DFT-optimized structures of [FeIVpoat(O)]− (A), [FeIVpoat(O)---MgII]+ (B), view along the C3 axis for [FeIVpoat(O)]− (C), and view along the C3 axis for [FeIVpoat(O)---MgII]+ (D). FeIV ions are colored in orange, O atoms in red, N atoms in blue, P atoms in magenta, C atoms in white, and MgII ions in teal. Hydrogen atoms are omitted for clarity. In C and D, the two P=O units that change positions are highlighted in black. Hydrogen atoms are omitted for clarity and the 15-crown-5 unit in D is represented by grey sticks.