Cationic Palladium(II) Complexes of Phosphine鈥揝ulfonamide Ligands: Synthesis, Characterization, and Catalytic Ethylene Oligomerization

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• 作者：Yanlu Zhang ; Yanchun Cao ; Xuebing Leng ; Changle Chen ; Zheng Huang
• 刊名：Organometallics
• 出版年：2014
• 出版时间：July 28, 2014
• 年：2014
• 卷：33
• 期：14
• 页码：3738-3745
• 全文大小：384K
• ISSN：1520-6041

文摘

A series of cationic palladium(II) complexes bearing phosphine鈥搒ulfonamide ligands, [(P,O)PdMe(lutidine)][SbF₆], were synthesized and used for catalytic ethylene oligomerization. The molecular structure of the complex {[N,N-dicyclohexyl-2-(diphenylphosphanyl)benzenesulfonamide]PdMe(lutidine)}[SbF₆] shows that the phosphorus atom and the oxygen atom coordinate to the palladium center. The ethylene oligomerization behavior is greatly influenced by the phosphino substituents, while the substituents on sulfonamide show only minimal effects. Complexes containing the diphenylphosphanyl group are highly selective for ethylene dimerization, affording 1-butene exclusively with moderate activity. The bulkier bis(2-methoxyphenyl)phosphanyl group leads to higher activity and gives 伪-olefins containing mainly 1-butene and 1-hexene, with a 1-hexene content of up to 35%. The palladium complexes bearing alkyl phosphino substituents give 1-butene and 1-hexene as the major products; a small amount of 2-butene (<5%) was observed, suggesting the occurrence of chain walking. The addition of B(C₆F₅)₃ greatly enhances the catalytic activity. Experimental results suggest that the increase in activity is likely due to the abstraction of lutidine, not from the coordination of B(C₆F₅)₃ to the sulfonamide oxygen atom.