Why `E^(-)` values for Mn, Ni and Zn are more negative than expected?

Explanation

The values of `E^(@)` for Mn and Zn are more negative than expected because `Mn^(2+)` and `Zn^(2+)` have stable exactly half- filled and fully filled configuration respectively. The high negative value of `E^(@)` for Ni is due to its highest negative enthalpy of hydration