Syntheses of Re(V) Alkylidyne Complexes and Ligand Effect on the Reactivity of Re(V) Alkylidyne Complexes toward Alkynes

A series of new d2 Re (V) alkylidyne complexes were synthesized, including Re­(CCH2Ph)­Cl2(PR3)3 (PR3 = PMe3, and PMePh2), Re­(CCH2Ph)­I2(PMePh2)3, Re­(CPh)­(S2CNEt2)2(PMePh2), [CpRe­(CPh)­(PMePh2)2]­Cl, and Re­(CCH2Ph)­(mnt)­(PMePh2)2. The complexes Re­(CCH2Ar)­Cl2(PR3)3 (PR3 = PMe3, PMe2Ph, and PMePh2) as well as Re­(CCH2Ph)­I2(PMePh2)3 were found to undergo alkyne metathesis reactions with PhCCPh, while the other complexes are inactive. The activity of Re­(CCH2Ar)­Cl2(PR3)3 toward alkyne metathesis reactions with PhCCPh is in the order of PMe3 2Ph 2. The complex Re­(CCH2Ph)­I2(PMePh2)3 is slightly less reactive than its chloride analog. The difference in the reactivity of the alkylidyne complexes has been studied computationally.