Alkane Metathesis with the Tantalum Methylidene [(≡SiO)Ta(═CH2)Me2]/[(≡SiO)2Ta(═CH2)Me] Generated from Well-Defined Surface Organometallic Complex [(≡SiO)TaVMe4]
2015
By grafting TaMe5 on Aerosil700, a stable, well-defined, silica-supported tetramethyl tantalum(V) complex, [(≡SiO)TaMe4], is obtained on the silica surface. After thermal treatment at 150 °C, the complex is transformed into two surface tantalum methylidenes, [(≡SiO)2Ta(═CH2)Me] and [(≡SiO)Ta(═CH2)Me2], which are active in alkane metathesis and comparable to the previously reported [(≡SiO)2TaHx]. Here we present the first experimental study to isolate and identify a surface tantalum carbene as the intermediate in alkane metathesis. A systematic experimental study reveals a new reasonable pathway for this reaction.
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