A mixed-valence compound with one unpaired electron delocalized over four molybdenum atoms in a cyclic tetranuclear ion

The first oxidation of a species derived from a compound having two linked, quadruply-bonded Mo2 units has been performed and [[cis-Mo2 (DAniF)2]2((mu)-Cl)4]PF6, 2, has been isolated and characterized in many ways; it has one unpaired electron and a fully delocalized structure where the Mo–Mo distances increase from 2.1191(4)A in the reduced species to 2.1453(3)A in 2 and the Kc of 1.3 × 10^9 is three orders of magnitude larger than that of the Creutz–Taube ion.