Wang, Meng-HuiKalita, Amlan J.Orozco-Ic, MesíasYan, Gai-RuChen, ChenYan, BingCastillo-Toraya, GabrielaTiznado, WilliamGuha, Ankur K.Pan, SudipMerino, GabrielCui, Zhong-Hua2024-11-252024-11-252023-07Chemical Science. Volume 14, Issue 33, Pages 8785 - 879114. July 20232041-6520https://repositorio.unab.cl/handle/ria/62196Indexación: ScopusThe presence of a delocalized π-bond is often considered an essential criterion for achieving planar hypercoordination. Herein, we show that σ-delocalization could be sufficient to make the planar configuration the most stable isomer in a series of planar pentacoordinate s-block metals. High-level ab initio computations reveal that the global minimum of a series of interalkali and interalkali-alkaline earth clusters (LiNa5, Li5Mg+, Na5Mg+, K5Ca+, CaRb5+, Rb5Sr+, and SrCs5+) adopts a singlet D5h structure with a planar pentacoordinate lithium or alkaline earth metal (AE = Mg, Ca, Sr). These clusters are unusual combinations to stabilize a planar pentacoordinate atom, as all their constituents are electropositive. Despite the absence of π-electrons, Hückel's rule is fulfilled by the six σ-electrons. Furthermore, the systems exhibit a diatropic ring current in response to an external magnetic field and a strong magnetic shielding, so they might be classified as σ-aromatic. Therefore, multicenter σ-bonds and the resulting σ-delocalization stabilize these clusters, even though they lack π-aromaticity. © 2023 The Royal Society of Chemistry.https://pubs.rsc.org/en/content/articlelanding/2023/sc/d2sc05939henAb initio ComputationsAlkaline EarthAlkaline-earth MetalsGlobal MinimumHypercoordinationPlanar ConfigurationsS-block MetalsStable Isomersπ-electronsσ-delocalizationArtículoAttribution-NonCommercial 3.0 Unported Deed (CC BY-NC 3.0 )10.1039/d2sc05939h