Tickner Ben J, Duckett Simon B
Centre for Hyperpolarisation in Magnetic Resonance, University of York Heslington YO10 5NY UK.
Department of Chemistry, University of York Heslington YO10 5DD UK
Chem Sci. 2024 Dec 12;16(3):1396-1404. doi: 10.1039/d4sc06138a. eCollection 2025 Jan 15.
This work details how the unusual iridium tetrahydride [Ir(H)(IMes)(sulfoxide)]Na and trihydride [Ir(H)(IMes)(sulfoxide)] can be formed in a solvent dependent reaction of [IrCl(COD)(IMes)] with sulfoxide (dimethyl or methylphenyl), base, and H. In the case of dimethyl sulfoxide, the four hydride ligands of the tetrahydride are equivalent, and the IMes and sulfoxide ligands mutually . However, for phenyl methyl sulfoxide, this isomer of the tetrahydride forms alongside its 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 hydrogen-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.
这项工作详细阐述了异常的四氢铱化合物[Ir(H)(IMes)(亚砜)]Na和三氢铱化合物[Ir(H)(IMes)(亚砜)]如何在[IrCl(COD)(IMes)]与亚砜（二甲基或甲基苯基）、碱和H的溶剂依赖性反应中形成。在二甲基亚砜的情况下，四氢铱化合物的四个氢化物配体是等效的，并且IMes和亚砜配体相互作用。然而，对于苯甲基亚砜，四氢铱化合物的这种异构体与其对应物一起形成，其中亚砜的显著对称破缺效应导致其呈现四个化学性质不同的氢化物配体。使用核磁共振光谱和氢超极化方法对这些产物及其配体排列进行了表征，并探究了导致它们形成的反应途径。随后，它们在丙酮酸的重要SABRE催化超极化过程中作为先前未鉴定的低浓度副产物形成，为了实现有效的极化转移，应将它们的浓度降至最低。
