426827-42-1Relevant articles and documents
Organoborane-modified silica supports for olefin polymerization: Soluble models for metallocene catalyst deactivation
Metcalfe, Robert A.,Kreller, David I.,Tian, Jun,Kim, Hoon,Taylor, Nicholas J.,Corrigan, John F.,Collins, Scott
, p. 1719 - 1726 (2002)
Treatment of silsesquioxane 1 with 3.3 equiv of the reactive organoboranes 2 [(C6F5)2BX; X = H or Cl] provides the novel, trifunctional organoborane 3, which was characterized by spectroscopic means and single-crystal X-ray crystallography. Compound 3 is an effective cocatalyst for ethylene polymerization in combination with Cp2ZrMe2 but only when these two compounds are combined in situ, in the presence of monomer, suggesting limited stability of the putative ion-pair derived from these compounds. Reaction of 3 with Cp2ZrMe2 in toluene solution leads to formation of MeB(C6F5)2- and Cp2Zr-functionalized silsesquioxane 5 at room temperature. Monitoring of this reaction by NMR spectroscopy at low temperatures indicates that the only ion-pair present is [Cp2ZrMe] [Me2B(C6F5)2] (4), which results from reaction of Cp2ZrMe2 with the byproduct MeB(C6F5)2. Formation of 4 is reversible under these conditions, while production of 5 (from 3 and Cp2ZrMe2) is not; the latter process occurs at a rate that exceeds that observed for independent decomposition of 4 to form Me2B(C6F5) and Cp2Zr(C6F5)Me. These studies suggest that the active polymerization catalyst generated in situ from 3 and Cp2ZrMe2 is probably ion-pair 4.
