Chalcogen-Bond-Assisted Formation of the N→C Dative Bonds in the Complexes between Chalcogenadiazoles/Chalcogenatriazoles and Fullerene C60

Abstract

The existence of the N→C dative bonds in the complexes between N-containing molecules and fullerenes have been verified both theoretically and experimentally. However, finding stable N→C dative bonds is still a highly challenging task. In this work, we investigated computationally the N→C dative bonds in the complexes formed by fullerene C₆₀ with 1,2,5-chalcogenadiazoles, 2,1,3-benzochalcogenadiazoles, and 1,2,4,5-chalcogenatriazoles, respectively. It was found that the N→C dative bonds are formed along with the formation of the N-Ch···C (Ch = S, Se, Te) chalcogen bonds. In the gas phase, from S-containing complexes through Se-containing complexes to Te-containing complexes, the intrinsic interaction energies become more and more negative, which indicates that the N-Ch···C chalcogen bonds can facilitate the formation of the N→C dative bonds. The intrinsic interaction energies are compensated by the large deformation energy of fullerene C₆₀. The total interaction energies of Te-containing complexes are negative, while both total interaction energies of the S-containing complexes and Se-containing complexes are positive. This means that the N→C dative bonds in the Te-containing complexes are more easily observed in experiments in comparison with those in the S-containing complexes and Se-containing complexes. This study provides a new theoretical perspective on the experimental observation of the N→C dative bonds in complexes involving fullerenes. Further, the formation of stable N→C dative bonds in the complexes involving fullerenes can significantly change the properties of fullerenes, which will greatly simulate and expand the application range of fullerenes.

Keywords: N→C dative bond; chalcogen bond; chalcogenadiazole; fullerene C60.

Figure 1

PBE0-D3/def2-TZVPP optimized structures of the complexes S-1, S-2, Se-1, Se-2, Te-1 and Te-2. The red dashed line indicates the possibility of a chalcogen bond.

Figure 2

The electrostatic potential mapped electron density surfaces (isoval = 0.001 au) of 1,2,5-chalcogenadiazoles and 2,1,3-benzochalcogenadiazoles. The most positive electrostatic potential of each σ-hole (V_S,max) is also shown. The electrostatic potentials are given in kcal/mol.

Figure 3

The correlation between V_S,max (kcal/mol) of 1,2,5-chalcogenadiazoles and ∆E^INTR (kcal/mol) of S-1, Se-1 and Te-1.

Figure 4

The correlation between V_S,max (kcal/mol) of 2,1,3-benzochalcogenadiazoles and ∆E^INTR (kcal/mol) of S-2, Se-2 and Te-2.

Figure 5

The bond critical points (small red dots) and bond paths of the complexes Se-1 and Se-2.

Figure 6

PBE0-D3/def2-TZVPP optimized structures of the complexes N–S, N–Se and N–Te. The red dashed lines represent the chalcogen bonds. The numbers shown are the interatomic distances (Å). The red dashed lines represent chalcogen bonds.

Figure 7

The electrostatic potential mapped electron density surface (isoval = 0.001 au) of fullerene C₆₀. The color bar is in kcal/mol.