Spectroscopic studies on adsorbed metal carbonyls. Part 1. Interaction of [Rh4(CO)12] and [Rh6(CO)16] with alumina, silica, and titania
Abstract
The interaction of [Rh4(CO)12](1) and [Rh6(CO)16](2) with Al2O3, TiO2, and SiO2 has been monitored by i.r. spectroscopy, using isotopic substitution and spectrum simulation techniques. Conversion of (1) into (2) has been demonstrated on Al2O3 and TiO2. Isolated RhI(CO)2 sites are considered to exist on all three oxides after oxidative fragmentation of (1) or (2). Rh(CO)n(n= 3, or possibly 4) sites were also suggested from (1) and TiO2 or SiO2. Extended reaction times (TiO2 and Al2O3) or exposure to the i.r. spectrometer beam (Al2O3) causes aggregation to metal crystallites.