Beryllium iodide

Beryllium iodide is an inorganic compound with the chemical formula BeI₂. It is a hygroscopic white solid. The Be²⁺ cation, which is relevant to salt-like BeI₂, is characterized by the highest known charge density (Z/r = 6.45), making it one of the hardest cations and a very strong Lewis acid.^[4]

Beryllium iodide

Names
Systematic IUPAC name Beryllium iodide
Identifiers
CAS Number	7787-53-3 Y
3D model (JSmol)	Interactive image Interactive image
ChemSpider	74209 Y
ECHA InfoCard	100.029.199
PubChem CID	82231
UNII	9E9VD36EWN Y
CompTox Dashboard (EPA)	DTXSID9064849
InChI InChI=1S/Be.2HI/h;2*1H/q+2;;/p-2 Y Key: JUCWKFHIHJQTFR-UHFFFAOYSA-L Y InChI=1/Be.2HI/h;2*1H/q+2;;/p-2 Key: JUCWKFHIHJQTFR-NUQVWONBAT
SMILES I[Be]I I[Be-2](I)([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1([I+]1)[I+][Be-2]1(I)I
Properties
Chemical formula	BeI2
Molar mass	262.82112 g·mol−1
Appearance	colorless needle-like crystals
Density	4.325 g/cm3
Melting point	480 °C (896 °F; 753 K)
Boiling point	590 °C (1,094 °F; 863 K)[1]
Solubility in water	reacts with water[1][citation needed]
Solubility	Slightly soluble in CS2 Soluble in ethanol, diethyl ether[2]
Structure
Crystal structure	orthorhombic
Thermochemistry
Heat capacity (C)	71.14 J/(mol·K)
Std molar entropy (S⦵298)	130 J/(mol·K)
Std enthalpy of formation (ΔfH⦵298)	−192.62 kJ/mol
Gibbs free energy (ΔfG⦵)	−210 kJ/mol
Std enthalpy of combustion (ΔcH⦵298)	19 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	see Berylliosis
NFPA 704 (fire diamond)	3 3 2 W
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.002 mg/m3 C 0.005 mg/m3 (30 minutes), with a maximum peak of 0.025 mg/m3 (as Be)[3]
REL (Recommended)	Ca C 0.0005 mg/m3 (as Be)[3]
IDLH (Immediate danger)	Ca [4 mg/m3 (as Be)][3]
Related compounds
Other anions	Beryllium fluoride Beryllium chloride Beryllium bromide
Other cations	Magnesium iodide Calcium iodide Strontium iodide Barium iodide Radium iodide
Related compounds	Hydrogen iodide Zinc iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Reactions

Beryllium iodide can be prepared by reacting beryllium metal with elemental iodine at temperatures of 500 °C to 700 °C:^[1]

Be + I₂ → BeI₂

When the oxidation is conducted on an ether suspension of elemental Be, one obtains colorless dietherate:^[5]

Be + I₂ + 2 O(C₂H₅)₂ → BeI₂(O(C₂H₅)₂)₂

The same dietherate is obtained by suspending beryllium iodide in diethyl ether:^[5]

BeI₂ + 2 O(C₂H₅)₂ → BeI₂(O(C₂H₅)₂)₂

This ether ligands in BeI₂(O(C₂H₅)₂)₂ can be displaced by other Lewis bases.

Beryllium iodide reacts with fluorine giving beryllium fluoride and fluorides of iodine, with chlorine giving beryllium chloride, and with bromine giving beryllium bromide.

Structure

Two forms (polymorphs) of BeI₂ are known. Both structures consist tetrahedral Be²⁺ centers interconnected by doubly bridging iodide ligands. One form consist of edge-sharing polytetrahedra. The other form resembles zinc iodide with interconnected adamantane-like cages.^[6]

Applications

Beryllium iodide can be used in the preparation of high-purity beryllium by the decomposition of the compound on a hot tungsten filament.