Dialkylaluminium-(N-methylsilyl)amides give characteristic massspectrometric fragments dependent on alkyl or aryl substituents at nitrogen in addition to the methylsilyl group. The mass spectra of these compounds formulated as R1N(R2)AlR32 (R1 HMe2Si, Me3Si; R2 alkyl, Ph; R3 alkyl) were interpreted with regard to substituent effects. To verify the given interpretations some energy data are