Synthesis, Structure Determination, and Reactivity of C2-Symmetrical Ethylene-Bridged ansa-Bis(DiMeBCOCp)titanium Dichlorides

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• 作者：Ronald L. Halterman ; Zhouliang Chen ; and Masood A. Khan
• 刊名：Organometallics
• 出版年：1996
• 出版时间：September 17, 1996
• 年：1996
• 卷：15
• 期：19
• 页码：3957 - 3967
• 全文大小：537K
• 年卷期：v.15,no.19(September 17, 1996)
• ISSN：1520-6041

文摘

The bridging of C₂-symmetric8,10-dimethyltricyclo[5.2.2.0^2,6]-2,5-undecadiene(DMeBCOCpH) by silicon, methylene, and ethylene was investigated. Thedimethylsilyl-bridgedbis(BCOCp) ligand was accessible but could not be converted to itstitanium, zirconium, orniobium chloride complexes.8,10-Dimethyl-4-(1-methylethylidene)tricyclo[5.2.2.0^2,6]-2,5-undecadiene (DMeBCOCp-dimethylfulvene) was formed, but did not reactwith cyclopentadienyl anions. A regioisomeric mixture of1,2-bis[(1R,7R,8R,10R)-8,10-dimethyltricyclo[5.2.2.0^2,6]-2,5-undecadienyl]ethane[en(DMeBCOCpH)] ligands could be formed andmetalatedto form(+)-[ethylene-1,2-bis[⁵-(1R,7R,8R,10R)-8,10-dimethyltricyclo[5.2.2.0^2,6]-2,5-undecadien-4-yl]]titanium dichloride[(+)-,-en(DMeBCOCp)₂TiCl₂,(+)-11] along with its ,- and,-bridged regioisomeric titanocene dichlorides.(+)-11 is unique in that it is a chiralethylene-bridged ansa-metallocene which contains onlyhomotopic cyclopentadienyl faces.(+)-11 was characterized by X-ray crystallography andwas applied as a catalyst for theenantioselective isomerization of alkenes. (+)-11 wasless active and less enantioselectivethan a known chiral ansa-bis(indenyl)titanium catalystfor the enantioselective alkeneisomerization.