Fig. 6: Comparison of charge transfer around active sites with On-Off ligand rotation of the two materials.

Bader charges analysis for the cases of (a) Cr(h-fpyz)2 and (b) Cr(pyz)2 systems in the left panels shaded in gray and those with O2 adsorption. In the central panels shaded in shallow green with O2 adsorption, the structures are optimized without any constraints, i.e., ligand rotation is turned on. In the right panels shaded in pink, the angles of the organic ligands and the positions of Cr atoms are fixed to that in the pristine Cr(h-fpyz)2 and Cr(pyz)2, i.e., ligand rotation is turned off upon O2 adsorption. Positive and negative values represent charge depletion and accommodation, respectively.