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

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