Thermal decomposition of the [Pt(NH3)4]2+ complex in NaX zeolite

The effect of the calcination procedure on the decomposition of the [Pt(NH₃)₄]²⁺ complex in a cesium-containing NaX zeolite was studied by thermal decomposition accompanied by mass spectrometry and diffuse reflectance spectroscopy, as well as electron paramagnetic resonance and infrared spectroscopy. The decomposition of the complex took place in two steps. Under oxygen, the [Pt(NH₃)₄]²⁺ complex was first converted into the [Pt(NH₃)₂]²⁺ complex in the first step, with predominant nitrogen release. In the second step, corresponding to the decomposition of the remaining two amine ligands, NO was also formed and adsorbed. Oxygen paramagnetic species were also observed. Under He, the decomposition also occurred in two steps with H₂ release.     

Suzuki cross‐coupling reaction of aryl and heterocyclic bromides and aromatic polybromides on a Pd(II)‐hydrotalcite catalyst

The Suzuki cross‐coupling reaction of various bromine‐containing substrates and phenylboronic acid in toluene at 90 °C on a Pd(AcO)₂Py₂ catalyst supported on an Mg? Al hydrotalcite, using K₂CO₃ as the base, was studied. The conversion and selectivity results obtained for many of the substrates were excellent and similar to those provided by more active or even homogeneous catalysts. The reactions of aryl polybromides and phenylboronic acid gave the corresponding polyaromatic compounds in variable yields depending on the particular substrate. Arylation occurred in a consecutive manner by substitution of the different Br atoms. ICP‐MS measurements of the palladium content of the catalyst performed prior to and after the reaction revealed that part of the metal is incorporated into the bulk solution; therefore, the catalytic process is not purely heterogeneous. Copyright © 2008 John Wiley & Sons, Ltd.     

Les systèmes imprimitifs dans lesquels se répartissent les combinaisonsi ài dem éléments par les substitutions du groupe cyclique de degrém

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A mechanical approach to the dissipation process in NC-AFM: experiments, model and simulation

Experiments performed using NC-AFM on a pure graphite surface suggest that the mechanical deformation of the surface under test is able to explain the observed damping signal. A simple analytical model has been built to evaluate the damping signal in terms of the mechanical properties of the surface, the amplitude of the oscillation and the tip-surface distance. Besides these experiments and a model, a virtual NC-AFM microscope has been developed, based on the Matlab language. This virtual machine allows some assumptions of the analytical model to be validated or invalidated, since no approximations are made in solving the nonlinear differential equation which controls the tip-surface interaction and the NC-AFM electronic loop is included.