Pure Trinuclear 4f Single-Molecule Magnets: Synthesis, Structures, Magnetism and Ab Initio Investigation

A family of linear Dy-3 and Tb-3 clusters have been facilely synthesized from the reactions of DyCl3, the polydentate 3-methyloxysalicylaldoxime (MeOsaloxH(2)) ligand with auxiliary monoanionic ligands, such as trichloroacetate, NO3, OH, and Cl. Complexes 1-5 contain a nearly linear Ln(3) core, with similar Ln center dot center dot center dot Ln distances (3.6901(4)-3.7304(3) angstrom for the Dy-3 species, and 3.7273(3)-3.7485(5) angstrom for the Tb-3 species) and Ln center dot center dot center dot Ln center dot center dot center dot Ln angles of 157.036(8)-159.026(15)degrees for the Dy-3 species and 157.156(8)-160.926(15)degrees for the Tb-3 species. All three Ln centers are bridged by the two doubly-deprotonated [MeOsalox](2-) ligands and two of the four [MeOsaloxH](-) ligands through the N,O-eta(2)-oximato groups and the phenoxo oxygen atoms (Dy-O-Dy angles=102.28(16)-106.85(13)degrees; Tb-O-Tb angles=102.00(11)-106.62(11)degrees). The remaining two [MeOsaloxH](-) ligands each chelate an outer Ln(III) center through their phenoxo oxygen and oxime nitrogen atoms. Magnetic studies reveal that both Dy-3 and Tb-3 clusters exhibit significant ferromagnetic interactions and that the Dy-3 species behave as single-molecule magnets, expanding upon the recent reports of the pure 4f type SMMs.