Synthesis of Hafnium and Zirconium Imino−Amido Complexes from Bis-imine Ligands. A New Family of Olefin Polymerization Catalysts

Abstract

The reaction of 2,6-diisopropylaniline-based bis-imine ligands (4, 9) with M(CH2Ph)4 (M = Hf, Zr) led to formation of novel imino−amido tribenzyl complexes via migratory insertion of a benzyl group into a CN bond. Imino−amido complexes were found to undergo unprecedented dibenzyl elimination to form ene−diamido complexes. Imino−amido complexes were found to be active ethylene polymerization catalysts.

Conversion of imine ligands in allyl–nickel(II) complexes

“…The transformation of an imine ligand in the coordination sphere of a transition metal proceeding through formal insertion of a C@N moiety into the M-C bond was previously demonstrated for organometallic complexes Zr(CH 2 Ph) 4 and Hf(CH 2 Ph) 4 when combined with 2,5-bis(N-aryliminomethyl)pyrrole [23,35]. Alkylation of a diene in the reaction between diethyl zinc and bis(2,6-diisopropylphenyl)diazabutadiene was also described to form an imine(amide)ethylzinc complex [36].…”

Group 4 metal complexes bearing new tridentate (NNO) ligands: Benzyl migration and formation of unusual C–C coupled products

“…Scott and coworkers reported that titanium and zirconium benzyl complexes bearing bridged phenoxyimine ligands can undergo migrations of one of the benzyls to the imino carbon of the ligand backbone [19,[44][45][46]. Other systems based on pyrrolylimines and a-diimine ligands show similar reactivities [47][48][49][50]. We have found that 6 and 7 also undergo benzyl transfer reactions in solution leading to the corresponding dibenzyl complexes 11 and 12 (Scheme 4).…”

Post‐Metallocenes in the Industrial Production of Polyolefins

“…Complexes of type 15 can be prepared by reaction of α‐diimine ligands with MBn 4 (M=Hf, Zr) by transfer of one benzyl group to the ligand backbone. However, complexes synthesized by this procedure exhibit multisite behavior in olefin polymerization, because these imino–amido complexes can undergo various side reactions, especially at elevated temperatures 113. When prepared from α‐di(aldimine) ligands, a second benzyl group can be transferred to the ligand backbone under formation of the corresponding diamido complex 18 b 114.…”