Showing papers on "Palladium published in 1974"

Catalyst for electroless deposition of metals

Abstract: A solvent method for the metallization of a non-conductive surface with gold, nickel or copper is shown whereby on a substrate a thermosensitive coordination complex of palladium is deposited; the complex has the formula LmPdXn wherein L is a ligand or unsaturated organic radical, X is a halide, alkyl group or a bidentate ligand and m is an integer from 1 to 4 and n is from 0 to 3; trimethyl phosphite palladium dichloride complex is an appropriate illustration of the complex; the palladium complex is applied on the substrate in a suitable non-aqueous solution such as tetrahydrofuran solution; the complex is then baked in air at elevated temperature; the exposure to high temperature decomposes the complex leaving a residue which is catalytic to the deposition of gold, nickel, cobalt or copper from an electroless bath thereof; the non-conductive material is then immersed in an electroless bath to metallize the areas which have been rendered catalytic; the preferred thermosensitive coordination complex of palladium is trimethyl phosphite palladium dichloride; a requirement for a proper thermal exposure of the complex is that the substrate is capable of withstanding the elevated temperatures such as above 210°C; illustrative organic substrates are polyimides, polysulfones, silicones, vulcanizates, fluoroplastics, polyphenylene sulfides, polyparabanic acids, and polyhydantoin, etc.

Catalysts for electroless deposition of metals on comparatively low-temperature polyolefin and polyester substrates

Abstract: A method for the metallization of a nonconductive surface with gold, nickel or copper whereby on a nonconductive, relatively low temperature surface (such as a polyester or a polyolefin) a thermosensitive coordination complex of palladium (or platinum) is deposited from a solvent; the complex has the general formula LmPdXn wherein L is a ligand or unsaturated organic radical, X is a halide, alkyl group or a bidentate ligand and m is an integer from 1 to 4 and n is from 0 to 3; bis-benzonitrile palladium dichloride complex is an appropriate illustration; the palladium complex is applied in a thin film from a suitable nonaqueous solution solvent such as xylene, toluene or a chlorobenzene onto the surface of the nonconductive material and that thin film is thermally decomposed, such as by an infrared irradiation; the method in the preferred embodiment can be practiced without the necessity of surface etching or similar chemical conditioning of the polyester, polyamide, polyvinyl chloride, or polyolefin substrate prior to the catalytic coating; circuit element intermediates of said substrates are also disclosed.

On the Origin of the Photocatalytic Deposition of Noble Metals on TiO2

Abstract: In connection with studies on the photographic properties of the photocatalytic deposition of palladium and the electrochemical properties of were investigated. In order to study both phenomena simultaneously the experiments were performed with thin, layers deposited on a conducting substrate. It could be shown that the primary step is an anodic photocurrent (O2 evolution) which catalyzes the cathodic deposition of palladium under open‐circuit conditions. Various parameters such as space charge effects, film thickness, and doping were studied and are discussed in detail.

Palladium-catalyzed formylation of aryl, heterocyclic, and vinylic halides

Abstract: Die Bromide (I) werden in Gegenwart von Tri-n-butyl- oder Triathylamin und dem Pd-Komplex (II) mit einem CO-H2-Gemisch bei 80 bis 150°C uber die sich wahrscheinlich zunachst bildenden Organo-Pd-Verbindungen zu den Aldehyden (III) formyliert.

Reactions of Bis(acetylacetonato)palladium(II) with Triphenylphosphine and Nitrogen Bases

Abstract: Bis (acetylacetonato)palladium (II) reacts with triphenylphosphine and nitrogen bases such as pyridine, diethylamine, and N-methylbenzylamine to transform one of the chelating ligands into the carbon-bonded state. The product complexes of the type Pd(acac)2L have been isolated in high yields and characterized by IR and NMR spectra. Several reactions of Pd(acac)2PPh3 and Pd(acac)2py were also examined.

High superconducting transition temperatures in the palladium-noble metal-hydrogen system

Abstract: High superconducting transition temperatures, Tc, of 16.6, 15.6 and 13.6 K have been observed in Pd-(Cu, Ag and Au) alloys, charged with large amounts of H by means of ion implantation at liquid Helium-temperatures. A peculiar phase-transition indicates that weak phonon modes might be responsible for the high Tc-values. The difference between the maximum Tc-values can be described as a type of isotope effect Tc∞M−1/2.

Carbene complexes. Part VIII. Chromium(0), iron(0), rhodium(I), iridium(I), nickel(II), palladium(II), platinum(II), and gold(I) mono- and oligo-carbene species from electron-rich olefins

Abstract: The reaction of the electron-rich olefin 1,1′,3,3′-tetramethyl-2,2′-bi-imidazolidinylidene (I)(L2) or, in one case, of bis(N-methylbenzothiazolinylidene)(II)(L′2) with various transition metal d6 or d8 complexes yields mono- di-, or tri-carbene metal complexes of Cr0, Fe0, RhI, IrI, NiII, PdII, PtII, or AuI, such as cis-Cr(CO)4(L)2, [Ir(CO)(L)3]+, or cis-[PtMe(PPh3)(L)2]+. The reactions involve (i) displacement from the metal of a negative (Cl–, I–) or neutral [CO, tertiary phosphine, or π-allyl (transformed into σ-allyl)] ligand or ligands by one or more nucleophilic carbene moieties L or L′, (ii), for [Rh(CO)2Cl]2, bridge-splitting by L, or (iii) displacement of a halide anion by BF4–. The twenty-four new carbene complexes are stable and their ready formation in high yield serves as a further demonstration of the scope of electron-rich olefins as reagents in transition metal chemistry. They clearly behave as nucleophilic carbene (L or L′) transfer reagents.

Acetylenes and noble metal compounds. Part XI. Reactions of di-methyl acetylenedicarboxylate with dibenzylideneacetone–palladium and –platinum complexes: pallada- and platina-cyclopentadienes

Abstract: Dimethyl acetylenedicarboxylate (RC2R) reacted with the zerovalent dibenzylideneacetone (dba) palladium complexes to give the palladacyclopentadiene, [Pd(C4R4)]n, characterised as the adducts Pd(C4R4)L2[L = Ph3P, (PhO)3P, p-toluidine; L2= Ph2PCH2CH2PPh2, bipy and phen]. [Pd(C4R4)]n reacted with bromine to give Br(CR)4Br, with air and Pd(PhCN)2Cl2 to give the furan R4C4O, and with acetylenes R′C2R′to give the benzenes R4R′2C6(R′= COOMe or Ph). The platinum analogue, [Pt(C4R4)]n, has also been detected and was characterised as [Pt(C4R4)(Ph3P)2]. The mechanism of the formation of the metallacyclopentadienes and benzenes is discussed.

Determination of the noble metals in geological materials by neutron activation analysis

Abstract: Gold, ruthenium, palladium, osmium, iridium, and platinum were determined in geological materials using thermal neutron irradiation, selective adsorption of the noble metal group on Srafion NMRR ion exchange resin, and high- resolution gamma spectrometry. The method was used to analyze three USGS standard rocks, a meteorite, and a lunar soil sample. (auth)

Experimental study of the critical-point behaviour of the hydrogen in palladium system. I. Lattice gas aspects

Abstract: For the hydrogen in palladium (PdH) system, the critical point has been located at Tc=566+or-1K, rho c=0.29+or-0.01 atomic H/Pd ratio, Pc=19.89+or-0.05 atm (hydrogen pressure surrounding the palladium). Critical-point exponents delta , gamma and Delta have been determined for the critical isotherm, the isothermal compressibility of the hydrogen lattice gas (this being proportional to the relaxation strength of the elastic after-effect for the interstitial hydrogen in the palladium) and the relaxation time of the elastic after-effect, respectively. The experimental values of these exponents ( delta =3.2+or-0.3, gamma =1.01+or-0.01, Delta =1.01+or-0.1) and information from the specific heat measurements indicate that the critical-point behaviour of the PdH system is described by mean-field theory at least for epsilon =(T-Tc)/Tc approximately=10-3. This behaviour is compatible with the interaction between the interstitial hydrogens being a long-range elastic type between lattice defects in the palladium.

Critical Analysis of Heat—Capacity Data and Evaluation of Thermodynamic Properties of Ruthenium, Rhodium, Palladium, Iridium, and Platinum from 0 to 300K. A Survey of the Literature Data on Osmium.

Abstract: The literature sources of heat‐capacity data on ruthenium, rhodium, palladium, osmium, iridium, and platinum have been compiled and the data critically analyzed. Except for osmium where data are lacking, best values of thermodynamic properties have been evaluated between 0 and 300 K from the analyses. The literature values of heat capacity, the electronic coefficient of heat capacity (γ), and the zero K limiting Debye characteristic temperature (θD(0)) are compared. The sources of data are tabulated chronologically along with the temperature range of measurements, purity of sample, and the pertinent experimental procedures used. A bibliography of the references is listed.

Interaction of Palladium(II) Acetate with Sodium and Lithium Acetate in Acetic Acid

Abstract: Palladium(II) acetate in acetic acid in the absence of acetate ion exists as the trimeric species Pd3(OAc)6. The reaction of the trimer with NaOAc or LiOAc at 25° was not instantaneous. Spectral st...

Isotope effect in the superconducting palladium-hydrogen-deuterium system

Abstract: The dependence of critical temperature on hydrogen (deuterium) content in palladium hydride (deuteride) was measured on samples hydrogenized under equilibrium conditions with H(D) at high pressure. The superconductivity transitions can be observed for atomic ratios of hydrogen (deuterium) to palladium H(D)/Pd above 0.83 (0.77). The critical temperatures of deuteride are about 2.5K higher than those of hydride (at the same atomic ratios). The highest critical temperatures so far observed for the hydride and deuteride are 9.1K and 10.7K respectively. For both phases the effect of hydrostatic pressures is to decrease the critical temperature. The observed isotope effect does not support a metallic behaviour of hydrogen in palladium but is in reasonable agreement with Ganguly's model (see abstr. A6687 of 1974) for the superconductivity of palladium hydride or deuteride.