In this paper, Grubbs- and Hoveyda–Grubbs-type olefin metathesis catalysts featuring N-cyclopentyl/N’-mesityl backbone-substituted N-heterocyclic carbene (NHC) ligands were synthesized. Their propensity to promote the alternating ring-opening metathesis copolymerization (ROMP) of norbornene (NBE) with cyclooctene (COE) or cyclopentene (CPE) was evaluated and compared to that shown by analogous N-cyclohexyl complexes. High degrees of chemoselectivity were achieved in both copolymerizations. The presence of the N-cyclopentyl substituent allowed for the achievement of up to 98% and 97% of alternating diads for NBE-COE and NBE-CPE copolymers, respectively, at low comonomer ratios. Density functional theory (DFT) studies showed that both the sterical and electronic effects of NHC ligands influence catalyst selectivity.
Alternating Ring-Opening Metathesis Polymerization Promoted by Ruthenium Catalysts Bearing Unsymmetrical NHC Ligands
Troiano R.;Costabile C.;Grisi F.
2023-01-01
Abstract
In this paper, Grubbs- and Hoveyda–Grubbs-type olefin metathesis catalysts featuring N-cyclopentyl/N’-mesityl backbone-substituted N-heterocyclic carbene (NHC) ligands were synthesized. Their propensity to promote the alternating ring-opening metathesis copolymerization (ROMP) of norbornene (NBE) with cyclooctene (COE) or cyclopentene (CPE) was evaluated and compared to that shown by analogous N-cyclohexyl complexes. High degrees of chemoselectivity were achieved in both copolymerizations. The presence of the N-cyclopentyl substituent allowed for the achievement of up to 98% and 97% of alternating diads for NBE-COE and NBE-CPE copolymers, respectively, at low comonomer ratios. Density functional theory (DFT) studies showed that both the sterical and electronic effects of NHC ligands influence catalyst selectivity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
