A new μ1,5-dicyanamide bridged cyclic tetranuclear copper (II) complex with 1,5,9-triazacycledodecane ligands: structure, ESR spectroscopic and magnetic properties

The tetranuclear complex [Cu2L2(dca)2(ClO4)2]2 (1) (L = 1,5,9-triazacyclododecane, dca = dicyanamide [N(CN)2]−) has been synthesized and its crystal structure, ESR spectra and magnetic properties determined. The complex contains a tetranuclear copper (II) moiety in which two dimeric units are bridged by two dca ligands. In each dimeric moiety the two copper (II) ions are bridged by one μ1,5-dicyanamide ligand. Magnetic susceptibilities for the complex in the solid state are measured over the temperature range 4–300 K. The complex shows a weak antiferromagnetic coupling with a best fit J value −0.436 cm−1. The μ1,5-dicyanamide bridges are the principal pathway for the super-exchange interaction and the weak antiferromagnetic coupling of the complex is interpreted in term of the μ1,5-dicyanamide ligand behavior as a poor magnetic mediator.