Comparison of group 14 elements in sp³ and sp² environment by fragment structure energy analysis

Abstract

To explore the characteristics of group 14 elements in sp3 and sp2 hybrid environments systematically, the concept of fragment structure energy (FSE) was proposed through ab initio molecular orbital method. A fragment in this study means a building block of molecular structure and the energy of each kind of fragments (FSE) is obtained from the total electronic energy of different size of model compounds by just a simple algebraic method. The model compounds are the hydrogen‐terminated diamond and graphene analogs as the typical compounds in the ideal sp3‐ and sp2‐environment, respectively. As a result, the sp3 environment was found to be more stable than the sp2 for all the group 14 elements (C–Pb) in the ideal hybrid environment. Furthermore, a mixing effect of carbon and heavier group 14 elements (E = Si, Ge, Sn, and Pb) was investigated by comparing the E/C‐alternately mixed‐ and the pure FSEs.

Theoretical Study of Si/C Equally Mixed Dodecahedrane Analogues

“…For comparison, the energy gap of diamond-type molecules with molecular sizes similar to those of dodecahedranes is also shown in Table 3 as the model of silicon carbide. C 30 H 40 and Si 30 H 40 are the model compounds of the diamond-type crystal terminated by hydrogens and the silicon analogue, respectively, while C 10 Si 20 H 40 and C 20 Si 10 H 40 are the two types of Si/C mixed congeners [ 31 ]. The frontier molecular orbitals of the seven isomers a to f , dodecahedrane, and persiladodecahedrane are displayed in Figures S2–S10 of the Supplementary Materials .…”

“…However, there are only a few theoretical studies for two-element-mixing analogues of tetrahedrane and cubane [ 29 , 30 ]. In this situation, our fragment structure energy (FSE) analysis demonstrated that Si/C alternately mixing contributes to the stabilization of the systems in the ideal (with no angle strain) sp 3 environment as well as the sp 2 environment, which was not observed for the mixing of carbon or the other heavier group 14 elements [ 31 ].…”