User:Praseodymium-141/Zirconium compounds

Zirconium compounds are compounds formed by the element zirconium (Zr). Like other transition metals, zirconium forms a wide range of inorganic compounds and coordination complexes. In general, these compounds are colourless diamagnetic solids wherein zirconium has the oxidation state +4. Far fewer Zr(III) compounds are known, and Zr(II) is very rare.

Oxides, nitrides, and carbides
The most common oxide is zirconium dioxide, ZrO2, also known as zirconia. This clear to white-coloured solid has exceptional fracture toughness (for a ceramic) and chemical resistance, especially in its cubic form. These properties make zirconia useful as a thermal barrier coating, although it is also a common diamond substitute. Zirconium monoxide, ZrO, is also known and S-type stars are recognised by detection of its emission lines.

Zirconium tungstate has the unusual property of shrinking in all dimensions when heated, whereas most other substances expand when heated. Zirconyl chloride is a rare water-soluble zirconium complex with the relatively complicated formula [Zr4(OH)12(H2O)16]Cl8.

Zirconium carbide and zirconium nitride are refractory solids. The carbide is used for drilling tools and cutting edges. Zirconium hydride phases are also known.

Lead zirconate titanate (PZT) is the most commonly used piezoelectric material, with applications such as ultrasonic transducers, hydrophones, common rail injectors, piezoelectric transformers and micro-actuators.

Halides and pseudohalides
All four common halides are known, ZrF4, ZrCl4, ZrBr4, and ZrI4. All have polymeric structures and are far less volatile than the corresponding monomeric titanium tetrahalides. All tend to hydrolyse to give the so-called oxyhalides and dioxides.

The corresponding tetraalkoxides are also known. Unlike the halides, the alkoxides dissolve in nonpolar solvents. Dihydrogen hexafluorozirconate is used in the metal finishing industry as an etching agent to promote paint adhesion.

Organic derivatives
Organozirconium chemistry is key to Ziegler–Natta catalysts, used to produce polypropylene. This application exploits the ability of zirconium to reversibly form bonds to carbon. Zirconocene dibromide ((C5H5)2ZrBr2), reported in 1952 by Birmingham and Wilkinson, was the first organozirconium compound. Schwartz's reagent, prepared in 1970 by P. C. Wailes and H. Weigold, is a metallocene used in organic synthesis for transformations of alkenes and alkynes.

Most complexes of Zr(II) are derivatives of zirconocene, one example being (C5Me5)2Zr(CO)2.