Six MnIII complexes of general formula [Mn(L)XY], in which L is a dideprotonated Schiff base ligand N,N′‐bis(pyridoxylidene)ethylenediamine (L1H2 or pydxen) or N,N′‐bis(pyridoxylidene)‐1,3‐propanediamine (L2H2 or pydxpn), X = Cl, N3, NCS, and Y = H2O, MeOH, EtOH, and another MnIII compound [Mn(L1)(H2O)2]Cl have been synthesized. The structures of five of the complexes were determined by single‐crystal X‐ray diffraction studies. The compounds show a quasireversible MnIII/MnII couple at ca. 0 V (vs. Ag/AgCl) and two to three overlapping oxidations at 1.0–1.3 V, which are assigned to MnIII/MnIV oxidation and ligand (phenolate) oxidation. The redox potential of the phenolate moiety reported here is very similar to the Yz/Yz·+ potential of photosystem II (PS II, Yz = tyrosine). Spectrochemical studies and DFT calculations support this assignment. The DFT calculations also show that there is considerable covalence in the metal–ligand bonds and the covalence increases with the oxidation state of the central metal ion. The geometry of the metal ion is found to be dependent on the oxidation state as well as spin state of the metal ion, the nature of the N,O‐donor ligand used as model, and solvation effects. In silico stepwise one and two electron oxidation of a model pydxen‐type complex shows strengthening of the metal–ligands interactions, but three‐electron oxidation could significantly weaken one of the Mn–O bonds, which might trigger splitting into a diphenoxyl diradical species and a transient MnIV complex, in agreement with the experimental results.