tetrahydroxostannateIV

Tetrahydroxostannate(IV) is an inorganic chemical compound with the formula [Sn(OH)4]2-. It is an anionic complex of tin in the +4 oxidation state, coordinated by four hydroxide ligands. This species is typically found in alkaline solutions where tin(IV) hydroxide precipitates, and in the presence of excess hydroxide ions, redissolves to form the tetrahydroxostannate(IV) anion.

The formation of tetrahydroxostannate(IV) is a reversible process. In acidic conditions, the complex will protonate, leading to the precipitation of tin(IV) hydroxide, Sn(OH)4, which is often described as hydrous tin dioxide, SnO2·2H2O. The solubility of tin in alkaline solutions is primarily due to the formation of this complex.

Tetrahydroxostannate(IV) can be prepared by dissolving tin(IV) oxide or tin(IV) hydroxide in a concentrated solution of a strong base, such as sodium hydroxide or potassium hydroxide. The resulting solution contains the [Sn(OH)4]2- anion. This anion is stable in alkaline environments but will decompose upon acidification.

The compound is of interest in inorganic chemistry due to its role in the solubility of tin oxides and hydroxides and its participation in various tin-based chemical reactions. It is an example of an amphoteric behavior of metal oxides and hydroxides, where they can react with both acids and bases.