Halogen substituted iron(III) di(imino)pyridine complexes as catalysts for 1- pentene/1-hexene co-oligomerization reactions

Nine different bis(arylimino)pyridine complexes of Fe(III) with different halide substituents (F, Cl, Br, I) at different positions of the iminophenyl group of the ligand have been synthesized, characterized and applied for homogeneous 1-pentene and 1-hexene oligomerization and co-oligomerization reactions after activation with methylaluminoxane (MAO). The best activity in 1-hexene oligomerization (152 kg/mol.h) was observed for 4/ MAO with an iodine substituent in para position of the iminophenyl group. Fluorine substituents in the meta position of the iminophenyl group proved as disadvantageous (1 kg/mol.h) in homo-oligomerization reactions but advantageous in co-oligomerization reactions of 1-pentene and 1-hexene. Obviously, tiny electronic or steric differences at the active sites of the corresponding catalysts are responsible for this result (structure-property relationship). The product distributions of the co-dimerization reactions of 1-pentene and 1-hexene reflected a binominal behaviour with dominating co-products. The ratio of dimers is 1:2:1 (C10:C11:C12) while the trimers (pentadecenes up to octadecenes) show proportions of 1:3:3:1.