title: Pyrazine-2-amidoxime Ni(II) complexes: from ferromagnetic cluster to antiferromagnetic layer.
abstract: Tetranuclear [Ni(4)(Hpzaox)(2)(pzaox)(2)(py)(4)](ClO(4))(2)·2py (1), [Ni(4)(Hpzaox)(2)(pzaox)(2)(py)(4)](NO(3))(2)·4py (2), and two-dimensional (2D) [Ni(4)(Hpzaox)(2)(pzaox)(2)(H(2)O)(2)](NO(3))(2)·2H(2)O (3) are prepared via the reaction of NiX(2)·6H(2)O and pyrazine-2-amidoxime (H(2)pzaox). All compounds contain [Ni(4)(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.
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing, People's Republic of China.
authors.forename: Guang-Yu
authors.initials: GY
authors.lastname: An
authors.forename: Cong-Min
authors.initials: CM
authors.lastname: Ji
authors.forename: Ai-Li
authors.initials: AL
authors.lastname: Cui
authors.forename: Hui-Zhong
authors.initials: HZ
authors.lastname: Kou