Bond orders from ab initio calculations and a test of the principle of bond order conservation

Abstract

Bond orders and valence indexes of atoms were calculated from ab initio wave functions using the definition suggested by Mayer. Changes of these quantities were investigated under conditions occurring in chemical reactions. Calculations were performed to reveal the dependence of bond orders on bond length. The results are compared with Pauling's bond order-bond length relation. Bond orders were also calculated in triatomic metathesis reactions. Bond orders are able to describe the similarity of the transition state of reactants or products. Along the minimum-energy path the principle of conservation of bond order is valid a good approximation. The obtained correlations are applied to a bond energy-bond order type model to estimate trends in reaction series.