Procacci, Barbara orcid.org/0000-0001-7044-0560, Jiao, Yunzhe, Evans, Meagan E. et al. (3 more authors) (2015) Activation of B-H, Si-H, and C-F bonds with Tp′Rh(PMe3) complexes:Kinetics, mechanism, and selectivity. Journal of the American Chemical Society. pp. 1258-1272. ISSN 1520-5126
Abstract
The photochemical reactions of Tp′Rh(PMe3)H2 (1) and thermal reactions of Tp′Rh(PMe3)(CH3)H (1a, Tp′ = tris(3,5-dimethylpyrazolyl)borate) with substrates containing B-H, Si-H, C-F, and C-H bonds are reported. Complexes 1 and 1a are known activators of C-H bonds, including those of alkanes. Kinetic studies of reactions with HBpin and PhSiH3 show that photodissociation of H2 from 1 occurs prior to substrate attack, whereas thermal reaction of 1a proceeds by bimolecular reaction with the substrate. Complete intramolecular selectivity for B-H over C-H activation of HBpin (pin = pinacolate) leading to Tp′ Rh-(PMe3)(Bpin)H is observed. Similarly, the reaction with Et2SiH2 shows a strong preference for Si-H over C-H activation, generating Tp′Rh-(PMe3)(SiEt2H)H. The Rh(Bpin)H and Rh(SiEt2H)H products were stable to heating in benzene in accord with DFT calculations that showed that reaction with benzene is endoergic. The intramolecular competition with PhSiH3 yields a ∼1:4 mixture of Tp′Rh(PMe3)(C6H4SiH3)H and Tp′Rh(PMe3)(SiPhH2)H, respectively. Reaction with pentafluoropyridine generates Tp′Rh(PMe3)(C5NF4)F, while reaction with 2,3,5,6-tetrafluoropyridine yields a mixture of C-H and C-F activated products. Hexa fluorobenzene proves unreactive. Crystal structures are reported for B-H, Si-H, and C-F activated products, but in the latter case a bifluoride complex Tp′Rh(PMe3)(C5NF4)(FHF) was crystallized. Intermolecular competition reactions were studied by photoreaction of 1 in C6F6 with benzene and another substrate (HBpin, PhSiH3, or pentafluoropyridine) employing in situ laser photolysis in the NMR probe, resulting in a wide-ranging map of kinetic selectivities. The mechanisms of intramolecular and intermolecular selection are analyzed. (Chemical Equation Presented).
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Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2014 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) The University of York |
Funding Information: | Funder Grant number EPSRC EP/F037740/1 |
Depositing User: | Pure (York) |
Date Deposited: | 22 Jun 2015 15:37 |
Last Modified: | 01 Dec 2024 01:06 |
Published Version: | https://doi.org/10.1021/ja5113172 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1021/ja5113172 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:87375 |
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Description: Activation of B−H, Si−H, and C−F Bonds with Tp′Rh(PMe3) Complexes: Kinetics, Mechanism, and Selectivity