Synthesis and Structural Analysis of Zr–Al Heterobimetallic Complexes, [ZrX{(O-2,4‑tBu2C6H2‑6-CH2)3(μ2‑O-2,4‑tBu2‑C6H2‑6-CH2)}N][R2Al(μ2‑OiPr)] [X = Cl, Et, iBu; R = Me, Et, iBu]. Unique Reactivity of the iBu Complex

A series of heterobimetallic Zr–Al complexes, [ZrCl­{(O-2,4-tBu2C6H2-6-CH2)3­(μ2-O-2,4-tBu2-C6H2-6-CH2)}­N]­[R2Al­(μ2-OiPr)] [R = Me (3), Et (4)] and [ZrR­{(O-2,4-tBu2C6H2-6-CH2)3­(μ2-O-2,4-tBu2-C6H2-6-CH2)}­N]­[R2Al­(μ2-OiPr)] [R = Et (5), iBu (6)], have been prepared by reactions of Zr­(OiPr)­[(O-2,4-tBu2C6H2-6-CH2)3N] (1) with 1.0 equiv of Al alkyls (Me2AlCl, Et2AlCl, AlEt3, and AliBu3), and their structures (3, 5, 6) were determined by X-ray crystallography. The isobutyl complex (6) is stable in C6D6 and toluene-d6 at 45 °C; the thermolysis of 6 at >60 °C gradually afforded 1 with liberation of AliBu3. These complexes exhibited remarkable catalytic activities for ethylene polymerization at 80–120 °C in the presence of MAO; only complex 6 exhibited the high activity even at 45–60 °C.