Nickel complexes have gained sustained attention as efficient catalysts in cross-coupling reactions and co-catalysts in dual systems due to their ability to react with radical species. Central to this reactivity is nickel's propensity to shuttle through several accessible redox states from Ni to Ni . Here, we report the catalytic generation of trifluoromethyl radicals from a nickel complex bearing redox-active iminosemiquinone ligands. This unprecedented reactivity is enabled through ligand-based oxidation performing electron transfer to an electrophilic CF source while the nickel oxidation state is preserved. Additionally, extension of this reactivity to a copper complex bearing a single redox equivalent is reported, thus providing a unified reactivity scheme. These results open new pathways in radical chemistry with redox-active ligands.
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http://dx.doi.org/10.1002/chem.201704049 | DOI Listing |
Inorg Chem
January 2025
School of Chemistry, University of Melbourne, Parkville 3010, Victoria, Australia.
A search for switchable molecules has afforded a family of cobalt complexes featuring derivatives of 2-aminophenol: 4,6-di--butyl aminophenol (HL) and 2-anilino-4,6-di--butyl aminophenol (HL). The heteroleptic cobalt complexes incorporate a Metpa ligand (tpa = tris(2-pyridylmethyl)amine; = 0-3), which involves the methylation of the 6-position of the pyridine ring). Eight members of this family have been synthesized and characterized: [Co(HL)(tpa)](BPh) (), [Co(HL)(Metpa)](BPh) (), [Co(L)(Metpa)](BPh) (), [Co(HL)(Metpa)](BPh) (), [Co(L)(Metpa)](BPh) (), [Co(HL)(tpa)] (BPh)(ClO) (), [Co(L)(tpa)](BPh)(ClO) () and [Co(HL)(Metpa)](BPh) (), where the aminophenol-derived ligands are monoanionic in either the open shell radical iminosemiquinonate (L) or the closed shell protonated aminophenolate (HL).
View Article and Find Full Text PDFChembiochem
December 2024
University of Minnesota, Department of Genetics, Cell Biology, and Development, MCB 5-130, 420 Washington Avenue SE, 55455, Minneapolis, UNITED STATES OF AMERICA.
RNA exhibits remarkable capacity as a functional polymer, with broader catalytic and ligand-binding capability than previously thought. Despite this, the low side chain diversity present in nucleic acids (two purines and two pyrimidines) relative to proteins (20+ side chains of varied charge, polarity, and chemical functionality) limits the capacity of functional RNAs to act as environmentally responsive polymers, as is possible for peptide-based receptors and catalysts. Here we show that incorporation of the modified nucleobase 2-thiouridine (2sU) into functional (aptamer and ribozyme) RNAs produces functionally inactivated polymers that can be activated by oxidative treatment.
View Article and Find Full Text PDFJACS Au
December 2024
Department of Chemistry, University of Puerto Rico, Río Piedras Campus, Río Piedras, Puerto Rico 00931, United States.
Targeting iron metabolism has emerged as a novel therapeutic strategy for the treatment of cancer. As such, iron chelator drugs are repurposed or specifically designed as anticancer agents. Two important chelators, deferasirox (Def) and triapine (Trp), attack the intracellular supply of iron (Fe) and inhibit Fe-dependent pathways responsible for cellular proliferation and metastasis.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Universität Heidelberg: Universitat Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120, Heidelberg, GERMANY.
Electromerism (aka. valence tautomerism) corresponds to the switching of electronic distributions between redox-active ligands and central elements. While this phenomenon is well established for several transition metals, the Pd(0)/Pd(II) couple could not yet be involved due to the high energy of the Pd(0) state.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States.
In Nature, the four-electron reduction of O is catalyzed at preorganized multimetallic active sites. These complex active sites often feature low-coordinate, redox-active metal centers precisely positioned to facilitate rapid O activation processes that obviate the generation of toxic, partially reduced oxygen species. Very few biomimetic constructs simultaneously recapitulate the complexity and reactivity of these biological cofactors.
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