Synthesis and structural studies of four- and five-coordinated monomeric alkylaluminum O,N-chelate compounds derived from 2-aminoacetophenone. Crystal and molecular structure of the five-coordinated MeAl[OC(Me)C 6H 4-2-NH] 2 complex

Abstract

The reaction of Me 3Al with 1 and 2 equiv. of 2-aminoacetophenone yielded Me 2Al[OC(Me)C 6H 4-2-NH] ( 1) and MeAl[OC(Me)C 6H 4-2-NH] 2 ( 2), respectively. Compound 2 was also obtained in the reaction of 1 with 1 equiv. of 2-aminoacetophenone. The addition of 4-methylpyridine (py-Me) to 1 produced the Lewis acid-base adduct Me 2Al[OC(Me)C 6H 4-2-NH]·py-Me ( 3). The resulting compounds have been characterized by elemental analysis, cryometric molecular weight determination and 1H and 27Al NMR spectroscopy. These studies revealed that compound 1 has a four-coordinated chelate structure in solution, while 2 and 3 are five-coordinated monomeric complexes. The molecular structure of 2 has been confirmed by single-crystal X-ray crystallography.