Praseodymium compounds#Oxides

File:Praseodymium(III)-chloride-heptahydrate.jpg

Praseodymium metal reacts with all the stable halogens to form green trihalides:{{cite web| url =https://www.webelements.com/praseodymium/chemistry.html| title =Chemical reactions of Praseodymium| publisher=Webelements| access-date=9 July 2016}}

:2 Pr (s) + 3 F₂ (g) → 2 PrF₃ (s)

:2 Pr (s) + 3 Cl₂ (g) → 2 PrCl₃ (s)

:2 Pr (s) + 3 Br₂ (g) → 2 PrBr₃ (s)

:2 Pr (s) + 3 I₂ (g) → 2 PrI₃ (s)

Praseodymium(III) fluoride is the most stable fluoride of praseodymium. It can be prepared the reaction between praseodymium(III) nitrate and sodium fluoride will produce praseodymium(III) fluoride as a green crystalline solid.{{cite journal|author=Lin Ma, Wei-Xiang Chen, Yi-Fan Zheng, Jie Zhao, Zhude Xu|date=May 2007|title=Microwave-assisted hydrothermal synthesis and characterizations of PrF3 hollow nanoparticles|url=https://www.sciencedirect.com/science/article/abs/pii/S0167577X06012316|journal=Materials Letters|language=en|volume=61|issue=13|pages=2765–2768|doi=10.1016/j.matlet.2006.04.124|access-date=2019-03-26|url-access=subscription}} Praseodymium(III) chloride is a light green solid that can be prepared by treating praseodymium metal with hydrogen chloride.J. Cybinska, J. Sokolnicki, J. Legendziewicz, G. Meyer, Journal of Alloys and Compounds, 341, 115–123 (2002).L. F. Druding, J. D. Corbett, "Lower Oxidation States of the Lanthanides. Neodymium(II) Chloride and Iodide", J. Am. Chem. Soc. 83, 2462 (1961); J. D. Corbett, Rev. Chim. Minerale 10, 239 (1973)^, It is usually purified by vacuum sublimation. It is Lewis acidic, classified as "hard" according to the HSAB concept. Rapid heating of the hydrate may cause small amounts of hydrolysis.F. T. Edelmann, P. Poremba, in: Synthetic Methods of Organometallic and Inorganic Chemistry, (W. A. Herrmann, ed.), Vol. 6, Georg Thieme Verlag, Stuttgart, 1997. PrCl₃ forms a stable Lewis acid-base complex K₂PrCl₅ by reaction with potassium chloride; this compound shows interesting optical and magnetic properties.J. Cybinska, J. Sokolnicki, J. Legendziewicz, G. Meyer, Journal of Alloys and Compounds, 341, 115–123 (2002).

Praseodymium(III) bromide is the only stable bromide of praseodymium. It adopts the uranium(III) chloride crystal structure.{{ cite book | first1 = A. F. | last1 = Wells | title = Structural Inorganic Chemistry | edition = 5th | year = 1984 | publisher = Oxford University Press | isbn = 978-0-19-965763-6 | page = 421 }} The praseodymium ions are 9-coordinate and adopt a tricapped trigonal prismatic geometry. The praseodymium–bromine bond lengths are 3.05 Å and 3.13 Å.{{ cite journal | title = Structure and crystal fields of PrBr₃ and PrCl₃: A neutron study | first1 = B. | last1 = Schmid | first2 = B. | last2 = Hälg | first3 = A. | last3 = Furrer | journal = J. Appl. Phys. | year = 1987 | volume = 61 | issue = 8 | pages = 3426–3428 | doi = 10.1063/1.338741 | bibcode = 1987JAP....61.3426S }} Praseodymium(III) iodide can be prepared by heating praseodymium and iodine in an inert atmosphere produces praseodymium(III) iodide,{{Cite book |last=Haynes |first=William M. |url=https://books.google.com/books?id=VVezDAAAQBAJ&pg=SA4-PA81%20CRC%20Handbook%20of%20Chemistry%20and%20Physics |title=CRC Handbook of Chemistry and Physics |pages=2016–2652 |date=2016-06-22 |publisher=CRC Press |isbn=978-1-4987-5429-3 |language=en}} or by heating praseodymium with mercury(II) iodide.{{ cite journal | first1 = L. B. | last1 = Asprey | first2 = T. K. | last2 = Keenan | first3 = F. H. | last3 = Kruse | title = Preparation and Crystal Data for Lanthanide and Actinide Triiodides | journal = Inorg. Chem. | year = 1964 | volume = 3 | issue = 8 | pages = 1137–1141 | doi = 10.1021/ic50018a015 | url = https://digital.library.unt.edu/ark:/67531/metadc867868/ }} It forms orthorhombic crystals which are hygroscopic. It crystallizes in the PuBr₃ type{{ cite book | first1 = A. F. | last1 = Wells | title = Structural Inorganic Chemistry | edition = 5th | year = 1984 | publisher = Oxford University Press | isbn = 978-0-19-965763-6 | page = 421 }} with space group Cmcm (No. 63) with a = 4.3281(6) Å, b = 14.003(6) Å and c = 9.988(3) Å.{{citation|surname1=E. Warkentin, H. Bärnighausen|periodical=Zeitschrift für anorganische und allgemeine Chemie|title=Die Kristallstruktur von Praseodymdiiodid (Modifikation V)|volume=459|issue=1|at=pp. 187–200|date=1979|language=German|doi=10.1002/zaac.19794590120

}}

The tetrafluoride, PrF₄, is also known, and is produced by reacting a mixture of sodium fluoride and praseodymium(III) fluoride with fluorine gas, producing Na₂PrF₆, following which sodium fluoride is removed from the reaction mixture with liquid hydrogen fluoride.Greenwood and Earnshaw, p. 1240–2 Additionally, praseodymium forms a bronze diiodide; like the diiodides of lanthanum, cerium, and gadolinium, it is a praseodymium(III) electride compound.

Praseodymium can form many different oxides, although the only oxides that are stable at room temperature are Pr₂O₃, Pr₆O₁₁ and PrO₂. Praseodymium(III) oxide is a green powder that forms hexagonal crystals,{{Citation| last = Lide | first = David R. | year = 1998| title = Handbook of Chemistry and Physics| edition = 87 | publication-place = Boca Raton, Florida | publisher = CRC Press | isbn = 0-8493-0594-2 | pages = 478, 523}} and crystallizes in the manganese(III) oxide or bixbyite structure.{{Citation| last1 =Dabrowski| first1 = Jarek| last2 = Weber| first2 = Eicke R.| year = 2004| title = Predictive Simulation of Semiconductor Processing| publisher = Springer| isbn = 978-3-540-20481-7| pages = 264| url = https://books.google.com/books?id=oCH9tiY7VeoC&dq=%22Praseodymium(III)+oxide%22+OR+%22Praseodymium+oxide%22&pg=PA270| access-date = 2009-03-18}} Praseodymium(IV) oxide can be produced by boiling Pr₆O₁₁ in water or acetic acid:{{lang-zh|《无机化学丛书》.第七卷 钪 稀土元素. 科学出版社. 1.3.4 氧化态+4的化合物.|translation=Inorganic Chemistry Series. Volume VII Rare Earth Elements. Science Press. 1.3.4 Compounds with oxidation state +4.}} P_193~195

: Pr₆O₁₁ + 3 H₂O → 4 PrO₂ + 2 Pr(OH)₃

Praseodymium(III,IV) oxide is the most stable form of the praseodymium oxides at ambient temperature and pressure.{{Cite journal|last1=Zinatloo-Ajabshir|first1=Sahar|last2=Salavati-Niasari|first2=Masoud|title=Novel poly(ethyleneglycol)-assisted synthesis of praseodymium oxide nanostructures via a facile precipitation route|journal=Ceramics International|volume=41|issue=1|pages=567–575|doi=10.1016/j.ceramint.2014.08.105|year=2015}} It is soluble in water{{Cite web|url=https://www.reade.com/products/praseodymium-oxide-pr6o11|title=Praseodymium Oxide (Pr6O11)|website=www.reade.com|access-date=2018-03-15}} and has a cubic fluorite structure.{{Cite journal|last1=Matović|first1=Branko|last2=Pantić|first2=Jelena|last3=Prekajski|first3=Marija|last4=Stanković|first4=Nadežda|last5=Bučevac|first5=Dušan|last6=Minović|first6=Tamara|last7=Čebela|first7=Maria|title=Synthesis and characterization of Pr6O11 nanopowders|journal=Ceramics International|volume=39|issue=3|pages=3151–3155|doi=10.1016/j.ceramint.2012.09.098|year=2013}} It can be prepared via solid-state methods such as thermolysis, molten salt method, calcination or precipitation.Shamshi Hassan, M., Shaheer Akhtar, M., Shim, KB. et al. Morphological and Electrochemical Properties of Crystalline Praseodymium Oxide Nanorods. Nanoscale Res Lett 5, 735 (2010). https://doi.org/10.1007/s11671-010-9547-8

File:Praseodymium-oxygen system.png

In addition to Pr₆O₁₁, praseodymium also forms a system of oxides at different phases:{{Greenwood&Earnshaw2nd|pages=643-4}}

{{See also|Organolanthanide chemistry}}

Organopraseodymium compounds are compounds with a praseodymium-to-carbon bond. These compounds are very similar to those of the other lanthanides, as they all share an inability to undergo π backbonding. They are thus mostly restricted to the mostly ionic cyclopentadienides (isostructural with those of lanthanum) and the σ-bonded simple alkyls and aryls, some of which may be polymeric.{{Greenwood&Earnshaw2nd|pages=1248-9}} The coordination chemistry of praseodymium is largely that of the large, electropositive Pr³⁺ ion, and is thus largely similar to those of the other early lanthanides La³⁺, Ce³⁺, and Nd³⁺. For instance, like lanthanum, cerium, and neodymium, praseodymium nitrate forms both the 4:3 and 1:1 complexes with 18-crown-6, whereas the middle lanthanides from promethium to gadolinium can only form the 4:3 complex and the later lanthanides from terbium to lutetium cannot successfully coordinate to all the ligands. Such praseodymium complexes have high but uncertain coordination numbers and poorly defined stereochemistry, with exceptions resulting from exceptionally bulky ligands such as the tricoordinate [Pr{N(SiMe₃)₂}₃]. There are also a few mixed oxides and fluorides involving praseodymium(IV), but it does not have an appreciable coordination chemistry in this oxidation state like its neighbour cerium.{{Greenwood&Earnshaw2nd|pages=1244-8}} However, the first example of a molecular complex of praseodymium(IV) has recently been reported.{{cite journal |title= Accessing the +IV Oxidation State in Molecular Complexes of Praseodymium. |author1=Willauer, A.R. |author2=Palumbo, C.T. |author3=Fadaei-Tirani, F. |author4=Zivkovic, I. |author5=Douair, I. |author6=Maron, L. |author7=Mazzanti, M. |date=2020 |pages=489–493|volume=142 |journal=Journal of the American Chemical Society |issue=12 |doi=10.1021/jacs.0c01204|pmid=32134644 |bibcode=2020JAChS.142.5538W |s2cid=212564931 |url=http://infoscience.epfl.ch/record/277306 }} Like the other organolanthanide compounds, properties of organopraseodymium compounds include:

• Organopraseodymium compounds are very air- and water-sensitive and pyrophoric.
• Chemistry in the 0 oxidation state is far more limited. In fact, their electropositive nature makes their organometallic compounds more likely to be ionic.
• Organopraseodymium compounds form no stable carbonyls at room temperature; organopraseodymium carbonyl compounds have been observed only in argon matrices, and decompose when heated to 40 K.

Metal-carbon σ bonds are found in alkyls of praeodymium such as [PrMe₆]³⁻ and Pr[CH(SiMe₃)₂]₃.

Cyclopentadienyl complexes, are known for praseodymium. It can be produced by the following reaction scheme:

:3 Na[Cp] + PrCl₃ → Pr[Cp]₃ + 3 NaCl

These compounds are of limited use and academic interest.{{cite book|author=J. J. Zuckerman|title=Inorganic Reactions and Methods, The Formation of Bonds to Elements of Group IVB (C, Si, Ge, Sn, Pb)|url=https://books.google.com/books?id=bWAfgilsYYMC|access-date=28 July 2013|date=17 September 2009|publisher=John Wiley & Sons|isbn=978-0-470-14547-0}}

Praseodymium(III) nitride is used in high-end electric and semiconductor products, and as a raw material to produce phosphor. Also it is used as a magnetic material and sputtering target material.{{cite web |title=Praseodymium Nitride (PrN) Powder |url=https://www.samaterials.com/nitrogen/1907-praseodymium-nitride-powder.html |publisher=Stanford Advanced Materials |access-date=18 June 2021 |language=en}} Many praseodymium compounds, such as praseodymium(III) oxalate, are used to colour some glasses and enamels. If mixed with certain other materials, praseodymium(III) oxalate paints glass intense yellow.{{cite web |title=Praseodymium Oxalate 99%-99.999% from Metall Rare Earth Limited |url=http://www.metall.com.cn/prox.htm |publisher=metall.com.cn |access-date=17 June 2021}}

Praseodymium(III,IV) oxide has a number of potential applications in chemical catalysis, and is often used in conjunction with a promoter such as sodium or gold to improve its catalytic performance. It has a high-K dielectric constant of around 30 and very low leakage currentsOsten HJ, Liu JP, P Gaworzewski, E Bugiel, Zaumseil P: IEDM Technical Digest 653. 2000. which have also made it a promising material for many potential applications in nanodevices and microelectronics.Shamshi Hassan, M., Shaheer Akhtar, M., Shim, KB. et al. Morphological and Electrochemical Properties of Crystalline Praseodymium Oxide Nanorods. Nanoscale Res Lett 5, 735 (2010). https://doi.org/10.1007/s11671-010-9547-8

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| File:Praseodymium acetate.jpg

| Praseodymium(III) acetate (Pr(CH₃COO)₃)

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| File:Praseodymium(III) oxide (sample).jpg

| Praseodymium(III) oxide (Pr₂O₃)

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| File:Praseodymium chloride.jpg

| Praseodymium(III) chloride (PrCl₃)

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| File:Praseodymium nitrate.jpg

| Praseodymium(III) nitrate (Pr(NO₃)₃)

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| File:Praseodymium sulphate octahydrate crystals.JPG

| Praseodymium(III) sulfate octahydrate (Pr₂(SO₄)₃·8H₂O)

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| Praseodymium(III) hydroxide (Pr(OH)₃)

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| Praseodymium(III) phosphate (PrPO₄)

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{{reflist|2}}

• Neodymium compounds
• Europium compounds

{{Praseodymium compounds}}

{{Chemical compounds by element}}

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Category:Chemical compounds by element