Ru‐Based Olefin Metathesis Catalysts Bearing pH‐Responsive N‐Heterocyclic Carbene (NHC) Ligands: Activity Control via Degree of Protonation | Zendy

Balof Shawna L. | Zendy; Yu Bing | Zendy; Lowe Andrew B. | Zendy; Ling Yan | Zendy; Zhang Yong | Zendy; Schanz HansJörg | Zendy

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Ru‐Based Olefin Metathesis Catalysts Bearing pH‐Responsive N‐Heterocyclic Carbene (NHC) Ligands: Activity Control via Degree of Protonation

Author(s) -

Balof Shawna L.,

Yu Bing,

Lowe Andrew B.,

Ling Yan,

Zhang Yong,

Schanz HansJörg

Publication year - 2009

Publication title -

european journal of inorganic chemistry

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.667

H-Index - 136

eISSN - 1099-0682

pISSN - 1434-1948

DOI - 10.1002/ejic.200801145

Subject(s) - chemistry , romp , carbene , metathesis , protonation , ring opening metathesis polymerisation , ligand (biochemistry) , catalysis , medicinal chemistry , ruthenium , polymer chemistry , polymerization , organic chemistry , polymer , ion , biochemistry , receptor

Abstract Olefin metathesis catalysts (H 2 ITap)(PCy 3 )Cl 2 Ru=CHPh ( 4 ) and (H 2 ITap)Cl 2 Ru=CH‐(C 6 H 4 ‐O‐ i Pr) ( 5 ) [H 2 ITap = 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 NMe 2 groups of the H 2 Tap 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)

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