Strongly σ Donating Thiophenoxide in Silica-Supported
Tungsten Oxo Catalysts for Improved 1‑Alkene Metathesis Efficiency
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Abstract
We report the synthesis of tungsten
oxo alkylidene complexes bearing
bulky thiophenoxide ligands [W(O)(CHtBu)(SHMT)<sub>2</sub>(PMe<sub>2</sub>Ph)] and [W(O)(CHtBu)(SHMT)<sub>2</sub>] (SHMT = 2,6-dimesitylthiophenoxide) and their grafting on
partially dehydroxylated silica, affording the supported complexes
[(SiO)W(O)(CHtBu)(SHMT)(PMe<sub>2</sub>Ph)]
and [(SiO)W(O)(CHtBu)(SHMT)]. While the molecular
precursors are not significantly active in the metathesis of alkenes,
the grafted analogue without bound phosphine ligands displays activity
comparable to that of its aryloxide analogue [(SiO)W(O)(CHtBu)(OHMT)]
(OHMT = 2,6-dimesitylphenoxide). It is worth noting that [(SiO)W(O)(CHtBu)(SHMT)]
showed unprecedented activity in the metathesis of 1-alkenes, probably
because of the lower stability of metallacyclobutane intermediates
