While the Zr12-acetate and Zr12-propionate clusters are known in literature, the others are not. To prove their structure, we analyzed the clusters with X-ray total scattering and Pair Distribution Function (PDF) analysis. Total scattering takes into account both Bragg and diffuse scattering. The real space PDF is ideal to study nanomaterials, local effects and amorphous materials. We measured the experimental PDF of all the above clusters and ordered them according to increasing carbon content, see Figure . Focusing first on the PDF of acetate capped clusters and comparing with the structure from single crystal XRD, we easily recognize the Zr-O distance at 2.2 Å and the Zr-Zr distances within one Zr6 cluster at 3.5 Å and 5 Å. We label them as intra-Zr6 distances. The longer range Zr-Zr distances are specific to the Zr12 dimer and are present at 5.7 Å, 8.4 Å, and 11.5 Å. They are labeled as inter-Zr6 distances. When the chain length increases, the same features remain present in the PDF, except for the case of methylbutanoate and methylheptanoate where the inter-Zr6 distances are missing. This suggests that both the Zr6-methylbutanoate and Zr6methylheptanoate clusters are monomers while the others are dimers. This is in agreement with our earlier hypothesis that branching of the carboxylic acid at the alpha position is the deciding factor between monomer and dimer. 2 With increasing chain length, we also observe the growth of a peak at 1.5 Å, which we assign to C-C distances in the ligand chain.