Treatment of a solution of benzyltricarbonyl-π-cyclopentadienylmolybdenum in acetonitrile with phosphines and phosphites (L) affords the crystalline complexes trans-PhCH2·COMo(CO)2(L)(π-C5H5); allyltricarbonyl-π-cyclopentadienylmolybdenum undergoes analogous reactions forming the complexes trans-C3H5·COMo(CO)2(L)(π-C5H5). cls-But-2-enyltricarbonyl-π-cyclopentadienylmolybdenum reacts with triphenylphosphine in acetontrile to form trans-CH3·CH[graphic omitted]CH·CH2·COMo(CO)2(Ph3P)(π-C5H5). When trans-PhCH2·COMo(CO)2(Ph3P)(π-C5H5) is heated (140°) decarbonylation occurs with the formation of PhCH2Mo(CO)2)Ph3P)(π-C5H5). Kinetic measurements show that the rate-determining step in the carbonylation reactions does not involve the reacting ligand. The stereochemistry of these reactions is discussed on the basis of 1H n.m.r. and i.r. spectroscopic measurements.
