Three trinuclear Cu–M–Cu (M = Co, Ni and Zn) complexes including macrocyclic oxamido bridge: Synthesis, structures and magnetic properties

Based on the complex ligand (CuL H2L = 2,3-dioxo-5,6:15,16-dibenzo-1,4,8,13-tetraazacyclotetradeca-7,13-diene), which includes macrocyclic oxamido bridge, three trinuclear complexes were prepared. They are of the formula [(CuL)2M(ClO4)2] (M = Co(1), Ni(2)) and [(CuL)2Zn(CH3OH)2] · (ClO4)2 (3). The crystal structures of the three complexes have been determined and the M(II) of the three complexes all exist on the mirror plane. Complex 1 is the first Cu–Co complex bridged by oxamido. Their magnetic properties were studied by susceptibility versus temperature measurement, the best fitting of the experimental data led to J = −28.12 cm−1 for 1, J = −42.88 cm−1 for 2, and J = −2.13 cm−1 for 3.