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Published June 15, 2010 | public
Journal Article

Latent ruthenium olefin metathesis catalysts featuring a phosphine or an N-heterocyclic carbene ligand


The synthesis and characterization of latent 18-electron ruthenium benzylidene complexes (PCy_3)((^κN,O)-picolinate)_2RuCHPh (5) and (H_2IMes)((^κN,O)-picolinate)_2RuCHPh (6) are described. Both complexes appear as two isomers. The ratio between the isomers is dependent on l-type ligand. The complexes are inactive in ring-closing metathesis and ring-opening metathesis polymerization reactions even at elevated temperatures in the absence of stimuli. Upon addition of HCl, complexes 5 and 6 become highly active in olefin metathesis reactions. The advantage of the latent catalysts is demonstrated in the ring-opening metathesis polymerization of dicyclopentadiene, where the latency of 6 assures adequate mixing of catalyst and monomer before initiation. Trapping experiments suggests that the acid converts the 18-electron complexes into their corresponding highly olefin metathesis active 14-electron benzylidenes.

Additional Information

© 2010 Elsevier B.V. Received 4 March 2010; revised 14 April 2010; accepted 16 April 2010. Available online 24 April 2010. Financial support from the Swedish Research Council, National Science Foundation (NSF CHE-0809418), and National Institute of Health (NIH GMO-31332) is gratefully acknowledged. We thank Drs I. Gorodetskaya, M. F. Z. Page, and I. C. Stewart for fruitful discussions. L. M. Henling and Dr M. W. Day are acknowledged for the crystal structure of 6a. We thank B. Edgecombe at Materia Inc for helping with the ROMP of DCPD and for analysis of the poly-DCPD. We thank Materia Inc for the donation of catalyst 1 and 2.

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