Double Möbius Aromaticity in the Oxo–Platinum Complex

Decades ago, theoretical studies predicted Möbius annulenes that show special aromaticity, which violates Hückel’s rule. Generally, the 4n electronic system is called Hückel antiaromatic, while this can also be called Möbius aromatic, provided there is phase inversion. This triggered various approaches to predict Möbius aromatic compounds. Herein, we analyzed the electronic structure of the experimentally detected oxo–platinum complex [PtO 2 –H 2 O] and showed that it contains both 4n σ and π systems. Our analysis confirms that the three-membered PtO 2 ring is doubly aromatic, having both Hückel and Möbius topology. Our magnetic as well as electronic structure study confirms its aromatic character.