Spin Frustration in Triangular Cu3(II) Complexes with 6-Methyl-2-pyridyloxime as Ligand - Synthesis, Structural and Magnetic Characterization

In the present work, new examples of μ3-OH/oximato Cu3 triangles have been obtained by treatment of different copper salts with 6-methyl-2-pyridylaldoxime [6-MepyC(H)NOH, 6-mepaoH]. Depending on the anion, the compounds [Cu3(OH)(6-mepao)3(O2CPh)2] (1), [Cu6(OH)2(6-mepao)6(NO3)3](NO3)·H2O (2·H2O) and [Cu6(OH)2(6-mepao)6(ClO4)3](ClO4) (3) formed and were characterized. Complex 1 is an isolated triangle, whereas 2 and 3 are hexanuclear compounds with two triangular subunits linked by anionic bridges. Susceptibility measurements show very strong antiferromagnetic interactions and the presence of antisymmetric exchange at low temperature. The magnetic properties of these frustrated triangles have been analyzed in terms of susceptibility, magnetization and electron paramagnetic resonance (EPR) experiments.