How do the thiolate ligand and its relative position control the oxygen activation in the cysteine dioxygenase model?

In the iron(II)-thiolate models of cysteine dioxygenase, the thiolate ligand is a key factor in the oxygen activation. In this contribution, four model compounds have been theoretically investigated. This comparative study reveals that the thiolate ligand itself and its relative position are both important for the activation of O(2). Before the O(2) binding, the thiolate ligand must transfer charge to Fe(II), and the effective nuclear charges of Fe(II) is decreased, which results in a lower redox potential of compounds. In other words, the thiolate ligand provides a prerequisite for the O(2) activation. Furthermore, the relative position of the thiolate ligand is discovered to determine the reaction path of O(2) activation. The amount of charge transfer is crucial for these reactions; the more charge it transfers, the lower the related redox potentials. This work really helps think deeper into the O(2) activation process of mononuclear nonheme iron enzymes.