Procacci, Barbara orcid.org/0000-0001-7044-0560, Aguiar, Pedro M., Halse, Meghan Eileen orcid.org/0000-0002-3605-5551 et al. (2 more authors) (2016) Photochemical Pump and NMR Probe to monitor the formation and kinetics of hyperpolarized metal dihydrides. Chemical Science. SC-EDG-05-2016-001956.R1. pp. 7087-7093. ISSN 2041-6539
Abstract
On reaction of IrI(CO)(PPh 3) 21with para-hydrogen(p-H 2),Ir(H) 2I(CO)(PPh 3) 22 is formed which exhibits strongly enhanced 1H NMR signals for its hydride resonances. Complex 2 also shows similar enhancement of its NMR spectra when it is irradiated under p-H 2. We report the use of this photochemical reactivity to measure the kinetics of H 2 addition by laser-synchronized reactions in conjunction with NMR. The single laser pulse promotes the reductive elimination of H 2 from Ir(H) 2I(CO)(PPh 3) 22 in C 6D 6 solution to form the 16-electron precursor 1, back reaction with p-H 2 then reforms 2 in a well-defined nuclear spin-state. The build up of this product can be followed by incrementing a precisely controlled delay (τ), in millisecond steps, between the laser and the NMR pulse. The resulting signal vs. time profile shows a dependence on p-H 2 pressure. The plot of k obs against p-H 2 pressure is linear and yields the second order rate constant, k 2, for H 2 addition to 1 of (3.26 ± 0.42) × 10 2 M −1 s −1. Validation was achieved by transient-UV-vis absorption spectroscopy which gives k 2 of (3.06 ± 0.40) × 10 2 M −1 s −1. Furthermore, irradiation of a C 6D 6 solution of 2 with multiple laser shots, in conjunction with p-H 2 derived hyperpolarization, allows the detection and characterisation of two minor reaction products, 2a and 3, which are produced in such low yields that they are not detected without hyperpolarization. Complex 2a is a configurational isomer of 2, while 3 is formed by substitution of CO by PPh 3
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Royal Society of Chemistry |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) |
Funding Information: | Funder Grant number EPSRC EP/K022792/1 |
Depositing User: | Pure (York) |
Date Deposited: | 09 Aug 2016 13:42 |
Last Modified: | 23 Jan 2025 00:08 |
Published Version: | https://doi.org/10.1039/C6SC01956K |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1039/C6SC01956K |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:103527 |
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