Calculations. 1 J C1,C2 values in 1 c were calculated in Gaussian16 as described previously. The Fermi contact, diamagnetic and paramagnetic spin-orbit, and spin-dipole 50 terms were calculated using the B3LYP functional and a [5s2p1d|3s1p] basis set, and the reported calculated 1 J C1,C2 values were unscaled. The J-coupling calculations included the effect of solvent water, which was treated using the Self-Consistent Reaction Field Figure . (A) Plot of calculated 1 J C1,C2 values as a function of q 2 in 1 c (black), 2 c (blue), 3 c (purple), 4 c (green) and 5 c (lime). The curves were generated from eqs. [2], [3], [4], [5] and [6], respectively. The shaded grey area shows the range of 1 J C1,C2 values observed experimentally (Table ). (B) Data shown in (A) fit to give a generalized equation (eq. [9]). (SCRF) and the Integral Equation Formalism (polarizable continuum) model (IEFPCM) as implemented in Gaussian16.