Formation of an imino-stabilized cyclic tin(II) cation from an amino(imino)stannylene.

The novel amino(imino)stannylene 1 was prepared by conversion of HNIPr (NIPr = bis(2,6-diisopropylphenyl)imidazolin-2-imino) with one equivalent of Lappert's tin reagent (Sn[N(SiMe3)2]2). Treatment of 1 with DMAP (4-dimethylaminopyridine) yields its Lewis acid-base adduct 2. The reaction of 1 with one equivalent of trimethylsilyl azide results in replacement of the amino group at the tin center by an N3 substituent with concomitant elimination of N(SiMe3)3 to afford dimeric [N3SnNIPr]2 (3). Remarkably, the reaction of 1 with B(C6F5)3 produces the novel tin(II) monocation 4(+)[MeB(C6F5)3](-) comprising a four-membered stannacycle through methyl-abstraction from the trimethylsilyl group.