Olefin Oligomerization via Metallacycles: Dimerization, Trimerization, Tetramerization, and Beyond

Recent advances in the area of Olefin Oligomerization via metallacycles that include dimerization, trimerization, tetramerization, and beyond, are reviewed. Studies have found that metallacyclopentane decomposition to 1-butene many not be particularly facile due to the absence of metallacycle expansion. Follow-up studies concentrated on the N-H functionality and the Cr oxidation state and role of MAO show that activities and selectivities to 1-hexene are similar to the original Cr(III) complexes. Nenu and Weckhuysen prepared silica-supported triazacyclohexane complexes, by treating the reduced Phillips polymerization catalyst with triazacyclohexane ligands in dichloromethane. The influence of N-aryl functionality investigated by Killian et al. shows that the selectivity was mainly dependent upon the steric bulk attached to nitrogen, and less so on the group's basicity.