Syntheses, structure and magnetic properties of oxamido-bridged trinuclear Cu–M–Cu macrocyclic complexes (M = Cu, Co and Mn)

Three isomorphic oxamido-bridged trinuclear complexes of formulae [Cu(CuL(EtOH))2] · (EtOH)2(ClO4)2(H2O)0.5 (1), [Co(CuL(EtOH))2(EtOH)2] · (ClO4)2(H2O)0.5 (2), and [Mn(CuL(EtOH))2(EtOH)2] · (ClO4)2(H2O)0.5 (3) (H2L = 2,3-dioxo-5,6:13,14-dichlorobenzo-7,12-diphenyl-1,4,8,11-tetraazacyclotetradeca-7,11-diene) have been synthesized and structurally characterized. The central ions of complexes 1–3 (Cu, Co, Mn) are all bridged by macrocyclic oxamido groups. The χM and μeff vs T plots in the 1.8–300 K range for the three complexes exhibit antiferromagnetic coupled (based on isotropy image), with the best fit J = −188.85, −25.64 and −14.26 cm−1, respectively. The values of magnetic exchange interactions through oxamido-bridge show: Cu–Cu > Cu–Co > Cu–Mn.