Di(imino)pyridine Complexes as Catalysts for Homogeneous Olefin Oligomerization Reactions

Abstract

The synthesis of bis(arylimino)pyridine complexes of seven different transition metals and their applications after activation with methylaluminoxane (MAO) in homogeneous olefin dimerization and oligomerization reactions is described. The synthesis of bis(arylimino)pyridine ligand precursors was achieved via condensation reactions of 2,6-diacetylpyridine with different substituted anilines. The bis(arylimino)pyridine compounds were reacted with 3d transition metal halides of the metals Ti, V, Cr, Mn, Fe, Ni and Co to give the corresponding mono-ligated complexes. Among a series of complexes with varying metal centers, but containing the same ligand, the bis(arylimino)pyridine iron(III) complex provided the best results for the dimerization of 1-hexene after activation with MAO. Beside linear products, methyl branched olefins were detected as well. For all product compositions, a marginal higher amount of hexene dimers was observed, e.g. the insertion of 1-hexene proceeds slightly faster than the insertion of 1-pentene.