Disproportionation of Monovalent Thulium Iodide

Monovalent thulium iodide TmI, formed by the reaction of thulium with iodine at 680°C, does not dissolve in isopropylamine (IPA), but quickly disproportionates to form finely dispersed thulium metal and TmI 2 (IPA) 2 . Similar transformations are observed in dimethoxyethane, but disproportionation proceeds significantly slower. It is impossible to isolate the powdered thulium formed in this case. The observed transformations are the first example of disproportionation of a monovalent lanthanide salt.