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Vanadium(III) fluoride

Vanadium(III) fluoride is the chemical compound with the formula VF<sub>3</sub>. It is a yellow-green crystalline solid with hexacoordinate vanadium atoms and bridging fluorine atoms. The magnetic moment indicates the presence of two unpaired electrons. Similar to other transition-metal fluorides (such as MnF<sub>2</sub>), it exhibits magnetic ordering at low temperatures (e.g. V<sub>2</sub>F<sub>6</sub>.4H<sub>2</sub>O orders below 12 K).

Preparation

Vanadium(III) fluoride is obtained in a two-step procedure from V<sub>2</sub>O<sub>3</sub>.

The first step entails conversion to the hexafluorovanadate(III) salt using ammonium bifluoride:

V<sub>2</sub>O<sub>3</sub> + 6 (NH<sub>4</sub>)HF<sub>2</sub> → 2 (NH<sub>4</sub>)<sub>3</sub>VF<sub>6</sub> + 3 H<sub>2</sub>O

In the second step, the hexafluorovanadate is thermally decomposed.

(NH<sub>4</sub>)<sub>3</sub>VF<sub>6</sub> → 3 NH<sub>3</sub> + 3 HF + VF<sub>3</sub>

The thermal decomposition of ammonium salts is a relatively common method for the preparation of inorganic solids.

It can also be prepared by treatment of V<sub>2</sub>O<sub>3</sub> with HF.

References

General references