NHC‐stabilized Silicon(II) Halides: Reactivity Studies with Diazoalkanes and Azides

Abstract

Detailed studies of the reactivity of the NHC‐stabilized (NHC = N‐heterocyclic carbene) silicon(II) halides SiI2(Idipp) (1) and SiClR(IMe4) (2‐Trip: R = ArTrip; 2‐Mes: R = ArMes) towards diazoalkanes and azides are presented (Idipp = C[N(C6H3–2,6‐iPr2)CH]2, IMe4 = C[N(Me)CMe]2, ArTrip = C6H3‐2,6‐Trip2, ArMes = C6H3‐2,6‐Mes2, Trip = C6H2‐2,4,6‐iPr3, Mes = C6H2‐2,4,6‐Me3). Treatment of 1, 2‐Trip, and 2‐Mes with the diazoalkanes (p‐Tol)2CN2 (p‐Tol = C6H4‐4‐Me) and ArMesCHN2 afforded the NHC‐stabilized silazines SiI2{N2C(p‐Tol)2}(Idipp) (3) and SiClR{N2CH(ArMes)}(IMe4) (4‐Trip: R = ArTrip, 4‐Mes: R = ArMes) as orange to yellow solids, respectively. No N2 elimination from the diazoalkanes was observed in these reactions. In comparison, the reactions of 1 or 2‐Trip with the covalent azides MesN3 or Me3SiN3, yielded after N2 elimination the yellow to colorless NHC‐stabilized silaimines SiI2(NMes)(Idipp) (5), Si(ArTrip)Cl(NMes)(IMe4) (6) and Si(ArTrip)(N3)(NSiMe3)(IMe4) (7), respectively. All compounds were characterized by elemental analyses, FT‐IR and multinuclear magnetic resonance spectroscopy. Moreover, the molecular structures of 4‐Mes, 5, 6, and 7 were determined by single‐crystal X‐ray diffraction analyses.