A Tin Analogue of Carbenoid: Isolation and Reactivity of a Lithium Bis(imidazolin-2-imino)stannylenoid

The lithium bis(imino)stannylenoid (NIPr)₂Sn(Li)Cl (1; NIPr=bis(2,6-diisopropylphenyl)imidazolin-2-imino) was prepared by the reaction of LiNIPr with 0.5 equiv of SnCl₂diox (diox=1,4-dioxane) and the ambiphilic character of the compound was demonstrated by investigations into its reactivity. Treatment of 1 with I₂or MeI yielded the oxidative addition products (NIPr)₂SnI₂and (NIPr)₂Sn(Me)I, respectively. In contrast, the reaction of 1 with one equivalent of Me₃SiCl resulted in the formation of Me₃SiNIPr and the chlorostannylene dimer [NIPrSnCl]₂. Moreover, the substitution reaction of compound 1 with MeLi led to the formation of the methyl-substituted stannate (NIPr)₂Sn(Li)Me. Ambiphilic tin(II): An elusive bis(imino)stannylenoid, a tin carbenoid analogue, was synthesized by using the highly basic imidazolin-2-imino group. Through investigations into the reactivity of the system and computational studies, the ambiphilic character of the stannylenoid was demonstrated.