CdI2

Cadmium iodide (CdI2) is an inorganic compound consisting of cadmium(II) cations and iodide anions. It forms white crystalline solids that are highly hygroscopic and readily form hydrates in air.

In the solid state CdI2 adopts a layered CdI2-type structure. Each Cd2+ ion is octahedrally coordinated by six iodide ligands, and the iodide ions stack into sheets separated by weak van der Waals gaps. This two-dimensional arrangement contributes to its properties and reactivity.

CdI2 is soluble in water. In aqueous iodide solutions, Cd2+ can coordinate with excess iodide to form the tetraiodocadmate(II) complex [CdI4]2−, though the exact speciation depends on concentration and pH.

Preparation can be accomplished by direct combination of cadmium and iodine at elevated temperature, or by reacting cadmium oxide or carbonate with hydroiodic acid, followed by purification.

Uses are primarily as a reagent and precursor in inorganic synthesis, supplying Cd2+ and iodide for the preparation of cadmium salts, coordination compounds, and cadmium-containing semiconductor materials via specialized routes. It is also studied as a reference material for the structural chemistry of metal dihalides.

Safety: Cadmium compounds are toxic; exposure should be avoided. Handle CdI2 under appropriate safety protocols with gloves, eye protection, and work in a well-ventilated area. Dispose as hazardous waste.

Storage: Keep in a tightly closed container, in a dry place away from moisture.