The onehyphen;electron theory is applied tolhyphen;3hyphen;aminopyrrolidhyphen;2hyphen;one. The rotatory strength of thenpgr;*transitionRagr;0is evaluated with various models of the amide chromophore and of the perturbing amino group. It is found that: (1)Ragr;0is very sensitive to the degree of delocalization of the nonbonding orbital of the amide oxygen; (2) in the perturbation treatment the transition charge distribution in the amide group is well represented by point quadrupoles on oxygen and carbon, the next higher, 26hyphen;pole, terms making only a small contribution toRagr;0; (3) the perturbing electrostatic field, as derived from the groundhyphen;state electron density of the amino group, is fairly well represented by partial charges on the nuclei, except at very short distance; (4) the representation of all overlap charges in the amino group by point monopoles, an elaboration of a method introduced by London, gives a perturbing field that is about five times too high.
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