Comprehensive DFT study on molecular structures of Lewisites in support of the Chemical Weapons Convention

• The structure of all of Lewisite's stereoisomers (9 isomers) has been examined by B3LYP/6–311++G(3df,3pd) calculations.
• The bonding trends and Mulliken charge distribution in Lewisites can be explained by the Bent's rule and the donor–acceptor interaction between arsenic and carbon atoms, respectively.

The structure of all of Lewisite's stereoisomers has been examined by B3LYP/6–311++G(3df,3pd) calculations. The geometry analysis for trans Lewisite L1–1 shows that the calculated bond angles, bond distances and dipole moment have a satisfactory relation compared with experimental values. HOMO-LUMO analysis of Lewisites reveals that L1–2 and L3–7 have the maximum and minimum electrophilicity index, respectively. The calculated chemical shifts were compared with experimental data, showing a very good agreement both for 1H and 13C. The vibrational and Raman frequencies of Lewisites have been precisely assigned and theoretical data were compared with the experimental vibrations. The bonding trends and Mulliken and atomic polar tensor charge distribution in Lewisites can be explained by the Bent's rule and the donor–acceptor interaction, respectively.

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