Again, the Zr6 model delivered a worse fit (Figure ). We can thus distinguish the Zr6 structures from the Zr12 structures, based on the refinement. However, we notice that the Figure : PDF refinement of the Zr12-acetate cluster with various models, derived from the reported crystal structure. The best fit is obtained when including the oxygen and carbon atoms from the carboxylate ligand. The refined parameters are given in Table .