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

Abstract: 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 χ M and μ eff vs T plots in the 1.8–300K range for the three complexes exhibit antiferromagnetic coupled (based on isotropy ), with the best fit J =−188.85, −25.64 and −14.26cm−1, respectively. The values of magnetic exchange interactions through oxamido-bridge show: Cu–Cu>Cu–Co>Cu–Mn. [Copyright &y& Elsevier]