AlI3
aluminum iodide · aluminium triiodide
Aluminum iodide is a stable, insulating chemical compound primarily utilized as a reagent in organic synthesis.

About aluminum iodide
Aluminum iodide is a thermodynamically stable compound characterized by its insulating electronic nature. Due to its distinct chemical properties, it serves as a valuable reagent in various synthetic pathways, particularly in organic chemistry where it acts as a powerful catalyst or iodinating agent.
This material is recognized for its structural versatility, as evidenced by the significant number of reported crystal structures across major databases. Its role as a stable halide makes it an essential component in specialized industrial and laboratory applications requiring precise chemical reactivity.
Key Properties
Cross-validated computational properties for aluminum iodide, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Reported Structures
Lowest-energy structures reported for AlI3, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| P21/c (No. 14) | monoclinic | 3.26 | 0.0000 | -3.035 | 3.73 |
| P2/m (No. 10) | Monoclinic | — | — | — | 5.11 |
| P4/mmm (No. 123) | Tetragonal | — | — | — | 4.70 |
| Cmmm (No. 65) | Orthorhombic | — | — | — | 3.60 |
| P4/mmm (No. 123) | Tetragonal | — | — | — | 7.21 |
| Cm (No. 8) | Monoclinic | — | — | — | 4.66 |
| P1 (No. 1) | Triclinic | — | — | — | 3.62 |
| Cm (No. 8) | Monoclinic | — | — | — | 7.19 |
| P2/m (No. 10) | Monoclinic | — | — | — | 7.87 |
| P21/m (No. 11) | Monoclinic | — | — | — | 4.80 |
| C2/c (No. 15) | Monoclinic | — | — | — | 5.02 |
| P21/m (No. 11) | Monoclinic | — | — | — | 5.32 |
Applications
Where aluminum iodide is used.
Frequently Asked Questions
Common questions about aluminum iodide, answered from cross-validated data.
What is AlI3?
Aluminum iodide is a stable, insulating chemical compound primarily utilized as a reagent in organic synthesis.
What is AlI3 used for?
What is the band gap of AlI3?
Is AlI3 a metal, semiconductor, or insulator?
Is AlI3 thermodynamically stable?
What is the crystal structure of AlI3?
What is the density of AlI3?
How many polymorphs of AlI3 are known?
What elements does AlI3 contain?
Where does the data for AlI3 come from?
How It Compares
As a stable halide in its class, aluminum iodide functions as a critical chemical intermediate. It is distinguished by its specific reactivity profile compared to other aluminum-based halides, making it a preferred choice for targeted synthetic transformations where iodine-based chemistry is required.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
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