To further support the relative sign and magnitude of the coupling constants, we have performed DFT calculations (see the SI for computational details) on model complexes derived from 1 and 2 (Figures S9-10, Tables ). All computed exchange interactions are antiferromagnetic in nature. For 1 the eleven independent coupling constants fall in the range -3.5 < J < -12.8 cm -1 (Figure ). For 2 the three independent coupling constants fall in the range -7.1 < J < -12.7 cm -1 (Figure ). The narrower range of J values for 2 is consistent with the structural similarity of nearest neighbour bridging. [19] DFT computed spin densities suggest a strong spin-delocalization mechanism for the magnetic exchange interaction in both cases, with the spin on Fe III centres ranging between 4.128-4.187 for 1 (Figure ) and 4.014-4.165 for 2 (Figure ). Both the experimentally and computationally derived J values agree with previous magneto-structural correlations developed for O-bridged Fe III complexes in which the magnitude of J is dictated by the Fe-O-Fe angle and Fe-O distance. [19] In summary, we have synthesised and characterised two structurally related wheels of Fe III , specifically the odd numbered [Fe11] and the even numbered . The former is the first example of an odd numbered Fe wheel. Synthetically, the formation of one over the other can be controlled via choice of solvent, a mixture of MeCN and MeOH for the former, and a mixture of MeCN and DMF for the latter. The asymmetry in 1 originates from the presence of protonated/non-bonded arm in one triethanolamine arm which is replaced in the bridging unit by methoxide anion. Magnetic susceptibility, magnetisation and heat capacity measurements reveal relatively strong antiferromagnetic exchange between nearest neighbours, J = -10.0 cm -1 for 1 and J = -12.0 cm -1 for 2. This leads to a frustrated S = 1/2 ground state in the former and an S = 0 ground state in the latter, with the relatively large value of J resulting in sizeable level spacings between the lowest Zeeman levels. High field magnetisation data collected up to ~32.5 T reveals a series of step-like level crossings for both compounds.