Affiliation:
1. Centre for Hyperpolarisation in Magnetic Resonance (CHyM) University of York Heslington, York YO10 5NY United Kingdom
2. Department of Chemistry University of York Heslington, York YO10 5DD United Kingdom
3. Centro de Investigacións Científicas Avanzadas (CICA) Departamento de Química, Facultade de Ciencias Universidade da Coruña A Coruña 15001 Spain
Abstract
AbstractMetal dihydride dihydrogen‐derived intermediates can be short‐lived and difficult to detect despite their ubiquitous role in chemical transformations such as hydrogenation. Here, highly reactive [Ir(H)3(η2‐η2‐COD)(IMes)] forms by trapping [Ir(H)2(η2‐H2)(η2‐η2‐COD)(IMes)]X [X=Cl or MeO], resulting from reaction of the Ir(I) precatalyst [IrCl(η2‐η2‐COD)(IMes)] with a base and H2. This trihydride allows access to the unusual [Ir2(H)4(OMe)(IMes)2(pyridine)3]X, [Ir2(H)2(μ2‐H)2(η2‐η2‐COD)(IMes)2], [Ir3(H)9(IMes)3], [Ir4(H)12(IMes)4] and [Ir2(H)4(μ2‐H)2(IMes)2(pyridine)2]. A combination of 2D NMR, parahydrogen hyperpolarized NMR, MS, and XRD are used to characterise these reaction products and rationalise their formation via the moiety {Ir(H)3(IMes)}. Consequently, the results of these studies have implications for iridium‐catalyzed polarization transfer from parahydrogen via the well‐known precursor [IrCl(η2‐η2‐COD)(IMes)].