Tris(pyrazolyl)methane–chromium(III) complexes as highly active catalysts for ethylene polymerization

Reaction of complex CrCl3(THF)3 with the tris(pyrazolyl)methane ligands, HC(Pz)3, HC(3,5-Me2Pz)3 and their substituted derivatives RC(Pz)3 (R = Me, CH2OH, CH2OSO2Me) in THF lead to the formation of neutral complexes of the types [RC(Pz)3CrCl3] and [RC(3,5-Me2Pz)3CrCl3]. After reaction with methylalumoxane (MAO) these complexes are active in the polymerization of ethylene. The substituent on the methane central carbon atom of the ligand has some influence in polymerization behavior. This compounds present higher activities than similar chromium complexes, in the ethylene polymerization reaction.

Five chromium compounds with tris(pyrazolyl)methane ligands were obtained. These complexes in the presence of methylalumoxane (MAO) are highly active in ethylene polymerization. It was found that the activity of catalyst depends on their structure. The changes in the reaction conditions of polymerization were studied. Figure optionsDownload as PowerPoint slide