Search results for "Platinum"
showing 10 items of 629 documents
The abundance of Au, Pt, Pd, and the mode of heavy metal fixation in highly polluted sediments from the Rhine River near Mainz, West Germany
1984
The Au, Pt and Pd contents of the sediments of Ginsheimer‐Altrhine River, a channel of the Rhine river which drains one of the most industrialized regions of western Europe, have been determined by flameless atomic absorption spectrophotometry. The abundances of these noble metals range from 96–460 ppb Au; 734 ppb‐31 ppm Pt and 32 ppb‐4 ppm Pd. The extremely high concentrations, particulary those of Pt and Pd, are attributed to their use in industry and are due to the formation and concentration of metal‐organic complexes, mainly at the interface between an extremely reducing and an oxidizing aquatic environment. Differential thermal analyses of the polluted sediments in comparison to the p…
Triple associates based on (oxime)Pt(II) species, 18-crown-6, and water: Synthesis, structural characterization, and DFT study
2014
Abstract The associates 2(cis-[PtCl2(acetoxime)2])⋅18-crown-6⋅2H2O (1), 2(cis-[PtBr2(acetoxime)2])⋅18-crown-6⋅2H2O (2), and trans-[PtCl2(acetaldoxime)2]⋅(18-crown-6)⋅2H2O (3) were synthesized by co-crystallization of free corresponding platinum species and 18-crown-6 from wet solvents and characterized by 1H NMR and IR spectroscopies, high-resolution mass-spectrometry (ESI), TG/DTA, and X-ray crystallography. The (oxime)Pt(II) species are assembled with 18-crown-6 and water by hydrogen bonding between the hydroxylic hydrogen atoms of the oxime ligands and the oxygen atom of water and between the hydrogen atoms of water and the oxygen atoms of 18-crown-6. In 2(cis-[PtX2(acetoxime)2])⋅18-crow…
Electrocatalytic Properties of Carbosilane‐Based Hyperbranched Polymers Functionalized with Interacting Ferrocenyl Units
2012
Two types of hyperbranched ferrocene-containing polycarbosilanes were obtained by hydrosilylation of polydiallylmethylsilane (hb-PDAMS) and polymethyldiundecenylsilane (hb-PMDUS) with diferrocenylmethylsilane. The redox properties of both polymers have been investigated both in solution and confined onto platinum electrodes. The electrocatalytic activity of polymer-modified electrodes toward the reduction of oxygen as well as the electrochemical reduction and oxidation of hydrogen peroxide has been examined.
Structural evolution of Pt/ceria-zirconia TWC catalysts during the oxidation of carbon monoxide
2004
The structural evolution of two Pt/ceria–zirconia catalysts, characterized by different amounts of supported Pt, was monitored by in situ X-ray diffraction during the anaerobic oxidation of CO at different temperatures. In a first phase, oxygen coming from the surface layers of the ceria–zirconia mixed oxide is consumed and no structural variation of the support is observed. After this induction time, bulk reduction of Pt/ceria–zirconia takes place as a step-like process, while the CO2 production continues at a nearly constant rate. This behavior is totally different from that of the metal-free support in similar reaction conditions, that show a gradual bulk reduction. In repeated oxidation…
Catalytic Performance of the New Delaminated ITQ-2 Zeolite for Mild Hydrocracking and Aromatic Hydrogenation Processes
2001
Abstract Catalysts based on NiMo and Pt supported on the new delaminated ITQ-2 zeolite have been prepared and their catalytic properties evaluated for the mild hydrocracking (MHC) of vacuum gasoil and aromatic hydrogenation. The results were compared with those obtained using other conventional supports, e.g., silica, γ-alumina, amorphous silica–alumina (25 wt% Al 2 O 3 ), and USY zeolite, all of which contain the same metal loading as the ITQ-2 material. In the case of MHC of vacuum gasoil, NiMo/ITQ-2 displayed a higher hydrocracking activity than NiMo/SiO 2 –Al 2 O 3 and NiMoγ-Al 2 O 3 , and even higher activity than NiMo/USY in the range 375–425°C. Moreover, NiMo/ITQ-2 had a selectivity …
Liquid crystal polymers from swallow-tailed mesogens
1990
Abstract Swallow-tailed compounds containing an acetylenic unit have been synthesized. Only those compounds with a three ring structure exhibited liquid-crystalline phases. The platinum catalysed addition of these monomers to compounds containing Si-H groups was used to synthesize polymeric materials. Only those polymers with the tetramethyldisiloxane unit showed mesophases. The synthesis, characterization, and phase behaviour are described.
Synthesis of aldonamide siloxanes by hydrosilylation
1998
Abstract The synthesis of hydrophobic/hydrophilic hybrid polymers based on polydimethylsiloxanes (PDMS) and carbohydrate derivatives involving a hydrosilylation step is reported. Starting with poly(dimethyl- co -hydromethyl)siloxanes (PDMS- co -HMS), O -acetylated N -allylaldonamides of various sugars can be attached to the siloxane backbone using platinum catalysts. The characteristics of different transition metal complexes in the polymer-analogous formation of SiC bonds are investigated. A generalized reaction pathway applicable to several reducing carbohydrates is established to synthesize aldonamide siloxanes in a broad variety of molecular weight and composition. The products obtaine…
Highly Luminescent Half-Lantern Cyclometalated Platinum(II) Complex: Synthesis, Structure, Luminescence Studies, and Reactivity.
2012
The half-lantern compound [{Pt(bzq)(μ-C 7H 4NS 2-κN,S)} 2]•Me 2CO (1) was obtained by reaction of equimolar amounts of potassium 2-mercaptobenzothiazolate (KC 7H 4NS 2) and [Pt(bzq)(NCMe) 2]ClO 4. The Pt(II)•••Pt(II) separation in the neutral complex [{Pt(bzq)(μ-C 7H 4NS 2-κN,S)} 2] is 2.910 (2) Å, this being among the shortest observed in half-lantern divalent platinum complexes. Within the complex, the benzo[h]quinoline (bzq) groups lie in close proximity with most C•••C distances being between 3.3 and 3.7 Å, which is indicative of significant π-π interactions. The reaction of 1 with halogens X 2 (X 2 = Cl 2, Br 2, or I 2) proceeds with a two-electron oxidation to give the corresponding d…
<strong>Synthesis and Platinum (II) Complexes of Different Polyazacyclophane Receptors</strong>
2015
During the last years, research on coordination chemistry of platinum has aroused great interest due to their potential biological applications. Herein, we report the interaction of PtCI42- with different polyazacyclophanes containing a pyridine unit as aromatic spacer. Formation of complexes has been studied by 1H and 195Pt NMR spectroscopy. Analysis of the recorded spectra of D2O solutions containing L and PtCl42- in a 1:1 molar ratio at acidic pH shows the evolution with time of the 1H and 195Pt signals. Different crystal structures have been solved by X-ray diffraction analysis. At acidic pHs, the metal ion is coordinated by the central amino group of the macrocyclic cavity and three ch…
{1,1′-Bis[bis(5-methyl-2-furyl)phosphino]ferrocene-κ2P,P′}dichloroplatinum(II) dichloromethane hemisolvate
2005
The synthesis of the title compound, [FePtCl2(C15H14O2P)2]·0.5CH2Cl2, has been achieved by reacting PtCl2(PhCN)2 with the 1,1′-bis[bis(5-methyl-2-furyl)phosphino]ferrocene chelating ligand. The environment at the Pt atom can be described as distorted square-planar, with two cis-Cl atoms and two cis-P atoms.