TRANSITION-STATES FOR HYDROALUMINATION OF ALKENES AND ALKYNES - ABINITIO MOLECULAR-ORBITAL STUDIES

The insertion reaction of an alkene or alkyne into an Al-H bond as well as its reverse reaction, beta-hydride elimination, were investigated. High level ab initio molecular orbital techniques were used to characterize the transition structure which connects the intermediate pi-complex of the aluminum alkyl and the alkene or alkyne to the insertion product. An analysis of the bonding and relative energies of various methyl-substituted transition structures provides insight into the factors controlling the regio- and stereochemistry of the final products.