共查询到20条相似文献,搜索用时 968 毫秒
1.
Potekhin V. V. Solov'eva S. N. Potekhin V. M. 《Russian Journal of General Chemistry》2004,74(5):647-650
The catalytic oxidation of iron(II) with oxygen occurs along with an autocatalytic reaction between palladium(II) tetraaqua complex and iron(II) aqua complex in an oxygen atmosphere. The reaction is catalyzed by a compound of palladium in an intermediate oxidation state, presumably by a small palladium cluster formed in the course of the reduction of palladium(II) tetraaqua complex with iron(II) aqua complex. 相似文献
2.
《Electrochemistry communications》2001,3(2):102-106
The deposition and dissolution of palladium(0) at non-modified carbon paste electrode (CPE) is studied in aqueous chloride solution. During the dissolution one or two Pd oxidation peaks are observed at + 0.1 V and about + 0.45 V vs. SCE, indicating the existence of different states of Pd0 at the CPE. In accordance with the experimental results it is assumed that a palladium monolayer is formed when low amounts of Pd are deposited and that multilayers are formed in the case of larger amounts of deposited palladium. The formation of a metal monolayers at CPE is described for the first time. 相似文献
3.
Soreta TR Strutwolf J O'Sullivan CK 《Langmuir : the ACS journal of surfaces and colloids》2007,23(21):10823-10830
The vast majority of reports of self-assembled monolayers (SAMs) on metals focus on the use of gold. However, other metals, such as palladium, platinum, and silver offer advantages over gold as a substrate. In this work, palladium is electrochemically deposited from PdCl2 solutions on glassy carbon electrodes to form a substrate for alkanethiol SAMs. The conditions for deposition are optimized with respect to the electrolyte, pH, and electrochemical parameters. The palladium surfaces have been characterized by scanning electron microscopy (SEM) and the surface roughness has been estimated by chronocoulometry. SAMs of alkane thiols have been formed on the palladium surfaces, and their ability to suppress a Faradaic process is used as an indication for palladium coverage on the glassy carbon. The morphology of the Pd deposit as characterized by SEM and the blocking behavior of the SAM formed on deposited Pd delivers a consistent picture of the Pd surface. It has been clearly demonstrated that, via selection of experimental conditions for the electrochemical deposition, the morphology of the palladium surface and its ability to support SAMs can be controlled. The work will be applied to create a mixed monolayer of metals, which can subsequently be used to create a mixed SAM of a biocomponent and an alkanethiol for biosensing applications. 相似文献
4.
2-(2-Pyridyl)benzo[b]selenophene has been investigated as a possible reagent for palladium. From a consideration of its reactions with diverse metal ions, and the probable structure of the complex formed between the compound and palladium(II) it is postulated that the group may be highly selective for palladium. From the experimental evidence it is suggested that the delocalization of the metal electron density by pi-bond formation between the palladium and selenium atoms is a major factor in determining the stability of the chelated complex. 相似文献
5.
A selective and sensitive method for determination of platinum and palladium(Ⅱ)in an aqueous solution simultaneously by laser thermal lens spectrometry,based on the complex reaction of 2-(3,5-dichloropyridylazo)-5-dimethylaminoamiline(3,5-diCl-PADMA) with platinum and palladium,has been developed.It is shown that the palladium complex can be fromed at room temperature, while the platinum complex can be only formed after being heated in a boiling water bath.By using this difference of reaction temperature and the characteristic of the complexes mentioned above,the method for simultaneous determination of platinum and palladium was established in an aqueous solution without a pre-separation.The results show that the dynamic linear ranges of determination for platinum and palladium are 0.005-0.04μg/mL and 0.005-0.25μg/mL respectively,and that the detection limits are both 0.002/μg/mL.The method has been applied to the determination of platinum and palladium simultaneously in alloy and catalyst samples with satisfactory results. 相似文献
6.
二苄基硫醚树脂对钯的固相萃取吸附性能研究 总被引:1,自引:0,他引:1
基于二苄基硫醚树脂与钯的络合反应,建立了一种高选择性固相萃取吸附钯的方法。在0.1~6.0 mol/L的HCl介质中,钯可以被二苄基硫醚树脂吸附富集并形成1∶2稳定络合物,该络合物可用20 g/L酸性硫脲溶液洗脱,洗脱液经处理后用分光光度法测定,树脂结构不被破坏且可重新处理使用。方法用于吸附分离钯,回收率达90%以上。 相似文献
7.
8.
Love JC Wolfe DB Haasch R Chabinyc ML Paul KE Whitesides GM Nuzzo RG 《Journal of the American Chemical Society》2003,125(9):2597-2609
The adsorption of n-alkanethiols onto polycrystalline thin films of palladium containing a strong (111) texture produces well-organized, self-assembled monolayers. The organization of the alkane chains in the monolayer and the nature of the bonding between the palladium and the thiol were studied by contact angle measurements, optical ellipsometry, reflection absorption infrared spectroscopy (RAIRS), and X-ray photoelectron spectroscopy (XPS). The XPS data reveals that a compound palladium-sulfide interphase is present at the surface of the palladium film. The RAIR spectra, ellipsometry data, and wetting properties show that the palladium-sulfide phase is terminated with an organized, methyl-terminated monolayer of alkanethiolates. The local molecular environment of the alkane chains transitions from a conformationally disordered, liquidlike state to a mostly all-trans, crystalline-like structure with increasing chain length (n = 8-26). The intensities and dichroism of the methylene and methyl stretching modes support a model for the average orientation of an ensemble of all-trans-conformer chains with a tilt angle of approximately 14-18 degrees with respect to the surface normal and a twist angle of the CCC plane relative to the tilt plane of approximately 45 degrees. The SAMs are stable in air, although the sulfur present at the surface oxidizes in air over a period of 2-5 days at room temperature. The differences in chain organization between SAMs formed by microcontact printing and by solution deposition are also examined by RAIRS and XPS. 相似文献
9.
Karl-Heinz Lubert Markus Guttmann Lothar Beyer 《Journal of Solid State Electrochemistry》2002,6(8):545-552
The study of the electrode reactions of palladium(II) at non-modified carbon paste electrodes (CPEs) in chloride solution
has revealed the existence of a chloropalladate(II) complex at the electrode surface. The complex is formed during the application
of anodic potentials after preceding palladium deposition. In the present paper the electrode reactions of PdII at CPEs modified with some N′,N′-disubstituted derivatives of N-benzoylthiourea [as selective ligands for palladium(II)] are studied in chloride solution by cyclic voltammetry. Two reduction
peaks are observed in the cathodic scans recorded after deposition of palladium and anodization of the electrode. From the
results it is concluded that [in addition to the chloropalladate(II) complex, observed at the non-modified electrode] a second
palladium complex is formed at positive potentials. The formation of the palladium(II) complex of the N-benzoylthiourea derivatives by ligand exchange at the electrode surface is assumed. The ligand exchange itself occurs without
charge transfer across the electrode|solution interface; therefore, it cannot be detected electrochemically. After palladium
deposition and anodic treatment a pronounced "inverse" peak (i.e., an anodic peak in the cathodic scan) with peak currents
up to 100 μA is observed at about +0.8 V. Its peak current increases with the amount of deposited palladium and the number
of cycles. The reactions at the electrode surface are discussed. The results of the study reveal the existence of two different
surface complexes of palladium(II) at ligand-modified CPEs, but the surface reactions could not be elucidated in detail.
Electronic Publication 相似文献
10.
Various mechanisms for the cyclometalation of dimethylbenzylamine by palladium acetate have been studied by DFT calculations. Contrary to previous suggestions, the rate-limiting step is the electrophilic attack of the palladium on an ortho arene C-H bond to form an agostic complex rather than a Wheland intermediate. The cyclometalated product is then formed by intramolecular deprotonation by acetate via a six-membered transition state; this step has almost no activation barrier. 相似文献
11.
Dneprovskii A. S. Ermoshkin A. A. Kasatochkin A. N. Boyarskii V. P. 《Russian Journal of Organic Chemistry》2003,39(7):933-946
Addition of bromotrichloromethane and tetrachloromethane to alkenes in the presence of palladium(II) complexes begins with single-electron transfer from the palladium atom to polyhalomethane molecule, followed by fragmentation of the radical anion thus formed and generation of trichloromethyl radical. Halogen transfer to a carbon-centered radical arising from addition of trichloromethyl radical at the double bond occurs both from the polyhalomethane molecule and from halide palladium complex. 相似文献
12.
Formation of Four Different Aromatic Scaffolds from Nitriles through Tandem Divergent Catalysis
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Dr. Ju Hyun Kim Prof. Jean Bouffard Prof. Sang‐gi Lee 《Angewandte Chemie (International ed. in English)》2014,53(25):6435-6438
A zinc bromide complex, formed by the sequential reaction of nitriles with a Reformatsky reagent and terminal alkynes, is used as an intermediate for divergent palladium‐catalyzed reactions. The reaction pathway of the intermediate is precisely controlled by the choice of the reaction solvent or the palladium catalyst to quickly form four different aromatic scaffolds—arylamines, aminoindenes, pyrroles, and quinolines—starting from readily available nitriles. 相似文献
13.
The complex formed between palladium(II) and tin(II) in hydrochloric acid solutions, and its extractability by tri-n-octylamine were investigated. Two different species were obtained: one a brown-red complex and the other yellow. Both were extracted into tri-n-octylamine in benzene, but the yellow species which had a definite absorption maximum at 410 mμ was more suitable for the determination of palladium. A method is described for the spectrophotometric determination of palladium in the presence of many other elements. Both species are considered to be anionic and a mechanism for their extraction is proposed. 相似文献
14.
15.
Kris Randell 《Journal of organometallic chemistry》2006,691(16):3411-3415
The attempted synthesis of bis(NHC)palladium complexes via the direct reaction of an imidazolium salt with palladium acetate results in the formation of a mixed NHC/aniline complex. The route by which the aniline is formed has not been completely elucidated, but it does originally derive from an imidazolium salt. 相似文献
16.
A. Dakshinamoorthy V. Venugopal 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(3):425-429
Summary For the recovery of palladium from high level liquid waste (HLLW) a rapid and selective method of separation of palladium
have been developed using alpha benzoin oxime (ABO) in Solvesso 100 in our laboratory. In continuation of this work, a detailed
study is presented to determine the empirical formula (composition) of the palladium-alpha benzoin oxime (Pd-ABO) complex
formed during solvent extraction with ABO in Solvesso 100. Both, the molar ratio method and the isomolar series method extended
to two phase system are followed to establish the empirical formula of the Pd-ABO complex. The ligand to metal ratio is computed
by analyzing the palladium concentration in the organic phase by direct spectrometry, by analysis of the aqueous phase using
Arsenazo-III and also by using the 109Pd tracer technique. Degree of dissociation and apparent instability constant of the Pd-ABO complex are reported. 相似文献
17.
Kitson PJ Song YF Gamez P de Hoog P Long DL Parenty AD Reedijk J Cronin L 《Inorganic chemistry》2008,47(6):1883-1885
The formation of a pentanuclear palladium(II) complex with a phenanthridinonetriazine-based ligand system, which itself is formed by a metal-mediated rearrangement of a triazinephenanthridinium proligand, is described. 相似文献
18.
羊毛负载钯络合物的合成及其加氢催化作用 总被引:6,自引:0,他引:6
以天然生物高分子羊毛为载体制备了羊毛-钯络合物催化剂。用XPS、IR方法对羊毛-钯络合物进行了初步表征。证明羊毛-钯络合物在常温常压下能够催化各种化合物,如硝基苯、苯甲醛、丙烯醇、丁烯睛、醋酸乙烯酯、苯乙烯和1-己烯的加氢,分别以大约100%的收率得到了苯胺、苯甲醇、正丙醇、丙胺、醋酸乙酯,乙苯和己烷。对于用以往的催化剂较难加氢的各种脂肪醛,如丙醛、丁醛、戊醛和己醛,在常温常压下也能够进行催化加氢,分别以大约100%的收率得到正丙醇、正丁醇、正戊醇和正己醇。这种催化剂稳定性也很高,长时间反应也能保持高活性,钯不脱落。 相似文献
19.
Bis(allylic)palladium complexes can be induced to undergo reductive elimination by replacement of phosphine ligands in the system with π-acidic ligands. The product 1,5-diencs, formed in high yield, are predominantly the ‘head-to-head’ coupled isomers. The bis(allylic)palladium intermediatesmay be formed by addition of an allylic Grignard or trialkyl(allylic)tin reagent to an (η3-allyl)palladiuin chloride complex, or by 1,3-diene condensation. The latter process leads to cydodimerization, ‘unusual’ for palladium catalysed reactions. 相似文献
20.
《应用有机金属化学》2017,31(4)
Palladium‐catalysed cross‐coupling reactions are some of the most frequently used synthetic tools for the construction of new carbon–carbon bonds in organic synthesis. In the work presented, Pd(II) complex catalysts were synthesized from palladium chloride and nitrogen donor ligands as the precursors. Infrared and 1H NMR spectroscopic analyses showed that the palladium complexes were formed in the bidentate mode to the palladium centre. The resultant Pd(II) complexes were tested as catalysts for the coupling of organobismuth(III) compounds with aryl and acid halides leading to excellent yields with high turnover frequency values. The catalysts were stable under the reaction conditions and no degradation was noticed even at 150°C for one of the catalysts. The reaction proceeds via an aryl palladium complex formed by transmetallation reaction between catalyst and Ar3Bi. The whole synthetic transformation has high atom economy as all three aryl groups attached to bismuth are efficiently transferred to the electrophilic partner. 相似文献