Cadmium iodide

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Cadmium iodide
Cadmium iodide
Cadmium iodide
Cadmium iodide (1).jpg
IUPAC name
Cadmium(II) iodide
Other names
Cadmium diiodide
3D model (JSmol)
ECHA InfoCard 100.029.294
EC Number 232-223-6
Molar mass 366.22 g/mol
Appearance white to pale yellow crystals
Density 5.640 g/cm3, solid
Melting point 387 °C (729 °F; 660 K)
Boiling point 742 °C (1,368 °F; 1,015 K)
787 g/L (0 °C)
847 g/L (20 °C)
1250 g/L (100 °C)
Solubility soluble in ethanol, acetone, ether and ammonia
-117.2·10−6 cm3/mol
Trigonal, hP3, space group P3m1, No. 164
Very Toxic T+ Harmful Xn Dangerous for the Environment (Nature) N
R-phrases (outdated) R23/25, R33, R68, R50/53
S-phrases (outdated) (S2), S22, S45, S60, S61
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gasReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
US health exposure limits (NIOSH):
PEL (Permissible)
[1910.1027] TWA 0.005 mg/m3 (as Cd)[1]
REL (Recommended)
IDLH (Immediate danger)
Ca [9 mg/m3 (as Cd)][1]
Related compounds
Other anions
cadmium fluoride
cadmium chloride
cadmium bromide
Other cations
zinc iodide
mercury(II) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Cadmium iodide, CdI2, is a chemical compound of cadmium and iodine. It is notable for its crystal structure, which is typical for compounds of the form MX2 with strong polarization effects.


Cadmium iodide is used in lithography, photography, electroplating and the manufacturing of phosphors.[2]


Cadmium iodide is prepared by the addition of cadmium metal, or its oxide, hydroxide or carbonate to hydroiodic acid.

Also, the compound can be made by heating cadmium with iodine.

Crystal structure[edit]

In cadmium iodide the iodide anions form a hexagonal close packed arrangement while the cadmium cations fill all of the octahedral sites in alternate layers. The resultant structure consists of a layered lattice. This same basic structure is found in many other salts and minerals. Cadmium iodide is mostly ionically bonded but with partial covalent character.[3]

Cadmium iodide's crystal structure is the prototype on which the crystal structures many other compounds can be considered to be based. Compounds with any of the following characteristics tend to adopt the CdI2 structure:

Compounds with the CdI2 crystal structure[edit]

The iodide anions in CdI2 form a hexagonal close-packed lattice, while the cadmium cations occupy all of the octahedral holes in alternating layers.


MgI2, TiI2, VI2, MnI2, FeI2, CoI2, CaI2, PdI2, PbI2.

Chlorides and bromides[edit]

TiCl2, VCl2;

MgBr2, TiBr2, VBr2, MnBr2, FeBr2, CoBr2.

Hydroxides of M2+[edit]

Mg(OH)2, Ni(OH)2, Ca(OH)2.

Chalcogenides of M4+[edit]

TiS2, ZrS2, SnS2, α-TaS2, PtS2;

TiSe2, ZrSe2, SnSe2, PtSe2; CrSe2

SiTe2, TiTe2, CoTe2, NiTe2, PdTe2, PtTe2.


AgF2, W2C.


  1. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0087". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  3. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1211–1212. ISBN 978-0-08-037941-8.