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 parametersa = 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]
^ abHaynes, William M. (2012). CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data. Boca Raton, Fla.: CRC. p. 84. ISBN978-1-4398-8049-4. OCLC793213751.
^ abcdhrsg. von Georg Brauer. Unter Mitarb. von M. Baudler (1975). Handbuch der präparativen anorganischen Chemie / 1 (in German). Stuttgart: Enke. p. 1081. ISBN3-432-02328-6. OCLC310719485.
^Meyer, G.; Naumann, Dieter; Wesemann, Lars (2006). Inorganic chemistry in focus. III. Weinheim: Wiley-VCH. p. 45. ISBN978-3-527-60993-2. OCLC86225074.
^Riedel, Erwin; Alsfasser, Ralf (2007). Moderne anorganische Chemie : mit CD-ROM : [133 Tabellen] (in German). Berlin: Gruyter. p. 366. ISBN978-3-11-019060-1. OCLC237200027.
