A cationic aluminum methyl complex supported by an anionic tacn ligand

Reaction of (tacn)H [(tacn)H = 1,4-diisopropyl-1,4,7-triazacyclononane] with AlMe3 leads to the formation of the thermally stable adduct [(tacn)H].AlMe3 (1). The dimeric aluminum dimethyl complex [(tacn)AlMe2](2) (2) was obtained by metathesis of (tacn)Li-2 with two equivalent of Me2AlCl in toluene at 80 degreesC. In 2 the anionic nitrogen atoms bridge the two AlMe2 units while the neutral amino atoms are free of coordination. Treatment of 2 with 2 equiv. of B(C6F5)(3) in CH2Cl2 yielded a well separated ionic aluminum methyl borate complex [((tacn)AlMe)(2)][MeB(C6F5)(3)](2) (3), featuring five-coordinate aluminum centers. Molecular structures of 2 and 3 were determined by single-crystal X-ray crystallography. (C) 2003 Elsevier Science B.V. All rights reserved.