Reactions of (Arylimido)vanadium(V)–Trialkyl Complexes with Phenols: Effects of Arylimido Ligands and Phenols for Formation of the Vanadium Phenoxides

[Image: see text] Reactions of a series of (arylimido)vanadium(V) trialkyl complexes, V(NAr′)(CH(2)SiMe(3))(3) (Ar′ = C(6)H(5), 2-MeC(6)H(4), 2,6-Me(2)C(6)H(3), 2,6-Cl(2)C(6)H(3)), with various phenols (ArOH, Ar = 2,6-F(2)C(6)H(3), 2,6-Cl(2)C(6)H(3), 2,6-Me(2)C(6)H(3), 2,6-(i)Pr(2)C(6)H(3), 2-(t)BuC(6)H(4), 2,6-(t)Bu(2)C(6)H(3); 1.0 equiv) affording V(NAr′)(CH(2)SiMe(3))(2)(OAr) were conducted in C(6)D(6) at 25 °C, and the effects of both arylimido ligands and phenols on the substitution rate were explored. Sterically hindered arylimido ligands showed lower reactivity, and the reaction proceeded in the order: Ar′ = 2,6-Me(2)C(6)H(3) < 2,6-Cl(2)C(6)H(3) < 2-MeC(6)H(4) < C(6)H(5). This order is somewhat different from that obtained from the chemical shifts in V(NAr′)(CH(2)SiMe(3))(3) in the (51)V NMR spectra. The conversions with various disubstituted phenols increased in the order: 2,6-(i)Pr(2)C(6)H(3)OH < 2,6-Me(2)C(6)H(3)OH < 2,6-Cl(2)C(6)H(3)OH < 2,6-F(2)C(6)H(3)OH, irrespective of the kind of arylimido ligands. The reactions of V(NAr′)(CH(2)SiMe(3))(3) with 2,6-(t)Bu(2)C(6)H(3)OH (1.0 or 3.0 equiv) did not take place even upon heating at 60 °C. These results suggest that the reactions proceed via coordination of ArOH toward vanadium, and the reactivity is highly dependent on steric bulk of both the arylimido ligand and the phenol.