Praseodymium(III) chloride

Praseodymium(III) chloride
IUPAC name

Praseodymium(III) chloride
Other names

Praseodymium chloride; praseodymium trichloride
Identifiers
CAS number 10361-79-2 Y
Properties
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 (anhydrous)
2.250 g/cm3 (heptahydrate)
Melting point

786 °C
Boiling point

1710 °C
Solubility in water 104.0 g/100 ml (13°C)
Structure
Crystal structure hexagonal (UCl3 type), hP8
Space group P63/m, No. 176
Coordination
geometry		 Tricapped trigonal prismatic
(nine-coordinate)
Hazards
EU Index Not listed
Main hazards Irritant
Related compounds
Other anions Praseodymium(III) fluoride
Praseodymium bromide
praseodymium iodide
Other cations Cerium(III) chloride
Neodymium(III) chloride
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Praseodymium(III) chloride is the inorganic compound with the formula PrCl3. It is a blue-green solid that rapidly absorbs water on exposure to moist air to form a light green heptahydrate.

Contents

Preparation

Praseodymium(III) chloride is prepared by treating praseodymium metal and hydrogen chloride:[1][2]

2 Pr + 6 HCl → 2 PrCl3 + 3 H2

It is usually purified by vacuum sublimation.[3]

Hydrated salts of praseodymium(III) chloride can be prpared 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

Anhydrous PrCl3 can be made by thermal dehydration of the hydrate at 400 °C in the presence of ammonium chloride.[3][4] Alternatively the hydrate can be dehydrated using thionyl chloride.[3][5]

Reactions

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.[3] PrCl3 forms a stable Lewis acid-base complex K2PrCl5 by reaction with potassium chloride; this compound shows interesting optical and magnetic properties.[1]

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

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.[6]

References

  1. ^ a b J. Cybinska, J. Sokolnicki, J. Legendziewicz, G. Meyer Journal of Alloys and Compounds 341, 115-123 (2002).
  2. ^ L. F. Druding, J. D. Corbett, J. Am. Chem. Soc. 83, 2462 (1961); J. D. Corbett, Rev. Chim. Minerale 10, 239 (1973),
  3. ^ 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.
  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).
  6. ^ Gerd Meyer "Ternary Chlorides and Bromides of the Rare-Earth Elements" Inorganic Syntheses, 1990, Volume 30, pp. 72–81. doi:10.1002/9780470132616.ch15

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.