Complexes be due to a magnetic interaction between the two Eu(II) ions. For 1-Eu and 3-Eu, the experimental values lie approximately 1.6 cm 3 K mol -1 above that predicted by CASSCF, whereas there are closer agreements with the experimental and calculated values for 4-Eu, which differ from those predicted by 0.18 cm 3 K mol -1 . Analogously to 1-Sm, complex 1-Eu exhibits a χMT value of 17.35 cm 3 mol - 1 K at 300 K, which is in close agreement with the free ion value for two Eu(II) ions; the low temperature magnetization data are also consistent with spin-only ions. Hence, we focus our discussion on the solid-state spectra. The spectra for the monometallic complexes were simulated, using EasySpin, with the simple Zeeman and ZFS spin Hamiltonian: