Studies on tetranuclear copper (II) complexes of a macrocyclic ligand bearing 2-thiophenoethylamine pendant arms

Two new tetranuclear copper (II) macrocyclic complexes, [Cu4L(OAc)2(OH)2](ClO4)2·2MeCN 1 and [Cu4L (OAc)2(OH)2](PF6)2(H2O)2 2, have been obtained via condensation of 2,6-diformyl-4-methylphenolate with N,N′-bis(3-aminopropyl)-2-thiophenoethylamine in the presence of copper (II) ions. The complexes were characterized by IR, ES-MS and X-ray diffraction techniques. It shows the similar chair-shaped Cu4O4 core structure for these two macrocyclic complexes, which is composed of two kinds of crystallographically independent Cu(II) ions. The coordination spheres of the Cu(II) ions are distorted square pyramid and approximate square-planar configuration, respectively. In addition, it was found that the crystal structures are stabilized by abundant hydrogen bonds between perchlorate anions and adjacent macrocyclic units for complex 1. The network structure of 2 was maintained by π–π stacking of thiopheno groups and CH···F hydrogen bond interactions between adjacent macrocycles. The variable temperature magnetic susceptibility of complex 1 was measured in the temperature range of 2–300 K. The best fitting with a quasi-butterfly magneto-structural model gave the magnetic exchange parameters of Jbb = −197.6 cm−1, Jwb1 = −60 cm−1 and Jwb2 = 103.5 cm−1.