He(I) and He(II) photoelectron spectra of some organozinc and organoaluminium radicals containing 1,2-bis(t-butylimino)ethane

Abstract

He(I) and He(II) spectra of the organometallic radicals AlEt₂(L)·, ZnMe(L)·, and ZnEt(L)·(L = Bu^tNCH–CHNBu^t) generated in the gas phase have been measured. The observed ionization energies (i.e.s) for AlEt₂(L)· are qualitatively in agreement with results from an MNDO calculation performed for the model radical AlMe₂(L)·(L = MeNCH–CHNMe). Very low i.e.s for the radical electrons (about 6 eV) are observed. These electrons reside mainly in the ligand π* orbital. Considerable delocalization of all valence molecular orbitals over the whole molecule is demonstrated. Strong charge donation from the N lone pairs towards the metal is apparent both in the i.e.s of the ligand orbitals without metal interactions and in the low i.e. values for Zn 3d ionizations.