Mondal Arpan, Kharwar Ajit Kumar, Sahu Pradip Kumar, Konar Sanjit
Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass road, Bhauri, Bhopal, 462066, MP, India.
Chem Asian J. 2020 Sep 1;15(17):2681-2688. doi: 10.1002/asia.202000666. Epub 2020 Jul 21.
Herein, we report a CN-bridged alternating Fe -Ni 1D chain to ensure the alignment of axial anisotropy and improve the single molecule magnet (SMM) behavior in seven coordinated Fe compound. The chain was constructed from hepta coordinated Fe(II) complex as an anisotropic building unit and diamagnetic nickel tetra cyanate as a bridging ligand. The magnetic measurements show the easy-axis anisotropy of the seven coordinated Fe(II) complex and field induced SMM behavior with spin reversal energy barrier U =61(2) K (42 cm ) and pre-exponential relaxation time τ =1.9×10 s. The detailed analysis of the relaxation dynamics discloses that the Orbach process plays an important role in slow relaxation of magnetization for this compound. Notably, this example represents a remarkable energy barrier observed in hepta coordinated Fe(II) SMMs. The ab initio calculations estimate the magnitude of axial anisotropy and show the parallel orientation of the anisotropic axis throughout the 1D polymeric chain. In addition, it is also reported that the presence of weak π accepter ligands in the distorted axial position enhance the easy-axis anisotropy.
在此，我们报道了一种由氰基桥连的交替铁 - 镍一维链，以确保轴向各向异性的排列，并改善七配位铁化合物中的单分子磁体（SMM）行为。该链由七配位的铁（II）配合物作为各向异性构筑单元和抗磁性的四氰酸镍作为桥连配体构建而成。磁性测量表明七配位铁（II）配合物具有易轴各向异性以及场诱导的单分子磁体行为，其自旋反转能垒U = 61(2) K（42 cm ），预指数弛豫时间τ = 1.9×10 s。对弛豫动力学的详细分析表明，奥巴赫过程在该化合物的磁化缓慢弛豫中起重要作用。值得注意的是，这个例子代表了在七配位铁（II）单分子磁体中观察到的显著能垒。从头算计算估计了轴向各向异性的大小，并表明各向异性轴在整个一维聚合物链中平行取向。此外，还报道了在扭曲的轴向位置存在弱π受体配体会增强易轴各向异性。
