N,N-Dialkylcarbamato complexes as precursors for the chemical implantation of metal cations on a silica support. Part 3 Palladium

Abstract

Chemical implantation of palladium(II) has been carried out under mild conditions by reacting trans-Pd(O ₂ CNEt ₂ ) ₂ (NHEt ₂ ) ₂ with the silanol groups of amorphous silica, carbon dioxide and secondary amine being released in the process. The palladium-containing silica has been characterized and the coordination environment of the implanted cation has been defined by ¹³ C CP MAS NMR, DRIFT and XPS spectra, and by WAXS measurements. Silica-bonded palladium(II) was reduced thermally in vacuo or with dihydrogen at room temperature. Catalytic activity in the hydrogenation of cyclohexene was found for all samples containing the silica-supported reduced palladium; the best results, with rates independent of olefin concentration, were found for the samples treated thermally (200°C) under reduced pressure.