HeI Photoelectron Spectroscopy of Trialkylaluminum and Dialkylaluminum Hydride Compounds and Their Oligomers

Abstract

The HeI photoelectron spectra of trimethylaluminum, triethylaluminum, dimethylaluminum, and diethylaluminum hydrides were recorded as a function of temperature. From the spectra observed at different temperatures the spectra of the pure monomers and the trimethylaluminum, dimethylaluminum, and diethylaluminum hydride dimers and some of the bands related to the dimethylaluminum hydride trimer have been obtained. The spectra were interpreted with the aid of ab initio quantum chemical calculations, including Hartree−Fock/Koopmans, outer valence Green's function, and equation of motion coupled-cluster ionization energy calculations. The vertical ionization energies predicted by the latter two methods are in excellent agreement with the experimental values. Furthermore, the association capability of these compounds, the effects of the substituents, and the degree of association on the electronic structure are also discussed.