Hafnium tetraiodide

Hafnium tetraiodide

270px
Identifiers
CAS Number	13777-23-6
Properties
Chemical formula	HfI4
Molar mass	686.11
Appearance	red-orange
Density	5.60 g/cm3
Melting point	449 °C (840 °F; 722 K)
Boiling point	394 °C (741 °F; 667 K) (sublimes)
Structure
Crystal structure	Monoclinic, mS40
Space group	C2/c, No. 15
Lattice constant	a = 1.1787 nm, b = 1.1801 nm, c = 1.2905 nm
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Hafnium tetraiodide is the inorganic compound with the formula HfI₄. It is a red-orange, moisture sensitive, sublimable solid that is produced by heating a mixture of hafnium with excess iodine. It is an intermediate in the crystal bar process for producing hafnium metal.

In this compound, the hafnium centers adopt octahedral coordination geometry. Like most binary metal halides, the compound is a polymeric. It is one-dimensional polymer consisting of chains of edge-shared bioctahedral Hf₂I₈ subunits, similar to the motif adopted by HfCl₄. The nonbridging iodide ligands have shorter bonds to Hf than the bridging iodide ligands.