MECHANISM OF PIPERIDINE (PIP) DISSOCIATION FROM CIS-(TRICYCLOHEXYLPHOSPHINE) (PIP)TETRACARBONYL MOLYBDENUM(0)

Piperidine (pip) dissociates from cis-eta(1)-(P(cy)(3))(pip)Mo(CO)(4) (cy = cyclohexyl) to produce cis-eta(2)-(P(cy)(3))Mo(CO)(4), where P(c y)(3) forms a five-membered ring bonded to molybdenum via phosphorus a t one end and hydrogen (agostic bond) at the other end. Results from k inetics studies suggest that loss of pip from cis-eta(1)-(P(cy)(3))(pi p)Mo(CO)(4) takes place via a dissociative mechanism, where the electr onically unsaturated species cis-eta(1)-(P(cy)(3))Mo(CO)(4) is formed during the reaction. This intermediate is very reactive and is concurr ently attacked by pip to produce the parent complex cis-eta(1)-(P(cy)( 3))(pip)Mo(CO)(4) and by cy from the coordinated P(cy)(3) to give the product of the reaction.