[Bis(amido)cyclodiphosph( III )azane]dichlorozirconium Complexes for Ethene Polymerization

A series of new zirconium dichloride complexes bearing bulky cis ‐bis(amino)cyclodiphosph( III )azane ligands, [(RN) 2 ( t BuNP) 2 ]ZrCl 2 [R = phenyl ( 7 ), diphenylmethyl ( 8 ), 2,6‐diethylphenyl ( 9 ), 2,5‐di‐ tert ‐butylphenyl ( 10 ), and 2,6‐diisopropylphenyl ( 11 )] were prepared in high yields by a two‐step synthetic route. The structure of cis ‐[(Ph 2 CHN)( t BuNP)] 2 Zr(NMe 2 ) 2 ( 8a ), determined by X‐ray analysis, shows that the zirconium atom has a distorted trigonal‐bipyramidal configuration consisting of four equidistant metal−amido nitrogen bonds and an additional coordination between the metal and a nitrogen atom from the cyclodiphosph( III )azane ring. After methylaluminoxane activation, these complexes exhibit moderate to high activities in ethene polymerization and produce high molar mass polyethene ( M w up to 1100 kg/mol). Polymerization experiments reveal that the behavior of bis(amido)cyclodiphosph( III )azane‐based Zr IV catalysts depends on the nature and steric bulkiness of the amido substituents, reaction temperature, MAO/zirconium ratio, as well as monomer pressure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)