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A series of Al complexes containing phenoxyimine ligands of the types R1(R2)Al[O-2-tBu-6-{(C6F5)N═CH}C6H3] [R1, R2 = Me, Me (1a); Et, Et (1b); Me, Cl (1c)] and Me2Al[O-2-tBu-6-(ArN═CH)C6H3] [Ar = 2...

A series of phenoxy-substituted tris(pyrazolyl)borate titanium complexes, Tp′TiCl2(OAr) and Tp*TiMe2(OAr) [Tp = HB(pyrazolyl)3, Tp* = HB(3,5-Me2-pyrazolyl)3; Ar = Ph, 2,6-Me2C6H3, 2,6-iPr2C6H3], we...

Treatment of V(NAr)(CH2SiMe3)3 (1, Ar = 2,6-Me2C6H3) with 1.0 equiv of various alcohols in n-hexane at 25 °C cleanly afforded the corresponding dialkyl complexes of the type V(NAr)(CH2SMe3)2(OR) [R = 2,6-Me2C6H3 (2a), 2,6-iPr2C6H3 (2b), C6F5 (2c), tBu (2d), CMe(CF3)2 (2e), yield 90−93%]. In contrast, the reactions with R′N(H)Me (R′ = Ph, cyclohexyl) or 2,6-Me2C6H3SH did not take place even if the reactions were attempted in C2D2Cl4 at 50 °C. Complexes 2a and 2b showed high catalytic activities for the ring-opening metathesis polymerization (ROMP) of norbornene in the presence of PMe3, and the activity increased at high temperature (80 °C). A vanadium(V)−alkylidene complex, V(CHSiMe3)(NAr)(O-2,6-iPr2C6H3)(PMe3)x (3, x = 0.89), has been isolated when the C6D6 solution containing 2b was heated at 80 °C in the presence of PMe3 (5.0 equiv). Complex 3 showed remarkable catalytic activity for the ROMP of norbornene, and the polymerization at 25 °C proceeded in a living manner.

A series of (arylimido)vanadium(V) complexes containing phenoxyimine ligands of the type V(NAr)Cl2[O-2-R-6-{(2,6-iPr2C6H3)N═CH}C6H3] [Ar = 2,6-Me2C6H3; R = H (1a), Me (1b), tBu (1c)] have been prepared in 64−78% yields from V(NAr)Cl3 with LiO-2-R-6-[(2,6-iPr2C6H3)N═CH]C6H3. The structures for 1a−c determined by X-ray crystallography indicate that these complexes have distorted square-pyramidal structures around vanadium, consisting of the arylimido ligands in the apical site of a distorted square-pyramid and the N,O-chelate ligand, which forms a plane including both the aryloxo ring and the imino nitrogen. The Cl−V−Cl bond angle for 1c [90.49(2)°] is apparently smaller than those in 1a,b [91.97(7)°, 91.25(2)°, respectively], and the V−N(imine) bond distance in 1c [2.203(2) A] is shorter than those in 1b,c [2.216(4), 2.2165(17) A, respectively]. These complexes (especially 1c) exhibited notable catalytic activities for ethylene polymerization in the presence of MAO, and the ortho substituent in the aryloxo...

The vanadium(V) alkylidene complex (ArN)V(CHSiMe3)(NCtBu2)(PMe3) (6; Ar = 2,6-Me2C6H3) has been isolated from (ArN)V(CH2SiMe3)2(NCtBu2) (5) by α-hydrogen elimination in benzene-d6 at 80 °C. The complex 6 initiated ring-opening metathesis polymerization (ROMP) of norbornene, yielding a high-molecular-weight polymer with unimodal molecular weight distribution (Mw = 1.15 × 106, Mw/Mn = 1.6) in high yield (98%), and the activity increased at higher temperatures (80 °C).