Diffuse reflectance infrared and temperature-programmed decomposition studies of (η6-benzene)tricarbonylchromium(0) and (η6-anisole)tricarbonylchromium(0) on NaX zeolite

Abstract The decomposition of (η 6 -benzene)tricarbonylchromium(0) (BTC) and (η 6 -anisole)tricarbonylchromium(0) (ATC) supported on NaX zeolite has been studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed decomposition (TPDE). TPDE shows that CO gas is evolved from both samples between about 425 and 575 K, with a maximum near 470 K. The DRIFTS spectra indicate that both BTC and ATC adsorb on NaX zeolite in two different sites. Samples of the adsorbed complexes prepared at different temperatures have a considerable amount of the Cr(CO) 3 /NaX surface species present below 425 K, the temperature at which CO begins to be evolved. The (arene)tricarbonylchromium(0) decomposes by forming the surface chromium tricarbonyl as the arene becomes detached from the chromium. Carbon monoxide is evolved when the surface tricarbonyl decomposes. By adding either benzene or anisole to a sample of Cr(CO) 3 /NaX at about 403 K, BTC or ATC is formed within the NaX zeolite.