Zirconium complexes bearing bis(phenoxy‐imine) ligands with bulky o‐bis(aryl)methyl‐substituted aniline groups: synthesis, characterization and ethylene polymerization behavior

Abstract

A series of bis(phenoxy-imine) zirconium complexes bearing bulky o-bis(aryl)methyl-substituted aryl groups on the aniline moiety have been synthesized, characterized and tested as catalyst precursors for ethylene polymerization. 1 H NMR spectroscopy suggests that these complexes exist as a single chiral C 2 -symmetric isomer in the solution. X-ray crystallographic analysis of the resulting biszwitterionic-type adduct complex C1 Á 2HCl reveals that the phenoxy-imine groups function as a monodentate phenoxy ligand and the oxygen atoms are oriented trans to each other at the central metal atom. Using modified methylaluminoxane (MMAO) as co-catalyst, C1 Á 2HCl, C2-C6 exclusively produce linear aluminium-terminated polyethylenes (Al-PEs) with high activity (up to 16.89 Â 10 6 g PE (mol Zr h) À1 , suggesting that chain transfer to aluminum is the predominant termination mechanism. It is noteworthy that the introduction of an excessively bulky o-bis(aryl)methyl substituent adjacent to the imine-N produces low molecular-weight Al-PEs (M v 1.6-10.1 Â 10 3 ) due to the enhanced rate of chain transfer to alkylaluminium groups during polymerization.

Polyazamacrocycle Ligands Facilitate 89Zr Radiochemistry and Yield 89Zr Complexes with Remarkable Stability

“…This conformation is characteristic of metal complexes, which demonstrate d 0 electron configurations and lack crystal-field stabilization. While the bond lengths and bond angles of Zr-TRITA, Zr-PCTA, and Zr-NOTA are comparable to those observed in structurally characterized Zr complexes, − each complex demonstrates unique structural features, which have been summarized below.…”

Unexpected Effect of Catalyst’s Structural Symmetry on the Branching Microstructure of Polyethylene in Late Transition Metal Polymerization Catalysis

“…The dibenzobarrelenedione and 2-diarylmethyl-4,6-dimethyl anilines were synthesized according to the reported literature. − The ligands L1–L3 were prepared in 57–62% yields by the acid-catalyzed condensation of 2-diarylmethyl anilines and dibenzobarrelenedione in refluxing toluene (Scheme ) and were characterized by NMR spectroscopy and high-resolution mass spectrometry (cf. SI).…”

Cobalt complex bearing β‐ketoamine ligand: syntheses, structure, catalytic behavior for styrene and methyl methacrylate polymerization

“…Recently, many new CRP methods such as nitroxide‐mediated polymerization, atom transfer radical polymerization and radical addition fragmentation chain transfer have been discovered . They all rely on the persistent‐radical effect (PRE), which is achieved by reversible conversion of the growing macroradicals (P·) to dormant species PX …”