Tetrahydroxozincate

In chemistry, tetrahydroxozincate or tetrahydroxidozincate is a divalent anion (negative ion) with formula, 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 Na2Zn(OH)4 and calcium zincate CaZn(OH)4·2H2O

Zincate salts can be obtained by reaction of zinc oxide (ZnO) or zinc hydroxide  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 ions.

Related anions and salts
The name "zincate" may also refer to a polymeric anion with formula approaching []n, which forms salts such as ·, or to mixed oxides of zinc and less electronegative elements, such as.