The bispyrimidine metal chlorides, MCl 2 (pym) 2 M = Fe, Co, Ni and MBr 2 (pym) 2 M = Co, unlike most materials in this family adopt 3D chiral diamondoid structures. MCl 2 (pym) all magnetically order with canted AFM structures, T N = 7.4 K, 4.7 K and 16.3 K for M = Fe, Co and Ni respectively, likely arising from the interplay between the superexchange interactions and the significant single-ion anisotropy, the principal axes of which are non-collinear. Bulk susceptibility studies have shown enhancement of T N at moderate pressure (∆T N /T N = 15% at 0.7 GPa), which suggests that high pressure investigations of Cr-based MOMs may also uncover pressure-switchable magnetic functionality. The presence of a JT distortion is strong evidence of Cr 2+ , which stands in contrast to the related CrCl 2 (pyrazine) 2 , in which Cr 2+ spontaneously reduces the ligated pyrazine to a radical anion, and thereby dramatically enhancing its conductivity and magnetic superexchange. The sensitivity of this metal-ligand redox to the coordination sphere is shown by Cr(OSO 2 CH 3 ) 2 (pyrazine) 2 , in which Cr remains as Cr 2+ with a JT distortion. Studies of molecular complexes have shown this non-innocent behaviour is favoured by a strong ligandfield environment and a low energy ligand LUMO, and is consistent with the observed innocence of CrCl 2 (pym), which has both weaker ligand field than CrCl 2 (pyz) 2 and a higher energy ligand LUMO (pyrazine, E red = +1.10 V and pym E red = +0.84 V vs. Li/Li + ). Our data clearly show that CrCl 2 (pym) has a conventional Néel AFM ground state, T N = 20.0(3) K, but also that there is significant magnetic low-dimensionality above T N .