A new approach of evaluating bond dissociation energy from eigenvalue of bonding orbital-connection matrix for C-C and C-H bonds in alkane.

A new bonding orbital-connection matrix was constructed, in which the diagonal elements were assigned the chemical potentials E(1) and E(2) of two radicals R(i)* and R(j)* obtained by cutting the interested bond, and the off-diagonal elements, representing bonding connections, were assigned values 1. The eigenvalues X(1CC) and X(1CH) of the bonding orbital-connection matrix were obtained for C-C and C-H bonds, respectively. Also a steric effect parameter S(ij) was proposed for C-C bond. Using X(1CC), X(1CH), and S(ij) as bond descriptors, good correlations with the Bond Dissociation Energies (BDEs) of the C-C and C-H bonds were obtained for alkanes. The result shows that the eigenvalue of bonding orbital-connection matrix is a good descriptor for expressing the relative bond energies of C-C and C-H bonds in alkane. This work provides a new physical insight and a principally novel general approach to the evaluation of the bond dissociation energies of carbon-carbon (C-C) and carbon-hydrogen (C-H) bonds in alkane. Also it builds a simple bridge linking the adjacent matrix of radicals R(i)* and R(j)* with the BDE of R(i)-R(j) and R(i)-H. Furthermore, the Heat of Atomization (HA) and Heat of Formation in Gas (HFG(0)) of alkane can be estimated well with the parameters X(1CC), X(1CH), and S(ij).