Extending bond orbital-connection matrix method to the QSPR study of alkylbenzenes: Some thermochemical properties

The properties of alkylbenzenes were estimated, using the contributions of the σ bonds, the conjugated π bond and the steric effect in alkylbenzene molecule. And a novel bond orbital-connection matrix, conjugated π bond orbital-connection matrix in aromatic molecules, was proposed. The eigenvalues of the conjugated π bond orbital-connection matrix can well express the contribution of the conjugated π bond to the properties of aromatic molecules. Using this eigenvalue together with the parameters proposed in our early works, the bond orbital-connection matrix method was extended successfully to the QSPR studies of alkylbenzenes and a general model was obtained to evaluate the thermochemical properties of alkylbenzenes, that is,p(alkylbenzene)=aNC-C+b∑X1CC+cNC-H+d∑X1CH+eSZ/E+k∑X1π,where, p(alkylbenzene) denotes the thermochemical property (heat of atomization, enthalpy of formation and boiling points) of alkylbenzenes; X1CC and X1CH are the eigenvalues of the C-C and C-H σ bond orbital-connection matrices, respectively. X1π is the eigenvalue of the conjugated π bond orbital-connection matrix. NC-C and NC-H are the number of C-C and C-H σ bonds in the alkylbenzene, respectively, and a, b, c, d, e, and k are coefficients.