Empirical Additivity of Coupling Pathways in Bicycloalkanes

Abstract

Multipath couplings involving ¹H-¹H, and ¹³C-¹³C nuclei in a variety of 1-substituted bicycloalkanes are treated according to additivity principles based on empirical coupling increments derived from model hydrocarbons. The coupling constants are essentially additive in practically all series except for derivatives of bicyclo [1.1.1]pentane; non-additivities of several couplings in the latter are ascribed to the effects of contributions arising from through-space bridgehead-bridgehead interactions, as well as from mutual electronic perturbations between the different pathways. The results are compared with those derived previously from theoretical calculations, which also have some difficulty in reproducing the experimental data in the case of the bicyclo [1.1.1] pentyl system.