The nature of G⋯E–Y σ(3c–4e) in o-Me_nGCH₂C₆H₄EY (Me_nG = Me₂N and MeE; E = O, S, Se and Te; Y = F, Cl, Br, EMe and Me) with contributions from CT and compliance constants in noncovalent G⋯E interactions

Abstract

The nature of E⋯E′ in 1-RECH2-2-R′E′C6H4 (E/E′ = O, S, Se and Te) is clarified with QTAIM approach and NBO analysis, after structural determinations.

Intrinsic dynamic and static natures of APn--X+--BPn σ(3c–4e) type interactions (APn = BPn = N, P, As and Sb; X = H, F, Cl, Br and I) in bicyclo[3.3.3] and bicyclo[4.4.4] systems and their behaviour, elucidated with QTAIM dual functional analysis

“…Eqn (4) shows that (1) H b (r c ) for Pn-*-H increases in the order of B Pn-*-H (ma + nsym ) < A/B Pn-*-H (ma + sym ) < A Pn-*-H (ma + nsym ); (2) regarding m, H b (r c ) increases in the order of m = (1 and 5: Pn = N) < (2 and 6: Pn = P) < (3 and 7: Pn = As) < (4 and 8: Pn = Sb); (3) the order in (2) is clearly observed for the strong interactions in B Pn-*-H and A/B Pn-*-H whereas the order becomes vague for the weak A Pn-*-H. In the case of eqn (5), the trends for X = F are very close to that observed X = H in eqn (4), although some discrepancies are observed in the order, such as A N-*-F (1b + nsym : −0.016 and 5b + nsym : −0.0015) and A/B P-*-F (2b + sym : −0.065 and 6b + sym : −0.035). The order in eqn (6) implies that (1) H b (r c ) of Pn-*-X increases in the order of X = Cl < Br < I; (2) the same order for H b (r c ) of B Pn-*-X (mx + nsym ) < A/B Pn-*-X (mx + sym ) < A Pn-*-X (mx + nsym ) was also observed for X = Cl, Br, and I. However, the order becomes unclear between B Pn-*-X (mx + nsym ) and A/B Pn-*-X (mx + sym ); (3) the difference in the reactivity between the bicyclo [4.4.4] system versus the bicyclo[3.3.3] system becomes much larger for X = Cl, Br, and I, if compared with the case of X = H and F.…”

“…Intrinsic dynamic and static natures of various types of chemical bonds and interactions have been elucidated with the quantum theory of atoms-in-molecules dual functional analysis (QTAIM-DFA). 1–4 Hydrogen bonds 5 and chalcogen bonds 6 are the typical examples of such interactions. What are the natures of the noncovalent interactions, that play a highly important role in the biological systems, such as enzymes?…”