Zirconium-chelate and mono-?- cyclopentadienyl zirconium-chelate/ methylalumoxane systems as soluble Ziegler-Natta olefin polymerization catalysts

Zirconium-chelate and mono-eta-cyclopentadienyl zirconium-chelate complexes were tested as ethene and propene polymerization catalysts in combination with methylalumoxane (MAO) as a co-catalyst: in particular (acac)(n)ZrCl4-n (1a-c) (acac = acetylacetonato), (dbm)(n)ZrCl4-n (2a-2c) (dbm = dibenzoylmethanato = 1,3-diphenylpropanedionato) (n=2-4) and (dbm)(2)ZrCl2(thf) (3) (thf = tetrahydrofuran), (eta-C5H5)[H2B (C3H3N2)(2)]ZrCl2 (4), (eta-C5H5)[HB (C3H3N2)(3)] ZrCl2 (5) and (eta-C5H5)[(Me3SiN)(2) CPh]ZrCl2 (6). Polymerization productivities comparable with the (eta-C5H5)(2)ZrCl2 reference system were observed towards ethene for all of the above complexes. In addition, compound 6 showed some minor polymerization activity towards propene, Ethylalumoxane or isobutylalumoxane did not exhibit a co-catalytic activity for these chelate complexes; in combination with MAO these higher alumoxanes were even found to be deactivating Zr-91 NMR data are reported for Ib, 1c, 4 and 5. Copyright (C) 2000 John Wiley & Sons, Ltd.