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Updated: Jun 4, 2025

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
Iridium trihydride and tetrahydride complexes and their role in catalytic polarisation transfer from parahydrogen to
Ben J Tickner1, Simon B Duckett2
1Centre for Hyperpolarisation in Magnetic Resonance, University of York Heslington YO10 5NY UK.
Abstract:
This work details how the unusual iridium tetrahydride [Ir(H)4(IMes)(sulfoxide)]Na and trihydride [Ir(H)3(IMes)(sulfoxide)2] can be formed in a solvent dependent reaction of [IrCl(COD)(IMes)] with sulfoxide (dimethyl or methylphenyl), base, and H2. In the case of dimethyl sulfoxide, the four hydride ligands of the tetrahydride are equivalent, and the IMes and sulfoxide ligands mutually trans. However, for phenyl methyl sulfoxide, this isomer of the tetrahydride forms alongside its cis counterpart where the remarkable symmetry breaking effect of the sulfoxide leads to it presenting four chemically distinct hydride ligands. These products and their ligand arrangements are characterised and the reaction pathways leading to their formation probed using NMR spectroscopy and parahydrogen-hyperpolarised methods. Subsequently, they form as previously unidentified low concentration by-products in the important SABRE-catalysed hyperpolarisation of pyruvate, and their concentration should be minimised for efficient polarisation transfer.
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