title: Tellurium monoiodide
text: # Tellurium monoiodide
  
  Tellurium iodide is an inorganic compound with the formula TeI. Two forms are known. Their structures differ from the other monohalides of tellurium. There are three subiodides of tellurium, α-TeI, β-TeI, and $Te_2I,$ and one tellurium tetraiodide.
  
  ## Preparation and properties
  
  TeI is a gray solid formed by the hydrothermal reaction of tellurium metal and iodine in hydroiodic acid. When this reaction is conducted near 270 °C gives the α-TeI, which is triclinic. When the same mixture is heated to 150 °C, one obtains the metastable monoclinic phase β-TeI. The compounds are related structurally to $Te_2I$ (see ditellurium bromide), but the additional iodide groups do not bridge to other Te centers.
  
  The corresponding monochloride and monobromide are molecular compounds with the formula $Te_2X_2.$
  
  ## Tellurium diiodide
  
  Although $TeI_2$ has not been isolated in bulk, complexes of the type $TeI_2(thiourea)_2$ are well characterized. These complexes precipitate upon treatment of aqueous solutions of the related tellurium dibromide complex with sodium iodide.
  
  