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Planar Tetracoordinate Silicon in Organic Molecules As Carbenoid‐Type Amphoteric Centers: A Computational Study
Author(s) -
Zhang Yuwei,
Zhang Caiyun,
Mo Yirong,
Cao Zexing
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202004298
Subject(s) - tetracoordinate , aromaticity , conjugated system , ring (chemistry) , atom (system on chip) , delocalized electron , chemistry , chemical physics , computational chemistry , silicon , substituent , density functional theory , carbenoid , crystallography , molecule , stereochemistry , planar , organic chemistry , computer graphics (images) , rhodium , computer science , catalysis , embedded system , polymer
Designing and synthesizing a stable compound with a planar tetracoordinate silicon (ptSi) center is a challenging goal for chemists. Here, a series of potential aromatic ptSi compounds composed of four conjugated rings shared by a centrally embedded Si atom are theoretically designed and computationally verified. Both Born–Oppenheimer molecular dynamics (BOMD) simulations and potential energy surface scannings verify the high stability and likely existence of these compounds, particularly Si‐16‐5555 (SiN 4 C 8 H 8 ) with 16 π electrons, under standard ambient temperature and pressure. Notably, the Hückel aromaticity rule, which works well for single rings, is inconsistent with the high stability of Si‐16‐5555 where the 16 p electrons are spread over four five‐membered rings fused together. Bonding analyses show that the strong electron donation from the peripheral 12‐membered conjugated ring with 16 π electrons to the vacant central atomic orbital Si 3p z leads to the stabilization for both the ptSi coordination and planar aromaticity. The partial occupation of Si 3p z results in the peculiar carbenoid‐type behaviors for the amphoteric center. By modulating the electron density on the ring with substituent groups, we can regulate the nucleophilic and electrophilic properties of the central Si.