文献类型：期刊文献

英文题名：A Triphenylsiloxy Complex of Chromium(II) as a Switchable Catalyst for Ethylene Polymerization and Nonselective Oligomerization

作者：Qiu, Pengyuan[1,2];Cheng, Ruihua[1];Liu, Boping[1];Tumanskii, Boris[2];Batrice, Rami J.[2];Botoshansky, Mark[2];Eisen, Moris S.[2]

机构：[1]E China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]Technion Israel Inst Technol, Schulich Fac Chem, IL-32000 Haifa, Israel

年份：2011

卷号：30

期号：8

起止页码：2144

外文期刊名：ORGANOMETALLICS

收录：;EI(收录号：20111713930595);WOS:【SCI-EXPANDED(收录号:WOS:000289501000010)】；

基金：The National Natural Science Fundation of China (No. 20774025) and Key Projects in the National Science & Technology Pillar Program during the 11th Five-Year Plan Period, (2007BAE50B04), Shanghai Pujiang Talent Plan Project (08PJ14032), and Program of Introducing Talents of Discipline to Universities (B08021) are thanked for financial support. Dr. I. Barzilai (Technion-Israel Institute of Technology) is thanked for GC-MS measurements.

语种：英文

外文关键词：Polymerization - Coordination reactions - Crystal structure - Argon - Ethylene - Nuclear magnetic resonance spectroscopy - Aluminum compounds - Oligomers - Aluminum - Chromium compounds - Electron spin resonance spectroscopy - Oligomerization - Paramagnetic resonance

摘要：A novel dinuclear oxygen-bridged chromium(II) complex of [(Ph3SiO)Cr center dot(THF)](2)(mu-OSiPh3)(2) (1) was successfully synthesized and structurally characterized. The crystal structure of complex 1 shows that the chromium centers adopt a tetrahedrally distorted square-planar coordination geometry. Complex 1 was tested for ethylene polymerization upon activation with and without aluminum alkyl cocatalysts. No ethylene polymerization activity was observed in the absence of aluminum alkyl cocatalysts; however, in the presence of methylaluminoxane (MAO), complex 1 demonstrates an unexpected transformation from ethylene polymerization to ethylene oligomerization, with the molar ratio of Al to Cr increasing from 50 to 1000. The activation of complex 1 with MAO was investigated by ESR and Si-29 NMR spectroscopy. It was found that the Ph3SiO- groups could be transferred from the chromium centers of complex 1 to the aluminum of MAO.