Observations and Mechanistic Insights on Unusual Stability of Neutral Nickel Complexes with a Sterically Crowded Metal Center

doi:10.1021/om100725h

CORC > 化学研究所 > 中国科学院化学研究所

	Observations and Mechanistic Insights on Unusual Stability of Neutral Nickel Complexes with a Sterically Crowded Metal Center
	Song, Dong-Po 1,2; Wang, Yong-Xia 1; Mu, Hong-Liang 1,2; Li, Bai-Xiang 1,2; Li, Yue-Sheng 1
刊名	ORGANOMETALLICS
	2011-03-14
卷号	30 期号:5 页码:925-934
ISSN号	0276-7333
DOI	10.1021/om100725h
英文摘要	A series of novel nickel(II) methyl pyridine complexes based on beta-ketiminato and phenoxyiminato ligands, [(2,6-(Pr2C6H3)-Pr-i)N=CH(8-R1C10H7)O]Ni(Me)(Py) (5a, R-1 = phenyl; 5b, R-1 = norbornyl), [(2,6-(Pr2C6H3)-Pr-i)N=CH(8-R1C10H5)O]Ni(Me)(Py) (6a, R-1 = phenyl; 6b, R-1 = norbornyl), and [(2,6-(Pr2C6H3)-Pr-i)N=CHCHC(2'-R2C6H4)O]Ni(Me)(Py) (7a, R-2 = H; 7b, R-2 = phenyl), have been synthesized and characterized. Molecular structures of 5a and 6b were further confirmed by X-ray crystallographic analysis. These complexes showed very different catalytic properties for ethylene polymerization. Design and construction of a special catalyst structure like 5a with a phenyl group directed toward the nickel(II) center proved to be an effective strategy for improving catalyst stability. Remarkably, according to H-1 NMR spectroscopy, bis-ligated deactivation of complex 5a was entirely avoided, while a rapid deactivation rate was observed with regard to the parent complex C without a phenyl group in the R-1 position. As a result, higher activities of complex 5a were obtained relative to complex C under the same polymerization conditions. In addition, the ligand backbone was found to have a great influence on polymerization behaviors. Specifically, the polyethylenes with greatly decreased molecular weights were produced by neutral nickel phenoxyiminato catalysts 6a,b in comparison with values for the corresponding beta-ketiminato catalysts 5a,b. This is best explained by DFT results that the ethylene insertion and chain termination barriers for complex 6a are very different from those of complex 5a.
语种	英语
出版者	AMER CHEMICAL SOC
WOS记录号	WOS:000287955800002
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/72947]
专题	中国科学院化学研究所
通讯作者	Li, Yue-Sheng
作者单位	1.Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Peoples R China 2.Chinese Acad Sci, Grad Sch, Changchun Branch, Changchun 130023, Peoples R China
推荐引用方式 GB/T 7714	Song, Dong-Po,Wang, Yong-Xia,Mu, Hong-Liang,et al. Observations and Mechanistic Insights on Unusual Stability of Neutral Nickel Complexes with a Sterically Crowded Metal Center[J]. ORGANOMETALLICS,2011,30(5):925-934.
APA	Song, Dong-Po,Wang, Yong-Xia,Mu, Hong-Liang,Li, Bai-Xiang,&Li, Yue-Sheng.(2011).Observations and Mechanistic Insights on Unusual Stability of Neutral Nickel Complexes with a Sterically Crowded Metal Center.ORGANOMETALLICS,30(5),925-934.
MLA	Song, Dong-Po,et al."Observations and Mechanistic Insights on Unusual Stability of Neutral Nickel Complexes with a Sterically Crowded Metal Center".ORGANOMETALLICS 30.5(2011):925-934.