The substituent effects on the potential energy surfaces of RBBiR (R = F, OH, H, CH3, SiH3, Tbt, Ar*, SiMe­(SitBu3)2, and SiiPrDis2) are determined using density functional theories (M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp). The theoretical results show that all of the triply bonded RBBiR molecules prefer to adopt a bent geometry (i.e., ∠RBBi ≈ 180° and ∠BBiR ≈ 90°), which agrees well with the valence-electron bonding model. It is also demonstrated that the smaller groups, such as R = H, F, OH, CH3, and SiH3, neither kinetically nor thermodynamically stabilize the triply bonded RBBiR compounds, except for H3SiBBiSiH3. However, triply bonded R′BBiR′ molecules that feature bulkier substituents (R′ = SiiPrDis2, SiMe­(SitBu3)2, Tbt, and Ar*) are predicted to have a thermodynamic and kinetic global minimum. This theoretical study finds that both the steric and the electronic effects of bulkier substituent groups play a significant role in forming triply bonded RBBiR species that are experimentally obtainable and isolable in a stable form.

The effect of substitution on the potential energy surfaces of RE 13 ≡BiR (E

Substituent effects on the potential energy surface of XSiSb (X = H, Li, Na, BeH, MgH, BH2, AlH2, CH3, SiH3, NH2, PH2, OH, SH, F, and Cl) were investigated by using B3LYP/Def2-TZVP, B3PW91/Def2-TZVPP, and CCSD(T) methods. The isomers include structures with formal double (Si=SbX) and triple (XSi≡Sb) bonds to silicon–antimony, so a direct comparison of these types of species is possible. Our model calculations indicate that electropositively substituted Si=SbX species are thermodynamically and kinetically more stable than their isomeric XSi≡Sb molecules. Moreover, the theoretical findings suggest that F, OH, NH2, and CH3 substitutions prefer to shift the double bond (Si=SbX) by forming a triple bond (XSi≡Sb).

) were investigated by using B3LYP/Def2-TZVP, B3PW91/Def2-TZVPP CCSD (T)//B3LYP/Def2-TZVP methods. The isomers include structures with formal double (Ge=SbX) and triple (XgeºSb) bonds to germanium-stibium, so a direct comparison of these types of species is possible. Our model calculations indicate that electropositively substituted Ge=SbX species are thermodynamically and kinetically more stable than their isomeric XgeºSb molecules. Moreover, the theoretical findings suggest that only the organic substitutions (such as CH 3 ) can make triply bonded XgeºSb molecule more stable than the doubly bonded Ge=SbX species.