Praseodymium(III) chloride

Praseodymium(III) chloride is prepared by treating praseodymium metal with hydrogen chloride:{{cite journal|url=https://pubs.acs.org/doi/10.1021/ja01472a010|author1=L.F. Druding|author2= J.D. Corbett|title=Lower Oxidation States of the Lanthanides. Neodymium(II) Chloride and Iodide|journal=J. Am. Chem. Soc.|volume=83|issue=11|pages=2462-2467|date=1961-06-01|doi=10.1021/ja01472a010}}

:2 Pr + 6 HCl → 2 PrCl₃ + 3 H₂

It is usually purified by vacuum sublimation.

Hydrated salts of praseodymium(III) chloride can be prepared by treatment of either praseodymium metal or praseodymium(III) carbonate with hydrochloric acid:

:Pr₂(CO₃)₃ + 6 HCl + 15 H₂O → 2 [Pr(H₂O)₉]Cl₃ + 3 CO₂

PrCl₃∙7H₂O is a hygroscopic substance, that will not crystallize from the mother liquor unless it is left to dry in a desiccator. Anhydrous PrCl₃ can be made by thermal dehydration of the hydrate at 400 °C in the presence of ammonium chloride, the so-called ammonium chloride route.{{cite journal|url=https://www.sciencedirect.com/science/article/abs/pii/0022190262800347|author1=M.D. Taylor|author2=P.C. Carter|title= Preparation of anhydrous lanthanide halides, especially iodides|journal=J. Inorg. Nucl. Chem.|volume=24|issue=4|pages=387-391|date=April 1962|doi=10.1016/0022-1902(62)80034-7}}{{cite journal|url=https://www.sciencedirect.com/science/article/abs/pii/0020165071802532|author1=J. Kutscher|author2=A. Schneider|title=Notiz zur Präparation von wasserfreien Lanthaniden-Haloge-niden, Insbesondere von Jodiden|journal=Inorg. Nucl. Chem. Lett.|volume=7|issue=9|pages=815-819|date=September 1971|doi=10.1016/0020-1650(71)80253-2|language=de}} Alternatively the hydrate can be dehydrated using thionyl chloride.{{cite journal|url=https://www.sciencedirect.com/science/article/abs/pii/0022190258800731|author1=J.H. Freeman|author2=M.L. Smith|title=The preparation of anhydrous inorganic chlorides by dehydration with thionyl chloride|journal=J. Inorg. Nucl. Chem.|volume=7|issue=3|pages=224-227|date=October 1958|doi=10.1016/0022-1902(58)80073-1}}

Praseodymium(III) chloride is Lewis acidic, classified as "hard" according to the HSAB concept. Rapid heating of the hydrate may cause small amounts of hydrolysis.{{cite book|author1=F.T. Edelmann|author2= P. Poremba|title=Synthetic Methods of Organometallic and Inorganic Chemistry|volume=6|publisher= Georg Thieme Verlag|location=Stuttgart|date= 1997|isbn=978-31-319-3921-0}} PrCl₃ forms a stable Lewis acid-base complex K₂PrCl₅ by reaction with potassium chloride; this compound shows interesting optical and magnetic properties.{{cite journal|url=https://www.semanticscholar.org/paper/Spectroscopic-and-magnetic-studies-of-the-ternary-Cybi%C5%84ska-Sokolnicki/2af96eacdd78d2ec04ac3c0342ca6d875f76130e|author1=J. Cybinska|author2= J. Sokolnicki|author3= J. Legendziewicz|author4= G. Meyer|title=Spectroscopic and magnetic studies of the ternary praseodymium chloride K₂PrCl₅|journal=Journal of Alloys and Compounds|volume=341|pages=115–123|date=2002-07-17|doi=10.1016/S0925-8388(02)00089-0}}

Aqueous solutions of praseodymium(III) chloride can be used to prepare insoluble praseodymium(III) compounds. For example, praseodymium(III) phosphate and praseodymium(III) fluoride can be prepared by reaction with potassium phosphate and sodium fluoride, respectively:

:PrCl₃ + K₃PO₄ → PrPO₄ + 3 KCl

:PrCl₃ + 3 NaF → PrF₃ + 3 NaCl

:2PrCl₃ + 3 Na₂CO₃----> Pr₂CO₃ + 6NaCl

When heated with alkali metal chlorides, it forms a series of ternary (compounds containing three different elements) materials with the formulae MPr₂Cl₇, M₃PrCl₆, M₂PrCl₅, and M₃Pr₂Cl₉ where M = K, Rb, Cs.{{cite journal|author=Gerd Meyer|title=Ternary Chlorides and Bromides of the Rare-Earth Elements|journal=Inorganic Syntheses|year=1990|volume=30|pages=72–81|doi=10.1002/9780470132616.ch15}}

File:Praseodymium chloride heptahydrate under fluorescent lamp light and halogen lamp light.png

{{reflist}}

1. CRC Handbook of Chemistry and Physics (58th edition), CRC Press, West Palm Beach, Florida, 1977.
2. N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, Pergamon Press, 1984.
3. S. Sugiyama, T. Miyamoto, H. Hayashi, M. Tanaka, J. B. Moffatt, "Effects of chlorine additives in the gas- and solid-phases on the oxidative dehydrogenation of ethane over praseodymium oxide", Journal of Molecular Catalysis A, 118, 129-136 (1997).
4. {{cite journal

| title = Rare Earth Metal-Metal Halide Systems. VI. Praseodymium Chloride

|author1=Druding L. F. |author2=Corbett J. D. |author3=Ramsey B. N. | journal = Inorganic Chemistry

| year = 1963

| volume = 2

| issue = 4

| pages = 869–871

| doi = 10.1021/ic50008a055

}}

{{Praseodymium compounds}}

{{Chlorides}}

{{Lanthanide halides}}

Category:Chlorides

Category:Praseodymium(III) compounds

Category:Lanthanide halides