The compound CrCl 2 (pym) is most similar to, both structurally and magnetically, is CrCl 2 , 26 which also has quasi-1D antiferromagnetic CrCl 2 chains formed from edge-sharing octahedra (J 1 = -1.13 (13) meV, D = -0.11(2) meV). However, closer examination reveals significant structural differences that make these magnetic similarities quite surprising. In CrCl 2 (pym) the JT distortion means every superexchange pathway within the CrCl 2 spin chain passes through a significantly lengthened bond, whereas in CrCl 2 the equivalent JT distortion lies out of the spin-chain plane and so all Cr-Cl bonds in the chain are short. Superexchange through a JT-lengthened pathway is ordinarily weak, as is indeed found for the direction perpendicular to the CrCl 2 spin chain in inorganic CrCl 2 , with an order of magntiude weaker exchange J 2 = -0.12(7) meV.