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Neodymium(III) iodide

Neodymium(III) iodide is an inorganic salt of iodine and neodymium with the formula NdI<sub>3</sub>. Neodymium uses the +3 oxidation state in the compound. The anhydrous compound is a green powdery solid at room temperature.

Preparation

Heating neodymium and iodine in an inert atmosphere produces this salt:

2 Nd + 3 I<sub>2</sub> → 2 NdI<sub>3</sub>

It can also be prepared by the reaction of neodymium(III) oxide and hydroiodic acid to make a hydrate:

Nd<sub>2</sub>O<sub>3</sub> + 6 HI → 2 NdI<sub>3</sub> + 3 H<sub>2</sub>O

The anhydrate can then be obtained by heating the nonahydrate with ammonium iodide:

NdI<sub>3</sub> • 9 H<sub>2</sub>O + nNH<sub>4</sub>I → NdI<sub>3</sub> + nNH<sub>3</sub> + nHI + 9H<sub>2</sub>O

Physical properties

Neodymium(III) iodide forms green, water-soluble hygroscopic crystals. It has a melting point of 784°C. It forms a nonahydrate crystal NdI<sub>3</sub>.9H<sub>2</sub>O – belongs to the orthorhombic crystal system, space group Pmmn, lattice constants a = 1.16604 nm, b = 0.80103 nm, c = 0.89702 nm, Z = 4.

Other compounds

NdI<sub>3</sub> also forms some compounds with N<sub>2</sub>H<sub>4</sub>, such as NdI<sub>3</sub>·3N<sub>2</sub>H<sub>4</sub>·2H<sub>2</sub>O which is a dark green crystal, soluble in methanol and ethanol and insoluble in water, benzene and toluene, d<sub>20°C</sub> = 3.42 g/cm³.

NdI<sub>3</sub> also forms some compounds with urea, such as NdI<sub>3 </sub>5CO(NH<sub>2</sub>)<sub>2</sub> which is a lavender color crystal.

NdI<sub>3</sub> also forms some compounds with thiourea, such as NdI<sub>3</sub>·2CS(NH<sub>2</sub>)2·9H<sub>2</sub>O which is a pale pink crystal.

See also

References