851090-85-2Relevant academic research and scientific papers
[Bis(amido)cyclodiphosph(III)azane]dichlorozirconium complexes for ethene polymerization
Axenov, Kirill V.,Klinga, Martti,Leskelae, Markku,Kotov, Vasily,Repo, Timo
, p. 4702 - 4709 (2004)
A series of new zirconium dichloride complexes bearing bulky cis-bis(amino)cyclodiphosph(III)azane ligands, [(RN)2-(tBuNP) 2]ZrCl2 [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-[(Ph2CHN)-(tBuNP)]2Zr(NMe2)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 (Mw up to 1100 kg/mol). Polymerization experiments reveal that the behavior of bis(amido)cyclodiphosph(III)azane-based ZrIV 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).
