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(SiMe 3 ) 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(SiMe 3 ) 3 to afford dimeric [N 3 SnNIPr] 2 ( 3 ). Remarkably, the reaction of 1 with B(C 6 F 5 ) 3 produces the novel tin(II) monocation 4 + [MeB(C 6 F 5 ) 3 ] − comprising a four‐membered stannacycle through methyl‐abstraction from the trimethylsilyl group.