A palladium-oxo complex. Stabilization of this proposed catalytic intermediate by an encapsulating polytungstate ligand

A terminal Pd-oxo unit is reported. The unit is encapsulated in a cavity defined by two [A-alpha-PW9O34]9- units fused together by one [WO(OH2)]4+ center and forms from Pd(II) in buffered media in the presence of O2. Both X-ray diffraction and EXAFS data are consistent with a Pd-oxo bond distance of ca. 1.65 A. 17O NMR studies confirm that the solid-state structure is maintained in solution.     

Growth of submicrometer-scale rectangular parallelepiped rutile TiO2 films in aqueous TiCl3 solutions under hydrothermal conditions

Evolution of a new morphology of rutile TiO2 films consisting of nearly single-crystalline parallelepipeds was achieved through hydrothermal treatments of aqueous TiCl3 solutions in the presence of NaCl.     

Infrared spectra and rotational isomerism of ethylenediammonium ion in aqueous solution

The infrared spectra of ethylenediamine hydrochloride, sulfate and their N-deuterium derivatives in water or heavy water were studied at various pH or pD and at various concentrations. The frequencies of the CH₂ deformation vibration bands in the region 1500-1250 dm^?1 were found to be sensitive to the conformation of the ethlenediamine molecule and mono- and diammonium ions. The behaviors of these bands indicate that in aqueous solution the ethylenediamine molecule takes the gauche form, the ethylenemonoamine monoammonium ion takes mostly the gauche form and the ethylenediammonium ion takes both the trans and gauche forms.     

Activation of electrode surfaces: semiquantitative characterization of electrode surfaces modified with heteropolyanions

Several Techniques have been used successively or in combination to approach a better understanding of surfaces modified by silicotungstic heteropolyanion. Due to the strikingly high activity of these electrodes for the hydrogen evolution reaction, in particular, there exists a need to identify the chemical composition of the catalyst, to evaluate the amount of catalyst on the surface, and to study the electrochemical behaviour of the “catalyst” itself. Plasma emission spectrometry shows semi-quantitatively that the catalyst resembles the starting material closely, although it is not possible at present to give the exact chemical formula. Electron microprobe analysis (EMA) confirms the presence of tungsten, and especially silicon, on the surface, even though the concentration of this last element is very low. The absence of platinum in the starting HPA, as well as on the electrode surface, is also clearly demonstrated by EMA, which is of prime importance in showing that the “HPA catalyst” is active by itself. Combined coulometry and UV-visible spectroscopy have been used to evaluate the amount of HPA consumed during electrolysis. Cyclic voltammetry shows a surface redox couple corresponding to the catalyst, and well separated from the first redox couple of SiW₁₂O^4-₄ in 0.5 M H₂SO₄ solution. A better understanding of the activation-deactivation processes of the catalytic electrode surface ensues.