Pd+Zr and Pd+Hf co-doped aluminide coatings were deposited on the Mar-M247 nickel superalloy by palladium electroplating followed zirconizing-aluminizing or hafnizing-aluminizing processes. Both consisted of two zones, outer interdiffusion one build ?-(Ni,Pd)Al phase. Hafnium zirconium formed inclusions that precipitated at border zones close to surface (only in Zr+Pd modified coating). Oxidati...

The experimental technique presented in this article is aimed at measuring the absorption of hydrogen or deuterium gas in a thin palladium sample while the system is at low temperature. A result for deuterium is described, consisting in the measurement of the equilibrium loading ratio X (called also D/Pd ratio, atomic), as a function of pressure, on a palladium film 3.6 μm-thick at 150 K. Value...

Pd(OAc)(2):pyridine (1:4) is an efficient catalyst system for the oxidation of alcohols with molecular oxygen. A mechanistic study of this reaction reveals that pyridine promotes the aerobic oxidation of palladium(0) but inhibits the oxidation of alcohol by palladium(II). Kinetic results reveal that turnover-limiting substrate oxidation consists of (i) formation of a palladium(II)-alkoxide, (ii...

The palladium-catalyzed decarboxylative allylic alkylation of enol carbonates derived from lactams and ketones is described. Employing these substrates with an electronically tuned Pd catalyst system trisubstituted chiral centers are produced. These stereocenters have been previously challenging to achieve using Pd complex/chiral P-N ligand systems.

Palladium nanohexagons were prepared using a seed-mediated method. Their catalytic performance in 2-methyl-3-butyn-2-ol hydrogenation was compared to the one of monodispersed Pd nanospheres. Quantitative correlations between initial turnover frequencies (TOFs) and nanoparticle surface compositions showed independence of TOFs calculated per atoms on Pd(111) facets on particle size and shape.

Intermolecular Heck reaction of common alkyl halides, a longstanding problem in palladium catalysis, is realized with a simple Pd/dppf catalyst. Both primary and secondary alkyl halides are suitable for coupling with aromatic olefins. Single electron transfer from (dppf)Pd(0) to alkyl halide initiated the catalytic cycle and gave alkyl radicals.

A cyclization reaction between enamides and alkynes catalyzed by palladium(II) acetate is described. In this method, the molecular oxygen serves as an efficient oxidant for the Pd(II)/Pd(0) catalytic cycle. The simple reaction conditions permit this methodology to be used as a general tool for the preparation of multi-substituted pyrroles.

The phenomenon of hydrogen absorption by metals, discovered about 100 years ago, nowadays demands some interest for technological reasons (hydrogen storage, fuel cells, hydrogen embrittle­ ment of construction materials). The palladium/hydrogen system claims for an exceptional position among the metal hydrides of the protonic type: because of its relative simplicity the Pd/H2-system serves as a...

A novel palladium-catalyzed cyclization of bromoacrylamides with isocyanides gives substituted 2,5-diimino-furans, which can be used as the precursor of maleamides. This synthesis likely proceeds, after isonitrile insertion into C–Pd(II) bond, through the coordination of the amide oxygen atom to the Pd(II) centre as a key step.

Palladium-catalyzed regio- and enantioselective addition of azole heterocycles to alkoxyallenes was developed (up to 92% yields and up to 94% ee). DFT calculations suggest a new Pd(0)-driven mechanistic pathway proceeding through protonation of the Pd-coordinated allene (4-PdL2), which develops a strongly nucleophilic character at the central C atom.