RT info:eu-repo/semantics/article T1 Shape‐shifting molecules: unveiling the valence tautomerism phenomena in bare barbaralones A1 Sanz Novo, Miguel A1 Mato, Mauro A1 León Ona, Iker A1 Echavarren, Antonio M. A1 Alonso Hernández, José Luis K1 Valence isomerization K1 Tautomerism K1 Structure elucidation K1 Rotational spectroscopy K1 23 Química K1 2307 Química Física AB We report a state-of-the-art spectroscopic study of an archetypical barbaralone, conclusively revealing the valence tautomerism phenomena for this bistable molecular system. The two distinct 1- and 5-substituted valence tautomers have been isolated in a supersonic expansion for the first time and successfully characterized by high-resolution rotational spectroscopy. This work provides irrefutable experimental evidence of the [3,3]-rearrangement in barbaralones and highlights the use of rotational spectroscopy to analyze shape-shifting mixtures. Moreover, this observation opens the window toward the characterization of new fluxional systems in the isolation conditions of the gas phase and should serve as a reference point in the general understanding of valence tautomerism. PB Wiley SN 1433-7851 YR 2022 FD 2022 LK https://uvadoc.uva.es/handle/10324/52505 UL https://uvadoc.uva.es/handle/10324/52505 LA eng NO Angewandte Chemie International Edition, 2022, vol. 61, e202117045. NO Producción Científica DS UVaDOC RD 17-jul-2024