The stannite ion is Sn(OH)−
3, or similar.
There are stannite compounds, for example, sodium stannite, Na2SnO2.
Stannite ion can be formed by adding strong base to stannous hydroxide.
Stannite ion is a strong reducing agent; also, it may disproportionate to tin metal plus stannate ion.
References
Stannite (ion) Wikipedia(Text) CC BY-SA