Praseodymium(III) iodide

Names
Other names Praseodymium triiodide
Identifiers
CAS Number	13813-23-5
3D model (JSmol)	Interactive image
ChemSpider	75566
ECHA InfoCard	100.034.046
EC Number	237-466-1
PubChemCID	83744
CompTox Dashboard(EPA)	DTXSID5065641
InChI InChI=1S/3HI.Pr/h3*1H;/q;;;+3/p-3 Key: PVEVRIVGNKNWML-UHFFFAOYSA-K
SMILES I[Pr](I)I
Properties
Chemical formula	PrI3
Molar mass	521.619 g/mol 683.75652 g/mol (nonahydrate)
Appearance	hygroscopic green crystals
Density	5.8 g/cm3[1]
Melting point	738 °C (1,360 °F; 1,011 K)[1]
Boiling point	1,380 °C (2,520 °F; 1,650 K)
Solubility in water	213.9 g/100 mL[2]
Hazards
GHS labelling:[3]
Pictograms
Signal word	Danger
Hazard statements	H317,H360
Precautionary statements	P203,P261,P272,P280,P302+P352,P318,P321,P333+P313,P362+P364,P405,P501
Related compounds
Otheranions	Praseodymium(III) fluoride Praseodymium(III) chloride Praseodymium(III) bromide
Othercations	Cerium(III) iodide Neodymium(III) iodide
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). Infobox references

Praseodymium(III) iodide is aninorganicsalt, consisting of therare-earth metalpraseodymium andiodine, with the chemical formula PrI₃. It forms green crystals.^[4] It is soluble in water.^[5]

• Heating praseodymium andiodine in an inert atmosphere produces praseodymium(III) iodide:^[1]

${\displaystyle \mathsf{2}\mathsf{P}\mathsf{r}\mathsf{+}\mathsf{3}{\mathsf{I}}_{\mathsf{2}}\stackrel{\mathsf{T}}{\to }\mathsf{2}\mathsf{P}\mathsf{r}{\mathsf{I}}_{\mathsf{3}}}$

• It can also be obtained by heating praseodymium with mercury(II) iodide:^[6]

${\displaystyle \mathsf{2}\mathsf{P}\mathsf{r}\mathsf{+}\mathsf{3}\mathsf{H}\mathsf{g}{\mathsf{I}}_{\mathsf{2}}\stackrel{\mathsf{T}}{\to }\mathsf{2}\mathsf{P}\mathsf{r}{\mathsf{I}}_{\mathsf{3}}\mathsf{+}\mathsf{3}\mathsf{H}\mathsf{g}}$

Praseodymium(III) iodide forms green crystals, which are soluble in water.^[5] It formsorthorhombic crystals which arehygroscopic.^[1] It crystallizes in thePuBr₃ type^[6][7] with space groupCmcm (No. 63) witha = 4.3281(6) Å,b = 14.003(6) Å andc = 9.988(3) Å.^[8] It decomposes through an intermediate phase 2 PrI₃·PrOI to a mixture ofpraseodymium oxyiodide and praseodymium oxide (5 PrOI·Pr₂O₃).^[9]

• PrI₃ forms compounds withhydrazine, like I₃Pr·3N₂H₄·4H₂O which has pale yellow crystals and soluble inmethanol, slightly soluble in water, and insoluble inbenzene, d_{20 °C} = 2.986 g/cm³.^[10]

• PrI₃ forms compounds withurea, like I₃Pr·5CO(NH₂)₂ which has pale green crystals.^[11]

• PrI₃ forms compounds withthiourea, like I₃Pr·2CS(NH₂)₂·9H₂O which is a green crystal with d = 2.27 g/cm³.^[5][12]

• Praseodymium(III) iodide forms anonahydrate, PrI₃·9H₂O. It can be obtained by dissolvingpraseodymium(III) oxide in concentrated aqueoushydroiodic acid:

Pr₂O₃ + 6 HI + 15H₂O → 2 PrI₃·9H₂O

• It adopts the same structure as other light rare earth iodides (La–Ho) and contains atriangular tricapped prismatic nonaaqua ion [Pr(OH₂)₉]³⁺ andiodide counterions.^[4]

• Praseodymium(III) iodide reacts with praseodymium metal at elevated temperatures to formpraseodymium diiodide:^[13]

2 PrI₃ + Pr → 3 PrI₂

• Praseodymium diiodide
• Praseodymium compounds

• Iodides
• Lanthanide halides

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