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871.
Akira Yogi Jae-Hwan Oh Takanori Nishioka Rika Tanaka Eiji Asato Isamu Kinoshita Satoshi Takara 《Polyhedron》2010
The syntheses and characterization of novel ruthenium(II) complexes containing bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza), a new class of scorpionate ligands, are reported herein. [RuCl(bdmpza)(η4-1,5-cyclooctadiene)] (1) was found to be a versatile precursor to synthesize a wide range of new ruthenium(II) complexes with the bdmpza ligand. The treatment of 1 with pyridine (py), diphenylphosphinoethane (dppe), 2,2′-bipyridyl (bpy), 1,10-phenanethroline (phen), or bispicolylamine (Hbpica) in refluxing N,N-dimethylformamide resulted in displacement of the 1,5-cyclooctadiene ligand to afford [RuCl(bdmpza)(py)2] (2), [RuCl(bdmpza)(dppe)] (3), [RuCl(bdmpza)(bpy)] (4), [RuCl(bdmpza)(phen)] (5), and [Ru(bdmpza)(Hbpica)]Cl (6Cl) in good yields, respectively. The structures of 1–4, and 6 were determined by X-ray structure analyses. 相似文献
872.
Kinetics of the ethynyl (C(2)H) radical reactions with H(2), D(2), CH(4) and CD(4) was studied over the temperature range of 295-396 K by a pulsed laser photolysis/chemiluminescence technique. The C(2)H radicals were generated by ArF excimer-laser photolysis of C(2)H(2) or CF(3)C(2)H and were monitored by the chemiluminescence of CH(A(2)Δ) produced by their reaction with O(2) or O((3)P). The measured absolute rate constants for H(2) and CH(4) agreed well with the available literature data. The primary kinetic isotope effects (KIEs) were determined to be k(H(2))/k(D(2)) = 2.48 ± 0.14 and k(CH(4))/k(CD(4)) = 2.45 ± 0.16 at room temperature. Both of the KIEs increased as the temperature was lowered. The KIEs were analyzed by using the variational transition state theory with semiclassical small-curvature tunneling corrections. With anharmonic corrections on the loose transitional vibrational modes of the transition states, the theoretical predictions satisfactorily reproduced the experimental KIEs for both C(2)H + H(2)(D(2)) and C(2)H + CH(4)(CD(4)) reactions. 相似文献
873.
Akira Matsumoto Akiyoshi UedaHiroyuki Aota Jun-ichi Ikeda 《European Polymer Journal》2002,38(9):1777-1782
The effect of physical interaction through hydrogen bonds on the intermolecular crosslinking reaction leading to the promoted gelation in free-radical crosslinking monovinyl/divinyl copolymerizations was discussed from the standpoint of the control of network formation. The solution copolymerizations of benzyl methacrylate (BzMA) with 2 mol% of 1,6-hexanediol dimethacrylate in t-butylbenzene were conducted in the absence and presence of different amounts of mono(2-methacryloyloxyethyl) succinate (MMOES). Gelation was promoted by the addition of MMOES and the ratio of the actual gel point to the theoretical one became smaller; this would be related to the formation of hydrogen bonds between carboxyl groups introduced into prepolymer and growing polymer radical. As an extension of the above discussion, we treated the effect of hydrogen bonds on the gelation in the crosslinking BzMA/triicosaethylene glycol dimethacrylate copolymerization. The addition of MMOES obviously promoted the gelation. The ratio of the actual gel point to the theoretical one calculated according to Stockmayer's equation [J. Chem. Phys. 12 (1944) 125] was obtained as 1.9, very close to unity. 相似文献
874.
Noda K Ohuchi Y Hashimoto A Fujiki M Itoh S Iwatsuki S Noda T Suzuki T Kashiwabara K Takagi HD 《Inorganic chemistry》2006,45(3):1349-1355
Controlled-potential electrochemical oxidation of cis-[Ru(ROCS2)2(PPh3)2] (R = Et, iPr) yielded corresponding Ru(III) complexes, and the crystal structures of cis-[Ru(ROCS2)2(PPh3)2] and trans-[Ru(ROCS2)2(PPh3)2](PF6) were determined. Both pairs of complexes exhibited almost identical coordination structures. The Ru-P distances in trans-[Ru(III)(ROCS2)2(PPh3)2](PF6) [2.436(3)-2.443(3) A] were significantly longer than those in cis-[Ru(II)(ROCS2)2(PPh3)2] [2.306(1)-2.315(2) A]: the smaller ionic radius of Ru(III) than that of Ru(II) stabilizes the trans conformation for the Ru(III) complex due to the steric requirement of bulky phosphine ligands while mutual trans influence by the phosphine ligands induces significant elongation of the Ru(III)-P bonds. Cyclic voltammograms of the cis-[Ru(ROCS2)2(PPh3)2] and trans-[Ru(ROCS2)2(PPh3)2]+ complexes in dichloromethane solution exhibited typical dual redox signals corresponding to the cis-[Ru(ROCS2)2(PPh3)2](+/0) (ca. +0.15 and +0.10 V vs ferrocenium/ferrocene couple for R = Et and iPr, respectively) and to trans-[Ru(ROCS2)2(PPh3)2](+/0) (-0.05 and -0.15 V vs ferrocenium/ferrocene for R = Et and iPr, respectively) couples. Analyses on the basis of the Nicholson and Shain's method revealed that the thermal disappearance rate of transient trans-[Ru(ROCS2)2(PPh3)2] was dependent on the concentration of PPh3 in the bulk: the rate constant for the intramolecular isomerization reaction of trans-[Ru(iPrOCS2)2(PPh3)2] was determined as 0.338 +/- 0.004 s(-1) at 298.3 K (deltaH* = 41.8 +/- 1.5 kJ mol(-1) and deltaS* = -114 +/- 7 J mol(-1) K(-1)), while the dissociation rate constant of coordinated PPh3 from the trans-[Ru(iPrOCS2)2(PPh3)2] species was estimated as 0.113 +/- 0.008 s(-1) at 298.3 K (deltaH* = 97.6 +/- 0.8 kJ mol(-1) and deltaS* = 64 +/- 3 J mol(-1) K(-1)), by monitoring the EC reaction (electrode reaction followed by chemical processes) at different concentrations of PPh3 in the bulk. It was found that the trans to cis isomerization reaction takes place via the partial dissociation of iPrOCS2(-) from Ru(II), contrary to the previous claim that it takes place by the twist mechanism. 相似文献
875.
Tainá Olivieri Chaves Akira Iwahara Luiz Tauhata Eduarda Alexandre Rezende Amanda Ribeiro Correia Estela Maria de Oliveira 《Journal of Radioanalytical and Nuclear Chemistry》2012,293(1):211-216
The radionuclide 131I has been increasingly used in nuclear medicine therapy procedures. Nowadays, the 131I source administered to the patient is manufactured in two different geometries: solution and capsules. The purpose of this study is the accurate measurement of the activity present in a 131I capsule without destroys it. The methodology to determine the capsules activity is to obtain the calibration factor of an IG12 secondary standard activity measurement system based on the IG12 well-type ionization chamber set up at Brazilian national metrology laboratory for ionizing radiation (LNMRI) of institute of radiation protection and dosimetry (IRD).The result obtained, 6.4670?±?0.0381?×?10?18?A?Bq?1, is quite similar to the calibration factor of the 131I solution contained in the standard ampoule geometry, 6.4515?±?0.0368?×?10?18?A?Bq?1. After obtaining the calibration factor it was used to measure 131I therapy capsules in order to check the performance of radionuclide calibrators of some Brazilian nuclear medicine centers. 相似文献
876.
877.
The polymerization of methyl methacrylate and acrylonitrile is shown to occur by an anionic mechanism initiated by a 1:1 complex between triethyl aluminum and hexamethyl phosphoric acid triamide at a relatively high temperature. This complex can also initiate the radical polymerization of vinyl monomers at relatively low temperatures. A tentative initiation mechanism is presented. 相似文献
878.
The reactions of aryl Grignard reagents with p- and m-bromochlorobenzenes catalyzed by non-ligated NiCl2 give selectively chlorobiphenyl derivatives. By the stepwise reaction, an unsymmetrical terphenyl was synthesized in a good yield. 相似文献
879.
Shigeru Kubota Toshimoto Moriwaki Torahiko Ando Akira Fukami 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1407-1422
The monomers were derived from pyromellitic dianhydride and α-(2-nitrophenyl)ethanol, which was prepared by selective reduction of 2-nitroacetophenone. Polyimide precursors were synthesized by an interfacial polycondensation technique. Their thermal properties in nitrogen were studied by dynamic thermogravimetry. The photore-arrangement of 2-nitrobenzyl ester having a methyl group at the α-position compared to that of the unsubstituted ester was investigated by infrared spectrophotometry. The polymers obtained in this study gave a high proportion of photorearrangement to show high sensitivity. The exposed areas dissolved in 2% aqueous KOH, forming high resolution patterns because they did not swell during the developing process. 相似文献
880.
Akira Hasegawa Minoru Morita Hideharu Ishida Makoto Kiso 《Journal of carbohydrate chemistry》2013,32(4):579-588
Abstract Various types of the O-protected derivatives and the 9-bromo analogs of methyl [2-(trimethylsilyl)ethyl 5-acetamido-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosid]onate were synthesized from methyl [2-(trimethyl-silyl)ethyl 5-acetamido-4,7-di-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosid]onate (1) or methyl [2-(trimethylsilyl)ethyl 5-acetamido-8,9-di-O-isopropylidene-D-glycero-α-D-galacto-2-nonulopyranosid]onate (3). 相似文献