A Novel Tetranuclear Copper(II) Complex with Alternating 1,1-Azido and Phenoxo Bridges: Synthesis, Structure, and Magnetic Properties of [Cu4(-salen)2((mu)1,1-N3)2(N3)2]

A novel tetranuclear copper(II) complex containing alternating (mu)1,1-azido and monophenoxo bridges has been synthesized and characterized by spectroscopic methods, X-ray single-crystal analysis, and variable-temperature magnetic measurements. The magnetic behavior, investigated in the temperature range 2-300 K, indicates that the interactions between copper ions are antiferromagnetic in nature for both azido and phenoxo bridges. The temperature dependence of the magnetic susceptibility was fitted with J1 = -12.8 cm^ -1, J2 = -10 cm^-1, g = 2.171, 2.1% paramagnetic component, and negligible temperature-independent paramagnetism (5 × 10^-8). At variance with the earlier reports of these types of complexes containing a (mu)1,1-azido group, the end-on double-azido-bridged copper(II) center in this complex shows an antiferromagnetic interaction.