2026-04-13T06:47:38Zhttps://recercat.cat/oai/request

oai:recercat.cat:10256/221212024-06-18T13:57:49Zcom_2072_452955com_2072_2054col_2072_453073

2024-06-18T13:57:49Z urn:hdl:10256/22121 In the quest of Hückel–Hückel and Hückel–Baird double aromatic tropylium (tri)cation and anion derivatives Escayola Gordils, Sílvia Proos Vedin, Nathalie Poater Teixidor, Albert Ottosson, Henrik Solà i Puig, Miquel Aromaticitat (Química) Aromaticity (Chemistry) Funcional de densitat, Teoria del Density functionals Besides the most common form of aromaticity involving a π-ring, hexaiodobenzene and hexakis(phenylselenyl)benzene dications also present σ-aromaticity in the outer ring formed by the main group substituents. These two compounds are considered σ- and π-double aromatic, and their characterization is of special interest to the fields of organic and structural chemistry. In this work, we decided to explore the double aromaticity in substituted tropylium cations for three reasons: (i) the seven neutral halogen substituents of the tropylium cations will, without oxidation, lead to 14 σ-electrons (a 4n + 2 Hückel number); (ii) tropylium cations are highly stable and can be easily generated experimentally; and (iii) whereas in substituted benzenes the distances between substituents in the optimized structures or X-ray crystals are too large to allow strong σ-aromaticity, these distances are expected to be shorter in substituted tropylium cations. Yet, instead of the expected σ-aromaticity, we found that the most stable geometries are highly puckered, meaning that delocalization in both π- and σ-systems is lost. Our results, which include also the tropylium anion and trication in the singlet and triplet state, show that there is a need to open a lone pair hole by oxidation to generate σ-aromaticity. Among the systems studied, only triplet C7Br7+3 with an internal Hückel aromatic tropylium ring and an external incipient Baird aromatic Br7 ring shows double π- and σ-aromaticity. This result, however, is functional-dependent and reveals that 3C7Br73+ is at the borderline for onset of double aromaticity Generalitat de Catalunya. Grant Number: 2017SGR39 Ministerio de Ciencia e Innovación. Grant Numbers: PID2020-113711GB-I00, PID2021-127423NB-I00 Swedish Research Council. Grant Number: 2019-05618 Universitat de Girona. Grant Number: IFUdG2019 Swedish National Infrastructure for Computing Open Access funding provided thanks to the CRUE-CSIC agreement with Wiley 2024-06-18T13:57:49Z 2024-06-18T13:57:49Z 2023-01 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion peer-reviewed http://hdl.handle.net/10256/22121 info:eu-repo/semantics/altIdentifier/doi/10.1002/poc.4447 info:eu-repo/semantics/altIdentifier/issn/0894-3230 info:eu-repo/semantics/altIdentifier/eissn/1099-1395 PID2020-113711GB-I00 PID2021-127423NB-I00 info:eu-repo/grantAgreement/AEI/Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020/PID2020-113711GB-I00/ES/DISEÑO Y SINTESIS DE FULLERENOS PARA LA CONSTRUCCION DE CELDAS SOLARES HIBRIDAS DE PEROVSKITA Y FULERENOS D ALTO RENDIMIENTO. UN ENFOQUE EXPERIMENTAL Y COMPUTACIONAL SINERGICO/ info:eu-repo/grantAgreement/AEI/Plan Estatal de Investigación Científica y Técnica y de Innovación 2021-2023/PID2021-127423NB-I00/ES/CATÀLISIS PREDICTIVA PARA CAMBIAR EL ORDEN SECUENCIAL ENTRE EXPERIMENTOS I CÁLCULOS/ Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess Wiley Journal of Physical Organic Chemistry, 2023, vol. 36, núm. 1, p. e4447 Articles publicats (D-Q)