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Disentangling Ligand Effects on Metathesis Catalyst Activity: Experimental and Computational Studies of Ruthenium–Aminophosphine Complexes

Chu, Crystal K. and Lin, Tzu-Pin and Shao, Huiling and Liberman-Martin, Allegra L. and Liu, Peng and Grubbs, Robert H. (2018) Disentangling Ligand Effects on Metathesis Catalyst Activity: Experimental and Computational Studies of Ruthenium–Aminophosphine Complexes. Journal of the American Chemical Society, 140 (16). pp. 5634-5643. ISSN 0002-7863. https://resolver.caltech.edu/CaltechAUTHORS:20180416-092159771

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Abstract

Second-generation ruthenium olefin metathesis catalysts bearing aminophosphine ligands were investigated with systematic variation of the ligand structure. The rates of phosphine dissociation (k_1; initiation rate) and relative phosphine reassociation (k_(–1)) were determined for two series of catalysts bearing cyclohexyl(morpholino)phosphine and cyclohexyl(piperidino)phosphine ligands. In both cases, incorporating P–N bonds into the architecture of the dissociating phosphine accelerates catalyst initiation relative to the parent [Ru]–PCy_3 complex; however, this effect is muted for the tris(amino)phosphine-ligated complexes, which exhibit higher ligand binding constants in comparison to those with phosphines containing one or two cyclohexyl substituents. These results, along with X-ray crystallographic data and DFT calculations, were used to understand the influence of ligand structure on catalyst activity. Especially noteworthy is the application of phosphines containing incongruent substituents (PR_1R′_2); detailed analyses of factors affecting ligand dissociation, including steric effects, inductive effects, and ligand conformation, are presented. Computational studies of the reaction coordinate for ligand dissociation reveal that ligand conformational changes contribute to the rapid dissociation for the fastest-initiating catalyst of these series, which bears a cyclohexyl-bis(morpholino)phosphine ligand. Furthermore, the effect of amine incorporation was examined in the context of ring-opening metathesis polymerization, and reaction rates were found to correlate well with catalyst initiation rates. The combined experimental and computational studies presented in this report reveal important considerations for designing efficient ruthenium olefin metathesis catalysts.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/jacs.8b02324DOIArticle
https://pubs.acs.org/doi/10.1021/jacs.8b02324PublisherArticle
https://pubs.acs.org/doi/suppl/10.1021/jacs.8b02324DOISupporting Information
ORCID:
AuthorORCID
Chu, Crystal K.0000-0002-7783-2564
Lin, Tzu-Pin0000-0001-7041-7213
Liberman-Martin, Allegra L.0000-0002-8447-905X
Liu, Peng0000-0002-8188-632X
Grubbs, Robert H.0000-0002-0057-7817
Additional Information:© 2018 American Chemical Society. Received: February 27, 2018; Published: April 5, 2018. We thank Dr. David VanderVelde for assistance with NMR spectroscopic experiments and Lawrence Henling for assistance with X-ray crystallography. Dr. Mona Shahgholi and Naseem Torian are acknowledged for assistance with mass spectrometry. Dr. Adam Johns is thanked for helpful discussions regarding aminophosphine and catalyst synthesis. Dr. Choon Woo Lee, Dr. Keary Engle, Dr. William Wolf, Lennon Luo, and Tonia Ahmed are acknowledged for helpful discussions of kinetics of olefin metathesis. Materia, Inc. is thanked for donation of catalyst G2. We acknowledge ONR (N00014-13-1-0895 and N00014-14-1-0650) and ARPA-E (DE-AR0000683) for financial support, and the Resnick Sustainability Institute for a fellowship to A.L.L.-M. DFT calculations were performed at the Center for Research Computing at the University of Pittsburgh and the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the National Science Foundation. The authors declare no competing financial interest.
Group:Resnick Sustainability Institute
Funders:
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-13-1-0895
Office of Naval Research (ONR)N00014-14-1-0650
ARPA-EDE-AR0000683
Resnick Sustainability InstituteUNSPECIFIED
NSFUNSPECIFIED
Issue or Number:16
Record Number:CaltechAUTHORS:20180416-092159771
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180416-092159771
Official Citation:Disentangling Ligand Effects on Metathesis Catalyst Activity: Experimental and Computational Studies of Ruthenium–Aminophosphine Complexes. Crystal K. Chu, Tzu-Pin Lin, Huiling Shao, Allegra L. Liberman-Martin, Peng Liu, and Robert H. Grubbs. Journal of the American Chemical Society 2018 140 (16), 5634-5643. DOI: 10.1021/jacs.8b02324
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85874
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Apr 2018 20:45
Last Modified:03 Oct 2019 19:36

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