Group 4 Metallocenes Bearing eta(5)-2-(N-Azolyl)indenyl Ligands: Synthesis, Structure Characterization, and Olefin Polymerization Catalysisстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация: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, [eta(5)-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.