ELECTRONIC-STRUCTURE AND PHOTOELECTRON-SPECTROSCOPY OF AL(ME3CNCHCHNCME3)2 AND GA(ME3CNCHCHNCME3)2

The He l and He ll spectra of M(Me3CNCHCHNCMe3)2 (M = Al or Ga) have been recorded. A complex band structure arising from ionization of the pi-3 levels of the diazadiene ligands can be understood by reference to the structural distortion from idealized D2d symmetry observed in the ground state. Other higher-lying bands are assigned to pi-2 and n + and n - ionizations. The electronic structure of the neutral molecules is discussed and the differences in bond lengths between the rings is attributed to a Jahn-Teller distortion that traps two electrons in the pi-3 orbital of one ring and one in the pi-3 orbital of the other.