comprising Heisenberg exchange, J ij , for the three nearest neighbours (i.e. along the CrCl 2 through the pym ligand and between layers) and a single ion anisotropy, D (Fig. ). We began by estimating the approximate values for each of J 1 , J 2 , J 3 and D using our bulk magnetic measurements and extrapolating from analogous compounds. These initial parameters were then optimised using least square requirements of the calculated spectrum, including a refined multiplicative scale factor and a background linear in both Q and ∆E, against the experiment data which gave J 1 = -1.13(4) meV, J 2 = 0.10( ) A grid search was undertaken to confirm this as a unique solution. Our experimental spectra were consistent with a negligible value for J 3 , however the ground state determined by PND indicates that J 3 must be ferromagnetic. The ratio of J 1 /J 2 = 11 (2) indicates that the magnetic interactions in this materials are primarily one-dimensional. We therefore decided to investigate the spectrum of CrCl 2 (pym) in the short-range ordered regime to search for coherent excitations (Fig. ). Energy cuts, integrated over momentum transfer, 0.76 < Q < 1.84 Å -1 , showed no clear evidence of a gap in the paramagnetic regime, for both E i = 12.14 meV and E i = 3.70 meV, suggesting this material is not within the Haldane phase (Fig. ), although the comparatively high temperature compared to the expected gap size, T /∆ = 25 will make this challenging.