cerium diiodide
{{Chembox
|ImageFile=LaI2.png
|Section3={{Chembox Structure
|SpaceGroup= I4/mmm (No. 139)}}
|Section1={{Chembox Identifiers
|CASNo= 19139-47-0
|StdInChI=1S/Ce.2HI/h;2*1H/q+2;;/p-2
|StdInChIKey=ORCLLRHIKXTOMX-UHFFFAOYSA-L
|SMILES = [I-].[I-].[Ce+2]
}}
|Section2={{Chembox Properties
|Ce=1|I=2
|Density=
|BoilingPt=
|Solubility=
}}
|Section9={{Chembox Related
|OtherCations=lanthanum diiodide
praseodymium diiodide
neodymium(II) iodide
|OtherCompounds=cerium(III) iodide
}}
}}
Cerium diiodide is an iodide of cerium, with the chemical formula of CeI2.
Preparation
Cerium diiodide can be obtained from the reduction of cerium(III) iodide with metallic cerium under vacuum at 800 °C to 900 °C.{{cite book | title=Handbuch der präparativen anorganischen Chemie | publisher=Enke | publication-place=Stuttgart | year=1975 | isbn=3-432-02328-6 | oclc=310719485 | language=de | ref={{sfnref | Enke | 1975}} |page=1081}}
:{{Chem2| Ce + 2 CeI3 -> CeI2}}
It can also be formed from the reaction of cerium and ammonium iodide in liquid ammonia at −78 °C. The reaction forms an ammonia complex of cerium diiodide, which decomposes to cerium diiodide under vacuum at 200 °C.
:{{Chem2| Ce + 2 NH4I -> CeI2 + 2 NH3 + H2}}
It was first created by John D. Corbett in 1961.{{cite journal | last1=Jungmann | first1=Angelika | last2=Claessen | first2=R. | last3=Zimmermann | first3=R. | last4=Meng | first4=Ge | last5=Steiner | first5=P. | last6=Hüfner | first6=S. | last7=Tratzky | first7=S. | last8=Stöwe | first8=K. | last9=Beck | first9=H. P. | title=Photoemission of LaI2 and CeI2 | journal=Zeitschrift für Physik B | publisher=Springer Science and Business Media LLC | volume=97 | issue=1 | year=1995 | issn=0722-3277 | doi=10.1007/bf01317584 | pages=25–34| bibcode=1995ZPhyB..97...25J | s2cid=124057481 }}
Properties
Cerium diiodide is an opaque dark solid with a metal-like appearance and properties. There is no cerium(II) in cerium diiodide, and its real structure is Ce3+(I−)2e−. It is easily hydrolyzed to form the corresponding iodide oxide. Like lanthanum diiodide and praseodymium diiodide, the cerium diiodide forms in the MoSi2-type structure,{{cite book | last=Macintyre | first=J. E. | title=Dictionary of inorganic compounds | url=https://archive.org/details/dictionaryofinor0004unse | publisher=Chapman & Hall | publication-place=London New York | year=1992 | isbn=0-412-30120-2 | oclc=26338506 |page=2820}} with space group I4/mmm (No. 139).{{cite book | last=Hulliger | first=Fritz | title=Structural chemistry of layer-type phases | url=https://archive.org/details/structuralchemis0005hull/page/247 | publisher=D. Reidel Pub. Co | publication-place=Dordrecht, Holland Boston | year=1976 | isbn=90-277-0714-6 | oclc=2372807 |page=247}}