shows that three resonances (1.7-2 ppm) have the same diffusion coefficient, while the fourth (2.1 ppm) diffuse more quickly, see Figure . The resonance at 2.1 ppm thus corresponds to the excess acetic acid, as also determined by FTIR and TGA. The measured diffusion coefficient (D = 1106 µm/s) is lower than the reference of free acetic acid (D = 1851 µm/s), and we conclude that the excess acetic acid is in fast exchange between two states: (i) free and (ii) hydrogen bonded to the cluster. The signals between 5 and 7 ppm in all clusters spectra are assigned to the exchangeable protons on the cluster core itself since the resonances disappear upon addition of D 2 O, see Figure . Apart from Zr12-acetate and -propionate, all the spectra show significant line broadening, similar to nanocrystal-bound ligands. The longer the ligands, the broader the alpha CH 2 resonance, but the sharper the methyl resonance becomes. Homogeneous line broadening depends on the rotational mobility and it is expect that the methyl group has increased mobility in a longer ligand. The alpha resonance is closest to the surface. Its mobility is not enhanced in a longer ligand and instead, the total rotational mobility of the cluster decreases as it becomes a bigger object. In contrast to nanocrystal-bound ligands, we find little contribution of heterogeneous broadening to the resonances, see Table .