Structures and Electron Attachment Properties of Halomethanes (CX_nY_m, X = H, F; Y = Cl, Br, I; n = 0,4; m = 4n)

Abstract

Theoretical studies of structures of neutral molecules and their anions as well as dissociative electron attachment properties are presented for the halomethanes of general formula CX _n Y _m ; X = H, F; Y = Cl, Br, I; n = 0,4; m = 4 – n. The dissociative electron attachment seems to be the primary process resulting in toxicity of these species. The halomethane anions containing hydrogens are formed as radical-anion adducts. When H is replaced by F, these species become true σ∗ radicals. The electron affinities are computed using a variety of computational techniques including the four-order M⊘ller-Plesset (MP4) technique that included 250 basis functions. It is challenging to compare the computed results with experiment due to dearth of experimental data and uncertainties in the existing experimental data. Thus in certain cases larger differences are found between the computed and experimental values.

Key Words:

• Electron attachment
• Halocarbons
• Toxicity
• Structures