Monomeric organoaluminium complexes RAl(OR*)2 and R2AlOR* with an optically active amino alkoxide ligand

The reactions of trialkylaluminium, R3Al, with (S)-(-)alpha,alpha-diphenyl-2-pyrrolidinyl-methanol have been investigated, in which unusual bis-complexes RA1(OR*)(2) were obtained [OR* = (S)-alpha,alpha-diphenyl-2-pyrrolidinyl-methoxide (Dpm), R = Me (1), Et (2), 1-Nor (3)]. A similar reaction carried out with R = t-Bu yields, by contrast, the expected mono-alkoxide R2AlOR* (4). All compounds were characterised by X-ray crystallography and NMR spectroscopy. The molecular structures are monomeric. In 1-3, the aluminium centres bonded to the nitrogen atoms of two chelating ligands are five-coordinate, while the metal atom contained in 4 is tetrahedrally surrounded. The absolute structures of all complexes were determined from X-ray diffraction data. The formation of the dative Al-N bonds is stereospecific in all cases. (C) 2000 Elsevier Science S.A. All rights reserved.