Cadmium iodide

Cadmium iodide
IUPAC name

Cadmium(II) iodide
Other names

Cadmium diiodide
Identifiers
CAS number 7790-80-9 Y
ChemSpider 23037 Y
UNII 2F2UPU4KCW Y
EC number 232-223-6
Jmol-3D images Image 1
Properties
Molecular formula CdI2
Molar mass 366.22 g/mol
Appearance white to pale yellow crystals
Density 5.640 g/cm3, solid
Melting point

387 °C, 660 K, 729 °F
Boiling point

742 °C, 1015 K, 1368 °F
Solubility in water 787 g/L (0 °C)
847 g/L (20 °C)
1250 g/L (100 °C)
Solubility soluble in ethanol, acetone, ether and ammonia
Structure
Crystal structure Trigonal, hP3, space group P3m1, No. 164
Coordination
geometry		 octahedral
Hazards
EU Index 048-007-00-8
EU classification Toxic (T)
Harmful (Xn)
Dangerous for the environment (N)
R-phrases R23/25, R33, R68, R50/53
S-phrases (S2), S22, S45, S60, S61
Related compounds
Other anions cadmium fluoride
cadmium chloride
cadmium bromide
Other cations zinc iodide
mercury(II) iodide
 Y (verify) (what is: Y/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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.

Contents

Uses

Cadmium iodide is used in lithography, photography, electroplating and the manufacturing of phosphors.[1]

Preparation

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

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.[2]

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

Iodides

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

Chlorides and bromides

TiCl2, VCl2;

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

Hydroxides of M2+

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

Chalcogenides of M4+

TiS2, ZrS2, SnS2, α-TaS2, PtS2;

TiSe2, ZrSe2, SnSe2, PtSe2;

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

Others

AgF2, W2C.

References

  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
  2. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann. pp. 1211–1212. ISBN 0080379419.