(3)
The sign (±) of the chirality Cσ, bond twist Tσ and bond-axiality Aσ determines the dominance of Sσ (Cσ> 0) and Rσ (Cσ< 0) character. A high degree of bond-axiality Aσ corresponds to a large difference in the value of the{e.dr}max for the CCW and CW torsion directions.
The stereoisomeric excess Xσ is defined as the ratio of the magnitude of the Cσ values of the Saand Ra stereoisomers of the torsional C1-N7 BCPand represents the Next generation QTAIM interpretation of the enantiomeric excess.