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 N-3 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.