Invited for the cover of this issue is the group of Sonja Herres-Pawlis from RWTH Aachen University, Germany. The cover image shows our entatic-state model. The research described in the article is the result of strongly collaborative work of four groups within the interdisciplinary DFG Research Unit FOR1405 (“Dynamics of Electron Transfer Processes within Transition Metal Sites in Biological and Bioinorganic Systems”).