HexahydroxostannateIV

Hexahydroxostannate(IV) refers to the hexahydroxo tin(IV) anion, [Sn(OH)6]2−. In strongly basic aqueous solution, tin(IV) adopts an octahedral coordination around the central tin atom, bound to six hydroxide ligands, giving an Oh-symmetric hexahydroxo complex. The overall charge is −2, reflecting deprotonation of coordinated hydroxyl groups.

In solution, it forms salts with alkali metals, for example Na2[Sn(OH)6] and K2[Sn(OH)6], which can be prepared by dissolving tin(IV) oxide SnO2 in concentrated NaOH or KOH and isolating the resulting salts. Dissolution of SnO2 in hot alkali yields the hexahydroxo tin(IV) anion, which is the dominant tin(IV) species under strongly basic conditions. These salts are typically white solids and can dissolve in water to give alkaline stannate solutions; on acidification they convert to other tin species.

Hexahydroxostannate(IV) is a common tin(IV) oxo-anion in alkaline aqueous chemistry and provides a convenient tin(IV) source in basic media. It serves as a precursor to tin(IV) oxide (SnO2) upon calcination and appears in ceramic and glass processing as a hydroxo-stannate intermediary. The chemistry largely reflects the behavior of tin(IV) species in strongly basic environments.

Safety considerations are primarily those of handling caustic bases; stannate salts are generally of low to moderate toxicity and should be handled with standard laboratory precautions. See also stannate, tin(IV) oxide, and tin chemistry in alkaline media.