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A new family of Fe4Ln4 (Ln = DyIII, GdIII, YIII) wheel type complexes with ferromagnetic interaction, magnetocaloric effect and zero-field SMM behavior
Inorganic Chemistry Frontiers ( IF 6.1 ) Pub Date : 2021-08-17 , DOI: 10.1039/d1qi00781e
Arpan Mondal 1 , Mukul Raizada 1 , Pradip Kumar Sahu 1 , Sanjit Konar 1
Affiliation  

In this work, we report three isostructural Fe4Ln4 wheel type complexes with molecular formula [{Fe4(dea)4Dy4(deaH)82-OMe)4}(NO3)4]·4(H2O) (1), [{Fe4(dea)4Gd4(deaH)82-OMe)4}·(NO3)4]·4(H2O)·4(MeOH) (2) and [{Fe4(dea)4Y4(deaH)82-OMe)4}(NO3)4]·4(H2O)·6(MeOH) (3), (where dea = diethanolamine). Detailed structural analysis discloses that the 4LnIII and 4FeIII ions are connected alternatively in a cyclic arrangement through the oxo-bridging of methanol and diethanolamine molecules. The detailed magnetic measurements reveal the presence of ferromagnetic exchange interactions between the LnIII and FeIII centers in complexes 1 and 2, whereas a weak antiferromagnetic interaction is observed between FeIII centers in complex 3. In addition, complex 1 shows slow magnetic relaxation behavior (Ueff = 9.8 K) under zero field and a remarkable entropy change was observed for complex 2 at 7 T magnetic field (magnetocaloric effect = 31.15 J kg−1 K−1). The ab initio calculations disclose the presence of strong axial anisotropy and a minimum transverse component (gx = 0.0024, gy = 0.0062, and gz = 19.82) in the ground state of each DyIII ion for complex 1. It was also found that the local anisotropy axis on each DyIII ion is arranged in a vortex-like structure as observed in single molecule toroics (SMTs). From BS-DFT calculations, it was found that the exchange interactions between Fe–Ln metal centers mainly follow the charge transfer process between 3d and 4f orbitals.

中文翻译:

具有铁磁相互作用、磁热效应和零场 SMM 行为的新系列 Fe4Ln4(Ln = DyIII、GdIII、YIII)轮型配合物

在这项工作中,我们报告三种同构的Fe 4 LN 4轮型配合物与分子式[{的Fe 4(DEA)4的Dy 4(DEAH)8(μ 2 -OMe)4 }(NO 34 ]·4(H 2 O) ( 1 ), [{Fe 4 (dea) 4 Gd 4 (deaH) 82 -OMe) 4 }·(NO 3 ) 4 ]·4(H 2 O)·4(MeOH) ( 2 ) 和 [{Fe 4 (dea) 4 Y4 (deaH) 8 2 -OMe) 4 }(NO 3 ) 4 ]·4(H 2 O)·6(MeOH) ( 3 ),(其中dea = 二乙醇胺)。详细的结构分析表明,4Ln III和 4Fe III离子通过甲醇和二乙醇胺分子的氧桥连以环状排列交替连接。详细的磁测量揭示了配合物12中Ln III和Fe III中心之间存在铁磁交换相互作用,而在Fe之间观察到弱反铁磁相互作用。III中心在复合体3 中。此外,配合物1在零场下表现出缓慢的磁弛豫行为( U eff = 9.8 K),并且在7 T磁场下观察到配合物2的显着熵变化(磁热效应= 31.15 J kg -1 K -1)。的从头计算披露强轴向各向异性的存在和最小横向分量(X = 0.0024,ÿ = 0.0062,和ž每个的Dy的基态= 19.82) III离子对络合物1. 还发现每个 Dy III离子上的局部各向异性轴排列成涡旋状结构,如在单分子环面 (SMT) 中观察到的那样。从 BS-DFT 计算发现,Fe-Ln 金属中心之间的交换相互作用主要遵循 3d 和 4f 轨道之间的电荷转移过程。
更新日期:2021-09-07
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