A study of the carbon-halogen bond breaking in tert-butyl halides by the PM3 quantum chemical method Original Research Article

Quantum chemical calculations by the semiempirical PM3 method are performed for halogen tert-butanes t-BuX (X = Cl, Br) and their radical anions in the gas phase and model polar solvent. It is shown that these radical anions are unstable in polar solvents. Potential energy surfaces for t-BuBr−.and t-BuI−. have shallow minima in the gas phase. In the range of the values of the distances R(C-halogen) from the equilibrium one R0to R ≈ 2.2–2.3 Å the potential curves for t-BuCl−.and t-BuBr−. may be well approximated by the exponential functions Uf = B exp[−2β(R−R0)]. Activation energies and the values R∗ for the transitional configuration for the reactions t-BuX + e → t-Bu. + X− in the gas phase are calculated.