Polymeric Perturbation to the Magnetic Relaxations of the <i>C</i>_2<i>v</i>-Symmetric [Er(Cp)₂(OBu)₂]⁻ Anion

To test the coordination symmetry effect on the magnetization-reversal barrier trend of ErIII-based single-ion magnets, the C2v-symmetric organolanthanide anion [Er­(Cp)2(OtBu)2]− has been incorporated with different countercations, resulting in two structures, namely, the discrete [K2(Cp)­(18-C-6)2]­[Er­(Cp)2(OtBu)2] (1) and the polymeric [ErK2(Cp)3(OtBu)2(THF)2]n (2), where 18-C-6 = 18-crown-6 ether and Cp = cyclopentadienide. Surprisingly, the polymeric 2 exhibits much stronger field-induced magnetization relaxing behavior compared to the monomeric 1. Such disparate dynamic magnetism is attributable to the subtle coordination environmental perturbations of the central ErIII ions.