Stannole is an organotin compound with the formula (CH)<sub>4</sub>SnH<sub>2</sub>. It is classified as a metallole, i.e. an unsaturated five-membered ring containing a heteroatom. It is a structural analog of cyclopentadiene, with tin replacing the saturated carbon atom. Substituted derivatives, which have been synthesized, are also called stannoles.
1,1-Dibutylstannole is a pale yellow oil prepared from 1,4-dilithio-1,3-butadiene and dibutyltin dichloride.
1,1-Dimethyl-2,3,4,5-tetraphenyl-1H-stannole, for example, can be formed by the displacement reaction of 1,4-dilithio-1,2,3,4-tetraphenyl-1,3-butadiene and dimethyltin dichloride.
Palladium and cobalt catalyze a [2+2+1] cycloaddition between two acetylene molecules and a stannylene SnR<sub>2</sub> to give the corresponding stannole.
1û<sup>2</sup>-Stannole has formula C<sub>4</sub>H<sub>4</sub>Sn, with no hydrogen on the tin atom, which is in the +2 oxidation state.