Thermodynamic Properties of C₁ and C₂ Bromo Compounds and Radicals. A Relativistic ab Initio Study

Heats of formation for a number of key C1 and C2 bromoalkanes and radicals have been calculated ab initio, both directly using an all-relativistic variant of W2 theory and indirectly using Douglas−Kroll relativistic CCSD(T)/Aug-VTZ reaction energies. For some of the bromoalkanes, our calculated values represent the first reliable data available. Bromine (3d) correlation contributes significantly to the molecular binding energies, but the effect of bromine (3s, 3p) correlation appears to be very small despite these orbitals lying above the carbon (1s) in energy. Thermodynamic functions have been obtained from molecular geometries and harmonic frequencies obtained at the B97-1/Aug-VTZ level and are given in the Supporting Information. These accurate thermodynamic parameters can be used to develop kinetic rate parameters.