Synthesis and reactivity of mixed cyclopentadienyl titanium and zirconium aryloxide complexes
Abstract
Much attention has been given to Group 4 metal compounds containing either bis(cyclopentadienyl) or bis(aryloxide) ancillary ligands. In recent years, a hybrid system with one cyclopentadienyl and one aryloxide has been investigated. [CpTiCl3] can be generated by the ligand exchange reaction of [Cp2TiCl2] and [TiCl4] in xylene. It is used as a starting material to produce [Cp(ArO)TiCl 2] when various substituted phenols are added to benzene solutions of [CpTiCl3] with pyridine. The Halide ligands of [Cp(ArO)TiCl 2] are subsequently replaced with alkyl groups, forming [Cp(ArO)TiR 2] (R = Me, CH2Ph, CH2SiMe3). The reduction of [Cp(ArO)TiCl2] with 2 equivalents of sodium amalgam or Negishi method has produced titanacyclic compounds, such as titanacyclopentadienes and titanabicyclic compounds. Displacement and insertion chemistry has been investigated in these titanacyclic compounds with olefins, alkynes, ketones and isocyanides. [CpZr(CH2Ph)3] has been used as a starting material to synthesize [Cp(ArO)Zr(CH2Ph)2] by the simple addition of a phenol. The insertion chemistry has been studied with the zirconium alkyl complexes to generate η1- or η2-inserted compounds with tert-butyl- or xylyl-isocyanides. The use of different phenoxides, chiral and achiral, has generated their unique structural and spectroscopic results. Variable temperature NMR studies have been performed for these inserted zirconium compounds.
Degree
Ph.D.
Advisors
Rothwell, Purdue University.
Subject Area
Chemistry
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