Further fluorination, as in the LaSrMnO4F1.8 phase, leads to even shorter Mn-O bond lengths, driven by the same mechanism: an increase in the manganese oxidation state, which now includes a mixture of Mn 4+ and Mn 5+ .This mixed-valence state introduces additional variability in the bond lengths and structural complexity is further enhanced by the disordered La and Sr ion distribution, which creates local variations in the bonding environment, and by the random distribution of fluoride ion vacancies. These vacancies cause alternating fully occupied and partially vacant fluoride layers, resulting in distinct bond lengths for the apical oxygen atoms.