3-b]pyrrol-4(3H)-ones through Cycloadditions of Azomethine Ylides with α,β-Unsaturated Esters
Authors: Ueno Kazunori , Kanemasa Shuji , Tsuge Otohiko 
Published: July 2006

Abstract
Cycloadditions of azomethine ylides generated from α-benzylideneamino nitriles bearing a hydroxyl or its O-protected moiety with α,β-unsaturated esters such as dimethyl maleate, fumarate, methyl acrylate, crotonate, methacrylate, and cinnamate lead stereoselectively to 3,3a-trans-3a,9b-cis-3a,9b-dihydro[1]benzopyrano[4,3-b]pyrrole-4(3H)-ones after subsequent lactonization.
Allylation of Quinones via Photoinduced Electron-Transfer Reactions from Allylstannanes
Authors: Maruyama Kazuhiro , Imahori Hiroshi 
Published: July 2006

Abstract
Photochemical reactions of quinones with allylstannanes provided four types of products: adducts of allyl group to the carbonyl oxygens of quinones, adducts of allyl group to the olefinic carbons, adducts of allyl group to the carbonyl carbons, and hydroquinones. An electron-transfer mechanism was confirmed by 1H-CIDNP (Chemically Induced Dynamic Nuclear Polarization) method. This study suggests that a) photoinduced electron transfer from allylstannanes to quinones produces the corresponding quinone anion radicals and tin cation radicals, b) the tin cation radicals cleave to give allyl radicals as well as tin cation, and c) the allyl radicals attack the quinone anion radicals resulting in the formation of final products, allylated quinones.
Synthesis and Enantiomer Recognition of Dipodands and Crown Ethers Containing the 2,3:6,7-Dibenzobicyclo[3.3.1]nona-2,6-diene Residue as the Chiral Subunit
Authors: Naemura Koichiro , Fukunaga Rink\={o} , Komatsu Masanori , Yamanaka Masatoshi , Chikamatsu Hiroaki 
Published: July 2006

Abstract
Five new optically active crown ethers and six optically active dipodands are reported. The crown ethers were synthesized by using (+)-(1S,4R,5S,8R)-2,3:6,7-dibenzobicyclo[3.3.1]nona-2,6-diene-4,8-diol and (+)-(1S,4R,5S,8R)-4,8-bis(hydroxymethyl)-2,3:6,7-dibenzobicyclo[3.3.1]nona-2,6-diene as a chiral subunit and the dipodands contained the 2,3:6,7-dibenzobicyclo[3.3.1]nona-2,6-diene residue as a chiral anchor group. The enantiomer recognition behaviour of these compounds was evaluated by the enantiomer differential transport of methyl (±)-phenylglycinate and (±)-1,2-diphenylethylamine hydrochloride through bulk liquid membrane.
Synthesis and Reductive Desulfurization of Crown Ethers Containing Thiophene Subunit
Authors: Sone Tyo , Sato Kazuaki , Ohba Yoshihiro 
Published: July 2006

Abstract
Crown ethers containing 3,4-thiophenediyl and 3,4-thiophenediylbis(methylene) subunits as a ring constituent were prepared starting from 2,5-bis(ethoxycarbonyl)-3,4-thiophenediol and 2,5-dichloro-3,4-bis(chloromethyl)thiophene, respectively. A Raney nickel desulfurization of the thiophene-containing crown ethers afforded crown ethers having two adjacent side chains, such as a methyl or ethoxycarbonylmethyl group. The extraction ability of these crown ethers towards alkali metal cations was also examined by the solvent extraction method.
Cycloaddition vs. Michael Addition in the Metal Halide/Amine-Induced Reactions of α-(Alkylideneamino) Esters with Electron-Deficient Olefins
Authors: Kanemasa Shuji , Yoshioka Manabu , Tsuge Otohiko 
Published: July 2006

Abstract
The lithiated intermediate derived from methyl 2-(benzylideneamino)propanoate and lithium bromide/triethylamine undergoes cycloaddition and Michael addition with methyl acrylate. 1,3-Dipole character of the intermediate is suggested on the basis of the product ratios obtained under a variety of conditions. The reaction mechanism via a four-centered transition state is proposed.
Isolation of Four 2,3,5,6,11,11b-Hexahydro-3-oxo-1H-indolizino[8,7-b]indole-5-carboxylic Acids from Clerodendron Trichotomum Thunb and Properties of Their Derivatives
Authors: Irikawa Hajime , Toyoda Yasuhiro , Kumagai Hiroaki , Okumura Yasuaki 
Published: July 2006

Abstract
Four 2,3,5,6,11,11b-hexahydro-3-oxo-1H-indolizino[8,7-b]indole-5-carboxylic acids, plausible precursors of trichotomine, were isolated as the methyl esters from Clerodendron trichotomum Thunb, and the structures elucidated on the basis of their spectral and chemical evidences. The existence of two pairs of the C-11b epimers in the above plant were supported by the methoxide-catalyzed equilibrations of the compounds having the substituent on C-11b. Blue pigments were formed from the isolated compounds.
Synthesis of Heterobinudear Cu(II)Ni(II) Complexes with Bis(tetraazamacrocycle)
Authors: Mochizuki Katsura , Endoh Yumiko 
Published: July 2006

Abstract
A new series of heterobinudear Cu(II)Ni(II) complexes with bis(tetraazamacrocycle), i.e., 7,7′-polymethylenebis[2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentaene]copper(II)nickel(II) perchlorates with polymethylene bridges with a length of 2–6-C, were synthesized by a template reaction.
Hydrolysis of Spiro Derivatives that Undergo No Shrinkage on Polymerization
Authors: Tagoshi Hirotaka , Endo Takeshi 
Published: July 2006

Abstract
Acid-catalyzed hydrolyses of spiroorthoeters (1, 2a, 2b, and 2c) and spiroorthocarbonates (3 and 4) were carried out to give the corresponding ring-opening reaction products. The ring-cleavage modes of these spiro derivatives depended on the structure of intermediate cations.
Sommelet–Hauser Rearrangement of Oxygen and Sulfur Containing Heteroaromatic Sulfonium Ylides
Authors: Yamamoto Makoto , Kakinuma Madoka , Kohmoto Shigeo , Yamada Kazutoshi 
Published: July 2006

Abstract
A Sommelet–Hauser rearrangement of sulfonium ylides of 4H-pyran-4-ones, furan, and thiophenes are discussed. The sulfonium halides which were prepared from excess dimethyl sulfide with corresponding halides were treated with NaH or NaOR in a polar solvent to give moderate to good yields of rearranged products.
Active Sites of a Reduced Molybdena–Alumina Catalyst. A Transient Study of Hydrodenitrogenation of Carbazole and Acridine
Authors: Nagai Masatoshi , Masunaga Takashi 
Published: July 2006

Abstract
A response study of the hydrodenitrogenation of acridine and carbazole on a reduced MoO3/Al2O3 catalyst was performed at 300 °C and 10.1 MPa total pressure. Acridine was strongly adsorbed on the acidic sites of the catalyst surface for hydrogenation, while carbazole was weakly adsorbed not only on the same sites as acridine, but also on the terminal oxygen anion sites in the presence of strong bases.
A Theoretical Study of the Ionized State of Polymers with the Localized Molecular Orbital Method
Authors: Imamura Akira , Ye Kehong , Taketoshi Masahiro 
Published: July 2006

Abstract
A localized molecular orbital method for the investigation of the ionized state of polymers is presented. It is based on the Crystal Orbital Method(CO). By performing a super-cell method and Edmiston and Ruedenberg’s LMO method, the Bloch function was transformed into a nearly completely localized Wannier function. Furthermore, the calculation of the configuration interaction was introduced to obtain more reasonable results. The present method was applied to polyacetylene (PA), polyethylene (PE), and polypropylene (PP). Ionization potentials of these polymers were calculated and compared with experimental and other theoretical results. All the calculations were performed using the CNDO/S approximation.
The Formation of Monodispersed Indium(III) Hydroxide Particles by Forced Hydrolysis at Elevated Temperature
Authors: Hamada Shuichi , Kudo Yoshiyuki , Minagawa Kazuhiro 
Published: July 2006

Abstract
Rather poorly crystallized spherical particles of indium(III) hydroxide were produced by forced hydrolysis at 100°C for 120 min under the conditions of 6.0×10−4 mol dm−3 for indium(III) ions, 1.0×10−3 mol dm−3 for nitric acid, and 1.25 for a concentration ratio, [SO42−]t/[In3+]t, respectively, having an average size of 0.48 μm with a relative standard deviation of 0.09. On the other hand, cubic particles of well-crystallized indium(III) hydroxide were yielded in a nitrate solution that was free from sulfate ions and at the same concentrations. The cubic particles grew through a polynuclear layers mechanism. Monomeric hydroxo complexes basically acted as precursors of the spherical particles, together partly with polymeric ones. The point of zero charge was estimated as being at the same pH (7.7) for both the hydroxide and oxide particles prepared from the nitrate system, in contrast to those of 7.0 and 5.4 for the respective particles obtained from the sulfate system.
Chiral Tolans: A New Family of Ferroelectric Liquid Crystals. Synthesis and Mesomorphic Properties
Authors: Seto Koji , Shimojitosho Hiroshi , Imazaki Hideyuki , Matsubara Hiroshi , Takahashi Shigetoshi 
Published: July 2006

Abstract
Diphenylacetylene homologues having a chiral alkyl group, synthesized by a palladium-catalyzed coupling reaction, provide a new series of liquid crystalline materials which form chiral smectic C (SmC*) phases exhibiting ferroelectric properties. Mesomorphic properties of the compounds composed of three aromatic rings is strongly affected by the position of an acetylenic linkage and the direction of an ester linking unit. The effect of variations in terminal chain length on the thermal stabilities of the smectic A (SmA) and SmC* the two and three aromatic ring systems has been systematically studied.
Structural Determination of Ancovenin, a Peptide Inhibitor of Angiotensin I Converting Enzyme
Authors: Wakamiya Tateaki , Ueki Yasuyuki , Shiba Tetsuo , Kido Yasuji , Motoki Yoshinobu 
Published: July 2006

Abstract
The structure of ancovenin, a new peptide inhibitor of angiotensin I converting enzyme was determined chemically. Ancovenin is composed of 16 amino acid residues including three lanthionine residues which form a complex tricyclic structure bridged by sulfide bonds. Moreover, this peptide includes dehydroalanine as one of its unusual amino acids. In the present study, plausible mechanisms of the Edman degradation of dehydroalanine and lanthionine-containing peptides were also elucidated.
Photochemical and Photophysical Behavior of p-Methoxyphenyl alkenyl Phenanthrenecarboxylates. I. Structure and Competitive Formation of Intramolecular Cycloaddition Products
Authors: Sakuragi Hirochika , Tokumaru Katsumi , Itoh Hiroki , Terakawa Kohki , Kikuchi Katsuo , Caldwell R A , Hsu Chien-Chung 
Published: July 2006

Abstract
Irradiation of (E)-3-(p-methoxyphenyl)-3-pentenyl, (E)-4-(p-methoxyphenyl)-4-hexenyl, and (E)-5-(p-methoxyphenyl)-5-heptenyl 9-phenanthrenecarboxylates (B-2E, B-3E, and B-4E, respectively) in benzene gave intramolecular [2+2] cycloadducts, cyclobutane derivatives (CB-2, CB-3, and CB-4, respectively) possessing the same conformation as an intermolecular [2+2] cycloadduct (CB-0) between methyl 9-phenanthrenecarboxylate (9-MCP) and trans-anethole (t-AN), and oxetane derivatives (OX-2, OX-3, and OX-4, respectively) arising from intramolecular cycloaddition between the carbonyl group and the olefinic double bond. However, (E)-4-(p-methoxyphenyl)-3-butenyl and (E)-5-(p-methoxyphenyl)-4-pentenyl 9-phenanthrenecarboxylates (A-2E and A-3E, respectively) afforded only products derived from oxetane precursors.
Preparation of Optically Pure (3S,5S)- and (3R,5R)-2,6-Dimethyl-3,5-heptanediol
Authors: Sugimura Takashi , Yoshikawa Masato , Yoneda Tohru , Tai Akira 
Published: July 2006

Abstract
Optically pure 2,6-dimethyl-3,5-heptanediol (1), a new chiral auxiliary, has been prepared by the enantiodifferentiating hydrogenation of 2,6-dimethyl-3,5-heptanedione over tartaric acid–NaBr–modified Raney nickel catalyst (TA–NaBr–MRNi), and the preferential recrystallization of the hydrogenation product. Absolute configuration of 1 was determined to be 3S, 5S by the chemical correlation with (−)-ethyl (S)-3-hydroxy-4-methylpentanoate.
Fluorescence Probes of Pyrene and Pyrene-3-carboxaldehyde for the Sol–Gel Process
Authors: Matsui Kazunori , Nakazawa Takumi 
Published: July 2006

Abstract
Silica sols and gels doped with pyrene (Py) and pyrene-3-carboxaldehyde (PyCHO) were prepared by the acidic hydrolysis of tetraethyl orthosilicate in ethanol. We studied the fluorescence of these molecules during the sol–gel–xerogel stages. The fluorescence intensity ratio of the vibronic bands of Py changed remarkably, while the fluorescence maximum of PyCHO showed a significant red shift as the gel dried. Such a spectral change was ascribed to an increase in the environmental polarity of the probe molecules upon the evaporation of the ethanol. The estimated dielectric constant of the gel after drying in a vacuum is about 72, just slightly less polar than water (80). The silica cage produced by the sol–gel process is probably rich in silanols, resulting in a relatively polar environment.
Promoter Effect of Alkali Metal Oxides and Alkali Earth Metal Oxides on Active Carbon-Supported Ruthenium Catalyst for Ammonia Synthesis
Authors: Aika Ken-ichi , Kawahara Toshikazu , Murata Shuzo , Onishi Takaharu 
Published: July 2006

Abstract
Promoter effects of alkali metal nitrates and alkali earth metal nitrates on Ru/A.C. (active carbon) were studied in order to prepare an effective catalyst for ammonia synthesis. Of alkali metal nitrates, RbNO3 was more effective than CsNO3 and KNO3. Alkali earth metal (Mg, Ca, Sr, Ba) nitrates were also found to be effective promoters on Ru/A.C. catalysts. Of them heavier alkali earth metal elements were more effective (Ba&gt;Sr&gt;Ca&gt;Mg). Ba(NO3)2 was as effective as CSNO3, which was not expected from the stand point of electronegativity. The transformation of promoter precursors to active compounds (nitrates to oxides or hydroxides) and the interaction of promoters and ruthenium were discussed. Precursor of ruthenium salt was also studied. RuCl3·3H2O and [Ru(NH3)6]Cl3 gave higher activities than Ru3(CO)12. It was discussed that RuCl3 gave finer Ru particles than Ru3(CO)12 on active carbon. The turn over frequency (TOF) of Ru–Rb+/A.C. was lower than those of RU–Cs+/Al2O3 and of Ru–Cs+/MgO.
The Hydrolytic Property of Imidodiphosphate in Solid and in an Aqueous Medium
Authors: Watanabe Makoto , Sato Shoji , Wakasugi Khosaku 
Published: July 2006

Abstract
Crystalline tetrasodium imidodiphosphate decahydrate, Na4P2O6NH·10H2O, was directly converted to diphosphate by heating above 200°C in air according to the equation:
Na_2O_3PNHPO_3Na_2+H_2O→Na_2O_3POPO_3Na_2+H_3
Amorphous tetrasodium imidodiphosphate was prepared by stirring the crystalline imidodiphosphate in excess ethanol. The substitution of an imino group of the amorphous imidodiphosphate for bridging oxygen took place much faster than that of the crystalline one. Imidodiphosphate was hydrolyzed to phosphoramidate and orthophosphate in an aqueous solution:
Na_2O_3PNHPO_3Na_2+H_2O→Na_2PO_3NH_2+Na_2HPO_4
X-Ray Structure Determination of Stereoisomers with Respect to Cyclobutene Ring of 10,10-Ethylenedioxy-1-methoxycarbonyl-2-methyl-7-oxatricyclo[6.4.0.02,5]dodec-3-en-6-one
Authors: Matsui Takanao , Hashimoto Takashi , Tada Toshiji , Nozaki Hiroshi , Nakayama Mitsuru 
Published: July 2006

Abstract
The structures of the title compounds were determined by X-ray crystallographic analysis. The results lead to a revision of the previously proposed structure for photochemical cycloadduct of 9,9-ethylenedioxy-6-methoxycarbonyl-5-methyl-2-oxabicyclo[4.4.0]dec-4-en-3-one with acetylene.
Formation Mechanism of the Complexes between DMSO and Halogen Atoms. I. Pulse Radiolysis Studies
Authors: Sumiyoshi Takashi , Katayama Meiseki 
Published: July 2006

Abstract
The formation mechanism of DMSO–halogen atom complexes in the solution of DMSO and halocarbons has been investigated by pulse radiolysis method. Three formation processes have been found depending on the the solution component. In the case of DMSO/CCl4 mixtures, the absorption band at 400 nm due to the complexes has been observed at any composition. In CCl4 solutions, the complex is formed by the reaction of the chlorine atom with DMSO, while in DMSO solutions, the reaction between the parent radical cations of DMSO and Cl− is dominant. It is suggested that the contribution of direct excitation of the strongly interacted ground state DMSO–CCl4 encounter pairs becomes more important with increasing CCl4 concentration.
Tris(6,6′-diamino-2,2′-bipyridine)ruthenium(II): Effect of High Interligand Steric Strain on the Structure
Authors: Araki Koji , Fuse Masahiro , Kishii Noriyuki , Shiraishi Shinsaku , Kodama Teruyuki , Uchida Yasuzo 
Published: July 2006

Abstract
A series of the ruthenium(II) complexes 1–4, [Ru(dabp)3−n(bpy)n](BF4)2 (n=0, 1, 2, and 3, respectively, dabp=6,6′-diamino-2,2′-bipyridine, and bpy=2,2′-bipyridine), having a different degree of interligand steric strain were synthesized, and the effect of the interligand steric strain caused by the amino substituents on their structures was examined. A crystallographic study showed that the two pyridine rings of dabp in the complex 1 were in a slightly twisted configuration in order to relieve the interligand strain. Similar twisted configurations were suggested for the bipyridine moieties of dabp and bpy in the complexes 1–3 in dimethyl sulfoxide solution.