화학공학소재연구정보센터
Macromolecules, Vol.38, No.6, 2072-2075, 2005
(E)-(Z) selectivity in the polymerization of 2-butene promoted by Ni(II) Brookhart-type catalysts
We offer a rationalization of the different reactivity observed in the polymerization of (E)and Z-2-butene isomers with (alpha-diiinine)Ni(II) complexes, known as "Brookhart catalysts". Quantum mechanics calculations suggest that the two isomers of 2-butene coordinate similarly to the metal and that the slower reactivity of the (Z) isomer is related to stronger steric interactions at the transition state for insertion into the Ni-chain bond. The similar coordination energies suggested that the presence of the (Z) isomer should not inhibit reactivity of the (E) isomer. This point was confirmed with polymerization experiments performed with a 40% (Z)-2-butene:60% (E)-2-butene mixture.