peak position, with an isotropic correlation length at 30 K λ = 2.8(2) Å. To measure the parameters of the magnetic Hamiltonian and search for signatures of lowdimensional magnetism, we collected INS spectra on the same powder sample of CrCl 2 (pym) at 1.7 and 25 K using the LET spectrometer at ISIS, using rep-rate multiplication to measure at multiple E i simultaneously (E i = 12.14, 3.70, 1.77 meV). The spectra collected at 1.7 K show a clear excitation centred at ∆E = 4.1(2) meV with an energy gap of 2.2(1) meV (Fig. ) despite the presence of an elevated background due to the incoherent 1 H scattering.