Mononuclear Lanthanide Complexes: Energy-Barrier Enhancement by Ligand Substitution in Field-Induced Dy SIMs.

The sequential reaction of 2-((6-(hydroxymethyl)pyridin-2-yl)-methyleneamino)phenol (LH), LnCl·6HO, and 1,1,1-trifluoroacetylacetone (Htfa) in the presence of EtN afforded [Ln(LH) (tfa)] [Ln = Dy (1), Ln = Tb (2), and Ln = Gd (3)], while under the same reaction conditions, but in the absence of the coligand, another series of mononuclear complexes, namely, [Ln(LH)]·Cl·2MeOH] [Ln = Dy (4) and Tb (5)] are obtained. Single-crystal X-ray diffraction analysis revealed that the former set contains a mono-deprotonated [LH] and two tfa ligands, while the latter set comprises of two mono-deprotonated [LH] ligands that are nearly perpendicular to each other at an angle of 86.9°.