The direct current (dc) molar magnetic susceptibilities, χ, of polycrystalline samples of 1-2 were measured in an applied magnetic field, B, of 0.1 T, over the 2-300 K temperature, T, range. Magnetisation (M) data was measured in the 2-10 K and 0.5-9.0 T, temperature and field ranges respectively. The results are plotted in Figure (and Figure ) in the form of the χT product versus T and M versus B (insets of Figure ). The susceptibility data for 1 and 2 are similar, showing relatively strong AF exchange interactions between nearest neighbours with χT decreasing rapidly with decreasing temperature and reaching values of 0.40 and 0.05 cm 3 K mol -1 at T = 2.0 K for 1 and 2, respectively. The variable-temperature-variable-field magnetisation data differ significantly between the two compounds. For 1 at T = 2 K, M rises rapidly with increasing field, before saturating at a value of M = 1.1 µB. At higher temperatures M rises in a more linear fashion with increasing B. At T = 2-3 K the magnetisation data for 2 remains close to zero, before increasing more rapidly for fields above ~4 T. The maximum value at T = 2 K and B = 9.0 T is just 0.88 µB. With increasing temperature (4-10 K) M increases in a more linear fashion with increasing field. The magnetic susceptibility data can be accurately simulated using an isotropic spin-Hamiltonian 𝐻 ̂= -2 ∑ 𝐽 𝑗 𝑖 𝑠 ⃗ ̂𝑖 • 𝑠 ⃗ ̂𝑗+1 with a coupling scheme that assumes just one independent exchange interaction between nearest neighbours, J = -10.0 cm -1 for 1 and J = -12.0 cm -1 for 2, with g = 2.0 in both cases (Figure , red lines). The susceptibility data is also approximated well with the DFT calculated J values (see below), though the magnetisation data is not (Figure , blue lines). DFT suggests that J values vary in some range for nearest neighbour exchange interactions. Likely this leads to incorrect approximation of ground and low-lying excited states. The ground state for 1 is an S = ½ state, [10b] and for 2 is S = 0 as can be clearly seen in Figure . All calculations have been performed by means of the finite-temperature Lanczos method. [16] The relatively large magnitude of J results in sizeable level spacings between the lowest Zeeman levels (Figure ), with the sequence of levels being as expected for odd and even spin rings. [10b,17,18] The large gap size explains the (very) small magnetization values, even in fields of up to 9 T. At fields of up to 32.5 T at T = 0.4 K the magnetisation data for 1 and 2 reveal a series of step-like level crossings (solid and dashed black lines in Figure , Figure ). For 2 these are relatively well resolved for B ≈ 7.5 T (S = 0→1), 17.5 T (S = 1→2) and 27.5 T (S = 2→3). For 1 there appear to be two broader, less well-resolved steps centred around B ≈ 18 T (S = 3/2→5/2) and 23 T (S = 5/2→7/2), the S = 1/2→3/2 step being smeared out. The remarkable difference between the two sets of data reflects the high and low symmetry of molecules with even and odd numbered metal ions, respectively. Specifically, for an odd numbered ring with lower symmetry the local anisotropy (single ion and exchange anisotropy) is not cancelled out, inducing mixing between energy levels and the broadening of magnetisation steps. The steps are remarkably well simulated using the same model employed to fit the low-field susceptibility and magnetisation data, particularly for 2, albeit slightly shifted in M and B. We attribute the small differences to (a) the simplicity of the (one-J) model, and (b) possible anisotropic contributions to the Hamiltonian relevant at very-low temperatures. This same model explains the differences observed in the heat capacity (C) of the two compounds (Figure ). For 1 the main feature of the zero-applied-field C is a broad Schottky anomaly centred at ~8 K, while 2 has a more prominent Schottky anomaly at ~3.5 K. Both features are quantitatively accounted for by the large energy gap existing between the two lowest multiplets for each respective compound (Figure ). (1), -12.0 cm-1 . The arrows highlight the Schottky anomalies. The increase of the experimental data with temperature must be ascribed to the ordinary lattice contribution, which is not considered by the simulations.