Lanthanide Triangles Supported by Radical Bridging Ligands.

The first examples of metallacycles containing rare earth ions bridged by radicals are reported. The molecular triangles [Ln3(hfac)6(bptz•-)3] (Ln = DyIII, YIII; hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; bptz = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine) consist of lanthanide ions bridged by bptz radical anion (bptz•-) ligands. Magnetic susceptibility measurements and CASSCF calculations performed on [Dy3(hfac)6(bptz•-)3] reveal the presence of antiferromagnetic coupling between the DyIII centers and the bptz•- ligands, with J = -6.62 cm-1.