Some investigations of inorganic and catalytic systems by esca and other spectroscopic

Abstract

x-ray photoelectron spectroscopy (ESCA) has been used to study platinum complexes, structural and bonding effects in complexes of the type (R(_3)P)(_2)PtXY have been investigated, bridging and terminal chlorines in dimeric complexes, L(_2)Pt(_2)Cl(_4), have been distinguished and a correlation found between C12p binding energies and (^35)CI n.q.r. frequencies in square-planar Pt-Cl complexes. At ambient temperature the complex (Ph(_3)P)(_2)Pt(C(_2_C1(_4)) has been found to undergo layer isomerisation to (Ph(_3)P)(_2)PtCl(CCl = CC1(_2)) . Using infrared spectroscopy, differences between surface and bulk effects have been followed and confirmed for related complexes. Isomerisation could be arrested by studying the olefin complex at -110 C. Some complexes of the methyleneamino (R(_2)C:N-) and aza-allyl/allene (R(_2)CNR(_2)) ligands with molybdenum and tungsten carbonyl derivatives have been studied by ESCA to gain further information on their possible bonding modes. A correlation has been found between the metal binding energies and the stretching frequencies of attached carbonyl groups. In order to acquire information on a Pt/Si0(_2) catalyst for eventual ESCA study, background investigations involving kinetic, deuterium addition/exchange and i.r. studies on the H(_2)-C(_2)H(_4)-Pt/Si0(_2) system have been performed. Catalyst poisoning has been investigated and eliminated, the reported occurrence of 'hydrogen spillover' has been disproved and the ethylene exchange rate found to be a sensitive probe of small, but reproducible support effects. The i.r. data obtained goes some way to resolving inconsistencies in the literature. The same catalyst has been subjected to preliminary ESCA investigation, with especial regard to the state of the metal during preparation and subsequent cleaning treatments. The available vacuum conditions were found to be unsuitable for adsorption studies.