Reacting the Free Radicals ClO ₂ and [O ₃ ] ^– : One‐Electron Transfer Instead of Bond Formation

We reacted ClO 2 and KO 3 in liquid ammonia and expected the radical coupling to form the compound [ClO 2 ···O 3 ] – . We noted the disappearance of the characteristic red color of the ozonide solution as a clear indication that a reaction took place. Over time, colorless crystals grew, which were unambiguously identified as [NH 4 ][ClO 2 ] by single‐crystal X‐ray diffraction. This finding has thus provided compelling evidence that, instead of the targeted radical coupling, a one‐electron transfer comprising oxidation of [O 3 ] − had occurred. It further demonstrates that the reduction potential of chlorine dioxide is higher than that of ozone in liquid anhydrous ammonia.