環状オレフィンの開環メタセシス重合に有効な芳香族イミド配位バナジウム錯体触媒の創製

首都大学東

(Arylimido)Vanadium(V)-Alkylidenes Containing Chlorinated Phenoxy Ligands: Thermally Robust, Highly Active Catalyst in Ring-Opening Metathesis Polymerization of Cyclic Olefins

A series of (imido)­vanadium­(V)-alkylidene complexes containing pentachlorophenoxy ligand of type, V­(CHSiMe₃)­(N-2,6-R₂C₆H₃)­(OC₆Cl₅)­(PMe₃)₂ [R = H, Cl, F, CH₃], have been prepared, and the structure of V­(CHSiMe₃)­(N-2,6-Me₂C₆H₃)­(OC₆Cl₅)­(PMe₃)₂ was determined by X-ray crystallographic analysis. Ring-opening metathesis polymerization (ROMP) of cyclic olefins such as norbornene (NBE), cyclopentene (CPE), cycloheptene (CHPE), and <i>cis</i>-cyclooctene (COE) using these alkylidene catalysts have been explored, and V­(CHSiMe₃)­(<i>N</i>-2,6-Cl₂C₆H₃)­(OC₆Cl₅)­(PMe₃)₂ showed higher activities in the ROMP of CPE, CHPE, and COE than those of the reported V­(CHSiMe₃)­(N-2,6-Cl₂C₆H₃)­(OC₆F₅)­(PMe₃)₂. The activity in the ROMP of COE increased at high temperature until 120 °C, and the ROMPs of CHPE and COE proceeded without chain-transfer or termination (nor catalyst decomposition); the (quasi) living nature thus maintained even at 80 °C. The activities in the ROMPs of CHPE and COE (at 25 °C) increased upon addition of 1.0 equiv of B­(C₆F₅)₃, whereas the activity in the ROMP of NBE became negligible upon the addition. The order in the activity in the ROMP of cyclic olefins displayed as COE ≪ CHPE < CPE ≪ NBE, which is different from not only that in the ring strain energy but also that reported in the ROMPs using ruthenium–carbene catalysts