Self-Consistent Field Spin-Orbit (CASSCF-SO) calculations (Selected parameters compiled in Table , see SI Figures S58-S69 for all magnetic data). In general, there is reasonable agreement between the measured and calculated susceptibility values as well as those for the respective free ion values (Sm(II) 4f F0; Eu(II) 4f S7/2) for all complexes, though calculated values for 1-Sm, 3-Sm and 4-Sm are slightly higher than predicted due to the thermal population of the lowest-lying FJ excited states; the shapes of the calculated curves are accurately reproduced. Complex 1-Sm exhibits a χMT value of 3.09 cm 3 mol -1 K at 300 K, which is in close agreement with the free ion value for two Sm(II) ions.