Bis(3,5-dimethylpyrazol-1-ato) zirconium complexes as precursors for ethylene polymerisation upon activation with MAO: Syntheses, characterisation and X-ray molecular structure of [Zr(η2
- 作者：Martial Sanz ; Marta E.G. Mosquera ; Tomá ; s Cuenca ; Carmen Ramí ; rez de Arellano ; Mark Schormann ; Manfred Bochmann
- 关键词：Zirconium ; 3 ; 5-Dimethylpyrazole ; 3 ; 5-Dimethylpyrazolato ; Ethylene polymerisation
- 刊名：Polyhedron
- 出版年：2007
- 期刊代码：87_02775387
- 类别：ch
- 出版时间：20 November 2007
- 卷：26
- 期：18
- 页码：5339-5348
- 文件大小：376 K
摘要
The bis(3,5-dimethylpyrazol-1-ato) zirconium complex [Zr(η2-3,5-Me2Pz)2(NMe2)2(NHMe2)2] (2) is obtained by treatment of [Zr(NMe2)4] with 2 equiv. of 3,5-dimethylpyrazole 1. The reaction of the [ZrCl4(THF)2] adduct with 2 equiv. of the potassium salt of 1 affords the dichloro derivative [Zr(η2-3,5-Me2Pz)2Cl2]n (3), while reaction with 4.1 equiv. of 1 in the presence of 2.1 equiv. of NEt3 affords the dichloro pyrazole adduct [Zr(η2-3,5-Me2Pz)2Cl2(η1-3,5-Me2PzH)2] (4). Treatment of [Zr(CH2Ph)4] with 2 equiv. of 1 gives the dibenzyl complex [Zr(η2-3,5-Me2Pz)2(CH2Ph)2] (5) via alkane elimination. Compound 4 presents fluxional behaviour in CDCl3 solution, which was studied and quantified by variable-temperature proton NMR experiments. All compounds were characterised by routine analyses and the molecular structures of 4 and 5 were established by single-crystal X-ray diffraction studies. The performance of precursors 3 and 5 was evaluated in ethylene polymerisation upon activation with MAO.