Neodymium(II) iodide
Neodymium iodide or neodymium diiodide is an inorganic salt of iodine and neodymium the formula NdI2. Neodymium uses the +2 oxidation state in the compound.
Neodymium iodide is a violet solid. The compound is not stoichiometric. It melts at 562°C.
Preparation
Neodymium iodide can be made by heating molten neodymium(III) iodide with neodymium metal at 800 and 580°C for 12 hours. It can also be obtained by reducing neodymium iodide with neodymium in a vacuum at 800 to 900°C:The reaction of neodymium with mercury(II) iodide is also possible because neodymium is more reactive than mercury:
Direct preparation from iodine and neodymium is also possible:
The compound was first synthesized by John D. Corbett in 1961.Angelika Jungmann, R. Claessen, R. Zimmermann, G. e. Meng, P. Steiner, S. Hüfner, S. Tratzky, K. Stöwe, H. P. Beck: Photoemission of LaI2 and CeI2. In: Zeitschrift für Physik B Condensed Matter. 97, 1995, S. 25–34,.
Properties
Neodymium iodide is a violet solid. The compound is extremely hygroscopic, and can only be stored and handled under carefully dried inert gas or under a high vacuum. 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:Neodymium iodide is not stoichiometric, and has a formula of closer to NdI1.95. It melts at 562°C. It has a strontium(II) bromide-type crystal structure. Under pressure, this transforms into the molybdenum disilicide structure typically seen in intermetallic compound, which is already present under normal conditions in other rare earth diiodides. It forms complexes with tetrahydrofuran and other organic compounds.Mikhail N. Bochkarev, Igor L. Fedushkin, Sebastian Dechert, Anatolii A. Fagin, Herbert Schumann: , der erste kristallographisch charakterisierte Neodym-Komplex. In: Angewandte Chemie. 113, 2001, S. 3268–3270,.G. V. Khoroshen kov, A. A. Fagin, M. N. Bochkarev, S. Dechert, H. Schumann: Reactions of neodymium, dysprosium, and thulium diiodides with cyclopentadiene In: Russian Chemical Bulletin. 52, S. 1715–1719,.
Neodymium iodide is an electrical insulator.
Reactions
Neodymium iodide reacts with organohalides by extracting the halogen, resulting in dimers, oligomers or reactions with the solvent.Solvates are known with tetrahydrofuran and dimethoxyethane: NdI22 and NdI22.
Neodymium iodide reduces hot nitrogen to form an iodide nitride: 3N which with THF also gives 3N2.
It reacts with cyclopentadiene in THF to give CpNdI23.