Esken, RobinAntoni, Patrick W.Lorenz, YannickBurdenski, ChrisKirchhoff, Jan-LukasStrohmann, CarstenHansmann, Max M.2025-06-032025-06-032025-04-17http://hdl.handle.net/2003/4371810.17877/DE290R-25492The synthesis of polarized N-heterocyclic olefins (NHOs) based on an imidazo[1,5-a]pyridine scaffold is presented. In contrast to regular NHOs the unique bicyclic heterocyclic core allows the incorporation of various substituents in close proximity to the highly polarized exocyclic C─C bond. The donor properties of the new carbon-based ligand class were quantified and the coordination chemistry explored. Alkenyl or alkynyl groups at the C5-position lead to spontaneous cyclization to yield imidazo[2,1,5-de]quinolizines. The unique cyclization strategy was compatible with a wide range of substitution patterns and yields highly electron-rich π-delocalized heterocycles. The electronic structure of the novel partially antiaromatic heterocycle was thoroughly investigated. One-electron oxidation occurs at low potentials and lead to a stable monomeric radical-cation confirmed by XRD, which showed solution phase fluorescence expanding into the field of open-shell organic materials.enAngewandte Chemie. International editionhttps://creativecommons.org/licenses/by/4.0/Imidazo[2,1,5-de]quinolizinesDonor ligandsFluorescent organic radicalsN-heterocyclic olefinsParatropic ring current540Article