Examinando por Autor "Chen, Chen"

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    Planar pentacoordinate s-block metals
    (Royal Society of Chemistry, 2023-07) Wang, Meng-Hui; Kalita, Amlan J.; Orozco-Ic, Mesías; Yan, Gai-Ru; Chen, Chen; Yan, Bing; Castillo-Toraya, Gabriela; Tiznado, William; Guha, Ankur K.; Pan, Sudip; Merino, Gabriel; Cui, Zhong-Hua
    The 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.