Molecular Orbital Theory Studies on Bond Energy I. Theoretic Equation

A new way of calculating bond energy is proposed proceeding from LCAO - MO. Onthe basis of using the equation EAB(i)= as the contribution to the bond energyof A - B bond from a pair of electrons in the i occupied MO, it is easy to obtain the bond energy ofA- B bond by summing up all MO, i.e. , EAB = .The bond energy between atoms linkaged each other in various molecules is calculated in this way, and the property of bond such asbond of σ, π or δ and the contribution of all AO for the bond energy is analysed at MO and AO views. Though this way is different from those in which the bond enthalpy and equilibrium dissociation energy De can be obtained, the results of calculation are well in accord with experiment values of De. By analysing the bond energy, the interacting relations between atoms and the strength of the chemical bond are well indicated and such chemical property as the chemical reactivity and reaction rate can be further probed.