Zirconium perchlorate
Zirconium perchlorate is an inorganic compound with the formula Zr4. It is a hygroscopic colorless solid that sublimes in a vacuum at 70 °C. These properties show that the compound is covalently bonded molecule, rather than a salt. It is an example of a transition metal perchlorate complex.
Synthesis and properties
It can be formed by treating zirconium tetrachloride with dichlorine hexoxide-perchloric acid mixture at −35 °C.Zirconium perchlorate reacts irreversibly with most organic compounds but is inert towards carbon tetrachloride, chloroformide. With benzene at -10 °C, crystals of Zr4•C6H6 are deposited.
Solid zirconium perchlorate undergoes a phase transition around 45 °C before melting between 95.5 and 96.0 °C. Thermolysis near 120 °C gives zirconyl perchlorate. Further heating around 290 °C gives form zirconia and chlorine oxides.
Structure
In the gas phase the Zr4 molecule has a D4 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, Zr4 crystals are monoclinic with a=12.899, b=13.188, c=7.937 Å, β=107.91°. There are four molecules per unit cell.
Related substances
Titanium perchlorate and hafnium perchlorate are both known.Salts of perchloratozirconates and hexaperchloratozirconates have been claimed including the caesium perchloratozirconates CsZr5, Cs2Zr6, and Cs4Zr8. 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 ..3H2O.
Zirconyl perchlorates have been claimed in older literature.