4NHQ:
reference: Interaction between proteins and Ir based CO releasing molecules: mechanism of adduct formation and CO release., Petruk AA, Vergara A, Marasco D, Bikiel D, Doctorovich F, Estrin DA, Merlino A, Inorg Chem. 2014 Oct 6;53(19):10456-62. doi: 10.1021/ic501498g. Epub 2014 Sep 12. PMID: 25215611

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