Slow Magnetization Relaxation in a Family of Triangular {Co₂^IIILn^III} Clusters: The Effect of Diamagnetic Co^III Ions on the Ln^III Magnetic Dynamics

The first use of the Schiff base chelate N-naphthalidene-o-aminophenol (naphH(2)) in Co/Ln chemistry has afforded a family of isostructural [Co(2)(III)Ln(III)(OMe)(2)(naph)(2)(O2CMe)(3)(MeOH)(2)] (Ln=Tb, Dy and Er) complexes, revealing a rare {Co(2)(III)Ln(mu(3)-OMe)}(8+) triangular core composed of two diamagnetic Co-III ions and a 4f-ion with slightly distorted square antiprismatic geometry. Alternating current (alpha c) magnetic susceptibility studies revealed that {Co2Dy}, and its magnetic diluted analogue {Co2Dy0.05Y0.95}, behave as mononuclear single-molecule magnets (SMMs) with similar energy barriers for the magnetization reversal, U-eff, of similar to 85-90 K. SMM properties were also detected for {Co2Er}, with the compound exhibiting a U-eff of 18.7 K under an applied magnetic field of 800 Oe. To interpret the experimental magnetic results, ab initio CASSCF/RASSI-SO and DFT calculations were performed as a means of exploring the single-ion characteristics of Ln(III) ions and comprehend the role of the diamagnetic Co-III ions in the magnetization relaxation of the three heterometallic compounds.