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 (SiN₄C₈H₈) 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.

中文翻译：

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作为类胡萝卜素两性中心的有机分子中的平面四配位硅：计算研究

设计和合成具有平面四配位硅（ptSi）中心的稳定化合物对化学家来说是一个挑战性的目标。在这里，理论上设计和计算验证了一系列潜在的芳香族ptSi化合物，这些化合物由一个中心嵌入的Si原子共享的四个共轭环组成。Born–Oppenheimer分子动力学（BOMD）模拟和势能表面扫描都验证了这些化合物的高稳定性和可能的​​存在性，特别是Si-16-5555（SiN ₄ C ₈ H ₈）在标准环境温度和压力下具有16个π电子。值得注意的是，适用于单环的Hückel芳香性规则与Si-16-5555的高稳定性不一致，后者的16 p电子散布在四个稠合在一起的五元环上。键合分析表明，周围的具有16个π电子的12元共轭环向空的中心原子轨道Si 3p _z的强电子贡献导致ptSi配位和平面芳香性的稳定。Si 3p _z的部分占据导致两性中心具有特殊的类胡萝卜素行为。通过用取代基调节环上的电子密度，我们可以调节中心Si的亲核和亲电性质。