Gunnar Westermark, I. Persson
Dec 1, 1998
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Influential Citations
15
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Journal
Colloids and Surfaces A: Physicochemical and Engineering Aspects
Abstract
Abstract The chemisorption of dimethylphenyl-, triphenyl- and tricyclohexylphosphine deposited from dilute toluene solution on the surfaces of purified gold, silver, copper, palladium, platinum and rhodium powders has been studied. The infrared spectra of the species adsorbed on the metal powder surfaces have been recorded by means of an FTIR spectrometer equipped with focusing diffuse reflectance unit optimized for specular reflectance and operating at ordinary temperature and pressure. Assembled layers of the tertiary phosphines were obtained on the surfaces of all metals studied. A subsequent ultrasonic treatment of the samples in ethanol left a thin layer of phosphine on the metal surfaces. The treatment of the powder samples in this study has been similar to a previous study performed on smooth metal surfaces to enable comparisons. The shifts and changes in intensities of bands caused by interactions of the phosphine molecules with the surface observed in this study are in good agreement with the results from a grazing angle study. Raman spectroscopy has also been applied in this study to show the possibility of recording spectra of ultrathin layers of organic molecules. The surface coverage has been estimated from the surface areas of the powders, determined by BET isotherm technique, and the concentration of dimethylphenylphosphine and dimethylphenylphosphine oxide in the solution phase as determined by gas chromatography. Solid coordination compounds of copper(I), silver(I) and gold(I) with the ligands dimethylphenyl-, methyldiphenyl- and triphenylphosphine have been synthesized. The corresponding phosphine oxides have been prepared by a simple procedure. The band shifts observed for the phosphines adsorbed to the metal surfaces have been compared with the infrared and Raman spectra of the coordination compounds and the phosphine oxides in order to improve our understanding of the chemisorption of tertiary phosphines on metal surfaces. The catalytic effect of coinage and platinum group metal powders at the oxidation of dimethylphenylphosphine to dimethylphenylphosphine oxide by oxygen has been studied.