EPR characterization of half-integer-spin iron molecule-based magnets

We report single crystal high-frequency electron paramagnetic resonance studies of two recently discovered half-integer Fe7 complexes: [Fe7O3(O2CBut)9(mda)3(H2O)3] (1) and [Fe7O4(O2CPh)11(dmem)2] (2). The obtained spectra confirm spin S = 5/2 ground states for both complexes. On the basis of detailed frequency and field orientation dependent studies, we find that complex 1 is a single-molecule magnet (uniaxial zero-field-splitting parameter, D < 0) while complex 2 is not (D > 0). The EPR linewidth for complex 1 is considerably narrower in comparison to spectra obtained for other single-molecule magnets, suggesting the possibility of reduced decoherence from nuclear spins (56Fe has no nuclear moment).

Graphical abstractThe results of high frequency single crystal EPR studies of two recently discovered half-integer Fe7 complexes: [Fe7O3(O2CBut)9(mda)3(H2O)3] (1) and [Fe7O4(O2CPh)11(dmem)2] (2) are presented. The obtained spectra confirm spin S = 5/2 ground states for both complexes. Detailed frequency and field orientation dependent studies showed complex 1 is a single-molecule magnet (uniaxial zero-field-splitting parameter, D < 0) while complex 2 is not (D > 0). The EPR linewidth for complex 1 is considerably narrower in comparison to spectra obtained for other single-molecule magnets.Figure optionsDownload full-size imageDownload as PowerPoint slide