Bis(imino)cyclodiphosph(V)azane complexes of late transition metals: Efficient catalyst precursors for ethene and propene oligomerization and dimerization

Abstract

New bis(imino)cyclodiphosph(V)azanes and their Fe, Co, and Ni complexes were synthesized and characterized. The MAO actived Ni and Co complexes exhibited high catalytic activity in ethene dimerization and oligomerization [up to 4000 kg of olefins/(mol cat h)], as well as in propene dimerization, whereas Fe derivatives yielded negligible activity. The dependence of catalytic behavior on oligomerization conditions was studied. The Ni catalysts revealed high selectivity in ethene (butene content up to 94%) and especially in propene dimerization (hexene content up to 100%). The Ni complexes catalyzed also codimerization of ethene and propene, with the yield of the resulting pentenes depending on the initial ethene/propene ratio. The main propagation route in the propene dimerization with Co catalysts was a 1,2 insertion of propene into the M H bond followed by a 2,1 insertion and β-H elimination, whereas with Ni catalysts, the reaction proceeded with equal probabilities via 1,2–1,2 and 1,2–2,1 propene insertions.