Group 4 Metallocenes Bearing η⁵-2-(N-Azolyl)indenyl Ligands: Synthesis, Structure Characterization, and Olefin Polymerization Catalysis

Abstract

The Pd-catalyzed cross-coupling reactions of readily available 2-bromo-1H-indene with 1H-pyrrole, 1H-indole, 9H-carbazole, and their derivatives were shown to be convenient methods to obtain novel ligands containing azole fragments bonded with cyclopentadienyl via nitrogen. An alternative protocol using enol triflates of 1-indanone or 2-indanone is also useful, particularly for synthesizing indenes bearing the N-azolyl fragment in position 1. On the other hand, the synthesis of 2-(1H-benzimidazol-1-yl)-1H-indene can be achieved via the Cu-catalyzed reactions only. The substituted indenes with the N-azolyl fragment in position 2 were further used for obtaining several semisandwich complexes of zirconium, [η5-2-(N-azolyl)indenyl]zirconium tribromides, as well as symmetrical and unsymmetrical Waymouth-type zirconium and hafnium complexes containing indenyl ligands bearing planar N-azolyl or aryl fragments in position 2. These metallocenes were unambiguously characterized, including by X-ray crystal structure analysis, and a study of the fluxional behavior of several Waymouth-type complexes in solution was carried out by NMR spectroscopy. Finally, novel Waymouth-type complexes, after being activated by MAO, were found to form active catalysts of ethylene homopolymerization and ethylene/1-octene copolymerization.

ansa-Metallocenes Bearing 4-(N-Azolyl)-2-methylindenyl and Related Ligands: Development of Highly Isoselective Catalysts for Propene Polymerization at Higher Temperatures

“…This is exactly what can be observed in rac - 13 , in which the larger dihedral angle corresponds to the longer C indenyl –N bond. Following this trend, the C indenyl –N bonds (1.373 Å) in the zirconocenes bearing nontwisted 2-( N -azolyl)­indenyl moieties are shorter than those in the 4-( N -azolyl)-substituted species under this study. The longer bonds for the complexes under investigation confirm the decreased π interaction between the respective azolyl and indenyl fragments originating from a noncoplanar orientation of the fragments (Table ), which seem to be inefficiently conjugated (vide infra).…”

Air-stable and highly efficient indenyl-derived phosphine ligand: Application to Buchwald–Hartwig amination reactions

“…Synthesis of (2-mesitylindenyl)dicyclohexylphosphine (1) (2-Mesitylindenyl) phosphine ligand can be easily prepared from 2-bromoindene and mesityl bromide (Scheme 2). 2-Mesitylindene was prepared according to the reported procedure [25], then the straightforward deprotonation of 2-mesitylindene by n BuLi and trapping of the lithiated intermediate by Cy 2 PCl afforded the corresponding phosphine 1 in high yields. It is interesting that this ligand is air-stable maybe because its structure is similar to that of Buchwald's ligand [26].…”

Ethylene and Ethylene/α-Olefin (Co)Polymerization Behavior of Bis(phenoxy−imine)Ti Catalysts: Significant Substituent Effects on Activity and Comonomer Incorporation

“…To gain further information about the polymerization catalysis of complexes 1 − 7 , ethylene/propylene copolymerizations were performed using these complexes with DMAO activation (complex 5 was examined as a comparison). − Table summarizes copolymerization results. It is interesting to note that complexes 1 − 4 with ortho substituents with tertiary α-C atoms attached to the phenoxy rings and complexes 5 and 6 with ortho substituents with quaternary α-C atoms behaved differently for ethylene/propylene copolymerization, unlike the ethylene homopolymerization (Figures and ).…”