Showing papers on "Palladium published in 1970"
TL;DR: A method has been developed for the preparation of uniform palladium particles of diameter from 55 to 450 angstroms and uniform particles of gold layered on palladium were synthesized, being four times smaller when sodium formate was used as a reducing agent instead of sodium citrate.
Abstract: A method has been developed for the preparation of uniform palladium particles of diameter from 55 to 450 angstroms. Uniform particles of gold layered on palladium were also synthesized. Hydrothermal treatment of aluminum hydroxide sol was used to prepare rods of alumina with uniform cross section from 100 to 500 angstroms and of varying lengths. The palladium was adsorbed as individual particles on alumina rods, both present in aqueous suspension. Then the suspension was dried to give a catalyst containing metal particles of uniform size dispersed in open pores produced by the intermeshing of the alumina rods. This procedure guaranteed the absence of diffusion control in the rate of reactions observed experimentally. All stages of the preparation were monitored with the electron microscope. The kinetics of the ethylene-hydrogen reaction were examined by means of a pulse technique. The number of active sites determined by carbon monoxide titration of the surface was equal to the number of surface atoms as determined by the calculation of the quantities of compounds involved in the synthesis and electron microscope examination. Furthermore, the activity per site depended on the method of preparation, being four times smaller when sodium formate was used as a reducing agent instead of sodium citrate. This may be due to the fact that the shape of particles makes certain crystallographic planes more favorable. Decrease in the size of particles to 56 angstroms produced no effect on catalytic activity beyond that due to the increase in the number of surface atoms. The activity of commercial 5 percent palladium on alumina diluted 100-fold with alumina gave 80.4 percent conversion with propylene and 82.7 percent conversion with ethylene. Thus there was little difference in the behavior of the two olefins.
343 citations
328 citations
TL;DR: In this article, a detailed analysis of the electronic structure of palladium is presented in terms of two different band models: (1) ab initio calculations using the augmented-plane-wave method, and (2) calculations using a combined interpolation scheme augmented by inclusion of relativistic corrections.
Abstract: A detailed investigation of the electronic structure of palladium is presented in terms of two different band models: (1) ab initio calculations using the augmented-plane-wave method, and (2) calculations using the combined interpolation scheme augmented by inclusion of relativistic corrections. The width and position of the $d$-band complex are found to be particularly sensitive features of the electronic structure of palladium. A highly detailed density-of-states histogram, and estimates for the first and second derivatives of the density of states at the Fermi energy are derived. In addition, detailed comparisons are made with Fermi-surface-static susceptibility, and specific-heat experimental results. Estimates for the effects of manybody enhancements suggest that paramagnons raise the effective mass at the Fermi energy by only about 41%. Owing to the strong $s\ensuremath{-}d$ hybridization in palladium, the Fermi surface is made up almost entirely of $d$-like states. Because the Fermi energy in palladium falls near the strongly spin-orbit split levels at $X$ and $L$, spin quenching reduces the effective $g$ factor at the Fermi energy from 2 to about 1.65. This increases an estimate of the effective Stoner-enhancement factor from 10 to about 15.
223 citations
TL;DR: In this paper, a convenient preparation method of a novel palladium(0) complex, bis(dibenzylideneacetone)palladium (0), is reported.
Abstract: A convenient preparative method of a novel palladium(0) complex, bis(dibenzylideneacetone)palladium(0), is reported.
203 citations
TL;DR: Ortho metalation by palladium was observed in the reaction of lithium tetrachloropalladate(II) with various aromatic aldoximes and ketoximes in methanol in the presence of sodium acetate.
Abstract: Ortho metalation by palladium(II) was observed in the reaction of lithium tetrachloropalladate(II) with various aromatic aldoximes and ketoximes in methanol in the presence of sodium acetate. The obtained chloro-bridged complexes(7) possessed both ortho-attached palladiumcarbon σ-bonding and palladium-nitrogen coordinate bonding to oximes. Reactions of O-acyl and O-methyl oximes with lithium tetrachloropalladate(II) were also carried out. An ortho metalation was observed in the former case, but dichlorobis(O-methyl oxime)palladium(II) type complexes containing no palladium-carbon σ-bonds were predominantly formed in the latter case. The bridge-splitting reaction of chloro-bridged complexes with triphenylphosphine and the metathetic reaction with sodium bromide in acetone were carried out. In the case of potassium tetrachloroplatinate(II), an ortho metalation reaction was observed giving the complexes(10) but chloro-bridged complexes could not be isolated.
161 citations
150 citations
TL;DR: Palladium(II) acetate has a trimeric structure, of approximate symmetry D3h, in which each of the palladium atoms is joined to the other two by double acetate bridges as mentioned in this paper.
Abstract: Palladium(II) acetate has a trimeric structure, of approximate symmetry D3h, in which each of the palladium atoms is joined to the other two by double acetate bridges.
145 citations
131 citations
Patent•
25 Sep 1970
TL;DR: An ELECTRODE for use in an ELECTTOLYTE RESISTANT and ELECTROLYSIS PRODUCT RESISTant MATERIAL is described in this paper, which has a core of a FILM-FORMING METAL and a LAYER having a thickness of about 0.054 micron.
Abstract: AN ELECTRODE FOR USE IN AN ELECTROLYTIC PROCESS. THE ELECTRODE HAS A CORE OF A FILM-FORMING METAL AND A LAYER HAVING AT LEAST THE OUTSIDE PORTION OF THE THICKNESS THEREOF OF AN ELECTTOLYTE RESISTANT AND ELECTROLYSIS PRODUCT RESISTANT MATERIAL, WHICH OUTSIDE PORTION HAS A THICKNESS OF AT LEAST ABOUT 0.054 MICRON. THE LAYER IS ON AT LEAST PART OF THE SURFACE OF SAID CORE. THE MATERIAL OF THE PORTION CONSISTS ESSENTIALLY OF AT LEAST ONE OXIDE WHICH IS AN OXIDE OF AT LEAST ONE PLATINUM METAL TAKEN FROM THE GROUP CONSISTING OF PLATINUM, IRIDIUM, RHODIUM, PALLADIUM, RUTHENIUM, AND OSMIUM. THE ELECTRODE IS ESPECIALLY USEFUL IN ELECTROLYSIS OF BRINE TO OBTAIN CHLORINE.
130 citations
120 citations
TL;DR: In this article, the catalytic effect of palladium on the synthesis of vinyl acetate from ethylene has been studied, and it was shown that co-catalysts such as potassium or other alkali metals promote the abstraction of hydrogen from acetic acid and weaken palladium-oxygen bonds in dissociatively adsorbed acetic acids.
TL;DR: In this article, the synthesis, reactions, and structures associated with the'sandwich-bonded bispi-(3)-1,2-dicarbollyl) complexes of nickel and palladium, (M(n+)(1, 2-B9C2H11)2(n-4)(M=Ni,Pd), and their carbon-substituted derivatives are discussed.
Abstract: : The synthesis, reactions, and structures associated with the 'sandwich'-bonded bis(pi-(3)-1,2-dicarbollyl) complexes of nickel and palladium, (M(n+)(1,2-B9C2H11)2(n-4)(M=Ni,Pd), and their carbon-substituted derivatives are discussed. The nickel and palladium bis(dicarbollyl) systems each contain species with the metal atoms in the formal +2 (d8, two unpaired electrons for nickel, diamagnetic for palladium), +3 (d7, one unpaired electron), and +4 (d6, diamagnetic) oxidation states. X-ray diffraction studies coupled with magnetic, spectral, and electrochemical data were obtained for structural information. The uncharged (pi-(3)-1,2-B9C2H11)2M(IV) derivatives are Lewis acids which form addition compounds with a variety of 'soft' Lewis bases, e.g., halide ions, thiocyanate ion, naphthalene, etc. The C, C'-dimethyl-substituted nickel and palladium systems, M(1,2-B9H9C2(CH3)2)2, exhibit facile thermal ligand rearrangement reactions leading to three isomeric series of complexes. In these isomerization reactions, a ligand carbon atom in the icosahedral surface was found to migrate away from the metal atom while remaining adjacent to the carbon atom in the open pentagonal face of the ligand. Similar rearrangements occur in the unsubstituted Ni(1,2-B9C2H11)2 complex at 360-400C in the vapor phase. Cyclic voltammetry, optical resolution studies, kinetic and nmr data and their roles in the structure elucidation of these complexes are presented. (Author)
TL;DR: The palladium(II)-catalysed dimerization of olefins has been investigated in this article, and a mechanism involving a hydridopalladium (II) compound as the catalytically active species is suggested.
TL;DR: The binuclear and trinuclear µ-sulphido-complexes [Pt2S2(PMe2Ph)4] and [P3S2Pme2Ph6]Cl2 have been prepared by the reaction of sodium sulphide and cis-dichlorobis(dimethylphenylphosphine)platinum(II).
Abstract: The binuclear and trinuclear µ-sulphido-complexes [Pt2S2(PMe2Ph)4] and [Pt3S2(PMe2Ph)6]Cl2 have been prepared by the reaction of sodium sulphide and cis-dichlorobis(dimethylphenylphosphine)platinum(II). Their properties, reactions, and structures are discussed in this paper. In ammoniacal ethanol solution sodium sulphide reacts with cis-[PtCl2(PPh3)2] to give the complex [Pt2S(PPh3)4], probably structurally analogous to [Pt2S(CO)(PPh3)3]. The platinum(0) and palladium (0) complexes ML4[M = Pd or Pt, L = PPh3, L2=(PPh2)2C2H4] by oxidative addition of elemental sulphur give the complexes [L2MS4], which contain the novel MS4 ring system.
TL;DR: A number of sulfoxide complexes of platinum(II and palladium(II) have been synthesized, and their infrared and proton magnetic resonance spectra indicate that sulfur is the donor atom as mentioned in this paper.
Abstract: A number of sulfoxide complexes of platinum(II) and palladium(II) have been synthesized, and their infrared and proton magnetic resonance spectra indicate that sulfur is the donor atom The Pt(II) complexes are of the type PtClL (L = sulfoxide) and far-ir data suggest all have cis configurations except the diisopropyl sulfoxide complex The Pd(II) complexes PdClL are trans in the solid state but in solution most appear to revert to the halo-bridged binuclear structures PdClL The pmr spectra of the Pt(II) complexes have been analyzed, and the values of Pt-H coupling constants have been rationalized in terms of preferred conformations about the C-S bonds In suitable sulfoxides, eg, diethyl, it is clear that S coordination to Pt(II) or Pd(II) results in a significant increase in the degree of methylene proton inequivalence Magnetic anisotropic effects in these d square-planar structures are suggested to be responsible
TL;DR: The allylic groups of ethers and esters exchange with a variety of active hydrogen compounds in the presence of palladium catalysts as discussed by the authors, and the reaction time of these groups is constant.
Abstract: The allylic groups of ethers and esters exchange with a variety of active hydrogen compounds in the presence of palladium catalysts.
TL;DR: The benzyl protons of the π-benzyl ligand appear as a double J = 9 Hz at -50° and as a more complex feature at higher temperature as mentioned in this paper.
TL;DR: In this paper, the authors show evidence of long-range magnetic polarization of the palladium matrix in dilute ferromagnetic Pd(Ni) alloys, for alloys containing up to 4.7 at.% nickel.
Abstract: Neutron-scattering experiments show evidence of long-range magnetic polarization of the palladium matrix in dilute ferromagnetic Pd(Ni) alloys. The measured cross sections, for alloys containing up to 4.7 at.% nickel, are interpreted in terms of a model in which the concentration of ferromagnetically aligned giant moments is less than the concentration of nickel atoms.
TL;DR: In this article, the preparation of complexes containing palladium(II) and platinum(II)-carbon bonds by proton abstraction from planar quinoline ligands, excludes a π-arene complex as a necessary intermediate during formation.
Abstract: The preparation of complexes containing palladium(II)– and platinum(II)–carbon bonds by proton abstraction from planar quinoline ligands, excludes a π-arene complex as a necessary intermediate during formation and presents the first examples of this reaction to include alkylprotons.
TL;DR: In this article, a planar asymmetric Pd unit was used to analyze bridge splitting reactions with mono-and bi-dentate ligands bearing nitrogen or phosphorous as donor atoms.
Abstract: I.r. spectra of palladium(II) halogeno-bridged complexes of the type [Pd(N–C)X]2= azobenzene-2-C,N; NN-dimethylbenzylamine-2-C,N; and 2-methoxy-3-NN-dimethylaminopropyl; X = Cl or (Br) have been recorded in the range (600–120 cm.–1). The bridging-halogen stretching frequencies are discussed on the basis of a planar asymmetric Pd[graphic omitted]Pd unit.Bridge-splitting reactions with mono- and bi-dentate ligands bearing nitrogen or phosphorous as donor atoms are reported and the structures of the resulting products are interpretated on the basis of their far-i.r. spectra. We have also established that the v(Pd–Cl) frequency in the products in the range 300–280 cm.–1 with chloride in the trans-position to the phenyl or alkyl groups.
TL;DR: The ortho-positions of azobenzene are chlorinated upon reaction with chlorine in the presence of catalytic quantities of PdCl2 as discussed by the authors, which is the same as chlorination of chlorinated chlorine.
Abstract: The ortho-positions of azobenzene are chlorinated upon reaction with chlorine in the presence of catalytic quantities of PdCl2.