Relation between bond order and delocalization index of QTAIM

The formal bond order is half the difference between the number of bonding and anti-bonding electrons. The relation between delocalization index (DI) from QTAIM and formal bond order is linear for CC, NN, GeGe, C–Si, C–Ge and CN bonds. The electronegativity is closely related with the correspondence between the DI and the formal bond order for the CC, NN and GeGe bonds. By using the electronegativity of C, N and Ge atoms, it was obtained a general relation between the formal bond order and the DI for CC, NN and GeGe atomic pairs.