Interference energy in C-H and C-C bonds of saturated hydrocarbons: dependence on the type of chain and relationship to bond dissociation energy.

Interference energy for C-H and C-C bonds of a set of saturated hydrocarbons is calculated by the generalized product function energy partitioning (GPF-EP) method in order to investigate its sensitivity to the type of chain and also its contribution to the bond dissociation energy. All GPF groups corresponding to chemical bonds are calculated by use of GVB-PP wave functions to ensure the correct description of bond dissociation. The results show that the interference energies are practically the same for all the C-H bonds, presenting only small variations (0.5 kcal.mol(-1)) due to the structural changes in going from linear to branched and cyclic chains. A similar trend is verified for the C-C bonds, the sole exception being the cyclopropane molecule, for which only the C-C bond exhibits a more significant variation. On the other hand, although the interference energy is quantitatively the most important contribution to the bond dissociation energy (DE), one cannot predict DE only from the bond interference energy. Differences in the dissociation energies of C-C and C-H bonds due to structural changes in the saturated hydrocarbons can be mainly attributed to quasi-classical effects.