Organometallic studies. Part XXXIII. Hydrogenation of olefins and ligand exchange reactions catalysed by iron carbonyl complexes
Abstract
The effect of diene-Fe(CO)3 and monoene-Fe(CO)4 complexes as hydrogenation catalysts in homogeneous solutions has been studied. The rates of hydrogenation of methyl sorbate (methyl hexa-2,4-dienoate) have been measured and the dependence on factors such as substrate and catalyst concentration, solvent, and pressure have been determined. Rate expressions have been derived to accommodate the experimental data. Ligand exchange between catalyst and substrate, and double-bond positional isomerization have been observed to accompany the hydrogenation reaction. Kinetic data for the ligand-exchange reaction have been obtained.
A mechanism has been proposed which is based on the concept of co-ordinate unsaturation and provides for common metal complex intermediates leading to hydrogenation, ligand exchange, or double-bond isomerization.