Global Planar Tetra‐, Penta‐ and Hexa‐coordinate Silicon Clusters Constructed by Decorating SiO3 with Alkali Metals

The achievement of the rule‐breaking planar hypercoordinate motifs (carbon and other elements) is mainly attributed to a practical electronic stabilization mechanism, where the bonding of the central atom pz π electrons is a crucial issue. We have demonstrated that strong multiple bonds between the central atom and partial ligands can be an effective approach to explore stable planar hypercoordinate species. A set of planar tetra‐, penta‐ and hexa‐coordinate silicon clusters were herein found to be the lowest‐energy structure, which can be viewed as decorating SiO3 by alkali metals in the MSiO3−, M2SiO3 and M3SiO3+ (M=Li, Na) clusters. The strong charge transfer from M atoms to SiO3 effectively results in [M]+SiO32−, [M2]2+SiO32− and [M3]3+SiO32− salt complexes, where the Si−O multiple bonding and structural integrity of the Benz‐like SiO3 framework is maintained better than the corresponding SiO32− motifs. The bonding between M atoms and SiO3 motif is best described as M+ forming a few dative interactions by employing its vacant s, p, and high‐lying d orbitals. These considerable M←SiO3 interactions and Si−O multiple bonding give rise to the highly stable planar hypercoordinate silicon clusters. Alkali metal decorated stable planar tetra‐, penta‐ and hexa‐coordinated SiO3 clusters are reported via numerical calculations. The bonding between the alkali atoms (M) and SiO3 motif is best described as M+ forming a few dative bonds through their vacant s, p, and high‐lying d orbitals.