Highly Reactive Cationic Molybdenum Alkylidyne N-Heterocyclic Carbene Catalysts for Alkyne Metathesis

The tetracoordinated cationic molybdenum alkylidyne N-heterocyclic carbene (NHC) complexes [Mo(≡CC6H4-p-OMe)(IMes)(OCMe(CF3)2)2][BPh4] (Mo5) and [Mo(≡CC6H4-p-OMe)(IMes)(OCMe(CF3)2)2][B(ArF)4] (Mo6, IMes = 1,3-dimesitylimidazol-2-ylidene)) were synthesized from the pentacoordinated progenitor Mo(≡CC6H4-p-OMe)(IMes)(OCMe(CF3)2)2(OTf) (Mo4). Complexes Mo4–Mo6 were evaluated for their ability to catalyze the self-metathesis of several internal...