We now consider the chirality Cσ, bond-flexing Fσ and bond-axiality Aσ values of the dominant torsional C1-N7 BCP , see Figure 2 andTable 2(b) . The formally achiral HH glycine comprises a significant degree of chirality Cσ (= 0.18963) for the torsional C1-N7 BCP with Sσ character, see Table 2(a-b) . The magnitude of Cσ increases similarly with the addition of the D isotope for both the Sa and Ra stereoisomers, where the Ra stereoisomer possesses the larger value, both stereoisomers are Sσ character. The bond-flexing Fσ is more affected by the substitution of the D isotope to HH glycine than either of the chirality Cσ or Aσ of the torsional C1-N7BCP , see Table 2(b) .
The substitution of the T isotope onto the alpha carbon of HH glycine to replace an H significantly changes Cσ, Fσ and Aσ values. The T isotope changes the character of the chirality Cσ toRσ character for both the Saand Ra stereoisomers and there is a pronounced difference in the magnitude of Cσ, that is significantly lower for the Sa stereoisomer. The bond-flexing Fσ increases in magnitude from HH glycine through to HD glycine and HT glycine, again the HD glycine values are similar for the Sa and Ra stereoisomers with a slight preference for the Sa stereoisomer. In addition, the bond-flexing Fσ changes from Sσcharacter, for HH glycine, to Rσ character for both the Sa and Ra stereoisomers of HD glycine and HT glycine. The bond-axiality Aσ increases in magnitude from HH glycine through to HD glycine and Sa stereoisomer of HT glycine, again the HD glycine values are similar for the Sa and Rastereoisomers with a slight preference for the Rastereoisomer. The Aσ value of the Rastereoisomer of HT glycine decreases significantly below that of HH glycine. The Aσ value of HH glycine possessesSσ character that changes toRσ character for both the Saand Ra stereoisomers of HD glycine and HT glycine. The stereoisomeric excess Xσ values indicate a very slight preference for the Ra stereoisomer that possesses chirality Cσ with Sσ character for HD glycine and a very strong preference for the Rastereoisomer that possesses chirality Cσ withRσ character for HD glycine.
Table 2(c). Values of the bond-twist Tσ = [(e∙dr)max ]CCW- [(e∙dr)max ]CW , bond-flexing Fσ and the bond-axiality Aσof the C-H/D/T BCP bond-paths corresponding to the torsional C1-N7 BCP bond-path of the isotopomers of glycine are presented, see the caption of Table 2(b) for further details.