Static magnetic properties of [Co(1-3)](ClO4)2. The static magnetic properties of [Co(1-3)](ClO4)2 were assessed by direct current (DC) susceptibility and magnetization measurements on the pelletized samples previously measured by HFEPR (Figure and Supplementary Information Figures ). The measured room temperature χT values of 1.90, 2.45, 2.24 cm 3 K mol -1 for [Co(1-3)](ClO4)2, respectively, are slightly higher than the value of χT = 1.88 cm 3 K mol -1 expected for S = 3/2 systems with g = 2 in the spinonly approximation, but lie in the typical range for five-coordinated Co II complexes with second-order SOC. The magnitude and thermal dependence of χT (Figure ) for [Co( )](ClO4)2 and [Co(3)](ClO4)2 confirms the HS state as the dominant state of these complexes, and the slightly smaller χT measured for [Co(3)](ClO4)2 compared to [Co( )](ClO4)2 is consistent with the higher amount of LS present in this sample (Figure ), which is in turn consistent with the predictions from molecular modelling.