Synthesis of chelating, C-2-symmetric bis(silylamido) complexes of zirconium, and their activities as olefin polymerization catalysts

摘要

The zirconium bis(silylamido) complexes {[DADMB]ZrCl2}(2) (3; DADMB=2,2'-bis(tert-butyidimethylsilylamido)-6,6'-dimethylbiphenyl), and [DMBN](ZrCl2THF)-T-. (41; DMBN=2,2'-bis(tert-butyldimethylsilylamido)-1,1'-binaphthyl) were prepared from the corresponding lithiated silylamines. The structure of 3 was determined by X-ray crystallography. The benzyl and methyl derivatives of 4, [DBMN]Zr(CH2Ph)(2) (5) and [DMBN]ZrMe2 (.) THF (6), were prepared by treatment of 4 with PhCH2K and MeLi, respectively. Reaction of 5 with B(C6F5)(3) produces the crystallographically characterized zwitterionic complex [DMBN]Zr(CH2Ph)[eta(6)-PhCH2B(C6F5)(3)] (7), in which the benzyl group of the anion is coordinated in an eta(6)-fashion to zirconium. Compounds 3 and 4 are moderately active as ethylene polymerization catalysts when activated with excess MAO. Activation of 5 with 1 equiv. of [Ph3C][B(C6F5)(4)] resulted in formation of a catalyst which polymerizes neat 1-hexene to give low molecular weight polyhexene. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 56]