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Europium(III) acetate

Europium(III) acetate is an inorganic salt of europium and acetic acid with the chemical formula of Eu(CH<sub>3</sub>COO)<sub>3</sub>. In this compound, europium exhibits the +3 oxidation state. It can exist in the anhydrous form, sesquihydrate and tetrahydrate. Its hydrate molecule is a dimer.

Preparation

Europium acetate can be obtained by stirring reaction of acetic acid and europium oxide under heating, and then diluting with water and crystallizing:

Eu<sub>2</sub>O<sub>3</sub> + 6 CH<sub>3</sub>COOH → 2 Eu(CH<sub>3</sub>COO)<sub>3</sub> + 3 H<sub>2</sub>O

Europium can also directly participate in the reaction:

2 Eu + 6 CH<sub>3</sub>COOH → 2 Eu(CH<sub>3</sub>COO)<sub>3</sub> + 3 H<sub>2</sub>↑

Properties

Physical properties

The anhydrous europium acetate crystallizes monoclinically in the space group C2/c (space group no. 15) with the lattice parameters a = 1126.0(3), b = 2900.5(6), c = 799.1( 2) pm and β = 132.03(2)° with four formula units per unit cell. The sesquihydrate crystallizes monoclinically in the space group Cc (No. 9) with the lattice parameters a = 1608.7(2), b = 1665.6(2), c = 839.1(1) pm and β = 115.75( 9)° with four formula units per unit cell. The heat capacity at 280 K is 803±16 J/(mol∙K).

Chemical properties

Europium acetate can be dissolved in water, acidified with acetic acid, and the compound of divalent europium [Eu(CH<sub>3</sub>COO)<sub>2</sub>(CH<sub>3</sub>COOH)(H<sub>2</sub>O)<sub>2</sub>] can be obtained by electrochemical reduction.

Europium acetate can be crystallized in excess glacial acetic acid to give the salt [Eu(H(CH<sub>3</sub>COO)<sub>2</sub>)<sub>3</sub>](H<sub>2</sub>O).

Decomposition

Europium acetate can be decomposed by heating, and the hydrate first loses water to obtain anhydrous, and then passes through basic acetate EuOCH<sub>3</sub>COO, basic carbonate Eu<sub>2</sub>O<sub>2</sub>CO<sub>3</sub>, and finally obtains europium oxide. The tetrahydrate of europium acetate decomposes in air over 6 stages to europium oxide.

Stage 1 at 135&nbsp;°C:

Eu(CH<sub>3</sub>COO)<sub>3</sub>·4H<sub>2</sub>O → Eu(CH<sub>3</sub>COO)<sub>3</sub>·H<sub>2</sub>O + 3H<sub>2</sub>O

Stage 2 at 170&nbsp;°C:

Eu(CH<sub>3</sub>COO)<sub>3</sub>·3H<sub>2</sub>O → Eu(CH<sub>3</sub>COO)<sub>3</sub>·0.5 H<sub>2</sub>O + 0.5 H<sub>2</sub>O

Stage 3 at 210&nbsp;°C:

Eu(CH<sub>3</sub>COO)<sub>3</sub>·0.5H<sub>2</sub>O → Eu(CH<sub>3</sub>COO)<sub>3</sub> + 0.5 H<sub>2</sub>O

Stage 4 at 310&nbsp;°C:

Eu(CH<sub>3</sub>COO)<sub>3</sub> → EuO(CH<sub>3</sub>COO) + C<sub>3</sub>H<sub>6</sub>O + CO<sub>2</sub>

Stage 5 at 390&nbsp;°C:

2EuO(CH<sub>3</sub>COO) → Eu<sub>2</sub>O<sub>2</sub>[CO<sub>3</sub>] + C<sub>3</sub>H<sub>6</sub>O

Stage 6 at 670&nbsp;°C:

Eu<sub>2</sub>O<sub>2</sub>[CO<sub>3</sub>] → Eu<sub>2</sub>O<sub>3</sub> + CO<sub>2</sub>

Notes

References