text: For example, using the OSLOs for ferrocene shows great consistency with the prediction. The metal center was assigned the oxidation state of +2, and the Cp ligands were assigned the oxidation state of -1, which is quite consistent with the aromatic behavior of Cp. Furthermore, the last FOLI for ferrocene is 1.313 and the Δ-FOLI is 1.800, both indicating the unambiguity of the result.
  However, for some complicated species possessing noninnocent ligands, the results become ambiguous. For example, several copper-trifluoromethyl complexes show small Δ-FOLI, which means the result is no longer unique. Moreover, whether the copper has the oxidation state of +3 or +1 remain controversial. Besides, for the Grubbs catalyst, the result is also inconsistent with conventional Fischer and Schrock classifications.