HexaaquazirconiumIV

Hexaaquazirconium(IV) is an inorganic chemical compound with the formula [Zr(H₂O)₆]⁴⁺. It is the hydrated cation of zirconium in its +4 oxidation state. In aqueous solutions, zirconium(IV) ions readily coordinate with water molecules to form this hexaaqua complex. The crystal structure of hexaaquazirconium(IV) salts, such as hexaaquazirconium(IV) chloride, [Zr(H₂O)₆]Cl₄, reveals that the zirconium ion is coordinated by six water ligands in an octahedral geometry. These water molecules are directly bonded to the central zirconium atom.

The presence of the highly charged Zr⁴⁺ ion in water leads to significant polarization of the coordinated water molecules. This polarization makes the hydrogen atoms of the water ligands more acidic compared to free water. Consequently, in aqueous solutions, hexaaquazirconium(IV) can undergo hydrolysis, where water molecules act as bases and deprotonate the coordinated water ligands, forming hydroxo and oxo species. This hydrolysis is a key factor in the chemistry of zirconium in aqueous environments and influences the solubility and reactivity of zirconium compounds. The hexaaquazirconium(IV) cation is not an isolated species but rather a representation of zirconium(IV) in acidic aqueous solutions.