CONFORMATIONAL DEPENDENCE OF SECONDARY BETA-DEUTERIUM ISOTOPE EFFECTS

The conformational dependence of secondary β-deuterium isotope effects on hypothetical reactions involving formation of the ethyl cation, ethyl radical, and ethyl anion from ethane has been investigated by means of ab initio molecular orbital theory. In all three systems the hyperconjugative componentof the calculated secondary isotope effect is found to closely follow a cos2 a relationship, a being the dihedral angle which theß CH bond makes with the vacant (half-filled or filled) orbital at the cation (radical or anion) center. © 1979, American Chemical Society. All rights reserved.