Relative stability of multiple bonds between silicon and bismuth. A theoretical study

Substituent effects on the potential energy surface of XSiBi (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 (SiBiX) and triple (XSiBi) bonds to silicon–bismuth, so a direct comparison of these types of species is possible. Our model calculations indicate that electropositively substituted SiBiX species are thermodynamically and kinetically more stable than their isomeric XSiBi molecules. Moreover, the theoretical findings suggest that F, OH, NH2, and CH3 substitution prefer to shift the double bond (SiBiX) by forming a triple bond (XSiBi).