Substituent effects on the through-space nuclear magnetic spin-spin coupling in van der Waals dimers

We have investigated the effect of substituents on the donor (benzene) and acceptor (C-H) moieties of CH/p interacting model systems 1-6, on the through-space nuclear spin-spin coupling JCH and JHH. These couplings were recently predicted, by ab initio and DFT calculations, to be of the order of 0.2-0.3 Hz at the equilibrium separation. Electronic effects due to the substitution are found not to increase significantly, and often to decrease, the calculated coupling, since they involve mainly p orbitals while the coupling is mainly transmitted through s orbitals