AB-INITIO STUDY ON THE DIMER STRUCTURES OF TRIMETHYLALUMINUM AND DIMETHYLALUMINUMHYDRIDE

The dimer structures of trimethylaluminum (Al(CH3)(3), TMA) and dimeth ylaluminumhydride (AIH(CH3)(2), DMAH) have been investigated using ab initio molecular orbital calculations. It has been shown that the stru cture of the TMA dimer is C-2h; on the other hand, that of the DMAH di mer has been calculated to be D-2h. The dissociation energy of the TMA dimer was only 4.2 kcal/mol, while that of the DMAH dimer was 32.3 kc al/mol, which is considerably larger than the TMA dimer. These results indicate that the dimer contributes directly to surface reactions whe n DMAH is used as the source material for ALE.