6N4L:
reference: Site-specific oxidation state assignments of the irons in the [4Fe:4S]2+/1+/0 states of the nitrogenase Fe-protein., Wenke BB, Spatzal T, Rees DC, Angew Chem Int Ed Engl. 2019 Jan 30. doi: 10.1002/anie.201813966. PMID: 30698901

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).