A computational study of chlorofluoro-methyl radicals Available to Purchase

Chorine- and fluorine-containing methyl radicals have been investigated by ab initio methods. Geometries and vibrational frequencies were derived with quadratic configuration methods at the $QCISD/6-311G(d,p)$ level of theory, and energies via $QCISD(T)/6-311+G(3df,2p)$ and Gaussian 3 theory. Anharmonicity of the out of plane bending mode was taken into account by numerical integration of the Schrödinger equation with a potential derived from a relaxed scan of this mode. The results are in good accord with experimental data where available. For the radicals $CHF2,$ $CF3,$ $CH2Cl,$ $CHCl2,$ and $CCl3,$ we compute $ΔfH2980$ values of −241.2, −465.9, 117.0, 91.1, and 72.2 kJ mol⁻¹, respectively, which agree with well-established experimental values to within 2.2 kJ mol⁻¹. For the more poorly characterized molecules $CH2F,$ CHClF, $CClF2,$ and $CCl2F$ we compute $ΔfH2980$ values of −29.0, −63.8, −274.7, and −94.3 kJ mol⁻¹, respectively, with recommended confidence limits of ±4.1 kJ mol⁻¹.