Theoretical additivity in multipath 13C, 1H coupling constants

Different path contributions to the Fermi contact term of carbon‐hydrogen coupling constants in several bicycloalkanes were calculated using the ‘inner projections of the polarization propagator’ (IPPP) approach. The ground‐state wave functions were calculated at the INDO level of approximation. Three and four‐bond contributions to the couplings, and the through‐space transmission via the rear lobes of the CX (X  H, F) bonds attached to the bridgehead carbon atoms, were calculated. The additivity of these contributions compared with the total INDO couplings is good. Similar paths in different molecules give dissimilar contributions to the couplings.