and Cu I Zn-MFU-4l. The d(Cu-N2 plane) is revealed to increase from 0.66(3) Å to 0.79(1) Å (Table ), consistent with the increased pyramidalization upon H2 adsorption. In view of the negligible cross-section of H atoms and the assumed proximity of the H2 molecules to heavy Cd and I atoms in the model, H2 molecules were not included in the refinement.