Linear Multiselenium Interactions in Dicationic Oligomers of 1,5-(Diselena)canes: Behavior of Se_mc σ(m_c c-n_e e) (6≤m_c...

The intrinsic dynamic and static nature m_c center-n_e electron interactions of the σ-type σ(m_c c-n_e e) were elucidated for the Se-Se interactions in dicationic oligomers of Se(CH₂ CH₂ CH₂ )₂ Se (1 (Se, Se)) [n²⁺ (Se, Se): n=1-8], especially for m_c ≥6, where n²⁺ (Se, Se: n=1-8) are abbreviated by n²⁺ (n=1-8), respectively. QTAIM dual functional analysis (QTAIM-DFA) was applied to the interactions. Perturbed structures generated using coordinates derived from the compliance constants (C_ii ) were employed for QTAIM-DFA. Each Se-*-Se in 1²⁺ and 2²⁺ has the nature of CT-TBP (trigonal bipyramidal adduct formation through CT) and Cov-w (weak covalent), respectively, which supply the starting points of the investigations. The asterisk emphasizes the existence of a bond critical point on the interaction. All Se-*-Se in 3²⁺ are classified by the regular closed shell (r-CS) interactions and characterized as CT-MC (molecular complex formation through CT), which are denoted as r-CS/CT-MC, except for the central interaction, of which nature is r-CS/CT-TBP. Most interactions in 4²⁺ -8²⁺ are r-CS/t-HB_wc (typical-HB with covalency) but some are pure-CS/t-HB_nc (t-HB with no covalency). The linear Se_2n ²⁺ interactions in 2²⁺ -8²⁺ seem close to those without any limitations, since the nature of Se-*-Se inside and outside of (CH₂ CH₂ CH₂ )₂ are very similar with each other. The linear Se_2n ²⁺ interactions in 3²⁺ -8²⁺ are shown to be analyzed as σ(m_c c-n_e e: 6≤m_c ≤16), not by the accumulated σ(3c-4e).