Na2SnOH4

Na2SnOH4, also known as sodium tetrahydroxostannate(IV), is an inorganic compound. It is a salt of tin in its +4 oxidation state and hydroxide ions. The compound is typically encountered in aqueous solution or as a hydrate. In solution, it exists as the complex anion [Sn(OH)4]2-. The formation of this anion is a characteristic reaction of tin(IV) oxides or hydroxides in strongly alkaline conditions. Sodium tetrahydroxostannate(IV) is soluble in water. It can be prepared by dissolving tin(IV) oxide (SnO2) in a concentrated solution of sodium hydroxide (NaOH). The reaction is as follows: SnO2 + 2NaOH + 2H2O → Na2[Sn(OH)6]. Note that while the formula given is Na2SnOH4, the more common and stable form in strongly alkaline solutions is often considered to be Na2[Sn(OH)6], sodium hexahydroxostannate(IV), indicating a higher coordination number for tin. The exact species present in solution can depend on the concentration of the alkali and the temperature. Sodium tetrahydroxostannate(IV) and related stannate species have applications in certain chemical processes, including as precursors for tin-containing materials.