A computational study to determine whether substituents make E13nitrogen (E13 = B, Al, Ga, In, and Tl) triple bonds synthetically accessible

Abstract

This study theoretically determines the effect of substituents on the stability of the triple-bonded L–E₁₃N–L (E₁₃ = B, Al, Ga, In, and Tl) compound using the M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp levels of theory. Five small substituents (F, OH, H, CH₃ and SiH₃) and four large substituents (SiMe(SitBu₃)₂, SiiPrDis₂, Tbt ( C₆H₂-2,4,6-{CH(SiMe₃)₂}₃) and Ar* (C₆H₃-2,6-(C₆H₂-2,4,6-i-Pr₃)₂)) are used. Unlike other triply bonded L–E₁₃P–L, L–E₁₃As–L, L–E₁₃Sb–L and L–E₁₃Bi–L molecules that have been studied, the theoretical findings for this study show that both small (but electropositive) ligands and bulky substituents can effectively stabilize the central E₁₃N triple bond. Nevertheless, these theoretical observations using the natural bond orbital and the natural resonance theory show that the central E₁₃N triple bond in these acetylene analogues must be weak, since these E₁₃N compounds with various ligands do not have a real triple bond.