title: Well-defined silica-supported Mo-alkylidene catalyst precursors containing one or substituent: methods of preparation and structure-reactivity relationship in alkene metathesis.
abstract: The monosiloxy surface complexes [([triple bond]SiO)Mo([triple bond]NAr)(=CHCMe(2)R')(OR)] (R' = Me or Ph; OR = OtBu, OCMe(CF(3))(2) or OAr) are obtained by grafting onto SiO(2-(700)) either symmetric Mo-alkylidene derivatives [Mo([triple bond]NAr)(=CHCMe(2)R')(OR)(2)] or asymmetric derivatives, that is, with two different pendant ligands, one amido and one alkoxy/aryloxy, [Mo([triple bond]NAr)(=CHCMe(2)R')(OR)(NC(6)H(8))]. The formation of these complexes was confirmed by mass-balance analysis, and infrared (IR) and NMR spectroscopies. These systems are highly efficient catalyst precursors for the metathesis of acyclic alkenes; the best results were seen when OR=OCMe(CF(3))(2). Nevertheless, they display poor performances in ring-closing metathesis, possibly due to the rigidity of the metal center (as evidenced by NMR spectroscopy), which therefore slows the rate of the metathesis.
authors.affiliation: Laboratoire de Chimie, Catalyse, Polymères et Procédés, Chimie Organométallique de Surface, UMR 5265 CNRS-ESCPE Lyon, Université de Lyon, 43 bd du 11 Novembre 1918, 69616 Villeurbanne Cedex, France.
authors.forename: Nuria
authors.initials: N
authors.lastname: Rendón
authors.forename: Romain
authors.initials: R
authors.lastname: Berthoud
authors.forename: Frédéric
authors.initials: F
authors.lastname: Blanc
authors.forename: David
authors.initials: D
authors.lastname: Gajan
authors.forename: Tarun
authors.initials: T
authors.lastname: Maishal
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Basset
authors.forename: Christophe
authors.initials: C
authors.lastname: Copéret
authors.forename: Anne
authors.initials: A
authors.lastname: Lesage
authors.forename: Lyndon
authors.initials: L
authors.lastname: Emsley
authors.forename: Smaranda C
authors.initials: SC
authors.lastname: Marinescu
authors.forename: Rojendra
authors.initials: R
authors.lastname: Singh
authors.forename: Richard R
authors.initials: RR
authors.lastname: Schrock