Spectroscopic evidence for the involvement of hydroxyl groups in the formation of dicarbonylrhodium(I) on metal oxide supports

Specific OH(a) groups on Al2O3 or SiO2 are consumed as CO interacts with supported Rh crystallites to produce Rh/sup I/(CO)2(a). The reaction Rh + -OH(a) + 2CO(g) Rh/sup I/(CO)2(a) + 1/2 H2(g) has been shown to involve isolated OH(a) groups rather than H-bonded associated OH(a) species. This reaction can be reversed by using H2(g) to destroy Rh/sup I/(CO)2 with regeneration of the isolated OH(a) species. Comparative kinetic studies of OH(a) and OD(a) species indicate that the rate-controlling step in the production of Rh/sup I/(CO)2(a) does not exhibit a measurable isotope effect.