Thallium iodide (TlI) (7790-30-9)

 Thallium iodide (CAS NO.7790-30-9) is also called Thallium iodide (Tl2I2) ; Thallium iodide (TlI), dimer ; Thallium iodide (VAN) ; Thallium iodide, TlI ; Thallium monoiodide ; Thallium(1+) iodide ; Thallium(I) iodide . The room temperature form of  Thallium iodide (CAS NO.7790-30-9) is yellow and has an orthorhombic structure which can be considered to be a distorted NaCl structure. The distorted structure is believed to be caused by favourable thallium-thallium interactions, the closest Tl-Tl distance is 383pm. At 175 °C the yellow form transforms to a red CsCl form. This phase transition is accompanied by about two orders of magnitude jump in electrical conductivity. The CsI structure can be stabilized down to room temperature by doping TlI with other iodides such as RbI, CsI, KI, AgI, TlBr and TlCl . Thus, presence of impurities might be responsible for coexistence of the cubic and orthorombic TlI phases at ambient conditions. Under high pressure, 160kbar, TlI becomes a metallic conductor.

Thallium and its compounds are on the Community Right-To-Know List. Reported in EPA TSCA Inventory.