Ru-Based Olefin Metathesis Catalysts Bearing pH-Responsive N-Heterocyclic Carbene (NHC) Ligands: Activity Control via Degree of Protonation
Document Type
Article
Publication Date
5-1-2009
Department
Chemistry and Biochemistry
School
Mathematics and Natural Sciences
Abstract
Olefin metathesis catalysts (H2ITap)(PCy3)Cl2Ru=CHPh (4) and (H2ITap)Cl2Ru=CH‐(C6H4‐O‐iPr) (5) [H2ITap = 1,3‐bis(2′,6′‐dimethyl‐4′‐dimethylaminophenyl)‐4,5‐dihydroimidazol‐2‐ylidene] were used for the ring‐opening metathesis polymerization (ROMP) of exo‐7‐oxanorbornene derivative 7 in the presence of various amounts of acid. Upon gradual protonation of the NMe2 groups of the H2Tap ligand, the metathesis activity of both catalysts were gradually reduced due to electronic changes of the N‐heterocyclic carbene (NHC) ligand donor capability. The investigation of the ROMP polymer 8, DFT calculations and measurements of the initiation kinetics prove that the reduced activity is solely due to reduced rates of propagation.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Publication Title
European Journal of Inorganic Chemistry
Issue
13
First Page
1717
Last Page
1722
Recommended Citation
Balof, S. L.,
Yu, B.,
Lowe, A. B.,
Ling, Y.,
Zhang, Y.,
Schanz, H.
(2009). Ru-Based Olefin Metathesis Catalysts Bearing pH-Responsive N-Heterocyclic Carbene (NHC) Ligands: Activity Control via Degree of Protonation. European Journal of Inorganic Chemistry(13), 1717-1722.
Available at: https://aquila.usm.edu/fac_pubs/8919