Oxide‐Bridged Heterobimetallic Aluminum/Zirconium Catalysts for Ethylene Polymerization

A bimetallic aluminum/zirconium complex Cp* 2 Zr(Me)OAl(DIPH) [DIPH‐H 2 = 3,3′‐bis(2‐methylallyl)‐(1,1′‐biphenyl)‐2,2′‐diol; Cp* = C 5 Me 5 ] was prepared in good yield by the reaction of (DIPH)AlMe with Cp* 2 Zr(Me)OH. In contrast to Roesky's catalyst, Cp 2 Zr(Me)O(Me)Al(DIPP‐nacnac) {DIPP‐nacnac = CH[(CMe)(2,6‐ i Pr 2 C 6 H 3 N)] 2 }, it contains no Al–Me functionality and has increased Lewis acidity at Al. Crystal structures and the NMR spectra of the aluminum complex (DIPH)AlMe and the bimetallic Al/Zr species reveal in both cases dimeric complexes. The crystal structure of [Cp* 2 Zr(Me)OAl(DIPH)] 2 shows a planar Al 2 O 2 core and a terminal Cp* 2 Zr(Me)O group. Ethylene polymerization in toluene was studied for the bimetallic complex with a variety of scavengers. Under comparable polymerization conditions, the methylalumoxane‐activated species show high activities that are similar to those obtained with Cp* 2 ZrCl 2 and Roesky's bimetallic complex Cp 2 Zr(Me)OAl(Me)(DIPP‐nacnac), with a relatively narrow polydispersity index (2.47).