A Vanadium(V) Alkylidene Complex Exhibiting Remarkable Catalytic Activity for Ring-Opening Metathesis Polymerization (ROMP)

The vanadium(V) alkylidene complex (ArN)V(CHSiMe3)(NCtBu2)(PMe3) (6; Ar = 2,6-Me2C6H3) has
been isolated from (ArN)V(CH2SiMe3)2(NCtBu2) (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).

钒(V)亚烷基配合物(ArN)V(=CHSiMe₃)(N=C(tBu)₂)(PMe₃)（编号6；Ar=2,6-二甲基苯基，2,6-Me₂C₆H₃）可由前驱体(ArN)V(CH₂SiMe₃)₂(N=C(tBu)₂)（编号5）在80℃的氘代苯（benzene-d₆）中通过α-氢消除反应分离得到。该配合物6可引发降冰片烯的开环易位聚合（ring-opening metathesis polymerization, ROMP），制备得到具有单峰分子量分布的高分子量聚合物，其重均分子量Mw=1.15×10⁶，分子量分布指数Mw/Mn=1.6，聚合产率高达98%；且聚合活性随温度升高至80℃时显著提升。