中文摘要：

平面六配位碳（phC）是碳原子的一种非经典成键方式。目前绝大部分的phC分子都是以B原子作为关键配体。文章以本课题组之前设计的不舍硼phC分子D3hCN3＋Be^＋为基础，通过“准等价”替换的方式设计了一系列不舍硼的phC分子聩DahCN3X^＋（X=Si,Ge,Sn,Pb）。电子结构分析表明这些分子内的共价相互作用与静电相互作用都具有夹心键合的特点，这对拉近C-X的距离起到了至关重要的作用，而分子整体的芳香性对保持分子的平面性至关重要，二者的共同作用使phC在这些分子中得以稳定化。分子的电子亲和能按照从Si到Pb的顺序依次减小。这些不合硼的phC分子都有三对与单线态卡宾类似的孤对电子，这使得它们在分子催化领域具有潜在的应用价值。

英文摘要：

Planar hexacoordinate carbon （phC） is a kind of non-classical carbon bonding and most of the phC species take the boron atom as the key ligand. Our group had reported recently a boron-free phC species Dah CN3B3^＋ ,based on which we designed in this work a new series of phC species D3h CN3X＋ （X=Si,Ge,Sn, Pb） through ＂quasi-equivalent＂ substitution. Our electronic structure analysis suggested that the covalent and electrovalent bonding in these phC species both show obvious sandwich characters,which is crucial to shorten the C-X inter-atomic distances;whereas, the aromaticity of whole molecule plays the important role for maintaining the planar structure. The effect of both factors stabilizes phC in these species. When X goes from Si to Pb, the electron affinities reduce successively. All these phC species has three lone pairs similar to singlet earbene,whieh make them potentially useful in the molecular catalysis.