Synthesis, structure and magnetic properties of trinuclear transition metal complexes based on pyridine-2-amidoxime

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• 作者：Guang-Yu An^a ; Bin Yuan^a ; Jun Tao^b ; ^{taojun@xmu.edu.cn} ; Ai-Li Cui^a ; Hui-Zhong Kou^a ; ^{kouhz@mail.tsinghua.edu.cn}
• 关键词：Oximato bridges ; Magnetic properties ; Polynuclear complexes ; Transition metal ; Crystal structure
• 刊名：Inorganica Chimica Acta
• 出版年：2012
• 期刊代码：40_00201693
• 类别：ch
• 出版时间：30 May, 2012
• 卷：387
• 期：Complete
• 页码：401-406
• 文件大小：323 K

摘要

Four oximato-bridged trinuclear complexes [Ni^II₂(Hpyaox)₆Mn^IV]Cl路ClO₄路6H₂O (1), [Ni^II₂(Hpyaox)₆Mn^IV](ClO₄)₂路2DMF路4H₂O (2), [Ni^II₂(Hpyaox)₆Cr^III]ClO₄路6H₂O (3) and [Ni^II₂(Hpyaox)₆Fe^III]ClO₄路6H₂O (4) based on pyridine-2-amidoxime (H₂pyaox) were prepared in water-DMF solution. X-ray diffraction analysis reveals that they are isomorphous, and consist of linear triply oximato-bridged Ni^II₂Mn^IV (1 and 2), Ni^II₂Cr^III (3) and Ni^II₂Fe^III (4) cations with Mn^IV, Cr^III and Fe^III ions at the centre. The Ni(II) ion is coordinated by three mono-deprotonated Hpyaox^{鈭?/sup> anions, giving a [Ni(Hpyaox)₃]鈭?/sup> anion. Two [Ni(Hpyaox)₃]鈭?/sup> anions coordinate to the central M(III/IV) ion with six oximato oxygen atoms, yielding the trinuclear unit. The magnetic susceptibility measurements show that complexes 1-4 exhibit antiferromagnetic interaction between adjacent metal ions through the triple oximato bridges. By comparison, the unusual antiferromagnetic property of complexes 1-3 has been found to be related to the distortion of the NiN₆ coordination configuration from octahedral to trigonal. The magnetic data were fitted by considering the magnetic coupling between adjacent ions, two terminal ions and nearest molecules, respectively.}