Linear Four-Chalcogen Interactions in Radical Cationic and Dicationic Dimers of 1,5-(Dichalcogena)canes: Nature of the Interactions Elucidated by QTAIM Dual Functional Analysis with QC Calculations.

The dynamic and static nature of extended hypervalent interactions of the E···E···E···E type are elucidated for four center-seven electron interactions (4c-7e) in the radical cationic dimers (1·) and 4c-6e in the dicationic dimers (1) of 1,5-(dichalcogena)canes (2: E(CHCHCH)E: E, E = S, Se, Te, and O). The quantum theory of atoms-in-molecules dual functional analysis (QTAIM-DFA) is applied for the analysis. Total electron energy densities H(r) are plotted versus H(r) - V(r)/2 [= (ℏ/8m)∇ρ(r)] at bond critical points (BCPs) of the interactions, where V(r) values show potential energy densities at BCPs.