Journal of Polymer Science Part A: Polymer Chemistry, Vol.55, No.18, 3028-3033, 2017
Tailored Molybdenum Imido Alkylidene N-Heterocyclic Carbene Complexes as Latent Catalysts for the Polymerization of Dicyclopentadiene
Three novel molybdenum imido alkylidene Nheterocyclic carbene (NHC) pre-catalysts, that is, Mo(N-t-Bu) (1-(2,6-diisopropylphenyl)-3-isopropyl-4-phenyl-1H-1,2,3-triazol-5-ylidene)(CHCMe2Ph)(OTf)(2) (I1, OTf5CF3SO3), Mo(N-t-Bu) (1-(2,6-diisopropylphenyl)-3-isopropyl-4-phenyl-1H-1,2,3-triazol5-ylidene)(CHCMe2Ph)(OTf)(t-BuO) (I2) and Mo(N-2,6-Me2-C6H3) (1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene)(CHCMe2Ph) (OTf)(2) (I-3) are presented. Compared to complexes based on imidazol-2-ylidenes or imidazolin-2-ylidenes, (1-(2,6-diisopropylphenyl)-3-isopropyl-4-phenyl-1H-1,2,3-triazol-5-ylidene) used in precatalysts I1 and I2 exerts a comparably strong trans effect to the triflate groups trans to the NHC, while (1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene) used in I3 has a weaker trans effect on the triflate. In combination with a suitable second anionic ligand at molybdenum, that is, OTf, t-BuO, compounds I1-I3 require higher temperatures to become active and can thus be used as truly room temperature latent pre-catalysts, even for a highly reactive monomer such as dicyclopentadiene (DCPD). When used as latent precatalysts, I1-I3 offer access to poly-DCPD with different degrees of cross-linking and glasstransition temperatures (T-g). (C) 2017 Wiley Periodicals, Inc.