Chemistry:Praseodymium diiodide
| |
| Identifiers | |
|---|---|
| Properties | |
| I2Pr | |
| Molar mass | 394.71660 g·mol−1 |
| Appearance | bronze solid[1][2] |
| Melting point | 758 °C[1][2] |
| Related compounds | |
Other cations
|
Lanthanum(II) iodide Cerium(II) iodide Neodymium(II) iodide |
Related compounds
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Praseodymium(III) iodide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Praseodymium diiodide is a chemical compound with the empirical formula of PrI2, consisting of praseodymium and iodine. It is an electride, with the ionic formula of Pr3+(I−)2e−,[2] and therefore not a true praseodymium(II) compound.
Preparation
Praseodymium diiodide can be obtained by reacting praseodymium(III) iodide with metallic praseodymium at 800 °C to 900 °C in an inert atmosphere:[3]
- Pr + 2 PrI3 → 3 PrI2
It can also be obtained by reacting praseodymium with mercury(II) iodide where praseodymium displaces mercury:[3]
- Pr + HgI2 → PrI2 + Hg
Praseodymium diiodide was first obtained by John D. Corbett in 1961.[4]
Properties
Praseodymium diiodide is an opaque, bronze-coloured solid with a metallic lustre that is soluble in water.[3] The lustre and very high conductivity can be explained by the formulation {PrIII,2I−,e−}, with one electron per metal centre delocalised in a conduction band.[2]
The compound is extremely hygroscopic, and can only be stored and handled under carefully dried inert gas or under a high vacuum.[citation needed] In air it converts into hydrates by absorbing moisture, but these are unstable and more or less rapidly transform into oxide iodides with the evolution of hydrogen:[citation needed]
- 2PrI2 + 2H2O → 2PrOI + H2↑ + 2HI
With water, these processes take place much faster.[3]
Praseodymium diiodide has five crystal structures, namely the MoSi2 structure, the hexagonal MoS2 structure, the trigonal MoS2 structure, the cadmium chloride structure and the spinel structure.[5] Praseodymium diiodide with the cadmium chloride structure belongs to the trigonal crystal system, with the space group R3m (No. 166), lattice parameters a = 426.5 pm and c = 2247,1 pm; however, the spinel structure of praseodymium diiodide is cubic,[6] with space group F43 (No. 216), and lattice parameter a = 1239.9 pm.[7]
References
- ↑ 1.0 1.1 Haynes, William M. (2012). CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data.. Boca Raton, Fla.: CRC. p. 84. ISBN 978-1-4398-8049-4. OCLC 793213751.
- ↑ 2.0 2.1 2.2 2.3 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 1240–1242. ISBN 978-0-08-037941-8.
- ↑ 3.0 3.1 3.2 3.3 hrsg. von Georg Brauer. Unter Mitarb. von M. Baudler (1975) (in de). Handbuch der präparativen anorganischen Chemie / 1.. Stuttgart: Enke. p. 1081. ISBN 3-432-02328-6. OCLC 310719485.
- ↑ Meyer, G.; Naumann, Dieter; Wesemann, Lars (2006). Inorganic chemistry in focus. III. Weinheim: Wiley-VCH. p. 45. ISBN 978-3-527-60993-2. OCLC 86225074.
- ↑ Riedel, Erwin; Alsfasser, Ralf (2007) (in de). Moderne anorganische Chemie : mit CD-ROM : [133 Tabellen]. Berlin: Gruyter. p. 366. ISBN 978-3-11-019060-1. OCLC 237200027.
- ↑ Warkentin, E.; Bärnighausen, H. (1979). "Die Kristallstruktur von Praseodymdiiodid (Modifikation V)". Z. anorg. allg. Chem. 459: 187–200. doi:10.1002/zaac.19794590120.
- ↑ Gerlitzki, Niels; Meyer, Gerd; Mudring, Anja-Verena; Corbett, John D. (2004). "Praseodymium diiodide, PrI2, revisited by synthesis, structure determination and theory". J. Alloys Compd. (Elsevier BV) 380 (1–2): 211–218. doi:10.1016/j.jallcom.2004.03.046. ISSN 0925-8388.
| HI | He | ||||||||||||||||
| LiI | BeI2 | BI3 | CI4 | NI3 | I2O4, I2O5, I4O9 |
IF, IF3, IF5, IF7 |
Ne | ||||||||||
| NaI | MgI2 | AlI3 | SiI4 | PI3, P2I4 |
S | ICl, ICl3 |
Ar | ||||||||||
| KI | CaI2 | Sc | TiI4 | VI3 | CrI3 | MnI2 | FeI2 | CoI2 | NiI2 | CuI | ZnI2 | Ga2I6 | GeI2, GeI4 |
AsI3 | Se | IBr | Kr |
| RbI | SrI2 | YI3 | ZrI4 | NbI5 | Mo | Tc | Ru | Rh | Pd | AgI | CdI2 | InI3 | SnI4, SnI2 |
SbI3 | TeI4 | I | Xe |
| CsI | BaI2 | HfI4 | TaI5 | W | Re | Os | Ir | Pt | AuI | Hg2I2, HgI2 |
TlI | PbI2 | BiI3 | Po | AtI | Rn | |
| Fr | RaI2 | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og | |
| ↓ | |||||||||||||||||
| La | Ce | Pr | Nd | Pm | SmI2 | Eu | Gd | TbI3 | Dy | Ho | Er | Tm | Yb | Lu | |||
| Ac | ThI4 | Pa | UI3, UI4 |
Np | Pu | Am | Cm | Bk | Cf | EsI3 | Fm | Md | No | Lr | |||
 |  |
