Two Four-Coordinate and Seven-Coordinate CoII Complexes Based on the Bidentate Ligand 1, 8-Naphthyridine Showing Slow Magnetic Relaxation Behavior
Two Four-Coordinate and Seven-Coordinate CoII Complexes Based on the Bidentate Ligand 1, 8-Naphthyridine Showing Slow Magnetic Relaxation Behavior
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基于双齿配体 1、8-萘啶的两个四配位和七配位 CoII 配合物表现出慢磁弛豫行为
DOI：
10.1002/asia.201901395
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发表时间：
2019-12-17
影响因子：
4.1
通讯作者：
Shao, Dong
中科院分区：
文献类型：
--
作者：
Huang, Xing-Cai;Xu, Rui;Shao, Dong
长期以来，钴配合物[Co（napy）（4）]（ClO 4）（2）（napy=1，8-萘啶）一直被认为是一个八配位配合物，没有任何结构证明。合成了两个以napy为配体的配合物[Co（napy）（2）Cl-2]（1）和[Co（napy）（4）]（ClO 4）（2）（2）。X射线单晶结构测定表明，[Co（napy）（2）Cl-2]（1）中的Co（II）中心为四配位的四面体构型（Td），而[Co（napy）（4）]（ClO 4）（2）（2）中的Co（II）中心为七配位的三角柱构型（C-2 v）。直流磁性数据显示配合物1和2具有正的零场分裂（zero-field splitting，ZFQ）参数，分别为11.08和25.30 cm（-1），具有易面磁各向异性。交流（ac）磁化率测量结果表明，这两个复合物表现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）的存在与实验数据一致。此外，这些结果铺平了道路，以获得四坐标和七坐标钴（II）单离子磁体（西姆斯）通过使用双齿配体。
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)Cl-2] (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)Cl-2] (1) is four-coordinate with a tetrahedral geometry (T-d), while [Co(napy)(4)](ClO4)(2) (2) is seven-coordinate rather than eight-coordinate with a capped trigonal prism geometry (C-2v). 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.