While both MOF series exhibit identical trends, the activity order is altered compared with the MOP samples, and an increasing proximity of Rh2 centers is no longer correlated with higher activity. To test whether mixing level-dependent differences in the stability under the reaction 20 conditions contributed to the observed performance differences of MOP and MOF structomers, we analyzed the recovered catalyst samples. The PXRD patterns of recovered catalysts (Supplementary Figs. ) were indistinguishable from fresh catalysts and no oxidation state changes were apparent from XP spectra (Supplementary Fig. ). Notably, even Rh24(BDC-OH)24 and Rh24(BDC-OH)24(dabco)6 catalysts, which feature the highest local Rh concentrations showed no substantial differences upon repeated recycling (Supplementary Fig. ), and no evidence for Rh 0 formation could be detected in XP spectra (Supplementary Fig. ) . We thus propose that the significant variation in propene hydrogenation between different structomers reflects the influence of the extended environment on the Rh2 active sites.