Barium diiodide

  • Formula: BaI2
  • Hill system formula: Ba1I2
  • CAS registry number: [13718-50-8]
  • Formula weight: 391.136
  • Class: iodide
  • Colour: white
  • Appearance: crystalline solid
  • Melting point: 711°C
  • Boiling point: 2027
  • Density: 5150 kg m-3

The following are some synonyms of barium diiodide:

  • barium diiodide
  • barium(II) iodide
  • barium iodide

The oxidation number of barium in barium diiodide is 2.


Barium iodide is made by the neutralization of barium carbonate with HI in water. The product crystallizes as the hydrate BaI2.2H2O [7787-33-9]. If this heated, dehydration to anhydrous BaI2 occurs.

BaCO3 + 2HI(aq) → BaI2(aq)

It is also made by the reaction of BaH2 with ammonium iodide in pyridine.

BaH2 + 2NH4I(aq) → BaI2(aq) + 2NH3(g) + H2(g)

Solid state structure

  • Geometry of barium:
  • Prototypical structure: PbCl2

Crystal structure of barium diiodide

Element analysis

The table shows element percentages for BaI2 (barium diiodide).

Element %
Ba 35.11
I 64.89

Isotope pattern for BaI2

The chart below shows the calculated isotope pattern for the formula BaI2 with the most intense ion set to 100%.


The data on these compounds pages are assembled and adapted from the primary literature and several other sources including the following.

  • R.T. Sanderson in Chemical Periodicity, Reinhold, New York, USA, 1960.
  • N.N. Greenwood and A. Earnshaw in Chemistry of the Elements, 2nd edition, Butterworth, UK, 1997.
  • F.A. Cotton, G. Wilkinson, C.A. Murillo, and M. Bochmann, in Advanced Inorganic Chemistry, John Wiley & Sons, 1999.
  • A.F. Trotman-Dickenson, (ed.) in Comprehensive Inorganic Chemistry, Pergamon, Oxford, UK, 1973.
  • R.W.G. Wyckoff, in Crystal Structures, volume 1, Interscience, John Wiley & Sons, 1963.
  • A.R.West in Basic solid state chemistry Chemistry, John Wiley & Sons, 1999.
  • A.F. Wells in Structural inorganic chemistry, 4th edition, Oxford, UK, 1975.
  • J.D.H. Donnay, (ed.) in Crystal data determinative tables, ACA monograph number 5, American Crystallographic Association, USA, 1963.
  • D.R. Lide, (ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 77th edition, 1996.
  • J.W. Mellor in A comprehensive treatise on inorganic and theoretical chemistry, volumes 1-16, Longmans, London, UK, 1922-1937.
  • J.E. Macintyre (ed.) in Dictionary of inorganic compounds, volumes 1-3, Chapman & Hall, London, UK, 1992.

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