Reactivity of a d ² Mo(IV) Alkylidyne Fragment Bearing a PNCNP Pincer Ligand Toward Alkynes: Coordination and Catalytic Alkyne Metathesis

ABSTRACT Currently, almost all alkyne metathesis catalysts are based on high valent d 0 Schrock‐type alkylidyne complexes. Although non‐d 0 transition‐metal alkylidyne complexes are also common, to date, only Re(V) alkylidyne have been reported to be capable of catalyzing alkyne metathesis. Herein, the reactivity of a d 2 Mo(IV) alkylidyne fragment bearing a PNCNP pincer ligand toward alkynes was studied. A series of novel Mo carbyne‐alkyne complexes was synthesized and characterized. The incorporation of N‐Me moieties in the pincer ligand reduced the energy barrier of the metathesis process. Accordingly, the first example of a catalytic system for alkyne metathesis reaction involving a d 2 Mo(IV) alkylidyne fragment was developed.