(Invited) 3D Aromaticity in Borane and Carborane Derivatives

We will start discussing the difference between 3D aromatic species and those that should be described as 2D-aromatic with three-dimensional molecular structures (abbr. 2D-aromatic-in-3D) and not as truly 3D-aromatic [1]. Then, we will show the connection between archetypal polycyclic aromatic hydrocarbons (PAH) and closo boranes to conclude that the 4n+2 Wade-Mingos rule for three-dimensional closo boranes is connected to the (4n+2)π Hückel rule for bidimensional PAHs [2]. Next, we will analyze the aromaticity of closo and nido boranes and carboranes. Quantum chemical calculations reveal that the nido cage retains part of the aromatic character that characterizes the closo borane cages [2]. Then, we will elaborate on the aromaticity in benzenoids (2D aromatic) linked to carboranes (3D aromatic) [3]. And finally, we will apply the Clar’s π-sextet model to explain the extrusion of benzenoids linked to cobaltabis(dicarbollide), [3,3’-Co(1,2-C 2 B 9 H 11 ) 2 ] - [4]. References 1) El Bakouri, O.; Szczepanik, D. W.; Jorner, K.; Ayub, R.; Bultinck, P.; Solà, M.; Ottosson, H. J. Am. Chem. Soc. 2022 , 144 , 8560-8575 2) a) Poater, J.; Solà, M.; Viñas, C.; Teixidor, F. Angew. Chem. Int. Ed. 2014 , 53 , 12191-12195. b) Poater, J.; Solà, M.; Viñas, C.; Teixidor, F. Chem. Eur. J. 2016 , 22 , 7437-7443. 3) a) Poater, J.; Viñas, C.; Solà, M.; Teixidor, F. Nat. Commun. 2022 , 13 , 3844. b) Sun, F.; Tan, S.; Lu, C.; Tu, D.; Poater, J.; Solà, M.; Yan, H.; submitted for publication. 4) Poater, J.; Viñas, C.; Olid, D.; Solà, M.; Teixidor, F. Angew. Chem. Int. Ed. 2022 , 61 , e202200672. Figure 1