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1.
The electronic absorption spectra of palladium(II) diacetate (PDA) complexes with phosphines and sulfides (D) with the composition Pd(OAc)2 · 2D (1: 2) contain an intense charge transfer band at λmax ∼ 300 nm (ɛ ∼ 15 000) and do not absorb in the region of 400 nm. Polynuclear compounds such as PDA trimer [Pd(OAc)2]3, trimer complexes with D, and four- and six-membered palladium metallocyclic compounds formed in the interaction of PDA with mercaptans absorb at longer wavelengths. The electronic absorption spectra of all the palladium polynuclear compounds (clusters) contain bands at λmax ∼ 400 nm (ɛ ∼ 1000). The appearance of these bands in the spectra of palladium clusters is evidence of the formation of chemical bonds between neighboring Pd atoms, although Pd…Pd distances substantially exceed the sum of the covalent radii of palladium atoms.  相似文献   

2.
Three palladium(II) complexes of the type [PdCl2(PPh3)L] (L—1-alkylperimidine) have been prepared by reactions of [PdCl2(PPh3)]2 with 1-alkylperimidine. The complexes were characterized by conventional spectroscopic methods and elemental analyses. The incorporation of N-coordinated perimidine complexes of palladium(II) gave high catalytic activity in the Suzuki coupling deactivated aryl chloride substrates.From Koordinatsionnaya Khimiya, Vol. 31, No. 2, 2005, pp. 153–156. Original English Text Copyright © 2005 by Özdemir, Alýcý, Gürbüz, B. Çetinkaya, E. Çetinkaya.This article was submitted by the authors in English.  相似文献   

3.
《Polyhedron》2002,21(14-15):1429-1437
N-Benzoylthioureas have been reported to form complexes with gold (III) and palladium (II) and other transition metals. In this study, an N-benzoyl-N′,N′-diethylthiourea (3f) ligand was used in the solvent extraction of palladium(II) and gold(III) from aqueous chloride media (0.1 mol l−1 NaCl). The distribution coefficient was determined as a function of both metal concentration in the aqueous phase and extractant concentration in the organic phase. The experimental distribution data were numerically analysed by letagrop-distr software in order to obtain the thermodynamic model corresponding to the metal extraction. It is found that pH does not affect the metal extraction process in the 1–2 pH range. Synthesis of the palladium benzoyl thiourea complexes was carried out by mixing quantities of metal and ligand solutions in methanol in a 1:2 ratio stoichiometric. Yields of 74 and 80.9% were obtained for the Pd-3c and Pd-3f complexes. In order to confirm the formation of the palladium complexes, NMR, FTIR and MS analyses were performed. From MS analyses a complex stoichiometry 1:2 (metal:ligand) was confirmed. The formation of crystals of palladium N-benzoyl-N′,N′-diethylthiourea complex (Pd-3f) in the methanolic solution allows the characterisation of the complex structure by XRD. The resulting structure is described and discussed. Bis(1,1,-diheptadecyl-3-benzoyl-thioureate)palladium(II) (Pd-3c) and bis(1,1,-diheptadecyl-3-benzoyl-thioureate)palladium(II) (Pd-3f) were used as ionophores in polymeric membrane electrodes. Their potentiometric responses to different anionic metal chlorocomplexes are evaluated and discussed taking into consideration the results obtained in the liquid–liquid distribution studies. A nernstian response was only obtained for AuCl4  (PDL=8.8×10−8) and PdCl4 2− (PDL=1.5×10−4 M) with a selectivity coefficient of KAuCl4-, PdCl42−pot=−3.4, calculated taking AuCl4  as being the primary anion.  相似文献   

4.
Summary The general course of reactions between [MCl4 ]2– (M = Pd, Pt) and primary and secondary phosphines containing phenyl, cyclohexyl, or 2-cyanoethyl groups, in polar solvents, is to yield L3MCl2 complexes which are probably ionic [L3MCl]+Cl These compounds can be isolated and characterized in the solid state, but in solution they are labile, and tend to react to give phosphines plus L2 MCI2.  相似文献   

5.
A series of palladium complexes of general formula [(Acac)PdL1L2]+A, where L1, L2 = phosphines and A = BF4, CF3SO3, were synthesized. Preliminary studies show that the complexes are active in selective dimerization of styrene and addition polymerization of norbornene.  相似文献   

6.
Volatile palladium(II) β-iminoketonates of the general formula Pd(R–C(NH)–CH–CO–R1),where R and R1 are CH3, CF3, C(CH3)3 in various combinations, were synthesized and identified. Thermal properties of the resulting palladium(II) complexes in the solid phase were studied by thermogravimetric analysis under an argon atmosphere. The temperature dependence of the saturated vapor pressure was measured for the compounds by the flow method and thermodynamic characteristics of vaporization processes, enthalpy ΔH T and entropy ΔS To, were determined. The atom-atomic potential calculation of the van der Waals energy (E cryst) of the crystal lattice was performed and the results were compared to the experimental values of the sublimation enthalpy for the complexes under study.  相似文献   

7.
The equilibrium constants and the thermodynamic parameters for the interaction of CoLx (L1 = 5-OMe-salabza, L2 = salabza, L3 = 5-Br-salabza and L4 = 5-NO2-salabza) as acceptors, with phosphines (PBu3, PPh2Me) as donors in dichloromethane were studied. This was performed by using UV-Vis spectrophotometry titration for 1:1 adduct formation of the selected complexes at various temperatures (T = 283–298 K). The trend of the adduct formation of the Co(II) complexes with a given phosphine donor decreases as CoL1 > CoL2 > CoL3 > CoL4. The stability of the resulting adducts with different Co(II)-schiff base complexes found to decrease in the order PBu3 > PPh2Me.  相似文献   

8.
In acetate buffer medium palladium(II) ions form with promazine hydrochloride (PM) two complexes: an orange one of a formula [Pd(C17H20N2S)]2+max = 460 nm, ε = 4.5 × 103, at 20 °C and pH = 2) and a violet one of a formula [Pd(C17H20N2S)2]2+max = 540 nm, ε = 8.8 × 103 at 20 °C and pH = 2).The values for instability constants determined by Bjerrum's method amount to pK1 = 3.95; pK2 = 3.07; pβ1 = 3.95; pβ2 = 7.02, respectively.A colorimetric method of the determination of palladium(II) has been elaborated. The method consists in a measurement of the absorbance of the violet complex of palladium(II) with promazine hydrochloride at λ = 540 nm. The method permits the determination of 2–17 μg Pd/ml with an error of ±2%. The time of the determination is 20 min. Iron(III), Ce(IV), Pt(IV), V(V), Cr(VI), and HNO3 interfere with the determination.  相似文献   

9.
Platinum(II) complexes [dichlorobis(triphenylphosphine)platinum(II), dichlorobis(tri-m-tolylphosphine)platinum(II), dichloro(2,9-dimethyl-1,10-N, N′-phenanthroline)platinum(II), etc.] showed catalytic activity in addition of tetrachloromethane across the double bond in 1-hexene, 1-heptene, 1-octene, 1-decene, and cyclohexene. The stability of the platinum catalysts was evaluated by GLC, gas chromatography-mass spectrometry, and 31P NMR and IR spectroscopy; the kinetic relationships of the addition reactions were determined. A reaction mechanism involving formation of trichloromethyl radical was suggested. A correlation was revealed for the first time between the catalytic activity of platinum, palladium, and rhodium complexes and the capability of these complexes to generate hexachloroethane.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 5, 2005, pp. 778–782.Original Russian Text Copyright © 2005 by Zazybin, Khusnutdinova, Osipova, Solomonov.  相似文献   

10.
The formation of palladium(II) complexes with aliphatic amines and their oxidation by chloramine‐T in perchloric acid medium has been studied. The spectrophotometric studies showed the formation of 1:1 and 1:2 complexes between palladium(II) and amine in absence of HClO4. An increase in [HClO4] in reaction mixture suppresses the complex formation and in presence of [HClO4] ~10?3 mol dm?3 only a 1:1 complex between palladium(II) and amine has been observed. The effect of Cl? on the complex formation has also been studied. Palladium(II)‐catalyzed oxidation of these amines by chloramine‐T showed a first‐order dependence of rate with respect to each—oxidant, substrate, catalyst, and H+. The mechanism consistent with kinetic data for the oxidation process has been proposed in absence as well as in presence of initial [Cl?]. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 603–612, 2002  相似文献   

11.
A series of 1 : 1 adducts have been prepared by treating the bis-η3-allyl complexes of nickel, palladium and platinum with tertiary phosphines. Investigations of their structure in solution as well as in the crystal have shown that both 18-electron (η3-allyl)2ML complexes as well as 16-electron (η1-allyl)-(η3-allyl)ML complexes may be formed.  相似文献   

12.
A study was made of the composition and behaviour of complexes formed at different pH's between gold(III) and palladium(II) with sodium diethyldithiocarbamate. The complexes obtained are: Pd(CBM)2 (insoluble); [Au(CBM)]+2 (insoluble); [Au2(CBM)3)+3 (soluble); [Au(CBM)2]+ (soluble).Analytical methods are presented for the determination of gold and palladium in mixtures. The heterometric curves obtained permit the determination of gold as well as of palladium in a single titration, with an error of 0–2%.  相似文献   

13.
Reactions of the monoterpenes β-pinene, limonene and myrcene with Pd(II) complexes in acetic acid solutions were studied by 1H NMR spectroscopy. Various π-allyl palladium complexes were detected in situ and their interaction with CuCl2 has been investigated. The results clarify the mechanism of allylic oxidation of these substrates mediated by Pd(II)/Cu(II)-based catalytic systems. Originally introduced to regenerate reduced palladium species, CuCl2 has been shown to play an important role in the formation and/or decomposition of key reaction intermediates - π-allyl palladium complexes. β-Pinene and myrcene readily react with Pd(OAc)2 giving corresponding π-allyls, with two complexes acyclic and cyclic being formed from myrcene. On the other hand, the formation of π-allyl complexes from limonene occurs at a significant rate only in the presence of CuCl2. NMR observations, including selective paramagnetic enhancement of spin-lattice relaxation, indicate that π-allyl palladium intermediates specifically interact with Cu(II) ions in the reaction solutions. Such interaction probably involves Cu(II) bonding to Pd(II) via bridging ligands, and seems to be responsible for the accelerative effect of CuCl2 in the palladium catalyzed oxidation of the monoterpenes. Indeed, most of these reactions do not occur at all in the absence of CuCl2.  相似文献   

14.
15.
Reduction of palladium(II) glycinate complexes in strongly acid 0.5 M NaClO4 solutions (pH 0.6 and 1.0) with variable palladium(II) complex and free glycine concentration was studied by the taking of cyclic voltammograms at palladium rotating disc electrode. It is shown that it was a chelate monoglycinate palladium(II) complex that was present in all studied solutions and underwent the reduction. The diffusion coefficient of the chelate monoglycinate palladium(II) complex D = (6.5 ± 0.5) × 10−6 cm2/s was determined from the limiting diffusion current of the complex reduction. The monoglycinate palladium(II) complex reduction occurred in the double-layer segment of the palladium charging curve; it was not complicated by hydrogen adsorption at electrodes. The palladium(II) complex reduction half-wave potential was determined (E 1/2 = ∼0.300 to 0.330 V (SCE)). It is shown that the decreasing of the number of ligands coordinated by palladium via nitrogen atom facilitates the complex reduction process. In particular, the reduction potentials of palladium(II) complexes with different ligand number at palladium electrode shifted markedly toward negative potentials in the series: Pdgly+ < Pd(gly)2 < Pd(gly)42−.  相似文献   

16.
Sterically modulated bis-imine ligands (L1-L3) were prepared by reacting 4,4′-methylene bis-(2,6-dialkyl aniline) and antipyrine-4-carboxaldehyde in a 1:2 stoichiometric ratio. The reactions of L1-L3 with dichloro(cycloocta-1.5-diene)palladium(II) [PdCl2(cod)] yield the corresponding binuclear palladium complexes with the general formula Pd2Cl4L (L = L1, L2, and L3). The binucleating ligands bind to the palladium ion via the lone pair on the imine nitrogen and amide oxygen atoms, resulting in a square-planar geometry around the metal center. All the palladium catalysts efficiently oligomerize ethylene to produce C4-C20 fractions at activities of up to 1308 kg-oligomer mol-Pd−1 bar−1 h−1 at 30 °C in combination with ethylaluminum sesquichloride. The formation of active sites by the change in geometry of the metal complexes could be traced using spectroscopic and electrochemical techniques.  相似文献   

17.
Potassium N-R-sulfonyldithiocarbimates, K2(RSO2N=CS2) (R = Me, Ph, 2-MeC6H4), react with Pd(OAc)2 to yield complex anions bis(N-R-sulfonyldithiocarbimato)palladate(II), [Pd(RSO2N=CS2)2]2–, which were isolated as their n-Bu4N+ salts. When the reaction was performed in the presence of Ph3P in a 2:1 ratio with respect to Pd(OAc)2, the N-R-sulfonyldithiocarbimatobis(triphenylphosphine)palladium(II) complexes were obtained. Elemental analyses, i.r. spectra and electronic spectra data were consistent with the formation of palladium–sulfur diamagnetic square planar complexes in the first case and mixed square planar complexes of palladium with Ph3P and dithiocarbimates in the second case. The 1H-n.m.r., 13C-n.m.r. and 31P-n.m.r. spectra showed the expected signals for the Bu4N+ cation, Ph3P and the dithiocarbimate moieties.  相似文献   

18.
The influence of the ligands L in η3-(3-methylbutenyl)palladium(L2) complexes on the rates and regiochemistry of nucleophilic addition has been studied. Acceptor ligands such as phosphines and 1,5-cyclooctadiene have been found to increase the rate of addition as well as the preference for reaction at the more substituted allyl terminus. There is a good correlation between the rates and the 13C NMR shifts of the more substituted η3-allyl terminus, indiating that the NMR shifts can be used to predict acceptor properties of the ligands. There is a fair agreement between the rates and the regiochemistry of the palladium catalyzed nucleophilic displacement of allylic acetate from these complexes and those for the stoichiometric reactions involving η3-allyl complexes.  相似文献   

19.
A new class of luminescent and thermally stable mononuclear group 10 platinum(II) and palladium(II) acetylides trans-[Pt(PR3)2(L)2] (R = Bu, Et) and trans-[Pd(PBu3)2(L)2] (LH = 3-(N-carbazolyl)-1-propyne) have been successfully synthesized and characterized. The structural properties of these discrete metal complexes have been studied by X-ray crystallography. We report their optical absorption and photoluminescence spectra and interpret the results in terms of the nature of the metal center and the type of phosphines used. Our investigations indicate that they display heavy metal-enhanced phosphorescence bands at 77 K and we find that the platinum complexes afford more intense triplet emission than that for the palladium congener, consistent with the stronger heavy-atom effect of the third row element than the second row neighbor of the same group.  相似文献   

20.
The primary photoreactions due to charge transfer excitation of d8 transition metal complexes of [MP2(N3)2] constitution (P2: mono‐ or diphosphane ligands) are strongly influenced by the central ion. While [MP2(N3)2] complexes of both palladium(II) and platinum(II) yield primarily the corresponding metal(I) species and azidyl radicals, nickel(II) complexes of the same constitution lead to intermediate generation of nitrenes as has been indirectly shown by various scavenging reactions. During the course of the succeeding reactions, the intermediate generation of nickelatetrazoles is assumed. Both nitrene and metallatetrazole intermediates could not be identified directly so far. Therefore, the proposed reaction pathway has been modeled theoretically to get indications regarding the probability of the formation of such intermediates. Based on density functional theory (DFT) calculations, the energetics of the proposed pathway is compared with those of possible other pathways. The calculations support the proposed reaction pathway and point to possible reasons for the different behaviour of nickel(II) compared to palladium(II) and platinum(II).  相似文献   

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