Indium mono-iodide, InI

Indium mono-iodide, InI, is produced when an excess of indium is heated with iodine. Small quantities must be used, unless the reaction is carried out in an atmosphere of carbon dioxide. Indium tri-iodide is reduced to the mono-iodide by repeated distillation in hydrogen. It is a brownish-red solid, which melts at 351° and boils at c. 700°, and maybe distilled in carbon dioxide.

Indium mono-iodide is not attacked by hot water, but dissolves in dilute acids with the evolution of hydrogen. It is insoluble in alcohol, ether, and chloroform. The simultaneous action of air and water leads to the production of indium hydroxide and hydriodic acid. This action is slow with cold water, and the hydroxide is obtained in colloidal solution, but with hot water the hydroxide separates in a form easily filtered.