Rhodium catalysts prepared by attachment of Rh6(CO)16 onto chemically modified silicas. Characterization of the infrared spectra in the carbonyl stretching region
Abstract
The carbonyl infrared spectra of catalysts prepared by adsorption of Rh6(CO)16 onto ligand-modified silica have been assigned with the assistance of 13CO substitution experiments. In the fully carbonylated state the catalysts contain Rh(CO)2 groups and partial decarbonylation leads to the formation of Rh(CO) groups. On the basis of infrared spectroscopic and other data it is deduced that the rhodium is not present as hexarhodium clusters but as mononuclear surface complexes, LnRh(CO)2 and LmRh(CO), where L are surface attached ligands and n and m are unknown.