Zr6-methylbutanoate and methylheptanoate. Zirconium propoxide (2.25 mL, 5 mmol, 1 eq.) was mixed with 8 equivalents acid and diluted with DCM to 0.5 M in Zr. After stirring 48 hours at 30°C, the solution was dried under vacuum and dissolved again in 1 mL DCM. Afterwards, the solution is divided over 2 centrifuge tubes and acetonitrile (4 mL per tube) was added to precipitate the clusters. Via centrifugation (5000 rcf, 5 min), the cluster precipitate was separated from the supernatant and redissolved in DCM (1 mL each). To both tubes acetonitrile (double the volume) was added to precipitate the cluster. This last step was repeated twice and finally, the clusters were dried overnight under vacuum. Zr6methylbutanoate was obtained as a white solid with a yield of 93 %. Zr6-methylheptanoate was obtained as a viscous oil with a yield of 55 %.