S-EPMC10865089 - 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† † Electronic supplementary information (ESI) available: Additional tables and figures, explanation of QTAIM-DFA, and the fully optimized and transition structures given by Cartesian coordinates, together with total energies of 1a+–8c+. See DOI: https://doi.org/10.1039/d3ra08926f