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 [( SiO)Mo( NAr)(=CHC-Me(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( NAr)(=CHCMe(2)R')(OR)(2)] Or asymmetric derivatives, that is, with two different pendant ligands, one amido and one alkoxy/aryloxy, [Mo( NAr)(=CHCMe(2)R')(OR)(NC(6)H(8))]. ne 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.


Published in:
CHEMISTRY-A EUROPEAN JOURNAL, 15, 20, 5083-5089
Year:
2009
Publisher:
WILEY-V C H VERLAG GMBH
ISSN:
0947-6539
Keywords:
Laboratories:




 Record created 2015-01-08, last modified 2018-09-13


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