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 trichlorides, 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 The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride ga ...

: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 Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

: :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.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 Thionyl chloride is an inorganic compound with the chemical formula . It is a moderately volatile, colourless liquid with an unpleasant acrid odour. Thionyl chloride is primarily used as a chlorinating reagent, with approximately per year bein ...

.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 HSAB concept is a jargon for "hard and soft (Lewis) acids and bases". HSAB is widely used in chemistry for explaining stability of compounds, reaction mechanisms and pathways. It assigns the terms 'hard' or 'soft', and 'acid' or 'base' to chemic ...

. Rapid heating of the

may cause small amounts of

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

.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 Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...

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 An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be rep ...

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 Potassium phosphate is a generic term for the salt (chemistry), salts of potassium and phosphate ions including: * Monopotassium phosphate (KH2PO4) (Molar mass approx: 136 g/mol) * Dipotassium phosphate (K2HPO4) (Molar mass approx: 174 g/mol) * ...

and

sodium fluoride Sodium fluoride (NaF) is an inorganic compound with the formula . It is used in trace amounts in the fluoridation of drinking water, in toothpaste, in metallurgy, and as a flux. It is a colorless or white solid that is readily soluble in water. I ...

, 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