Structural features of chalcogen bond and weak interactions involving chalcogens

The structural features of chalcogen bonding (ChB) interactions in linear fragments R–Ch Nu (Ch1⁄4S, Se, Te; R1⁄4C, N, O, S, Se, Te; Nu1⁄4N, O, S, Se, Te, F, Cl, Br, I) involving Ch Nu distances shorter than the sum of relevant van der Waals (vdW) radii are reviewed. For the R–Ch Nu fragments, the structural parameters dR–Ch and dCh Nu are analyzed along with the values of the functions dR–Ch and dCh Nu calculated by normalizing the differences between the involved covalent R–Ch and non-covalent Ch Nu distances and the sum of the relevant covalent and van der Waals (vdW) radii, in order to compare the data involving different Ch atoms. A systematic comparison of the ChB found in isologue fragments R–Ch Nu is presented sorted by the nature of the involved Ch atom, of the R atoms covalently bonded to the Ch, and of the Nu species playing the role of chalcogen bond acceptors.