A Structural Approach to the Strength Evaluation of Linear Chalcogen Bonds

The experimental structural features of chalcogen bonding (ChB) interactions in over 34,000 linear fragments R-ChMIDLINE HORIZONTAL ELLIPSISA (Ch = S, Se, Te; R = C, N, O, S, Se, Te; A = N, O, S, Se, Te, F, Cl, Br, I) were analyzed. The bond distances d(R-Ch) and the interaction distances d(ChMIDLINE HORIZONTAL ELLIPSISA) were investigated, and the functions d(R-Ch) and d(ChMIDLINE HORIZONTAL ELLIPSISA) were introduced to compare the structural data of R-ChMIDLINE HORIZONTAL ELLIPSISA fragments involving different Ch atoms. The functions d(R-Ch) and d(ChMIDLINE HORIZONTAL ELLIPSISA) were calculated by normalizing the differences between the relevant bond d(R-Ch) and ChB interaction d(ChMIDLINE HORIZONTAL ELLIPSISA) distances with respect to the sum of the relevant covalent (r(cov)R + r(cov)Ch) and the van der Waals (vdW) radii (r(vdW)Ch + r(vdW)A), respectively. A systematic comparison is presented, highlighting the role of the chalcogen involved, the role of the R atoms covalently bonded to the Ch, and the role of the A species playing the role of chalcogen bond acceptor. Based on the results obtained, an innovative approach is proposed for the evaluation and categorization of the ChB strength based on structural data.

Automated summary

The experimental structural features of over 34,000 linear fragments involving chalcogen bonding (ChB) interactions were analyzed. The role of the chalcogen, the covalently bonded atoms, and the chalcogen bond acceptor were highlighted. An innovative approach for the evaluation and categorization of ChB strength based on structural data was proposed.