Reactions of cis-2,3-dimethylaziridine, 3-pyrroline and pyrrolidine with Me3Al and Me3Ga: Adducts and dimeric amides
Zhang YK, Budzelaar PHM, Smits JMM, de Gelder R, Hageman PR, Gal AW
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY (4): 656-665 FEB 2003

Abstract:
The reactions of Me3Al and Me3Ga with cis-2,3-dimethylaziridine (1-H), 3-pyrroline (2-H) and pyrrolidine (3-H) have been investigated. At room temperature, monomeric adducts [(Me3MLH)-L-.] are obtained (M = Al, Ga; L = 1-3). [Me3Al-1-H] is the first example of a structurally characterized adduct of an aziridine and a group 13 metal. On heating in mesitylene, all adducts except [Me(3)Ga(.)2(.)H] evolve methane to form the corresponding amides; the Ga complexes require somewhat higher temperatures for this reaction. In contrast to the unsubstituted aziridine derivatives (which are trimers), dimethylaziridine amides Me2M-1 are dimers, as shown by X-ray crystallography. NMR spectroscopic data suggest the occurrence of a cis-trans equilibrium for these dimers in solution. For the pyrroline and pyrrolidine derivatives, the X-ray structures suggested large changes in the C-C and C-N bond lengths on formation of the adducts and amides. However, DFT calculations reveal that these changes are artefacts, and that the real bond length changes are fairly modest.