Carbonyl substitution reactions of chlorotricarbonyl-(π-tetrahydroindenyl)molybdenum: the ‘long-range effect’ of an aromatic ring

The mechanism, rate, and activation parameters for carbonyl substitution reactions of the π-tetrahydroindenyl complex (π-C9H11)Mo(CO)3Cl, but closely similar to those of the π-cyclopentadienyl complex (π-C5H5)Mo(CO)3Cl. This pattern cannot be predicted from the ground-state properties of the three complexes and would not be expected on simple steric grounds. It is suggested that the anomalous behaviour of the π-indenyl complex is due to a stabilizing effect of the six-membered aromatic ring on the transition state for carbonyl substitution reactions.