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Updated: Jul 12, 2026

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
Mechanistic insights into the reactivity and activation barriers of three-membered-ring formation by group 13
Zheng-Feng Zhang1, Ming-Der Su1,2
1Department of Applied Chemistry, National Chiayi University, Chiayi 60004, Taiwan. midesu@mail.ncyu.edu.tw.
Abstract:
To date, three distinct classes of main-group compounds featuring a pair of two-coordinate Group 13 (G13) centers have been experimentally synthesized and structurally characterized: [Type I] (L-G13G13-L)2-, [Type II] LB: → G13G13 ← :LB, and [Type III] (L-G13G13-L). Herein, we theoretically investigate the [1 + 2] cycloaddition reactions of Lewis base-free neutral G13G13-Rea (Ar'-G13G13-Ar'; Ar' = 2,6-(2,6-iPr2C6H3)2C6H3) species with Mes*P-PMe3 using density functional theory (DFT) calculations. The present theoretical analysis reveals that the central G13G13 bond in the G13G13-Rea systems possesses significant donor-acceptor character and can be better described as Ar'-G13 ⇄ G13-Ar'. From both kinetic and thermodynamic perspectives, these species are predicted to readily undergo [1 + 2] cycloaddition with Mes*P-PMe3 to form three-membered G132P heterocycles, except for the TlTl-Rea system. Our calculations further show that the three-membered ring in BB-Prod exhibits clear aromatic character, whereas the heavier congeners (G13' = Al, Ga, In, Tl) form nonaromatic G13'2P rings. A strong correlation is identified between the magnitude of the NICS index and the thermodynamic driving force, indicating that the NICS value can serve as a quantitative indicator of reaction exergonicity. Energy decomposition analysis combined with natural orbitals for chemical valence (EDA-NOCV) reveals that the bonding interaction is dominated by π-type forward donation from the filled p-π orbital of G13G13-Rea to the vacant p-π* orbital of Mes*P. In contrast, σ-type back-donation from the filled sp-σ orbital of Mes*P to the vacant sp-σ* orbital of G13G13-Rea contributes only marginally to the overall stabilization. The calculated activation barriers are found to be primarily governed by the structural deformation of the G13G13-Rea fragment.
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