Bipyridine Adducts of Molybdenum Imido Alkylidene and Imido Alkylidyne Complexes

• Main Authors: Lichtscheidl, Alejandro G. (Contributor), Ng, Victor Wee Lin (Contributor), Takase, Michael K. (Contributor), Malcolmson, Steven J. (Author), Meek, Simon J. (Author), Li, Bo (Author), Kiesewetter, Elizabeth T. (Author), Hoveyda, Amir H. (Author), Muller, Peter (Contributor), Schrock, Richard Royce (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Chemistry (Contributor)
• Format: Article
• Language: English
• Published: American Chemical Society (ACS), 2013-11-22T20:10:01Z.
• Subjects: Article
• Online Access: Get fulltext

 Seven bipyridine adducts of molybdenum imido alkylidene bispyrrolide complexes of the type Mo(NR)(CHCMe[subscript 2]R')(Pyr)[subscript 2](bipy) (1a-1g; R = 2,6-i-Pr[subscript 2]C[subscript 6]H[subscript 3] (Ar), adamantyl (Ad), 2,6-Me[subscript 2]C[subscript 6]H[subscript 3] (Ar'), 2-i-PrC[subscript 6]H[subscript 4] (Ar[superscript iPr]), 2-ClC[subscript 6]H[subscript 4] (Ar[superscript Cl]), 2-t-BuC[subscript 6]H[subscript 4] (Ar[superscript tBu]), and 2-MesitylC[subscript 6]H[subscript 4] (Ar[superscript M]), respectively; R' = 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-1g, HMTOH (2,6-dimesitylphenol), and ZnCl[subscript 2](dioxane) led to the formation of MAP species of the type Mo(NR)(CHCMe[subscript 2]R')(Pyr)(OHMT) (3a-3g). DCMNBD (2,3-dicarbomethoxynorbornadiene) is polymerized employing 3a-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)(CCMe[subscript 2]R')(Me[subscript 2]Pyr)(bipy) (Me[subscript 2]Pyr = 2,5-dimethylpyrrolide; 4a-4g) through a ligand-induced migration of an alkylidene α proton to a dimethylpyrrolide ligand. X-ray structures of Mo(NAr)(CHCMe[subscript 2]Ph)(Pyr)[subscript 2](bipy) (1a), Mo(NAr[superscript iPr])(CHCMe[subscript 2]Ph)(Pyr)(OHMT) (3d), Mo(NAr)(CCMe[subscript 2]Ph)(Me[subscript 2]Pyr)(bipy) (4a), the NAr' analog of 4a (4c), and Mo(NAr[superscript T])(CCMe[subscript 3])(Me[subscript 2]Pyr)(bipy) (Ar[superscript T] = 2-(2,4,6-i-Pr[subscript 3]C[subscript 6]H[subscript 2])C[subscript 6]H[subscript 4]; 4g) showed normal bond lengths and angles.