| Sumario: | Abstract: A recently developed method for calculating NMR J coupling in solid-state systems is applied to calculate hydrogen-bond-mediated J couplings across intra- or intermolecular N-H∙∙∙N hydrogen bonds in two 6-aminofulvene-1-aldimine derivatives and the ribbon structure formed by a deoxyguanosine derivative. Excellent quantitative agreement is observed between the calculated solid-state J couplings and those previously determined experimentally in two recent spin-echo magic-angle-spinning NMR studies (Brown, S. P.; et al. Chem. Commun.2002, 1852-1853 and Pham, T. N.; et al. Phys. Chem. Chem. Phys. 2007, 9, 3416-3423). For the 6-aminofulvene-1 -aldimines, the differences in 2hJNN couplings in pyrrole and triazole derivatives are reproduced, while for the guanosine ribbons, an increase in 2hJNN is correlated with a decrease in the N-H∙∙∙N hydrogen-bond distance. Jcouplings are additionally calculated for isolated molecules of the 6-aminofulevene-1 -aldimines extracted from the crystal with and without further geometry optimization. Importantly, it is shown that experimentally observed differences between J couplings determined by solution- and solid-state NMR are not solely due to differences in geometry; long-range electrostatic effects of the crystal lattice are shown to be significant also. J couplings that are yet to be experimentally measured are calculated. Notably, J couplings across N-H∙∙∙N hydrogen bonds are found to be of a similar magnitude to J couplings, suggesting that their utilization and quantitative determination should be experimentally feasible.
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