A cationic aluminum methyl complex supported by an anionic tacn ligand

Abstract

Reaction of (tacn)H [(tacn)H=1,4-diisopropyl-1,4,7-triazacyclononane] with AlMe 3 leads to the formation of the thermally stable adduct [(tacn)H]·AlMe 3 ( 1). The dimeric aluminum dimethyl complex [(tacn)AlMe 2] 2 ( 2) was obtained by metathesis of (tacn)Li 2 with two equivalent of Me 2AlCl in toluene at 80 °C. In 2 the anionic nitrogen atoms bridge the two AlMe 2 units while the neutral amino atoms are free of coordination. Treatment of 2 with 2 equiv. of B(C 6F 5) 3 in CH 2Cl 2 yielded a well separated ionic aluminum methyl borate complex [((tacn)AlMe) 2][MeB(C 6F 5) 3] 2 ( 3), featuring five-coordinate aluminum centers. Molecular structures of 2 and 3 were determined by single-crystal X-ray crystallography.