The double stranded CuII2-metallacyclic complex of formula [Cu2(mbpb)2]·2H2O (1) and the triple stranded NiII2-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–π(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 JCu–Cu = 21.1 cm−1 and JNi–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 CuII2 complexes with larger tetrahedral distortions of the CuN4 coordination environment.
式为[Cu2(mbpb)2]-2 (1)的双链 CuII2-
金属环配合物以及式为[Ni2(Hmbpb)3]PF6-21 (2)的三链 NiII2-
金属环配合物、[Co(
H2O)6][Ni2(mbpb)3]THF-10 (3)和Ag2( )[Ni2(mbpb)3]}-11 (4)(其中 H2mbpb 是 1,3-双(
吡啶-2-甲酰胺)苯的双二核桥接
配体),并通过单晶 X 射线衍射进行了表征。在双核分子中,
金属离子与完全或半质子化的双配位体桥接,配位体通过
吡啶和脒基氮供体原子配位。在复合物 4 中,三股双核 Ni2 单元通过 O-脒桥和 Ag-π(苯)相互作用与 Ag+ 阳离子相连,形成一维双
金属链。Cu2 (1) 和 Ni2 (2-4) 复合物通过桥接
配体显示出
金属离子之间的
铁磁耦合,JCu-Cu = 21.1 cm-1 和 JNi-Ni 分别在 2.9-3.6 cm-1 范围内。在含有
间苯二胺桥的
铜(II)双核配合物中,配合物 1 显示出迄今为止所报道的更强的
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,其次使我们能够预测在 CuN4 配位环境的四面体畸变较大的 CuII2 复合物中会产生更强的
铁磁耦合。