Stannylene

[5] The existence of this elusive SnMe2 was further confirmed by the discovery of visible light absorption matching the calculated electronic transition of SnMe2 in gas phase.

[7] Another method to prepare short-lived stannylene is laser flash photolysis using tetraalkyltin(IV) compound (e.g. SnMe4) as a precursor.

[3][9] With specific type of ligands, the electron deficiency of monomeric stannylene is reduced by the agostic interaction from B-H bond.

The mitigation of Sn electron deficiency was proved by the spectroscopic data, especially the 119Sn NMR spectra which showed the drastically low chemical shift (587 and 787 ppm comparing to 2323 ppm in analogous dialkylstannylene) indicating more electron density around Sn in this case.

[11] Apart from that, the stability of stannylene dimer is also affected by the steric repulsion and dispersion attraction between bulky substituents.

[12] Alkylstannylenes can react with various reagents (e.g. alkyl halides, enones, dienes) in an oxidative addition (or insertion) fashion.

[13] Although stannylenes are more stable than its lighter carbene analogs, they readily undergo [2+4] cycloaddition reaction with Z-alkenes.

In ammonia and water cases, the oxidative added product could also undergo reductive elimination, yielding O- or N-B bond formation.