Effect of Phosphine, B(C₆F₅)₃ in Ring Opening Metathesis Polymerization (ROMP) of Cyclic Olefins by (Arylimido)Vanadium(V)–Alkylidene Catalysts and the Chain Transfer ROMP of Cycloheptene

(Arylimido)niobium(V)–Alkylidenes as the Catalysts for Ring-Opening Metathesis Polymerization (ROMP) of Cyclic Olefins: Z-Specific ROMP of Cyclooctene by Nb(CHSiMe3)(NC6H5)[OC(CF3)3](PMe3)2

“…Certain high-oxidation-state metal–alkylidene complexes with early transition metals − have been known to play essential roles as catalysts in olefin metathesis reactions, − ,− which have been recognized as useful methods for the synthesis of functional polymers − as well as fine chemicals. − In particular, ring-opening metathesis polymerization (ROMP) of cyclic olefins is widely employed for the synthesis of advanced polymers. − ,, In contrast to successful examples of ROMP demonstrated by molybdenum(VI)– and tungsten(VI)–alkylidene catalysts, − , and later by vanadium(V)–alkylidene catalysts, − reports of organo-niobium complex catalysts still have been limited until recently (Chart ). − After the first report by Mashima et al in 1997 (catalyst A ), there were two reports for the ROMP of norbornene (NBE) in 2016 (catalysts B and C ). , In particular, (imido)niobium–alkylidenes, Nb(CHSiMe 3 )(NR)[OC(CF 3 ) 3 ](PMe 3 ) 2 ( C ), not only exhibited much higher catalytic activities tha...…”