Rendón Nuria, Berthoud Romain, Blanc Frédéric, Gajan David, Maishal Tarun, Basset Jean-Marie, Copéret Christophe, Lesage Anne, Emsley Lyndon, Marinescu Smaranda C, Singh Rojendra, Schrock Richard R
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.
Chemistry. 2009;15(20):5083-9. doi: 10.1002/chem.200802465.
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.
通过将对称的钼亚烷基衍生物[Mo(≡NAr)(=CHCMe₂R')(OR)₂]或不对称衍生物（即带有两个不同侧基配体，一个酰胺基和一个烷氧基/芳氧基的[Mo(≡NAr)(=CHCMe₂R')(OR)(NC₆H₈)]）接枝到SiO₂-(700)上，可得到单硅氧基表面配合物[([≡SiO)Mo(≡NAr)(=CHCMe₂R')(OR)]（R' = Me或Ph；OR = OtBu、OCMe(CF₃)₂或OAr）。通过质量平衡分析、红外（IR）光谱和核磁共振（NMR）光谱证实了这些配合物的形成。这些体系是无环烯烃复分解反应的高效催化剂前体；当OR = OCMe(CF₃)₂时效果最佳。然而，它们在闭环复分解反应中表现不佳，这可能是由于金属中心的刚性（如NMR光谱所证实），从而减缓了复分解反应的速率。
