Synthesis and structural characterization of 2,5-Bis(N-aryliminomethyl)pyrrolyl complexes of aluminum

Reaction of tridentate ligands, 2,5-bis(N-aryliminomethyl)pyrroles (la-e), with I equiv of AlMe3 in toluene afforded aluminum dimethyl complexes. AlMe2[2,5-bis(N-aryliminomethyl)pyrrolyl] (2a-e) with the release of one equiv of methane. In solution the aluminum complexes 2a-e showed C-s-symmetry as characterized by their H-1 NMR spectra, while in solid the geometry around the Al atom as crystallographically determined for 2a and 2b was found to a tetrahedral by an amido nitrogen atom of the pyrrolyl anion, a nitrogen atom of one of two imino groups and two methyl groups. The aluminum complex 2e upon activated by one equiv of B(C6F5)(3) became a catalyst for ethylene polymerization (Activity = 80 g-PE/mol-cat.h).