Zirconium perchlorate is an inorganic compound with the formula Zr(ClO<sub>4</sub>)<sub>4</sub>. It is a hygroscopic colorless solid that sublimes in a vacuum at 70 ðC. These properties show that the compound is covalently bonded molecule, rather than a salt. It is an example of a transition metal perchlorate complex.
It can be formed by treating zirconium tetrachloride with dichlorine hexoxide-perchloric acid mixture at −35 ðC.
Zirconium perchlorate reacts irreversibly with most organic compounds but is inert towards carbon tetrachloride, chloroformide. With benzene at -10 ðC, crystals of Zr(ClO<sub>4</sub>)<sub>4</sub>â¢C<sub>6</sub>H<sub>6</sub> are deposited.
Solid zirconium perchlorate undergoes a phase transition around 45 ðC before melting between 95.5 and 96.0 ðC. Thermolysis near 120 ðC gives zirconyl perchlorate. Further heating around 290 ðC gives form zirconia and chlorine oxides.
In the gas phase the Zr(ClO<sub>4</sub>)<sub>4</sub> molecule has a D<sub>4</sub> symmetry with eightfold square antiprism oxygen coordination. Each perchorate group is bidentate. The chlorine atoms are in a tetrahedral arrangement around the central zirconium.
In the solid phase, Zr(ClO<sub>4</sub>)<sub>4</sub> crystals are monoclinic with a=12.899, b=13.188, c=7.937 à, ò=107.91ð. There are four molecules per unit cell.
Titanium perchlorate and hafnium perchlorate are both known.
Salts of perchloratozirconates and hexaperchloratozirconates have been claimed including the caesium perchloratozirconates CsZr(ClO<sub>4</sub>)<sub>5</sub>, Cs<sub>2</sub>Zr(ClO<sub>4</sub>)<sub>6</sub>, and Cs<sub>4</sub>Zr(ClO<sub>4</sub>)<sub>8</sub>. The very close analogues of zirconium perchlorate are zirconium pertechnetates and perrhenates, however, unlike it, they crystallize from an aqueous solution in the form of dimers of the composition [Zr<sub>2</sub>(MO<sub>4</sub>)<sub>6</sub>(ü-OH)<sub>2</sub>(H<sub>2</sub>O)<sub>6</sub>]<sup>..</sup>3H<sub>2</sub>O (M = Tc and Re).
Zirconyl perchlorates have been claimed in older literature.