π-Complexes of Alkenes to Trivalent Aluminum

The structures of simple π-complexes of aluminum alkyls and aluminum alkyl halides were explored with use of ab initio molecular orbital theory. Such structures have been proposed as either intermediates or transition structures in mechanisms for oligomerization of ethylene, carbalumination, and hydroalumination. Complexes of AlR_3-nCl_n (R = H, CH₃) with ethylene and propene were found to be stable intermediates, not transition structures. The energies of binding have been estimated by using post-Hartree-Fock techniques.