Oxidation state localized orbitals (OSLOs) is a new concept used to determine the oxidation states of each fragment for the coordination complexes. Based on the result of density functional theory (DFT), all the occupied molecular orbitals are remixed to get the oxidation state localized orbitals. These orbitals are assigned to one of the fragments in this molecule based on the fragment orbital localization index (FOLI). After all the electrons are assigned, the oxidation states of each fragment could be obtained by calculating the difference between the number of electrons and protons in each fragment.