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oai:figshare.com:article/34050144 2026-10-01T18:03:26Z category_1 category_4 category_8 category_14 category_15 category_873 category_46 category_122 portal_63 item_type_6 month_year_10_2026

Influence of Solvent-Dependent Carbene–Carbanion Equilibrium for Tris(2-pyridylthio)methanido Ligand on the Dioxygen Reactivity of Bioinspired Iron–Benzilate Complexes Arghyadip Bhowmik (25158150) Shreetama Bhattacharya (25158153) Sridhar Banerjee (3600515) Partha Halder (562484) Satadal Paul (1995256) Tapan Kanti Paine (1311435) Biophysics Biochemistry Microbiology Molecular Biology Neuroscience Chemical Sciences not elsewhere classified Immunology Mental Health single crystal x ray diffraction studies cn )< sub 3 </ sub favored toward carbene 4 </ b 1 </ b directing dioxygen activation dependent rearrangement capability 1 </ sup 2 </ sub 2 </ b 2 </ sup dependent carbene valent diiron tridentate n reaction pathway findings highlight dimeric intermediate complete decarboxylation carbanionic ligand c mode bridged mixed bond cleavage Starting from the iron(II) complex, [(L¹)Fe^II(CH₃CN)₂]⁺ (<b>1</b>), of the tris(2-pyridylthio)methanido (L¹) ligand, an iron(II)-benzilate complex, [(L²)Fe^II(PyS)(benzilate)] (<b>2</b>), (L² = bis(2-pyridylthio)carbene and PyS = pyridine-2-thiolate) was isolated and characterized. Single crystal X-ray diffraction studies of <b>2</b> reveal that the iron(II) center is coordinated by the carbene ligand (L²) in a tridentate N₂C mode, along with a bidentate PyS formed upon C–S bond cleavage of L¹. A solvent-dependent carbene-carbanion equilibrium for L¹ is favored toward carbene in the presence of anionic benzilate in dichloromethane, leading to the formation of <b>2</b>. Complex <b>2</b>, upon reaction with dioxygen, undergoes a rearrangement of the carbene (L²) to carbanion (L¹), ultimately affording an iron(III)-benzilate complex, [(L¹)Fe^III(benzilate)] (<b>3</b>). Intriguingly, the iron(III)-benzilate complex in the presence of complex <b>1</b> reacts with dioxygen, leading to complete decarboxylation of the coordinated benzilate. This observation suggested possible cooperative involvement of a dimeric intermediate in the reaction pathway. Consistent with this hypothesis, a benzilate-bridged mixed-valent diiron, [(L¹)Fe^III(benzilate)(L²)Fe^II(PyS)]⁺ (<b>4</b>), was isolated independently, and its dioxygen reactivity was evaluated. Expectedly, complex <b>4</b> undergoes quantitative decarboxylation upon reaction with dioxygen. These findings highlight the importance of solvent-dependent rearrangement capability of the carbanionic ligand in directing dioxygen activation and benzilate decarboxylation at the iron center. 2026-10-01T00:00:00Z Text Journal contribution 10.1021/acs.inorgchem.6c03242.s001 https://figshare.com/articles/journal_contribution/Influence_of_Solvent-Dependent_Carbene_Carbanion_Equilibrium_for_Tris_2-pyridylthio_methanido_Ligand_on_the_Dioxygen_Reactivity_of_Bioinspired_Iron_Benzilate_Complexes/34050144 CC BY-NC 4.0