- New strategy to prepare platinum salts by electrochemical methods and subsequent synthesis of platinum nanoparticles
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As shown in the literature, most of Pt nanoparticles (NPs) were synthesized from precursors of commercial Pt salts. However, the impurity of the commercial Pt salts is a concerned issue. In this work, we report a new pathway based on electrochemical methods to prepare Pt-containing complexes with high purity in aqueous solutions from bulk Pt substrates. Experimental results indicate that Pt complexes with higher concentration can be obtained in 0.1 N HCl by using square-wave oxidation-reduction cycles (ORCs) under a frequency of 8 Hz with a step potential of 6.3 mV. Moreover, concentrations of other heavy metals of Hg and Cr in 65 ppm Pt complexes-containing solution are just 0.65 and 0.78 ppb, respectively. These Pt complexes were further reduced to Pt NPs by using NaBH4 and poly(vinylpyrrolidone) (PVP) as reducing agent and stabilizer, respectively. The concentration and the particle size of synthesized Pt (1 1 1) NPs are ca. 60 ppm and smaller than 5 nm, respectively.
- Mai, Fu-Der,Yu, Chung-Chin,Liu, Yu-Chuan,Hsu, Ting-Chu,Wu, Yi-Hao
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- Mechanism of tetrachloroplatinate(ii) oxidation by hydrogen peroxide in hydrochloric acid solution
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Oxidation of tetrachloroplatinate(ii) by hydrogen peroxide in hydrochloric acid was studied by UV-Vis spectrophotometry. Oxidation takes place via two parallel reactions with hypochlorous acid and hydrogen peroxide, respectively, according to the overall rate law d[Pt(iv)]/dt = (k0 + k H2O2[Pt(ii)])[H2O2]. For oxidation of [PtCl4]2- at relatively low concentrations, [PtCl4]2- ? 0.5 mM, hypochlorous acid formation is fast relative to the oxidation of [PtCl4]2- by hydrogen peroxide, as a result of the rate determining reaction H2O 2 + H+ + Cl- → HOCl + H2O, resulting in a rate law d[Pt(iv)]/dt = k0[H2O2] with a value k0 = (8 ± 2) × 10-7 s -1 at 35 °C. For concentrations of [PtCl4] 2- > 0.5 mM, oxidation by hydrogen peroxide becomes dominant, resulting in the pseudo-first order rate law d[Pt(iv)]/dt = kH2 O2[Pt(ii)][H2O2] with the value kH2O2 = (1.5 ± 0.1) × 10 -2 M-1 s-1 at 35°C. The final oxidation product is a mixture of [PtCl5(H2O)]- and [PtCl6]2-, with [PtCl6]2- formed as a result of [PtCl4]2- assisted chloride anation reactions. This journal is the Partner Organisations 2014.
- Murray, Pieter,Koch, Klaus R.,Van Eldik, Rudi
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p. 6308 - 6314
(2014/04/17)
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- Removal of platinum from water by precipitation or liquid-liquid extraction and separation from gold using ionic liquids
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Precipitation and liquid-liquid extraction of PtX62- (X = Cl-, Br-, SCN-) in acidified aqueous solutions ranging from 0.1 M to 9 M HBr or 11 M of HCl have been studied using water-soluble or hydrophobic ionic liquids. Divalent hexachloroplatinate(iv) anions appear to be extracted much less efficiently than tetrachloroaurate(iii) complexes. At a concentration of 11 M HCl, values of 15 and 800 for the distribution coefficients of PtCl62- and PtBr 62- in [OMIM][NTf2] have been obtained accordingly. The presence of a labile hydrogen on the imidazolium ring has been found to play a specific role in the extraction of platinum(iv) complexes in concentrated HCl or HBr. Pt(SCN)62- appears to be very efficiently extracted at pH 1 using [OMIM][NTf2], exhibiting a distribution coefficient of 6150. Finally, two methods for quantitative separation of gold and platinum in water using in each method two extraction steps have been proposed. The back extraction of platinum(iv) during the second separation process was also discussed.
- Genand-Pinaz, Sebastien,Papaiconomou, Nicolas,Leveque, Jean-Marc
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p. 2493 - 2501
(2013/09/12)
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- Outer-sphere electron transfer from platinum(II) to Keggin-type 12-tungstocobaltate(III) in the presence and absence of chloride ions
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The reaction between Pt(II) and [CoIIIW12I 40]5- proceeds with two, one-electron steps involving formation of unstable Pt(III) followed by its reaction with another oxidant. The reaction rate is unaffected by the [H+] as there are no protonation equlibria involved with both the reactants whereas, chloride ion accelerates the reaction and the reaction follows chloride independent and dependent paths leading to a two term rate law, rate= {k1 + Kk 2 [Cl-]} [Pt(II)] [CoIIIW12O 40]5-. The chloride ion dependent path is due to rapid substitution of chloride ion on PtCl42-. The products formed have been found to be PtCl4(aq) and PtC6 2- in the absence and presence of chloride ion respectively. Increase in the ionic strength and decrease in the relative permittivity of the medium increase the rate of the reaction. This is due to the formation of an outer-sphere complex between the two reactants. The activation parameters in the presence and absence of chloride ions have also been determined and the values support the proposed mechanism.
- Bhosale,Gokavi
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p. 799 - 802
(2007/10/03)
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- Reaction of cis-[Pt(C5H5N)2(SnCl3)2] with Oxidizing Agents
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The reactions of cis-[Pt(C5H5N)2(SnCl3)2] with Ce(SO4)2 and Cl2 in aqueous solution and also with Cl2 in the CCl4 medium were studied. It was established that the compounds of the cis-[Pt(C5H5N)2Cl4] type are formed in the reaction, i.e., oxidation of the coordinated SnCl3(-) anion is not accompanied by migration of pyridine molecules out of the complex internal sphere. This is attributable to the fact that the action of an oxidizing agent on the complex results in oxidation first of the coordinatedSnCl3(-) anion and thereafter - of the central Pt(II) atom.
- Vorob'ev-Desyatovskii, N. V.,Kukushkin, Yu. N.,Batorova, G. N.,Teterin, Yu. A.,Ivanov, K. A.
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p. 1124 - 1126
(2008/10/08)
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- Chelating ditelluroether complexes of palladium and platinum: Synthesis and multinuclear NMR studies. Structure of dibromo(meso-1,3-bis(phenyltelluro)propane)palladium(II), [Pd{meso -PhTe(CH2)3TePh}Br2]
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Palladium(II) and platinum(II) complexes of two chelating ditelluroether ligands [M(L-L)X2] (M = Pd or Pt, X = Cl, Br, or I, and L-L = PhTe(CH2)3TePh or MeTe(CH2)3TeMe) are described. The complexes have been characterized by analysis and IR, UV-visible and multinuclear NMR (1H, 125Te{1H}, 195Pt{1H}) spectroscopy. The NMR studies show that two diastereoisomers of the ligand are present in solution in each complex, meso and dl invertomers, with the former having the higher abundance. The structure of [Pd{meso-PhTe(CH2)3TePh}Br2] has been determined by X-ray diffraction. Crystals belong to the triclinic crystal system, space group P1, with a = 8.968 (1) ?, b = 10.978 (1) ?, c = 11.070 (2) ?, α = 108.16 (1)°, β = 113.15 (1)°, γ = 98.95 (1)°, and Z = 2. The structure was refined to an R value of 0.023 from 2545 reflections (F > 3σf(F)). The trends in the 125Te and 195Pt NMR chemical shifts and 1J(195Pt-125Te) coupling constants are reported and discussed and are compared with data on the corresponding diselenoether complexes. Close parallels exist between 125Te and 77Se chemical shifts in comparable complexes. Attempts to halogen oxidize the complexes to the M(IV) state have failed.
- Kemmitt, Tim,Levason, William,Webster, Michael
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p. 692 - 696
(2008/10/08)
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- Preparation and Vibrational Spectra of Fluoro-Chloro-Platinates(IV) Including Stereoisomers
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The reaction of 2- with BrF3 generates the mixed complexes 2-, n = 1 - 5, of which the species with n = 2, 3, 4 are cis-configurated.Due to the stronger trans-effect of Cl compared to F, on treatment of 2- and cis-2- with Cl- the trans-isomers are formed stereospecifically.The pure fluoro-chloro-platinates(IV) are separated by ion exchange chromatography on diethylaminoethyl-cellulose.The vibrational spectra of the mixed ligand complexes are completely assigned according to point groups D4h, C4v, C3v and C2v.The Pt-Cl stretching vibrations of 2- , trans-2-, mer-2- and >PtFCl5>2- are split by the isotopes 35Cl and 37Cl showing well resolved sharp Raman lines in the expected ratio of intensities. - Keywords: Fluoro-Chloro-Platinates(IV), Stereoisomers, trans-Effect; IR spectra, Raman Spectra
- Preetz, W.,Erlhoefer, P.
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p. 412 - 418
(2007/10/02)
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- Preparation of trans-(2-) and (2-) by Oxidative Addition to (2-)
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The oxidative addition of Br2 to (2-) in HBr yields almost pure trans-(2-), in HCl nearly pure (2-), and in CH2Cl2 by a quantitative and stereospecific reaction completely pure trans-(2-).This is confirmed by ion exchange chromatography on diethylaminoethyl cellulose and by analysis of the vibrational spectra in comparison with the IR and Raman spectra of the well-known species of the series (2-), n = 0 - 6.The literature concerning trans-(2-) and other mixed ligand complexes is critically discussed. - Keywords: Oxidative Addition, trans-Tetrachlorodibromoplatinate(IV), Pentachlorobromoplatinate(IV), IR Spectra, Raman Spectra
- Preetz, W.,Rimkus, G.
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p. 442 - 445
(2007/10/02)
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