Synthesis and Structural Characterization of 2,5-Bis(N-aryliminomethyl)pyrrolyl Complexes of Aluminum

Reaction of tridentate ligands, 2,5-bis(N-aryliminomethyl)pyrroles (1a-e), with 1 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 Cs-symmetry as characterized by their 1H 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).