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Praseodymium(III) chloride

Praseodymium(III) chloride
IUPAC name Praseodymium(III) chloride
Other names Praseodymium chloride; praseodymium trichloride
Molecular formula PrCl3
Molar mass 247.24 g/mol (anhydrous)

373.77 g/mol (heptahydrate)

Appearance blue-green solid (anhydrous)

light green solid (heptahydrate)

Density 4.02 g/cm³, solid (anhydrous)

2.250 g/cm³, solid (heptahydrate)

Melting point

786 °C

Boiling point

1710 °C

Solubility in water 104.0 g/100 ml (13°C)
Crystal structure Uranium(III) chloride
9-coordinate; trigonal prismatic
MSDS Praseodymium(III) chloride MSDS
Main hazards Irritant
Flash point  ?°C
Related Compounds
Other anions praseodymium fluoride, praseodymium bromide, praseodymium iodide
Other cations cerium(III) chloride, neodymium(III) chloride
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Praseodymium(III) chloride (PrCl3), also known as praseodymium trichloride, is a compound of praseodymium and chlorine. It is a blue-green solid which rapidly absorbs water on exposure to moist air to form a light green heptahydrate.


Chemical properties

Praseodymium(III) chloride is a moderately strong Lewis acid, which ranks as "hard" according to the HSAB concept. Rapid heating of the hydrate may cause small amounts of hydrolysis.[1] PrCl3 forms a stable Lewis acid-base complex K2PrCl5 by reaction with potassium chloride; this compound shows interesting optical and magnetic properties.[2]

Aqueous solutions of praseodymium(III) chloride can be used to prepare insoluble praseodymium(III) compounds, for example praseodymium(III) phosphate or praseodymium(III) fluoride:

PrCl3(aq) + K3PO4(aq) → PrPO4(s) + 3 KCl(aq)

PrCl3(aq) + 3 NaF(aq) → PrF3(s) + 3 NaCl(aq)


Praseodymium(III) chloride can be prepared as a green aqueous solution by reaction of either praseodymium metal or praseodymium(III) carbonate and hydrochloric acid. The anhydrous halide may alternatively be prepared from praseodymium metal and hydrogen chloride.[2][3]

2 Pr(s) + 6 HCl(aq) → 2 PrCl3(aq) + 3 H2(g)

Pr2(CO3)3(s) + 6 HCl(aq) → 2 PrCl3(aq) + 3 CO2(g) + 3 H2O(l)

Anhydrous PrCl3 can be made by dehydration of the hydrate either by slowly heating to 400 °C with 4-6 equivalents of ammonium chloride under high vacuum[1],[4], or by heating with an excess of thionyl chloride for four hours[1],[5]. The anhydrous halide may alternatively be prepared from praseodymium metal and hydrogen chloride[3]. It is usually purified by high temperature sublimation under high vacuum.[1]


PrCl3 has been used to increase the activity of Pr6O11 catalysts, which can be used for the oxidation of methane to ethene. This process is becoming an important route to ethene for the manufacture of polyethylene (a common plastic). There are no major uses for praseodymium(III) chloride, though it can be used as a starting point for the preparation of other praseodymium salts.


Praseodymium compounds are of low to moderate toxicity, although their toxicity has not been investigated in detail. Wear gloves and goggles.


  1. ^ a b c d F. T. Edelmann, P. Poremba, in: Synthetic Methods of Organometallic and Inorganic Chemistry, (W. A. Herrmann, ed.), Vol. 6, Georg Thieme Verlag, Stuttgart, 1997.
  2. ^ a b J. Cybinska, J. Sokolnicki, J. Legendziewicz, G. Meyer Journal of Alloys and Compounds 341, 115-123 (2002).
  3. ^ a b L. F. Druding, J. D. Corbett, J. Am. Chem. Soc. 83, 2462 (1961); J. D. Corbett, Rev. Chim. Minerale 10, 239 (1973),
  4. ^ M. D. Taylor, P. C. Carter, J. Inorg. Nucl. Chem. 24, 387 (1962); J. Kutscher, A. Schneider, Inorg. Nucl. Chem. Lett. 7, 815 (1971).
  5. ^ J. H. Freeman, M. L. Smith, J. Inorg. Nucl. Chem. 7, 224 (1958).

Further reading

  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. Moffat Journal of Molecular Catalysis A, 118, 129-136 (1997).
  4. Druding L. F., Corbett J. D., Ramsey B. N. (1963). "Rare Earth Metal-Metal Halide Systems. VI. Praseodymium Chloride". Inorganic Chemistry 2 (4): 869 - 871. doi:10.1021/ic50008a055.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Praseodymium(III)_chloride". A list of authors is available in Wikipedia.
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