Arteta, Sarah and Deegbey, Mawuli and Durand, Nicolas and Kibbe, Russell and Floss, Johannes and Barth, Alexandra T. and Muddiman, David C. and Jakubikova, Elena and Reiser, Oliver and Castellano, Felix N. (2025) Mechanistic Insights into Visible-Light-Induced ATRA Reactions Powered by the Symbiotic Relationship between Cu(II)/Cu(I) Phenanthroline Complexes. ACS CATALYSIS, 15 (17). pp. 15657-15669. ISSN 2155-5435
Full text not available from this repository. (Request a copy)Abstract
As photoredox catalysis continues to yield promising chemical transformations, there is an increased need to understand how specific photocatalysts function to improve reaction efficiencies while expanding their scope. Copper-phenanthroline-based photocatalysts such as Cu II (dap)Cl 2 (dap = 2,9-di(p-anisyl)-1,10-phenanthroline) and [Cu I (dap) 2 ]Cl were both found to be equally capable of olefin activation through electrophilic atom transfer radical addition (ATRA) reactions. Although these molecular catalysts have proven successful, many intermediates suggested in the proposed catalytic cycles have never been detected. One undetermined aspect in this chemistry is related to how one equivalent of Cu II (dap)Cl 2 generates half of an equivalent of [Cu I (dap) 2 ] + during the photocatalytic sequence. To this end, we initially used more synthetically accessible model systems, namely, [Cu I (dpp) 2 ]Cl and Cu II (dpp)Cl 2 (dpp = 2,9-diphenyl-1,10-phenanthroline), to glean detailed mechanistic insights into this unusual symbiotic relationship. We directly detected several intermediates involved in the ATRA photocatalytic cycle using these model chromophores in conjunction with electronic spectroscopy, infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry, electronic structure calculations, EPR spin-trap experiments, and 1H NMR spectroscopy. We found that the unique ligand lability and coordinating properties of acetonitrile enable both the in situ oxidation of [Cu I (dpp) 2 ] + by tosyl chloride into Cu II (dpp)Cl 2 and the visible-light-induced homolysis of the CuII-Cl bond, which initiates the conversion to the CuI species [Cu I (dpp) 2 ][Cu I Cl 2 ]. The combined findings from the present study of the catalytic cycle demonstrate that the symbiotic relationship between Cu II (dpp)Cl 2 and [Cu I (dpp) 2 ] + , as well as between Cu II (dap)Cl 2 and [Cu I (dap) 2 ] + , is the critical factor enabling the ATRA photoreaction by departing from either photocatalyst.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | PHOTOREDOX CATALYSIS; COPPER(I) COMPLEXES; LONG-LIFETIME; DYNAMICS; ELECTRON; LIGAND; photochemistry; photocatalysts; charge transfer; copper phenanthrolines; ATRA reactions |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie > Lehrstuhl Prof. Dr. Oliver Reiser |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 13 Aug 2026 04:54 |
| Last Modified: | 13 Aug 2026 04:54 |
| URI: | https://pred.uni-regensburg.de/id/eprint/66770 |
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