What question did this study set out to answer?

The research aims to evaluate the catalytic efficiency of NHC-supported niobium(V)–alkylidene catalysts for ROMP.

April 18, 2026Open Access

NHC-Supported (Arylimido)niobium(V)–Alkylidene Catalysts Exhibiting Exceptionally High Catalytic Activities for ROMPs

Key Points

The research aims to evaluate the catalytic efficiency of NHC-supported niobium(V)–alkylidene catalysts for ROMP.
Synthesis of NHC-supported niobium(V)–alkylidene catalysts with perhalophenoxide ligands.
Examination of catalytic activities in ROMP of norbornene.
Measurement of polymer properties such as molecular weight and turnover frequency.
Catalysts achieve M_n values between 2.02 and 3.84 × 106.
ROMP reactions complete within 5 seconds at 25 °C with TOF exceeding 4260 s–1.
Process yields cis-syndiotactic polymers without catalyst decomposition.

Abstract

The NHC-supported (arylimido)niobium(V)–alkylidene catalysts containing perhalophenoxide ligands, especially Nb(CHR)(NC6F5)(OC6X5)(NHC)(PMe3) R = SiMe3 or CMe2Ph; X = Cl, Br; NHC = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, display remarkable catalytic activities for ring-opening metathesis polymerization (ROMP) of norbornene (NBE), affording ultrahigh molar mass polymers with unimodal molecular weight distributions (Mn = 2.02–3.84 × 106). In particular, the ROMP by Nb(CHSiMe3)(NC6F5)(OC6Cl5)(NHC)(PMe3) reached completion within 5 s at 25 °C with a turnover frequency (TOF) of >4260 s–1. The ROMP by Nb(CHSiMe3)(N-2,6-F2C6H3)OC(CF3)3(NHC) gave the cis-syndiotactic polymers, and the polymerization proceeded in a controlled manner without catalyst decomposition.

NHC-Supported (Arylimido)niobium(V)–Alkylidene Catalysts Exhibiting Exceptionally High Catalytic Activities for ROMPs

Key Points

Abstract

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