Titanium isopropoxide complexes of a series of sterically demanding aryloxo based [N2O2]2- ligands as precatalysts for ethylene polymerization

Several titanium isopropoxide complexes [N,N'-bis(2-oxo-3-R-1-5-R-2-phenylmethyl)-N, N'-bis(methylene-p-R-3-C6H4)-ethylenediamine]Ti((OPr)-Pr-i)(2) [R-1 = t-Bu, R-2 = Me, R-3 = H (1b); R-1 = R-2 = t-Bu, R-3 = H, (2b); R-1 = R-2 = Cl, R-3 = H, (3b), R-1 = t-Bu, R-2 = Me, R-3 = Cl (4b); R-1 = R-2 = t-Bu, R-3 = Cl, (5b); R-1 = R-2 = R-3 = Cl, (6b)] supported over sterically demanding aryloxy based [N2O2]H-2 ligands have been designed as precatalysts for the ethylene polymerization. Specifically, the 1b-6b complexes, when treated with methylaluminoxane (MAO) under 88 +/- 0.5 psi of ethylene at 30 degrees C for 3 h, produced polyethylene polymers of high molecular weight (M-w = ca. 7.2-8.3 x 10(5) g mol(-1)) having broad molecular weight distribution (PDI = ca. 13.1-14.6). The 1b-6b complexes were conveniently synthesized from the direct reaction of the [N2O2]H-2 ligands, 1a-6a, with Ti((OPr)-Pr-i)(4) in 69-86% yield.