Praseodymium(III) chloride is the

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...

Pr Cl₃. Like other

lanthanide trichloride Lanthanide trichlorides are a family of inorganic compound with the formula Ln Cl3, where Ln stands for a lanthanide metal. The trichlorides are standard reagents in applied and academic chemistry of the lanthanides. They exist as anhydrous solids ...

s, it exists both in the anhydrous and hydrated forms. It is a blue-green solid that rapidly absorbs water on exposure to moist air to form a light green hepta

hydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

Preparation

Praseodymium(III) chloride is prepared by treating praseodymium metal with hydrogen chloride: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)^, :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 r(H₂O)₉l₃ + 3 CO₂ PrCl₃∙7H₂O is a hygroscopic substance, that will not crystallize from the

mother liquor The mother liquor (or spent liquor) is the solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approx ...

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 Lanthanide trichlorides are a family of inorganic compound with the formula Ln Cl3, where Ln stands for a lanthanide metal. The trichlorides are standard reagents in applied and academic chemistry of the lanthanides. They exist as anhydrous solids ...

.M. D. Taylor, P. C. Carter, "Preparation of anhydrous lanthanide halides, especially iodides", ''J. Inorg. Nucl. Chem.'', 24, 387 (1962); J. Kutscher, A. Schneider, ''Inorg. Nucl. Chem. Lett.'', 7, 815 (1971). Alternatively the hydrate can be dehydrated using thionyl chloride.J. H. Freeman, M. L. Smith, "The preparation of anhydrous inorganic chlorides by dehydration with thionyl chlorid", ''J. Inorg. Nucl. Chem.'', 7, 224 (1958).

Reactions

Praseodymium(III) chloride is

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

ic, classified as "hard" according to the HSAB concept. Rapid heating of the

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 Potassium chloride (KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt ...

; this compound shows interesting optical and

magnetic Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particle ...

properties.J. Cybinska, J. Sokolnicki, J. Legendziewicz, G. Meyer, ''Journal of Alloys and Compounds'', 341, 115–123 (2002). 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.Gerd Meyer, "Ternary Chlorides and Bromides of the Rare-Earth Elements", Inorganic Syntheses, 1990, Volume 30, pp. 72–81.

Preparation

Reactions

References

Further reading