一维、二维氰根桥联Pd^(Ⅱ)/Fe^(Ⅲ)-Ni^(Ⅱ)配位聚合物的合成、结构及磁性研究

One-and Two-dimensional Cyanide-bridged Pd^(Ⅱ)/Fe^(Ⅲ)-Ni^(Ⅱ) Coordination Polymers:Synthesis,Crystal Structure and Magnetic Property

分别采用K_(2)[Pd(CN)_(4)]、K_(3)[Fe(CN)_(6)]与[Ni(L)](ClO_(4))_(2)(L=2,12-二甲基-3,7,11,17-四氮杂双环[11.3.1]十七碳-1(17),13,15-三烯)通过挥发或者扩散的方法获得两种氰根桥联异金属配合物{[Ni(L)][Pd(CN)_(4)]}_(n)(1)和{{[Ni(L)]_(2)Ni(H_(2)O)_(4)}[Fe(CN)_(6)]_(2)}_(n)(2),利用元素分析、傅里叶红外光谱、X射线单晶衍射等方法对配合物1、2进行组成及结构表征。单晶X射线衍射表明,在配合物1中,平面型四齿氰根前躯体利用其互为反式位置的两个氰根基团,作为双齿配体与镍离子发生配位,从而形成具有[-NC-Pd-CN-Ni(L_(1))-]重复结构单元的一维中性链结构。在配合物2中,六氰合铁离子作为三齿配体,利用其呈“T”型的三个氰根分别与两个平面大环镍单元和一个四水合镍离子轴向位置发生配位,从而形成FeNi_(3)阳离子结构单元,进而相互连接形成氰根桥联二维网状结构。对配合物1变温磁化率研究表明,通过抗磁性氰根前驱体桥联的二价镍离子之间呈现微弱的反铁磁相互作用。配合物2变温磁化率和变场磁化强度测试结果表明,通过氰根桥联的低自旋三价铁离子和高自旋二价镍离子之间存在铁磁耦合效应。低温区的高摩尔磁化率预示着配合物2在低温下可能存在三维磁有序行为。

Using K_(2)[Pd(CN)_(4)],K_(3)[Fe(CN)_(6)]and[Ni(L)](ClO_(4))_(2)(L=2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene)as assembling segments,two new cyanide-bridged heterobimetallic coordination polymers(CPs)formulated as{[Ni(L)][Pd(CN)_(4)]}_(n)(1)and{{[Ni(L)]_(2)Ni(H_(2)O)_(4)}[Fe(CN)_(6)]_(2)}_(n)(2)were prepared by slow evaporation or single tube diffusion methods,and characterized by elemental analysis,IR spectroscopy and X-ray structure determination.Single X-ray diffraction analysis shows that CPs-1 belongs to cyanide-bridged neutral one-dimensional chain structure,while CPs-2 can be structurally characterized as two-dimensional sheet,indicating that the structure of the cyanide precursors plays important role on the structural type of the target product.The temperature dependent magnetic susceptibility investigation revealed the weak antiferromagnetic coupling and strong ferromagnetic interaction between the paramagnetic metal ions in CPs-1 and 2,respectively.For CPs-2,the ferromagnetic coupling between the low spin Fe(Ⅲ)ion and high spin Ni(Ⅱ)ion through the cyanide bridge could be further confirmed by the field dependence of magnetization measurement.Additionally,the unexpectedly high magnetic susceptibility in low temperature range implied maybe the three-dimensional magnetic ordering in CPs-2.