A zwitterionic carbene–stannylene adduct via cleavage of a dibenzotetraazafulvalene by a stannylene

Reaction of the tetraamine 1,2-C6H4-[NHCH2CH2N(CH3)2]2 (8) with bis(bis(trimethylsilyl)amido)tin(II) yields the N-heterocyclic stannylene 1,2-C6H4-[NCH2CH2N(CH3)2]2Sn (9) which contains additional 2-(dimethylamino)ethyl groups at the nitrogen atoms of the five-membered ring. These additional donor groups provide for an intramolecular stabilization of the electron deficient tin center. The X-ray structure analysis with crystals of 9 shows two three-coordinated tin atoms with different coordination environments in a dinuclear complex. Reaction of the stannylene 9 with the N,N′N′′N′′′-tetramethyldibenzotetraazafulvalene 4 leads via CC bond cleavage in the dibenzotetraazafulvalene to the yellow carbene–stannylene adduct 10. The X-ray structure analysis of 10 reveals bond parameters consistent with a zwitterionic species made up from a partially cationic carbene subunit and a partially anionic stannylene unit.