Synthesis, characterization and ethylene polymerization activity of titanium aminopyridinato complexes
摘要:
Three titanium complexes derived from 2-(2,6-difluoroanilino) pyridine and 2-(2- chloroanilino) pyridine were synthesized and characterized by X-ray diffraction or spectroscopic methods. All titanium complexes have been used to catalyze the polymerization of ethylene in the presence of MAO as cocatalyst. The mono(2,6- difluorophenylaminopyridinato) titanium catalyst was found to be more active in ethylene polymerization than the bis(2,6- difluorophenylaminopyridinato) and bis(2- chlorophenylaminopyridinato) titanium catalysts. ortho-Halogens disturbed the beta-elimination transition state of ethylene polymerization and formed higher molar mass polyethylene than their unhalogenated congener. Due to fluxionality, the bis(2- chlorophenylaminopyridinato) titanium catalyst formed broader molar mass distribution than the bis(2,6- difluorophenylaminopyridinato) titanium catalysts. (C) 2007 Elsevier B.V. All rights reserved.