Computationally efficient methodology to calculate C-H and C-X (X = F, Cl,and Br) bond dissociation energies in haloalkanes

A computationally efficient method for calculating C-H and C-X (X = F, Cl, and Br) bond dissociation energies in haloalkanes has been developed by det ermining correction factors to MP2/cc-pVtz energies. Corrections for basis set effects were determined by the difference in bond dissociation energies calculated at the MP2/cc-pVtz and MP2/cc-pV5z levels, and correlation effe cts were corrected by calculating the difference in energies at the MP2/cc- pVtz and CCSD(T)/cc-pVtz levels. Subsequent corrections for the spin-orbit energy of the atomic fragment and zero-point energy were applied to give a final bond dissociation energy. The correction factors were determined usin g CH4, CH3F, CH3Cl, and CH3Br and are found to yield bond dissociation ener gies in excellent agreement with experimental results. This correction may also be broadly applied to multihalogen compounds, as shown in calculations of the C-H and C-X bond dissociation energies of CH2X2 and CHX3 (X = F, Cl , and Br) compounds, which accurately reproduce experimental values.