High-resolution X-ray diffraction determination of the electron density of 1-(8-PhSC10H6)SS(C10H6SPh-8′)-1′ with the QTAIM approach: evidence for S4 σ(4c–6e) at the naphthalene peri-positions

摘要

An extended hypervalent S _(4) σ(4c–6e) system was confirmed for the linear ~(B) S-?- ~(A) S-?- ~(A) S-?- ~(B) S interaction in 1-(8-Ph ~(B) SC _(10) H _(6) ) ~(A) S– ~(A) S(C _(10) H _(6) ~(B) SPh-8′)-1′ ( 1 ) via high-resolution X-ray diffraction determination of electron densities. The presence of bond critical points (BCPs; ?) on the bond paths confirms the nature and extent of this interaction. The recently developed QTAIM dual functional analysis (QTAIM-DFA) approach was also applied to elucidate the nature of the interaction. Total electron energy densities H _(b) ( r _(c) ) were plotted versus H _(b) ( r _(c) ) ? V _(b) ( r _(c) )/2 for the interaction at the BCPs, where V _(b) ( r _(c) ) represents the potential energy densities at the BCP. The results indicate that although the data for an interaction in the fully optimized structure corresponds to a static nature, the data obtained for the perturbed structures around it represent the dynamic nature of the interaction in QTAIM-DFA. The former classifies the interaction and the latter characterises it. Although ~(A) S-?- ~(A) S in 1 is classified by a shared shell interaction and exhibits weak covalent character, ~(A) S-?- ~(B) S is characterized as having typical hydrogen-bond nature with covalent properties in the region of the regular closed shell interactions. The experimental results are supported by matching theoretical calculations throughout, particularly for the extended hypervalent E _(4) σ(4c–6e) (E = S) interaction.