Exploring the Role of Substitution on the Formation of Se···O/N Noncovalent Bonds

Abstract

In this article, we have examined the effect of substitution on the formation of neutral XHSe···O/N (X = -H, -F, -CH3, -CF3, -Cl, -OH, -OCH3, -NH2, -NHCH3, -CN) noncovalent bonds with the oxygen atom from H2O molecule and the nitrogen atom from NH3 being the electron donor atoms, respectively. In addition to this, analysis has also been performed on XMeSe···O/N complexes to study the effect of the role of hydrogen bonding with the hydrogen atoms of the methyl group on Se···O/N interactions. Binding energy calculations were performed to determine the strength of these contacts. The obtained results establish the fact that the presence of a methyl group influences the strength of the observed Se···O/N interactions. Also in some cases, the O-H···Se interaction was observed to be more preferable over the Se···O interaction. The major contribution for stabilization of such Se···O/N interactions is from an interplay among the electrostatics and the exchange energy. To obtain deeper insights and understanding of such Se···O/N contacts, a topological analysis, using the QTAIM approach were also performed. This analysis showed that although the presence of a Me group modifies the Se···O/N interaction, it does not necessitate the formation of hydrogen bonds. To obtain insights into the orbital contributions, a natural bond orbital (NBO) analysis were performed which depicts that the strength of such interactions were derived via charge transfer from the oxygen/nitrogen lone pair to the σ* orbital of the Se-X bond.

Characterization of N⋯O non-covalent interactions involving σ-holes: “electrostatics” or “dispersion”

“…The highest percentage contribution of electrostatics and polarization combined with the lowest percentage contribution of dispersion towards the stability of NO4 can be attributed to the dual character of pnicogen and chalcogen bonds in the complex. In contrast to previously studied chalcogen and pnicogen bonds, 66,68,74 the contribution of the electrostatic energy was observed to be less than that of dispersion energy. This shows that the characteristics of NÁ Á ÁO contacts are quite different from the previously studied s-hole interactions.…”

“…[61][62][63] Most of the studies on chalcogen bonds have been centered on S and Se atoms but the possibility of O participation in chalcogen bonds has not been explored previously. Also, in the various ab initio analyses of chalcogen bonds, there are studies where N can act as a nucleophile in the formation of SÁ Á ÁN and SeÁ Á ÁN chalcogen bonds [64][65][66] and hence it is of interest to study NÁ Á ÁO contact in this regard. Also, the fact that both pnicogen and chalcogen are capable of behaving both as an electron-acceptor and as an electron-donor, during the formation of non-covalent interactions makes the study of NÁ Á ÁO contact important.…”

Are Various σ‐Hole Bonds Steered by the Same Mechanisms?

“…Some of the complexes presented herein (Table 1) have been analyzed in previous studies. These are the FCl···NH 3 , [44][45][46][47][48][49][50][51][52] FBr···NH 3 , [52] SeFH···NH 3 , [53,54] PFH 2 ···NH 3 , [55] SFH···C 2 H 2 , [56] FCl···C 2 H 2 , [46][47][48][57][58][59] PFH 2 ···C 2 H 2 , [60] and Si/GeFH 3 ···NH 3 [61,62] complexes. However,c alculations were performed at different levels and these studies concerned rather narrow types of interaction;h erein the same high level of calculation was applied for the varioust ypes of s-hole bond.…”

“…[64] The calculations performed previously are usually in good agreement with the resultsp resented herein (Table 1). For example,t he binding energy for the SeFH···NH 3 complex, corrected for BSSE, was equal to À11.3 kcal mol À1 and the Se···N length was 2.45 (MP2/aug-cc-pVDZ); [53] for the PFH 2 ···NH 3 system E bin = À7.3 kcal mol À1 (noB SSE correction) and the P···N length was 2.609 (MP2/aug'-cc-pVTZ). [55] The energetic and geometrical results for complexeso fa cetylene that were analyzed previously are also in agreement with those presented herein.…”

Chalcogen Bonding “2S–2N Squares” versus Competing Interactions: Exploring the Recognition Properties of Sulfur

“…Chalcogenb onding (CB), categorized as the interaction between Group VI elements (O, S, Se, Te ,P o) [1][2][3][4][5][6][7][8][9][10][11][12] and aL ewisbasic partner atom, [13][14][15][16][17][18][19] has received significant attention in the past decade,l argely in response to the advances made in understanding halogen bonding( XB). [20][21][22][23][24][25][26][27] Seminalw ork [28][29][30] led to the realization that polarizable halogens can be tuned to exploit the electron-poorr egions of their surfaces, now defined as s-holes, [31][32][33][34] for efficient intermolecular interactions with Lewis-basic atoms.U nlike XB, the deliberate application of CB is still emerging.…”