Equilibria and kinetics in the CO-induced, reversible disproportionation of ((C 5H 5) 2TiCl) 2 to (C 5H 5) 2TiCl 2 and (C 5H 52Ti(CO) 2. An IR study at elevated CO gas pressures

Abstract

IR studies of toluene solutions of ((C 5H 5) 2TiCl) 2 under elevated CO pressures indicate the formation of a carbonyl complex, probably (C 5H 5) 2Ti(CO)Cl, with ν(CO) 2068 cm −. This species predominates at CO pressures above 100 bar, and is reasonably stable at temperatures around −30°C. At higher temperatures, disproportionation to (C 5H 5) 2Ti(CO) 2 and (C 5H 5) 2TiCl 2 occurs. This disproportionation is reversible; at +30°C and 1 bar of CO, roughly equal concentrations of ((C 5H 5) 2TiCl) 2 and of dicarbonyl and dichloride products are in equilibrium with each other. Practically complete formation of these products occurs at CO pressures above 10 bar. Rate laws and reaction mechanisms have been studied for the disproportionation reaction and for its reverse, the comproportionation of (C 5H 5) 2Ti(CO) 2 and (C 5H 5) 2TiCl 2 to ((C 5H 5) 2TiCl) 2, which predominates at lower CO pressures.