Synthesis, structures and characterization of the dinuclear nickel(II) complexes containing N,N,N′,N′-tetrakis[(1-ethyl-2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane and an azide ion

Two dinuclear nickel(II) complexes, [Ni2(L-Et)(N3)(H2O)3](NO3)2 · 2H2O (1) and [Ni2(L-Et)(μ-1,3-N3)(H2O)2](NO3)2 · 4H2O (2) containing (HL-Et = N,N,N′,N′-tetrakis[(1-ethyl-2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane), have been synthesized and characterized by their IR and UV–Vis spectra and magnetic susceptibilities. The crystal structures of [Ni2(L-Et)(N3)(H2O)3](NO3)2 · CH3OH (1′) and [Ni2(L-Et)(μ-1,3-N3)(H2O)2](NO3)2 · 2C2H5OH (2′) similar to 1 and 2 were determined by X-ray crystallography. In 1′, the two nickel(II) ions are bridged by only an alkoxo group of L-Et−, while an azido and an alkoxo connect two nickel(II) ions in 2′. Magnetic susceptibility measurements (2–300 K) showed a weak ferromagnetic exchange coupling between the two nickel(II) ions (2J = 10.1 cm−1) for 1. On the other hand, antiferromagnetic interactions were observed for 2 (2J = −15.8 cm−1).