Iron(I) and Iron(II) Amido-imidazolin-2-imine Complexes as Catalysts for H/D Exchange in Hydrosilanes

The unsymmetrical amino-imidazolin-2-imine ligand [HAmIm, 1,2-(DippNH)–C6H4–N=C­(NiPrCMe)2] is employed in the synthesis of the iron­(I) arene complex [(AmIm)­Fe­(η 6 -C6H6)] and the iron­(II) neosilyl complex [(AmIm)­Fe­(CH2SiMe3)]. These compounds are highly efficient precatalysts in H/D exchange reactions with deuterium (D2) in hydrosilanes. The scope comprises primary to tertiary silanes at a catalyst loading of 1 mol % at ambient temperature. In-depth mechanistic studies including various control experiments and the syntheses of isolated iron-hydride and iron-silyl compounds are performed. These studies reveal that the activation of both Fe­(I) and Fe­(II) complexes generates Fe–H/D species as key catalytic intermediates. An alternative catalytic pathway involving an iron-silyl intermediate, although shown to be less feasible by DFT calculations, may also be operative.