Carbonyl insertion reactions of methyl- and ethyl-tricarbonylcyclopentadienylmolybdenum

Abstract

Methyl- or ethyl-tricarbonylcyclopentadienylmolybdenum reacts in acetonitrile with a variety of phosphines and phosphites to afford the stable crystalline acyl complexes RCOMo(CO)₂(L)π-C₅H₅. The reactivity sequence Et > Me is observed, and rate studies with the methyl compound in acetonitrile show that the rate of reaction is independent of ligand and ligand concentration. In chloroform as solvent, the ethyl compound reacts with phosphorus ligands by simultaneous first- and second-order reactions. Arsenic, sulphur, or pyridine ligands do not react.

The mechanism and stereochemistry of these reactions is discussed in the light of infrared and ¹H n.m.r. spectroscopic measurements.