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Two Four-Coordinate and Seven-Coordinate CoII Complexes Based on the Bidentate Ligand 1, 8-Naphthyridine Showing Slow Magnetic Relaxation Behavior.
Chemistry - An Asian Journal ( IF 4.1 ) Pub Date : 2019-12-17 , DOI: 10.1002/asia.201901395
Xing-Cai Huang 1 , Rui Xu 1 , Yong-Zhi Chen 1 , Yi-Quan Zhang 2 , Dong Shao 3
Affiliation  

For a long time, the cobalt(II) complex ([Co(napy)4 ](ClO4 )2 ) (napy=1, 8-naphthyridine) has been considered as an eight-coordinate complex without any structural proof. After careful considerations, two complexes [Co(napy)2 Cl2 ] (1) and [Co(napy)4 ](ClO4 )2 (2) based on the bidentate ligand napy were synthesized and structurally characterized. X-ray single-crystal structural determination showed that the cobalt(II) center in [Co(napy)2 Cl2 ] (1) is four-coordinate with a tetrahedral geometry (Td ), while [Co(napy)4 ](ClO4 )2 (2) is seven-coordinate rather than eight-coordinate with a capped trigonal prism geometry (C2v ). Direct-current (dc) magnetic data revealed that complexes 1 and 2 possess positive zero-field splitting (ZFS) parameters of 11.08 and 25.30 cm-1 , respectively, with easy-plane magnetic anisotropy. Alternating current(ac) susceptibility measurements revealed that both complexes showed slow magnetic relaxation behaviour. Theoretical calculations demonstrated that the presence of easy-plane magnetic anisotropy (D>0) for complexes 1 and 2 is in agreement with the experimental data. Furthermore, these results pave the way to obtain four-coordinate and seven-coordinate cobalt(II) single-ion magnets (SIMs) by using a bidentate ligand.

中文翻译:

基于双齿配体1、8-萘啶的两个四坐标和七坐标CoII配合物,显示出缓慢的磁弛豫行为。

长期以来,钴(II)配合物([Co(napy)4](ClO4)2)(napy = 1,8-萘啶)被认为是没有任何结构证明的八坐标配合物。经过仔细考虑,合成了基于双齿配体napy的两种配合物[Co(napy)2 Cl2](1)和[Co(napy)4](ClO4)2(2),并对其结构进行了表征。X射线单晶结构确定表明[Co(napy)2 Cl2](1)中的钴(II)中心为四坐标,具有四面体几何形状(Td),而[Co(napy)4](ClO4 )2(2)是具有封顶的三棱柱几何形状(C2v)的七坐标而不是八坐标。直流(dc)磁数据表明,配合物1和2具有正零场分裂(ZFS)参数,分别为11.08和25.30 cm-1,具有易平面的磁各向异性。交流(ac)磁化率测量表明,两种配合物均显示出缓慢的磁弛豫行为。理论计算表明,配合物1和2的易平面磁各向异性(D> 0)的存在与实验数据相符。此外,这些结果为通过使用双齿配体获得四坐标和七坐标的钴(II)单离子磁体(SIM)铺平了道路。
更新日期:2019-12-18
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