Tetrahydroxozincate
# Tetrahydroxozincate

In chemistry, tetrahydroxozincate or tetrahydroxidozincate is a divalent anion (negative ion) with formula $Zn(OH)^{2−}$ $_4,$ with a central zinc atom in the +2 or (II) valence state coordinated to four hydroxide groups. It has Sp3 hybridization. It is the most common of the zincate anions, and is often called just zincate.

These names are also used for the salts containing that anion, such as sodium zincate $Na_2Zn(OH)_4$ and calcium zincate $CaZn(OH)_4·2H_2O$

Zincate salts can be obtained by reaction of zinc oxide (ZnO) or zinc hydroxide (Zn(OH) $_2)$ and a strong base like sodium hydroxide.

It is now generally accepted that the resulting solutions contain the tetrahydroxozincate ion. Earlier Raman studies had been interpreted as indicating the existence of linear $ZnO^{2−}$ $_2$ ions.

## Related anions and salts

The name "zincate" may also refer to a polymeric anion with formula approaching $[Zn(OH)^−$ $_3]_n,$ which forms salts such as NaZn(OH) $_3·H$ $_2O,$ or to mixed oxides of zinc and less electronegative elements, such as Na $_2ZnO$ $_2.$

