{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"submitter":["Ekanayake DM"],"funding":["Division of Computer and Network Systems","University of St. Thomas","National Institute of General Medical Sciences","NIGMS NIH HHS","National Science Foundation"],"pagination":["14432-14443"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC8721859"],"repository":["biostudies-literature"],"omics_type":["Unknown"],"volume":["50(40)"],"pubmed_abstract":["The activation of O<sub>2</sub> at thiolate-ligated iron(II) sites is essential to the function of numerous metalloenzymes and synthetic catalysts. Iron-thiolate bonds in the active sites of nonheme iron enzymes arise from either coordination of an endogenous cysteinate residue or binding of a deprotonated thiol-containing substrate. Examples of the latter include sulfoxide synthases, such as EgtB and OvoA, that utilize O<sub>2</sub> to catalyze tandem S-C bond formation and <i>S</i>-oxygenation steps in thiohistidine biosyntheses. We recently reported the preparation of two mononuclear nonheme iron-thiolate complexes (1 and 2) that serve as structural active-site models of substrate-bound EgtB and OvoA (<i>Dalton Trans.</i> 2020, <b>49</b>, 17745-17757). These models feature monodentate thiolate ligands and tripodal N<sub>4</sub> ligands with mixed pyridyl/imidazolyl donors. Here, we describe the reactivity of 1 and 2 with O<sub>2</sub> at low temperatures to give metastable intermediates (3 and 4, respectively). Characterization with multiple spectroscopic techniques (UV-vis absorption, NMR, variable-field and -temperature Mössbauer, and resonance Raman) revealed that these intermediates are thiolate-ligated iron(III) dimers with a bridging oxo ligand derived from the four-electron reduction of O<sub>2</sub>. Structural models of 3 and 4 consistent with the experimental data were generated <i>via</i> density functional theory (DFT) calculations. The combined experimental and computational results illuminate the geometric and electronic origins of the unique spectral features of diiron(III)-μ-oxo complexes with thiolate ligands, and the spectroscopic signatures of 3 and 4 are compared to those of closely-related diiron(III)-μ-peroxo species. Collectively, these results will assist in the identification of intermediates that appear on the O<sub>2</sub> reaction landscapes of iron-thiolate species in both biological and synthetic environments."],"journal":["Dalton transactions (Cambridge, England : 2003)"],"pubmed_title":["Electronic structures and spectroscopic signatures of diiron intermediates generated by O<sub>2</sub> activation of nonheme iron(II)-thiolate complexes."],"pmcid":["PMC8721859"],"funding_grant_id":["CNS-1828649","GM117120","R15 GM126522","R01 GM117120","CHE-0741901","GM126522"],"pubmed_authors":["Pham D","Probst AL","Fiedler AT","Ekanayake DM","Popescu CV","Miller JR"],"additional_accession":[]},"is_claimable":false,"name":"Electronic structures and spectroscopic signatures of diiron intermediates generated by O<sub>2</sub> activation of nonheme iron(II)-thiolate complexes.","description":"The activation of O<sub>2</sub> at thiolate-ligated iron(II) sites is essential to the function of numerous metalloenzymes and synthetic catalysts. Iron-thiolate bonds in the active sites of nonheme iron enzymes arise from either coordination of an endogenous cysteinate residue or binding of a deprotonated thiol-containing substrate. Examples of the latter include sulfoxide synthases, such as EgtB and OvoA, that utilize O<sub>2</sub> to catalyze tandem S-C bond formation and <i>S</i>-oxygenation steps in thiohistidine biosyntheses. We recently reported the preparation of two mononuclear nonheme iron-thiolate complexes (1 and 2) that serve as structural active-site models of substrate-bound EgtB and OvoA (<i>Dalton Trans.</i> 2020, <b>49</b>, 17745-17757). These models feature monodentate thiolate ligands and tripodal N<sub>4</sub> ligands with mixed pyridyl/imidazolyl donors. Here, we describe the reactivity of 1 and 2 with O<sub>2</sub> at low temperatures to give metastable intermediates (3 and 4, respectively). Characterization with multiple spectroscopic techniques (UV-vis absorption, NMR, variable-field and -temperature Mössbauer, and resonance Raman) revealed that these intermediates are thiolate-ligated iron(III) dimers with a bridging oxo ligand derived from the four-electron reduction of O<sub>2</sub>. Structural models of 3 and 4 consistent with the experimental data were generated <i>via</i> density functional theory (DFT) calculations. The combined experimental and computational results illuminate the geometric and electronic origins of the unique spectral features of diiron(III)-μ-oxo complexes with thiolate ligands, and the spectroscopic signatures of 3 and 4 are compared to those of closely-related diiron(III)-μ-peroxo species. Collectively, these results will assist in the identification of intermediates that appear on the O<sub>2</sub> reaction landscapes of iron-thiolate species in both biological and synthetic environments.","dates":{"release":"2021-01-01T00:00:00Z","publication":"2021 Oct","modification":"2024-11-12T09:51:27.882Z","creation":"2024-11-12T09:51:27.882Z"},"accession":"S-EPMC8721859","cross_references":{"pubmed":["34570147"],"doi":["10.1039/d1dt02286e"]}}