cobalt trichloride

Cobalt(III) chloride is of very dubious existence and the bromide and iodide have never been prepared. These halides are expectedly redox unstable, the Co3+ ion being a strong oxidant. Dissolution of cobalt(III) oxide in hydrochloric acid leads to evolution of chlorine. Indeed cobalt(III) compounds are estimated volumetrically as a result of their liberation of iodine from potassium iodide in acid solution.