* Lead(IV) Iodide (PbI4) is unstable: Lead(IV) is a highly oxidizing state, and iodide ions are easily oxidized. This means that PbI4 is highly unstable and tends to decompose into lead(II) iodide (PbI2) and iodine (I2).
* Lead(II) Iodide is also sparingly soluble: Even PbI2, a more common lead iodide compound, is only slightly soluble in water. This is due to the strong ionic interactions between lead(II) and iodide ions, which are difficult to overcome by the forces of solvation by water molecules.
In summary: PbI4 is not a stable compound and readily decomposes. Even if it could exist, its solubility would be extremely low due to the insolubility of lead(II) iodide.
