Furthermore, Evans method measurements of the reaction solution, taken before and after the addition of sPhIO, revealed a sharp decrease of the effective magnetic moment from 5.58 BM to 3.88 BM -the latter exactly matching with the theoretical value for an S = 3/2 system. This finding supported a quantitative transformation of the high-spin S = 5/2 Mn(II) complex into the corresponding Mn(IV) species.