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

Abstract

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. Data from the fully optimized structures correspond to the static nature of the interactions. Those from the perturbed structures around the fully optimized ones are also plotted, in addition to those of the fully optimized ones, which represent the dynamic nature of interactions. The E···E-E···E interactions in 1 are stronger than the corresponding ones in 1·, respectively. On the one hand, for 1 with E,E = S, Se, and Te, E···E are all classified by the shared shell interactions and predicted to have the weak covalent nature, except for those in 1a (E = E = S) and 1d (E = E = Se), which have the nature of regular closed shell (r-CS)/trigonal bipyramidal adduct formation through charge transfer (CT-TBP). On the other hand,E···E are predicted to have the nature of r-CS/molecular complex formation through charge transfer for 1a, 1b (E = Se; E = S), and 1d or r-CS/CT-TBP for 1c (E = Te; E = S), 1e (E = Te; E = Se), and 1f (E = E = Te). TheE···E-E···E interactions in 1· and 1 are well-analyzed by applying QTAIM-DFA.

Intrinsic Dynamic Nature of Neutral Hydrogen Bonds Elucidated with QTAIM Dual Functional Analysis: Role of the Compliance Force Constants and QTAIM‐DFA Parameters in Stability

“…QTAIM‐DFA was recently formulated on the basis of QTAIM . The H b ( r c ) parameters are plotted versus H b ( r c )− V b ( r c )/2 [=(ħ 2 /8 m )∇ 2 ρ b ( r c )] at the BCPs in QTAIM‐DFA.…”