Despite this low-dimensionality, our data indicate that like other S = 2 candidate AFM chains, CrCl 2 (pym) does not show clear Haldane physics. The presence of long range order at T N /J 1 = 1.5 hinders observations at low temperatures and the non-negligible single ion anisotropy (D = -0.15(3) meV, D/J 1 = 0.13(2)) is sufficient to suppress the Haldane phase, for which the critical value is predicted to be D/J 1 = 0.04. CrCl 2 (pym) is therefore comparable to the other identified candidate S = 2 spin chains in both of these parameters, including CrCl 2 , 26 MnCl 3 (bipy) and CsCrCl 3 , 71 but none have shown clear evidence of a gapped inelastic neutron spectrum in the disordered phase.