Computational Insight into the Nature and Strength of the π-Hole Type Chalcogen∙∙∙Chalcogen Interactions in the XO2∙∙∙CH3YCH3 Complexes (X = S, Se, Te; Y = O, S, Se, Te)

Abstract

In recent years, the non-covalent interactions between chalcogen centers have aroused substantial research interest because of their potential applications in organocatalysis, materials science, drug design, biological systems, crystal engineering, and molecular recognition. However, studies on π-hole-type chalcogen∙∙∙chalcogen interactions are scarcely reported in the literature. Herein, the π-hole-type intermolecular chalcogen∙∙∙chalcogen interactions in the model complexes formed between XO2 (X = S, Se, Te) and CH3YCH3 (Y = O, S, Se, Te) were systematically studied by using quantum chemical computations. The model complexes are stabilized via one primary X∙∙∙Y chalcogen bond (ChB) and the secondary C−H∙∙∙O hydrogen bonds. The binding energies of the studied complexes are in the range of −21.6~−60.4 kJ/mol. The X∙∙∙Y distances are significantly smaller than the sum of the van der Waals radii of the corresponding two atoms. The X∙∙∙Y ChBs in all the studied complexes except for the SO2∙∙∙CH3OCH3 complex are strong in strength and display a partial covalent character revealed by conducting the quantum theory of atoms in molecules (QTAIM), a non-covalent interaction plot (NCIplot), and natural bond orbital (NBO) analyses. The symmetry-adapted perturbation theory (SAPT) analysis discloses that the X∙∙∙Y ChBs are primarily dominated by the electrostatic component.

Unveiling the Nature and Strength of Selenium-Centered Chalcogen Bonds in Binary Complexes of SeO2 with Oxygen-/Sulfur-Containing Lewis Bases: Insights from Theoretical Calculations

“…The computed most positive and most negative MEP values ( V S,max and V S,min ) for the SeO 2 molecule are 52.05 kcal/mol and −29.82 kcal/mol, respectively. The V S,max value of the SeO 2 molecule is significantly larger than that of the SO 2 molecule (43.74 kcal/mol, calculated at the same level) [ 45 ]. This is consistent with the fact that the electronegativity of the S atom is larger than that of the Se atom.…”

“…The strength of these ChBs depends on both the chalcogen atom involved in the bonding and the groups covalently bonded to it [ 15 , 43 , 44 ]. Concretely, a ChB’s strength increases with increases in the radius of the electron-poor chalcogen atom, but gradually decreases as the radius of the electron-rich chalcogen atom grows [ 45 ]. Furthermore, the existence of an electron-withdrawing group covalently attached to the electron-deficient chalcogen atom and an electron-donating group connected to the Lewis base can enhance the ChB strength.…”

“…It is important to acknowledge that the above-mentioned SeChBs mainly belong to the group of σ–hole interactions, with a focus on the divalent selenium atom in the existing literature. However, studies on the π–hole interactions of the hypervalent selenium atom as the ChB donor remain limited to date [ 45 , 62 ].…”

“…For instance, Esrafili and coworkers [ 62 ] computationally investigated the cooperativity between π–hole-type Se ∙∙∙ N ChBs and σ–hole-type halogen bonds in CH 3 ∙∙∙ XCN ∙∙∙ SeO 2 complexes (X = F, Cl, Br, and I). Recently, we conducted a systematic examination of the π–hole-type chalcogen ∙∙∙ chalcogen interactions in XO 2 ∙∙∙ CH 3 YCH 3 complexes (X = S, Se, Te; Y = O, S, Se, Te) [ 45 ]. The results indicated that these X ∙∙∙ Y ChBs are strong in strength and have some degree of covalent character.…”

Te⋯I secondary-bonding interactions in crystals containing tellurium(ii), tellurium(iv) and iodide atoms: supramolecular aggregation patterns, nature of the non-covalent interactions and energy considerations

“…27–29 In crystals of chalcogen-containing molecules, π-hole interactions can cooperate with σ-hole interactions 30–32 or even operate independently. 33,34 Instances of bifurcated 35–37 and charge-assisted 38,39 chalcogen bonds are also known. Computational chemistry calculations on the aforementioned neutral systems 31–37 and other non-charged systems 26,40 confirm that the energy imparted by the different interactions involving the tellurium are like or exceed those imparted by conventional hydrogen bonding.…”