The model based on Zr4-methacrylate had a very poor agreement (Rw = 0.66). The Zr6 structure models also delivered poor fits (Rw = 0.24-0.31). The second best agreement was obtained for the Zr12-propionate model (Rw = 0.18). While this model is structurally very similar to the Zr12-acetate model, the Zr-Zr distances are slightly larger in the propionate model (Table ). We conclude that PDF is able to pick up the correct structure from a series of possible clusters structures, based on the goodness of fit.