Impact of Electronic Modification of the Chelating Benzylidene Ligand in cis-Dichloro-Configured Second-Generation Olefin Metathesis Catalysts on Their Activity

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• 作者：Eva Pump ; Albert Poater ; Michaela Zirngast ; Ana Torvisco ; Roland Fischer ; Luigi Cavallo ; Christian Slugovc
• 刊名：Organometallics
• 出版年：2014
• 出版时间：June 9, 2014
• 年：2014
• 卷：33
• 期：11
• 页码：2806-2813
• 全文大小：362K
• 年卷期：v.33,no.11(June 9, 2014)
• ISSN：1520-6041

文摘

A series of electronically modified second-generation cis-dichloro ruthenium ester chelating benzylidene complexes was prepared, characterized, and benchmarked in a typical ring-opening metathesis polymerization (ROMP) experiment. The electronic tuning of the parent chelating benzylidene ligand (2-ethyl ester benzylidene) was achieved by substitution at the 4- and 5-positions with electron-withdrawing nitro or electron-donating methoxy groups. The effect of the electronic tuning on the cis鈥搕rans isomerization process was studied experimentally and theoretically. Density functional theory calculations clearly revealed the influence of electronic modification on the relative stability between the cis and trans isomers, which is decisive for the activity of the studied compounds as initiators in ROMP.