Bipyridine Adducts of Molybdenum Imido Alkylidene and Imido Alkylidyne Complexes

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• 作者：Alejandro G. Lichtscheidl ; Victor W. L. Ng ; Peter M眉ller ; Michael K. Takase ; Richard R. Schrock ; Steven J. Malcolmson ; Simon J. Meek ; Bo Li ; Elizabeth T. Kiesewetter ; Amir H. Hoveyda
• 刊名：Organometallics
• 出版年：2012
• 出版时间：June 25, 2012
• 年：2012
• 卷：31
• 期：12
• 页码：4558-4564
• 全文大小：399K
• 年卷期：v.31,no.12(June 25, 2012)
• ISSN：1520-6041

文摘

Seven bipyridine adducts of molybdenum imido alkylidene bispyrrolide complexes of the type Mo(NR)(CHCMe₂R鈥?(Pyr)₂(bipy) (1a鈥?b>1g; R = 2,6-i-Pr₂C₆H₃ (Ar), adamantyl (Ad), 2,6-Me₂C₆H₃ (Ar鈥?, 2-i-PrC₆H₄ (Ar^iPr), 2-ClC₆H₄ (Ar^Cl), 2-t-BuC₆H₄ (Ar^tBu), and 2-MesitylC₆H₄ (Ar^M), respectively; R鈥?= Me, Ph) have been prepared using three different methods. Up to three isomers of the adducts are observed that are proposed to be the trans- and two possible cis-pyrrolide isomers of syn-alkylidenes. Sonication of a mixture containing 1a鈥?b>1g, HMTOH (2,6-dimesitylphenol), and ZnCl₂(dioxane) led to the formation of MAP species of the type Mo(NR)(CHCMe₂R鈥?(Pyr)(OHMT) (3a鈥?b>3g). DCMNBD (2,3-dicarbomethoxynorbornadiene) is polymerized employing 3a鈥?b>3g as initiators to yield >98% cis,syndiotactic poly(DCMNBD). Attempts to prepare bipy adducts of bisdimethylpyrrolide complexes led to the formation of imido alkylidyne complexes of the type Mo(NR)(CCMe₂R鈥?(Me₂Pyr)(bipy) (Me₂Pyr = 2,5-dimethylpyrrolide; 4a鈥?b>4g) through a ligand-induced migration of an alkylidene 伪 proton to a dimethylpyrrolide ligand. X-ray structures of Mo(NAr)(CHCMe₂Ph)(Pyr)₂(bipy) (1a), Mo(NAr^iPr)(CHCMe₂Ph)(Pyr)(OHMT) (3d), Mo(NAr)(CCMe₂Ph)(Me₂Pyr)(bipy) (4a), the NAr鈥?analog of 4a (4c), and Mo(NAr^T)(CCMe₃)(Me₂Pyr)(bipy) (Ar^T = 2-(2,4,6-i-Pr₃C₆H₂)C₆H₄; 4g) showed normal bond lengths and angles.