Editing Zirconium (section)

==Compounds==
{{Category see also|Zirconium compounds|Zirconium minerals}}
Like other [[transition metal]]s, zirconium forms a wide range of [[inorganic chemistry|inorganic compounds]] and [[coordination complex]]es.<ref name="Greenwd">{{Greenwood&Earnshaw2nd}}</ref> In general, these compounds are colourless diamagnetic solids wherein zirconium has the [[oxidation state]] +4. Some organometallic compounds are considered to have Zr(II) oxidation state.<ref name="Calderazzo"/> Non-equilibrium oxidation states between 0 and 4 have been detected during zirconium oxidation.<ref name="Ma"/>

===Oxides, nitrides, and carbides===

{{Redirect|ZrO||ZRO (disambiguation){{!}}ZRO}}

The most common oxide is [[zirconium dioxide]], ZrO<sub>2</sub>, also known as ''zirconia''. This clear to white-coloured solid has exceptional [[fracture toughness]] (for a ceramic) and chemical resistance, especially in its [[cubic zirconia|cubic]] form.<ref name="azomzirc">{{cite web |title=Zirconia |publisher=AZoM.com |date=2008 |url=http://www.azom.com/details.asp?ArticleID=133#_Key_Properties |access-date=2008-03-17 |archive-date=2009-01-26 |archive-url=https://web.archive.org/web/20090126182009/http://www.azom.com/details.asp?ArticleID=133#_Key_Properties |url-status=dead }}</ref> These properties make zirconia useful as a [[thermal barrier]] coating,<ref>{{cite journal|last1=Gauthier |first1=V. |last2=Dettenwanger|first2=F.|last3=Schütze|first3=M.|title=Oxidation behavior of γ-TiAl coated with zirconia thermal barriers |journal=Intermetallics |volume=10 |issue=7|pages=667–674|date=2002-04-10 |doi=10.1016/S0966-9795(02)00036-5}}</ref> although it is also a common [[diamond]] substitute.<ref name="azomzirc" /> Zirconium monoxide, ZrO, is also known and [[S-type star]]s are recognised by detection of its emission lines.<ref>{{cite journal|title= Classification of the S-Type Stars|last= Keenan|first= P. C.|year= 1954|journal= [[Astrophysical Journal]]|volume= 120|pages= 484–505|doi= 10.1086/145937|bibcode= 1954ApJ...120..484K}}</ref>

[[Zirconium tungstate]] has the unusual property of shrinking in all dimensions when heated, whereas most other substances expand when heated.<ref name="CRC2008" /> [[Zirconyl chloride]] is one of the few water-soluble zirconium complexes, with the formula [Zr<sub>4</sub>(OH)<sub>12</sub>(H<sub>2</sub>O)<sub>16</sub>]Cl<sub>8</sub>.<ref name="Greenwd"/>

[[Zirconium carbide]] and [[zirconium nitride]] are refractory solids. Both are highly [[corrosion]]-resistant and find uses in high-temperature resistant coatings and cutting tools.<ref>{{Cite journal |last1=Opeka |first1=Mark M. |last2=Talmy |first2=Inna G. |last3=Wuchina |first3=Eric J. |last4=Zaykoski |first4=James A. |last5=Causey |first5=Samuel J. |date=October 1999 |title=Mechanical, Thermal, and Oxidation Properties of Refractory Hafnium and zirconium Compounds |url=https://linkinghub.elsevier.com/retrieve/pii/S0955221999001296 |journal=Journal of the European Ceramic Society |language=en |volume=19 |issue=13–14 |pages=2405–2414 |doi=10.1016/S0955-2219(99)00129-6}}</ref> Zirconium hydride phases are known to form when zirconium alloys are exposed to large quantities of [[hydrogen]] over time; due to the brittleness of zirconium hydrides relative to zirconium alloys, the mitigation of zirconium hydride formation was highly studied during the development of the first commercial [[Nuclear reactor|nuclear reactors]], in which zirconium carbide was a frequently used material.<ref>{{Cite book |last=Puls |first=Manfred P. |url=https://link.springer.com/book/10.1007/978-1-4471-4195-2 |title=The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components |series=Engineering Materials |date=2012 |publisher=Springer London |language=en |doi=10.1007/978-1-4471-4195-2|isbn=978-1-4471-4194-5 }}</ref>

[[Lead zirconate titanate]] (PZT) is the most commonly used [[Piezoelectricity|piezoelectric]] material, being used as [[Transducer|transducers]] and [[Actuator|actuators]] in medical and [[MEMS|microelectromechanical systems]] applications.<ref>{{Cite journal |last1=Rouquette |first1=J. |last2=Haines |first2=J. |last3=Bornand |first3=V. |last4=Pintard |first4=M. |last5=Papet |first5=Ph. |last6=Bousquet |first6=C. |last7=Konczewicz |first7=L. |last8=Gorelli |first8=F. A. |last9=Hull |first9=S. |date=2004-07-23 |title=Pressure tuning of the morphotropic phase boundary in piezoelectric lead zirconate titanate |url=https://link.aps.org/doi/10.1103/PhysRevB.70.014108 |journal=Physical Review B |language=en |volume=70 |issue=1 |page=014108 |doi=10.1103/PhysRevB.70.014108 |bibcode=2004PhRvB..70a4108R |issn=1098-0121}}</ref>

===Halides and pseudohalides===
All four common halides are known, [[zirconium(IV) fluoride|ZrF<sub>4</sub>]], [[zirconium(IV) chloride|ZrCl<sub>4</sub>]], [[zirconium(IV) bromide|ZrBr<sub>4</sub>]], and [[zirconium(IV) iodide|ZrI<sub>4</sub>]]. All have polymeric structures and are far less volatile than the corresponding titanium tetrahalides; they find applications in the formation of organic complexes such as [[zirconocene dichloride]].<ref name=":1">{{Cite journal |last1=South Ural State University, Chelyabinsk, Russian Federation |last2=Sharutin |first2=V. |last3=Tarasova |first3=N. |date=2023 |title=Zirconium halide complexes. Synthesis, structure, practical application potential |url=https://vestnik.susu.ru/chemistry/article/view/12998 |journal=Bulletin of the South Ural State University Series "Chemistry" |language=ru |volume=15 |issue=1 |pages=17–30 |doi=10.14529/chem230102|doi-access=free }}</ref> All tend to [[hydrolyse]] to give the so-called oxyhalides and dioxides.<ref name="Ullmann" />

Fusion of the tetrahalides with additional metal gives lower zirconium halides (e.g. [[Zirconium(III) chloride|ZrCl<sub>3</sub>]]).  These adopt a layered structure, conducting within the layers but not perpendicular thereto.<ref>{{ cite book | title = Inorganic Chemistry | last1 = Housecroft | first1 = C. E. | last2 = Sharpe | first2 = A. G. | year = 2018 | publisher = [[Prentice-Hall]] | edition = 5th | isbn = 978-0273742753 | page = 812 }}</ref>  

The corresponding tetra[[alkoxide]]s 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.<ref>MSDS sheet for Duratec 400, DuBois Chemicals, Inc.</ref>

===Organic derivatives===
{{main|Organozirconium chemistry}}

[[File:Zirconocene-dichloride-from-xtal-3D-balls.png|right|upright=0.85|thumb|[[Zirconocene dichloride]], a representative [[organozirconium compound]]]]
[[Organozirconium chemistry]] is key to [[Ziegler–Natta catalyst]]s, used to produce [[polypropylene]]. This application exploits the ability of zirconium to reversibly form bonds to carbon. Zirconocene dibromide ((C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>ZrBr<sub>2</sub>), reported in 1952 by Birmingham and [[Geoffrey Wilkinson|Wilkinson]], was the first organozirconium compound.<ref>{{cite journal |author= Wilkinson, G. |date= 1954 |title= Bis-cyclopentadienyl Compounds of Ti, Zr, V, Nb and Ta |journal= Journal of the American Chemical Society|volume= 76 |issue= 17 |pages= 4281–4284 |doi= 10.1021/ja01646a008 |author-link= Geoffrey Wilkinson |last2= Birmingham |first2= J. M.|bibcode= 1954JAChS..76.4281W }}; {{cite journal |last=Rouhi|first=A. Maureen|title=Organozirconium Chemistry Arrives|journal= Chemical & Engineering News|volume=82|issue=16|pages=36–39|date=2004-04-19|url=http://pubs.acs.org/cen/nlw/8216sci1.html|issn=0009-2347 |access-date=2008-03-17|doi=10.1021/cen-v082n016.p036}}</ref> [[Schwartz's reagent]], prepared in 1970 by P. C. Wailes and H. Weigold,<ref>{{cite journal|author=Wailes, P. C.|author2=Weigold, H.|name-list-style=amp|title=Hydrido complexes of zirconium I. Preparation|journal=[[Journal of Organometallic Chemistry]]|date=1970|volume=24|pages=405–411|doi=10.1016/S0022-328X(00)80281-8|issue=2}}</ref> is a [[metallocene]] used in [[organic synthesis]] for transformations of [[alkenes]] and [[alkyne]]s.<ref name="hart">{{cite journal|author=Hart, D. W.|author2=Schwartz, J.|name-list-style=amp |title=Hydrozirconation. Organic Synthesis via Organozirconium Intermediates. Synthesis and Rearrangement of Alkylzirconium(IV) Complexes and Their Reaction with Electrophiles |journal= Journal of the American Chemical Society|volume=96 |issue=26|date=1974|pages=8115–8116|doi=10.1021/ja00833a048|bibcode=1974JAChS..96.8115H }}</ref>

Many complexes of Zr(II) are derivatives of zirconocene,<ref name=":1" /> one example being (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>Zr(CO)<sub>2</sub>.