共查询到20条相似文献,搜索用时 15 毫秒
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A phosphine-free arylation of naphthalene and benzene with aryl iodides to give biaryls in moderate to good yields is carried out in the presence of catalytic Pd(OAc)2 and stoichiometric CF3CO2 Ag in TFE or/and TFA. 相似文献
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I. V. Kozhevnikov 《Reaction Kinetics and Catalysis Letters》1976,5(4):439-443
The reaction between ethylene and 5-membered heterocyclic compounds (thiophene, furan, furfural) in solution in the presence of a palladium salt at 25–100°C and atmospheric pressure is found to give good yields of 2-vinyl derivatives of the heterocycles indicated.
5- (, , ) 25–100° 2- .相似文献
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Polycatenar saturated macrocycles 1,10-bis[3,4,5-tris(4-dodecyloxy)benzoy1]-1,10-diaza-4,7,13,16-tetrathiacyclo-octadecane (3b) and 1,10-bis[3,4-bis(4-dodecyloxy)benzoy1] -1,10-diaza-4,7,13,16-tetrathiacyclo-octadecane (3d) reacted with [Pd(MeCN)4][BF4]2 led to the cationic complexes [4b][BF4]2 and [4d][BF4]2, respectively. Complexes [4b][BF4]2 and [4d][BF4]2 showed smectic mesomorphism on heating as confirmed by small angle X-ray diffraction. A concurrent, irreversible structural change of the complex cations was observed and a tentative explanation is suggested. 相似文献
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Jitsuo Kiji 《Macromolecular Symposia》1996,105(1):167-171
The palladium-catalyzed arylation of ethylene under aqueous conditions has been studied. Both NaHCO3-soluble and -insoluble bromo-and iodoarenes possessing electron-withdrawing groups react with ethylene to afford styrenes in good yields by water-soluble PdCl2[tppms]2 (tppms, m-(diphenylphosphino)benzenesulfonate). The Cr(CO)3 complex of chlorobenzene reacts similarly under organic conditions. These reactions provide a synthetic route to poly(phenylenevinylenes). 相似文献
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Summary TheN-aminorhodanine (L) complexes: PdLX, (X = Br or I), ML1.5Cl2 (M = Pd or Pt), PtL2X2 (X = Br, I or ClO4), PdL3(ClO4)2, PdL1.5Cl4 and PdL3(ClO4)4 have been prepared and investigated. The ligand is bonded to the metal ion through the aminic nitrogen atom as monodentate or through this atom and the thiocarbonylic sulphur atom when it acts as chelating or bridging ligand. The carbonylic oxygen atom is never coordinated. 相似文献
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Denisov M. S. Dmitriev M. V. Gorbunov A. A. Glushkov V. A. 《Russian Chemical Bulletin》2019,68(11):2039-2047
Russian Chemical Bulletin - Complexes of palladium(II) with N-heterocyclic carbenes of the PEPPSI-type were synthesized by the reaction of PdCl2 with 1-adamantyl-3-(R-methyl)-1H-imidazolium salts.... 相似文献
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S. Yu. Troitskii A. L. Chuvilin S. V. Bogdanov E. M. Moroz V. A. Likholobov 《Russian Chemical Bulletin》1996,45(6):1296-1302
Adsorption of polynuclear palladium(ii) hydroxocomplexes (PHC) by carbon materials (CM) was studied. It was found that PHC are adsorbed from aqueous solutions without a change in their chemical composition and are composed of clusters (<10 A) with metalmetal distances typical of the PdO chain structure. Three-dimensional ordered particles with the PdO structure were formed upon adsorption of PlIC on carbon materials at room temperature or after the PHC suspension was dried in air at 400 °C (the size of the particles was 15 and 25 A, respectively). Calculation of the electron-microscopic images of the adsorbed PHC with atomic resolution based on crystal structure modeling showed that PdO particles containing -100 palladium atoms is the final product after drying of the adsorbed PHC.Translated fromIzvesfiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1366–1372, June, 1996. 相似文献
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Summary The kinetics of the palladium(II) catalysed oxidation of acrylic, methacrylic and crotonic acid by vanadium(V), in acid medium at constant ionic strength exhibit zeroth order dependence on vanadium(V) and first order dependence on palladium(II) and the unsaturated acid. Complex formation between the palladium(II) species and the unsaturated acid, with possible exchange of chloride ion and hydrogen ion in two successive steps, was invoked. The reaction rate is determined by a rearrangement leading to elimination of chloride ion. A plausible mechanism is proposed. 相似文献
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T. G. Nikiforova V. I. Kravtsov M. E. Kozelkova 《Russian Journal of Electrochemistry》2010,46(11):1215-1222
The electroreduction kinetics of Pd(Hgly)2Cl2 on rotating palladium disk electrode was studied by means of cyclic voltammetry. The double layer range of the palladium
charging curve showed a single wave with the diffusion limited current I
d, which yielded the diffusion coefficient of Pd(Hgly)2Cl2 complex D = 6 × 10−6 cm2/s. The plotted direct and reverse voltammetric curves were linearized in coordinates E, log[I/(I
d − I)]. The slope of this line gave b
k factor evidencing the slow electrochemical step. When [Cl−] decreased from 1 to 0.2 M, E
1/2 potential shifted to positive values. This was accounted for by reversible cleavage of Cl− ion from Pd(Hgly)2Cl2 complexes before the irreversible electrochemical step. The pulse galvanostatic experiment resulted in the double electrical
layer capacity and roughness factors f of electrolytic palladium deposits. The calculated values of f from 60 to 310 were attributed to adsorption of glycine particles on the electrodeposited palladium surface, which promotes
to increasing number of palladium microcrystal growing centers. 相似文献
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Kelin LiJames Darkwa Ilia A GuzeiSelwyn F Mapolie 《Journal of organometallic chemistry》2002,660(1):108-115
The substituted pyrazole palladium complexes, (3,5-tBu2pz)2PdCl2 (1) (3,5-Me2pz)2PdCl2 (2), (3-Mepz)2PdCl2 (3) and (pz)2PdCl2 (4) (pzH=pyrazole), can be prepared from the reaction of (COD)PdCl2 with the appropriate pyrazole. The chloromethyl derivative, (3,5-tBu2pz)2PdCl(Me) (5), was prepared from (COD)PdClMe and tBu2pzH. X-ray crystal structure determination of 1 and 5 established their structures in the solid state to be the trans-isomer. After activation of 1-4 and 5 with methylaluminoxane (MAO) the resulting palladium complexes were used as catalysts in ethylene polymerization, yielding linear high-density polyethylene (HDPE). The highest activity was observed for (3,5-tBu2pz)PdClMe. 相似文献
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The synthesis of a zwitterionic Pd(II) complex supported by an anionic bis(phosphino)borate ligand, Ph(2)B(CH(2)PPh(2))(2) (abbreviated as [Ph(2)BP(2)]), is reported. The new complex, [Ph(2)BP(2)]PdMe(THF), is active for CO and ethylene copolymerization. The copolymerization activity and polyketone molecular weight for the neutral, zwitterionic system are compared with those for the cationic systems [R(2)E(CH(2)PPh(2))(2)PdMe(THF)][B(C(6)F(5))(4)] where ER(2) = SiPh(2) and CH(2). Surprisingly, the more electron rich zwitterionic system is a catalyst of activity comparable to that of the more conventional cationic systems. 相似文献
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Reults are reported indicating the intermediacy of a symmetrical π-allyl species in the alkylation of an allylic lactone. A previous report indicating that another mechanism was operative is disputed. 相似文献
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We report the synthesis and characterization of perchlorate salts containing the following three novel complex cations each with a bidentate thioether ligand: binuclear cis-[Pt(CH3SCH2CH2CH2SCH3)(mu-OH)]22+, mononuclear cis-[Pt(CH3SCH2CH2CH2SCH3)(H2O)2]2+, and mononuclear cis-[Pd(CH3SCH2CH2CH2SCH3)(H2O)2]2+. Despite their analogous compositions, the mononuclear Pt(II) and Pd(II) complexes differ in the selectivity with which they promote the hydrolysis of polypeptides. The complex cis-[Pt(CH3SCH2CH2CH2SCH3)(H2O)2]2+ promotes slow but selective cleavage of Met-Pro peptide bonds at pH 2.0. The selectivity of the complex cis-[Pd(CH3SCH2CH2CH2SCH3)(H2O)2]2+ is pH-dependent. At pH 2.0, this Pd(II) complex promotes residue-selective hydrolysis of the X-Y bond in X-Y-Met and X-Y-His sequences; the rate is enhanced when residue Y is proline. At pH 7.0, this kinetic preference becomes sequence-selective in that the Pd(II) complex exclusively cleaves the X-Pro bond in X-Pro-Met and X-Pro-His sequences. The enhanced reactivity of the X-Pro amide group is attributed to the high basicity of its carbonyl oxygen atom. Binding of the metal(II) atom enhances the electrophilicity of the carbonyl carbon atom and promotes nucleophilic attack by a solvent water molecule. The bidentate thioether ligand disfavors the formation of hydrolytically unreactive complexes, allowing the Pd(II) complex to promote the cleavage reaction. 相似文献
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Gensch T Rönnefahrt M Czerwonka R Jäger A Kataeva O Bauer I Knölker HJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(3):770-776
Pd(II) caught in the act: The diaryl Pd(II) intermediate of a Pd(II)-catalyzed oxidative biaryl bond formation proceeding via a double C-H bond activation has been isolated and fully characterized, including an X-ray crystal structure analysis. Stabilization due to chelation by adjacent pivaloyloxy and acetyl groups has allowed the isolation of this long-sought crucial intermediate. On gentle warming, the complex is transformed into a carbazole product, and the catalytically active Pd(II) species is regenerated by oxidation with Cu(II). 相似文献
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Pérez-Temprano MH Casares JA de Lera AR Alvarez R Espinet P 《Angewandte Chemie (International ed. in English)》2012,51(20):4917-4920
It's the second step that counts: arylation of Pd by Au takes place through transition states and intermediates featuring strong Au???Pd metallophilic interactions. However, the aryl transfer from [AuArL] to [PdArClL(2)] is thermodynamically disfavored and will not occur unless an irreversible Ar-Ar coupling from [PdAr(2)L(2)] follows. 相似文献
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Mechanistic studies of a palladium-mediated decarboxylative olefination of arene carboxylic acids are presented, providing spectroscopic and, in two instances, crystallographic evidence for intermediates in a proposed stepwise process. Sequentially, the proposed pathway involves carboxyl exchange between palladium(II) bis(trifluoroacetate) and an arene carboxylic acid substrate, rate-determining decarboxylation to form an arylpalladium(II) trifluoroacetate intermediate (containing two trans-disposed S-bound dimethyl sulfoxide ligands in a crystallographically characterized form), then olefin insertion and beta-hydride elimination. Because of the unique mode of generation of the arylpalladium(II) trifluoroacetate intermediate, a species believed to be substantially electron-deficient relative to phosphine-containing arylpalladium(II) complexes previously studied, it has been possible to gain new insights into those steps that are common to the Heck reaction, namely, olefin insertion and beta-hydride elimination. The present results show that there are notable differences in reactivity between arylpalladium(II) intermediates generated by decarboxylative palladation and those produced in conventional Heck reactions. Specifically, we have found that more electron-rich alkenes react preferentially with an arylpalladium(II) trifluoroacetate intermediate formed by decarboxylative palladation, whereas an opposite trend is found in conventional Heck reactions. In addition, we have found that the aralkylpalladium(II) trifluoroacetate intermediates that are formed upon olefin insertion in the present study are stabilized with respect to beta-hydride elimination as compared to the corresponding phosphine-ligated aralkylpalladium(II) complexes. We have also crystallographically characterized an aralkylpalladium(II) trifluoroacetate intermediate derived from arylpalladium(II) insertion into norbornene, and this structure, too, contains an S-bound dimethyl sulfoxide ligand; the ipso-carbon of the transferred aryl group and trifluoroacetate function as the third and fourth ligands in the observed distorted square-planar palladium(II) complex. 相似文献