Kinetics and mechanism of substitution of olefinic ligands by carbon monoxide in tetracarbonyl-π-olefiniron complexes

Abstract

The mechanism of the reaction Fe(CO)₄(CH₂CHX)+ CO → Fe(CO)₅+ CH₂CHX (X = OEt, Bu, Ph, CO₂Me, and CN) has been studied in toluene. The reaction mode has been found to be dissociative with intermediate formation of Fe(CO)₄; an appreciable mass law retardation effect of the olefinic ligand has been found. The thermal stability of the olefinic complexes is correlated with the electron-withdrawing power of the substituent X. The relative order of thermodynamic stability of the complexes has been deduced from the mass law retardation effects of the olefinic ligands.