Kutin, YuryKoike, TaichiDrosou, MariaSchnegg, AlexanderPantazis, Dimitrios A.Kasanmascheff, MügeHansmann, Max M.2025-04-252025-04-252025-01-27http://hdl.handle.net/2003/4368510.17877/DE290R-25458This study introduces a novel class of carbon-centered diradicals: a monosubstituted C atom stabilized by a phosphine. The diradical Ph3P→C was photochemically generated from a diazophosphorus ylide precursor (Ph3PCN2) and characterized by EPR and isotope-sensitive ENDOR spectroscopy at low temperatures. Ph3P→C features an axial zero-field splitting parameter D=0.543 cm−1 with a vanishingly small rhombicity |E|/D=0.002. Time- and temperature-dependent measurements confirm a triplet ground state with a lifetime of approximately 10 min at 127 K in toluene-d8. Multireference electronic structure calculations predict a clear triplet ground state with a singlet-triplet gap greater than 20 kcal/mol. In contrast to divalent C(0) compounds, such as Ph3P→C←PPh3, in which carbon needs excitation into a highly-excited closed-shell 2s02p4 configuration, Ph3P→C can be explained by direct involvement of carbon in its natural 3P state arising from the 2s22p2 configuration.enAngewandte Chemie. International edition; 64(10)https://creativecommons.org/licenses/by/4.0/reactive intermediatescarbonEPR spectroscopydiradicalscarbones540Article