Pyrazine-2-amidoxime Ni(II) Complexes: From Ferromagnetic Cluster to Antiferromagnetic Layer

Tetranuclear [Ni4(Hpzaox)2(pzaox)2(py)4](ClO4)2·2py (1), [Ni4(Hpzaox)2(pzaox)2(py)4](NO3)2·4py (2), and two-dimensional (2D) [Ni4(Hpzaox)2(pzaox)2(H2O)2](NO3)2·2H2O (3) are prepared via the reaction of NiX2·6H2O and pyrazine-2-amidoxime (H2pzaox). All compounds contain [Ni4(Hpzaox)2(pzaox)2]2+ fragments, which assemble to form a tetranuclear or polymeric network. Magnetic studies show that the tetranuclear compounds display usual ferromagnetic coupling via the oxime N−O bridges, and the 2D compound displays unusual antiferromagnetic behavior.