Ferrocene-Substituted [Mn4] Dicubane Single-Molecule Magnets

Two new mixed-valent [Mn-4] single-molecule magnets (SMMs) have been synthesized by using N-alkylated diethanolamine ligands and ferrocenecarboxylic acid. Both complexes exhibit weak ferromagnetic exchange and appreciable axial zero-field splitting as evidenced by DC magnetic susceptibility and field-dependent magnetization measurements. A significant frequency-dependent out-of-phase signal in the AC susceptibility is also observed for both complexes, a feature that is characteristic of SMMs. The ground-state spin of each complex was determined from the DC data and extrapolation of the low-frequency AC data, giving a value of S = 8. This result is consistent with the previously reported and structurally similar S = 8 and S = 9 [Mn-4] dicubane SMMs. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)