Departamento de Química Inorgánica, Universidad de Granada, 18071, Granada, Spain.
Dalton Trans. 2009 Oct 28(40):8538-47. doi: 10.1039/b903986d. Epub 2009 Aug 25.
The double stranded Cu(II)2-metallacyclic complex of formula [Cu2(mbpb)2].2H2O (1) and the triple stranded Ni(II)2-metallacyclic complexes of formula [Ni2(Hmbpb)3]PF6.21H2O (2), [Co(H2O)6][Ni2(mbpb)3)]THF.10H2O (3) and {Ag2(H2O)[Ni2(mbpb)3]}.11H2O (4) (where H2mbpb is the bisbidentate dinucleating bridging ligand 1,3-bis(pyridine-2-carboxamide) benzene) have been synthesised and characterised by single-crystal X-ray diffraction. Within the dinuclear molecules, metal ions are bridged by either fully or semideprotonated bisbidentate ligands, which are coordinated through the pyridine and amidato nitrogen donor atoms. In complex 4 the triple stranded dinuclear Ni2 units are connected to the Ag+ cations through O-amidato bridges and Ag-pi(benzene) interactions to afford a 1D bimetallic chain. Cu2 (1) and Ni2 (2-4) complexes exhibit ferromagnetic coupling between the metal ions through the bridging ligand with J(Cu-Cu) = 21.1 cm(-1) and J(Ni-Ni) in the range of 2.9-3.6 cm(-1), respectively. Amongst copper(II) dinuclear complexes bearing m-phenylenediamidato bridges, complex 1 exhibits the stronger ferromagnetic exchange coupling reported so far. DFT calculations firstly confirm that the spin polarisation mechanism is responsible for the ferromagnetic coupling, and secondly allows us to predict stronger ferromagnetic couplings in Cu(II)(2) complexes with larger tetrahedral distortions of the CuN4 coordination environment.
具有不同桥联配体的二核和三核铜（II）和镍（II）金属环配合物的结构和磁性
具有式[Cu2(mbpb)2]·2H2O（1）的双链 Cu(II)2-金属环配合物和式[Ni2(Hmbpb)3]PF6·21H2O（2）、[Co(H2O)6][Ni2(mbpb)3)]THF·10H2O（3）和{Ag2(H2O)[Ni2(mbpb)3)]·11H2O（4）的三链 Ni(II)2-金属环配合物（其中 H2mbpb 是双齿双核桥联配体 1,3-双（吡啶-2-甲酰胺）苯）已经通过单晶 X 射线衍射合成和表征。在双核分子中，金属离子通过完全或半去质子化的双齿桥联配体桥接，这些配体通过吡啶和酰胺氮供体原子配位。在配合物 4 中，三链双核 Ni2 单元通过 O-酰胺桥和 Ag-π（苯）相互作用与 Ag+阳离子连接，形成一维双金属链。Cu2（1）和 Ni2（2-4）配合物通过桥联配体表现出金属离子之间的铁磁耦合，J（Cu-Cu）=21.1cm-1，J（Ni-Ni）在 2.9-3.6cm-1 范围内。在具有 m-苯二胺桥的铜（II）双核配合物中，配合物 1 表现出迄今为止报道的更强铁磁交换耦合。DFT 计算首先证实了自旋极化机制是铁磁耦合的原因，其次允许我们预测 CuN4 配位环境的四面体扭曲较大的 Cu(II)(2)配合物具有更强的铁磁耦合。
