The synthesis of new iron(II) and vanadium(III) diiminepyridyl complexes is reported. The ligands were synthesized and characterized by GC/MS, 1 H and 13 C NMR spectroscopy. The corresponding complexes are characterized by mass spectrometry and in part by elemental analyses. The activated vanadium complexes were found to be highly active and selective catalysts for the oligomerization of ethene to ␣-olefins.

A series of N,N,N-tridentate vanadium(III) complexes were tested after activation with methyl aluminoxane (MAO) for ethene oligomerization and polymerization. Variations in the catalyst structure as well as the influence of physical parameters were investigated and the properties of the obtained oligomeric products were determined. Methods of altering the Schulz-Flory distribution of the oligomeric products were investigated. The product properties of the polymers and oligomers obtained with the vanadium(III) complexes and the structurally identical iron(II) complexes were compared. Depending on their substitution pattern, the N,N,N-tridentate vanadium(III) catalysts exhibit high productivities and selectivities towards ␣-olefin oligomerization products under mild conditions when activated with MAO whereas the corresponding iron complexes produce higher molecular weight materials. The synthesis of these new vanadium(III)-and iron(II)-diiminepyridyl complexes was reported earlier.

ABSTRACT:The synthesis of iron(II) complexes with various tridentate di(imino)pyridine ligands and their potential as ethene oligomerization catalysts are described. The ligands are characterized by 1 H-and 13 C-NMR spectroscopy and the complexes only by mass spectrometry due to their paramagnetism. After activation either with methylalumoxane (MAO) or with a heterogeneous cocatalyst consisting of partially hydrolyzed trimethylaluminum and silica gel, the prepared complexes proved to be good catalysts for the oligomerization of ethene. 1-Octene, 1-hexene, and 1-decene were the major products, formed in very high isomeric purity (99.9 %).

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