Wang Hui-Sheng, Yin Cheng-Ling, Hu Zhao-Bo, Chen Yong, Pan Zhi-Quan, Song You, Zhang Yi-Quan, Zhang Zai-Chao
School of Chemistry and Environmental Engineering, Key Laboratory of Green Chemical Process of Ministry of Education, Wuhan Institute of Technology, Wuhan 430074, P. R. China.
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210046, P. R. China.
Dalton Trans. 2019 Jul 21;48(27):10011-10022. doi: 10.1039/c9dt00774a. Epub 2019 Jun 7.
Four tetranuclear 3d-4f complexes, namely FeLn(L)(teaH)(Cl)·4CHCN (HL = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine, teaH = triethanolamine, Ln = Dy for 1 and Ln = Gd for 1') and CoLn(L)(pdm)(CHCOO)(CHOH)·xCHOH·yHO (pdmH = 2,6-pyridinedimethanol, Ln = Dy, x = 5 and y = 2.5 for 2 and Ln = Gd, x = 6 and y = 1.5 for 2'), have been reported. Two Fe and two Dy in 1 formed a zigzag Fe1-Dy1-Dy1a-Fe1a arrangement with a Fe1-Dy1-Dy1a angle of 105.328(3)°. However, in contrast to 1, two Co and two Dy ions in 2 formed a more linear Co1-Dy1-Dy1a-Co1a arrangement with a Co1-Dy1-Dy1a angle of 141.86(2)°. Additionally, two Dy ions in 1 are eight-coordinated with a triangular dodecahedron geometry, while two Dy ions in 2 adopt nine-coordination with a muffin geometry. Magnetic studies revealed slow magnetic relaxation behavior for 1, with an energy barrier E of 6.9 K. For 2, single molecule magnet behavior was presented under a zero dc field with an effective energy barrier U of 64.0(9) K. Ab initio calculations for 1 and 2 indicate that compared to 2, complex 1 has a larger transversal magnetic moment of its ground Kramers doublets (KD) and a larger value of the tunnelling parameter (Δ) for the exchanged coupled ground state, which may result in poor single molecule magnet behavior for 1.
已报道了四种四核3d-4f配合物，即FeLn(L)(teaH)(Cl)·4CHCN（HL = N1,N3-双(3-甲氧基水杨醛)二亚乙基三胺，teaH = 三乙醇胺，Ln = 镝时为1，Ln = 钆时为1'）和CoLn(L)(pdm)(CHCOO)(CHOH)·xCHOH·yHO（pdmH = 2,6-吡啶二甲醇，Ln = 镝，x = 5且y = 2.5时为2，Ln = 钆，x = 6且y = 1.5时为2'）。1中的两个铁和两个镝形成了锯齿状的Fe1-Dy1-Dy1a-Fe1a排列，Fe1-Dy1-Dy1a角为105.328(3)°。然而，与1不同的是，2中的两个钴和两个镝离子形成了更线性的Co1-Dy1-Dy1a-Co1a排列，Co1-Dy1-Dy1a角为141.86(2)°。此外，1中的两个镝离子为八配位，具有三角十二面体几何构型，而2中的两个镝离子采用九配位，具有松饼几何构型。磁性研究表明1具有缓慢的磁弛豫行为，能垒E为6.9 K。对于2，在零直流场下呈现单分子磁体行为，有效能垒U为64.0(9) K。对1和2的从头算计算表明，与2相比，配合物1的基态克莱默斯双态（KD）具有更大的横向磁矩，且交换耦合基态的隧穿参数（Δ）值更大，这可能导致1的单分子磁体行为较差。
