To generalize our methodology to hafnium oxo clusters, we reacted hafnium butoxide with acetic acid, methylbutanoic acid, or oleic acid. After purification, the resulting clusters were characterized by PDF, FTIR, TGA, NMR and HR-MS. The acquisition and refinement of PDF data are more straightforward for the hafnium oxo clusters since hafnium has a higher scattering cross section, see Figure . All pairs that have a least one hafnium atom are enhanced in intensity, and all other pairs (e.g., C-C) loose relative intensity. Using a structure model of Hf12-acetate, we can readily describe the PDF data of the Hf12acetate and Hf12-oleate clusters. The goodness of fit is even better than for the respective Zr12 clusters that were refined in an equivalent way, see Figure . In the absence of a Hf6 structure model, we constructed a Hf6 cluster model from the Hf12 structure. This model accurately described the PDF data, confirming that the Hf6-methylbutanoate clusters is a monomer. The hafnium oxo clusters thus follow the same structure-directing rules as the zirconium oxo clusters. Also the FTIR spectra (Figure ) and NMR spectra (Figure )