Two isomeric pairs of cis- and trans-1-cyclohexyl-2-phenyl-3-benzoylaziridines
have been synthesized: (1) with a nitrogen-15 labelled nitrogen, and (2) with carbon-13
labelled ring carbons. The carbon-13 to X (where X=nitrogen-15, carbon-13 or
hydrogen-I) spin-spin coupling constants were measured and interpreted in terms
of stereoelectronic effects. X-ray crystallographic data (earlier determined for cisand
trans-1-cyclohexyl-2-phenyl-3-(p-toluyl)aziridines)1 appear in good agreement
with the NMR data. Bonding is discussed for the three-ring itself (NMR studies)
and for its substituents (X-ray studies). It is concluded that stereochemical interaction
of the Van der Waals type is an important determinant of aziridine bond
length. Three-ring to carbonyl hyperconjugation is correlated with stereoelectronic
interactions in the trans isomer