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Keywords:

  • Copper;
  • Schiff bases;
  • Magnetic properties

Abstract

The phenoxo-bridged dinuclear CuII complex [Cu2L2(NCNCN)2] (1) and the dicyanamide-bridged molecular rectangle [Cu4L41,5-(NCNCN)2}]·(ClO4)2(H2O)2 (2) were synthesized using the tridentate reduced Schiff-base ligand HL {2-[(2-dimethylamino-ethylamino)methyl]phenol}. The complexes were characterized by X-ray structural analyses and variable-temperature magnetic susceptibility measurements. Complex 2 was formed through the joining of the phenoxo-bridged dinuclear Cu2O2 cores of 1 via the μ1,5-bridging mode of dicyanamide. The structural properties of the Cu2O2 cores in two complexes are significantly different. The geometry of the copper ions is distorted trigonal bipyramid in 1 but is nearly square-pyramidal in 2. These differences have a marked effect on the magnetic properties of two compounds. Although both are antiferromagnetically coupled, the coupling constants (J = –185.2 and –500.9 cm–1 for 1 and 2, respectively) differ considerably.