Well-defined silica-supported Mo-alkylidene catalyst precursors containing one or substituent: methods of preparation and structure-reactivity relationship in alkene metathesis.
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.
Rendón
Nuria
N
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.
Berthoud
Romain
R
Blanc
Frédéric
F
Gajan
David
D
Maishal
Tarun
T
Basset
Jean-Marie
JM
Copéret
Christophe
C
Lesage
Anne
A
Emsley
Lyndon
L
Marinescu
Smaranda C
SC
Singh
Rojendra
R
Schrock
Richard R
RR