Radical cations of disubstituted cyclopropanes: stereoelectronic effects on hyperfine coupling

The positive hyperfine coupling constants of the geminal 1H nuclei in cis-1,2-dimethyl- and cis-1,2-diphenylcyclopropane radical cations show a significant stereoelectronic effect: the 1H nuclei trans (anti) to the substituents are coupled much more strongly than the corresponding nuclei cis (syn) to them. Theoretical calculations on these radical cations and on bismethano[2,2]paracylophane as well as new 1H-CIDNP experiments at 200 Mz elucidate the general features of these systems. Copyright © 2014 John Wiley & Sons, Ltd.