Kinetics and mechanism of the substitution of olefinic ligands by triphenylantimony in (π‐monoolefin) tetracarbonyliron complexes

The kinetics of the reaction have been studied in toluene solution. The reaction occurs by a dissociative mechanism and the observation of an appreciable mass law retardation effect shows that Fe(CO)4 is produced as an intermediate. Analysis of the effect of the substituent X on the stability of the complexes leads to the conclusion that π‐backbonding between the metal and the olefinic ligand is the major cause of the M‐olefin bond strength.