Jiang Lin, Liu Yue, Liu Xin, Tian Jinlei, Yan Shiping
College of Chemistry, Nankai University, Tianjin 300071, China.
Dalton Trans. 2017 Sep 26;46(37):12558-12573. doi: 10.1039/c7dt02351k.
Three series of Ni-Ln complexes were synthesized with the general formulae [(μ-CO){Ni(HL)(CH-CHOH)Ln(CHCOO)}]·2CHCHOH (1-6) (Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5), Yb (6); HL = N,N'-bis(3-methoxysalicylidene)-1,3-diamino-2-prop-anol), [Ni(HL)Ln(dbm)]·CHOH·2CHCl (7-10) (Ln = Tb (7), Eu (8), Gd (9), Ho (10); Hdbm = 1,3-diphenyl-1,3-propanedione) and [Ni(HL)(HO)(tfa)Ln(hfac)] (11-15) (Ln = Tb (11), Dy (12), Eu (13), Gd (14), Ho (15); Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, tfa = trifluoroacetate) using compartmental Schiff base ligands in conjunction with auxiliary ligands. For the NiLn series, the tetranuclear structure could be considered as two Ni-Ln dinuclear subunits bridged by two carbonates derived from atmospheric carbon dioxide. The Ln ions of complexes 1-6 were octa-coordinated with distorted triangular dodecahedral geometry, while the Ln ions of the dinuclear complexes 7-15 were nona-coordinated with distorted muffin geometry. The magnetic properties of the three series complexes were studied using dc and ac magnetic measurements. For the Ni-Gd complexes, the dc magnetic susceptibility measurements suggested the existence of the anticipated ferromagnetic interaction between Ni and Gd ions. The fitting of the χT vs. T data processed by PHI software provided the parameters g = 2.08 (J = +0.87 cm) for 9 and g = 2.02 (J = +1.83 cm) for 14. The interaction exchange was magneto-structurally correlated to the Ni-O-Gd angle (α) and Ni(μ-O)Gd dihedral angle (β). With an applied dc field, complexes 1 (Tb), 2 (Dy), 7 (Tb) and 12 (Dy) exhibited single magnetic relaxation with SMM parameters of U/k = 13.60 K, 11.52 K, 7.69 K and 5.14 K, respectively. Analysis of the Cole-Cole plots for complexes 2 and 7 suggested that a single relaxation process was mainly involved in the relaxation process, with α values in the range of 0.37-0.17 and 0.14-0.11, respectively.
使用间隔 Schiff 碱配体与辅助配体合成了三个系列的镍 - 镧系配合物，其通式分别为[(μ-CO){Ni(HL)(CH-CHOH)Ln(CHCOO)}]·2CHCHOH (1 - 6)（Ln = Tb (1)、Dy (2)、Ho (3)、Er (4)、Tm (5)、Yb (6)；HL = N,N'-双(3 - 甲氧基水杨醛)-1,3 - 二氨基 - 2 - 丙醇）、[Ni(HL)Ln(dbm)]·CHOH·2CHCl (7 - 10)（Ln = Tb (7)、Eu (8)、Gd (9)、Ho (10)；Hdbm = 1,3 - 二苯基 - 1,3 - 丙二酮）和[Ni(HL)(HO)(tfa)Ln(hfac)] (11 - 15)（Ln = Tb (11)、Dy (12)、Eu (13)、Gd (14)、Ho (15)；Hhfac = 1,1,1,5,5,5 - 六氟戊烷 - 2,4 - 二酮，tfa = 三氟乙酸盐）。对于镍 - 镧系系列，四核结构可视为由两个源自大气二氧化碳的碳酸盐桥联的两个镍 - 镧双核亚基。配合物 1 - 6 的镧系离子为八配位，具有扭曲的三角十二面体几何构型，而双核配合物 7 - 15 的镧系离子为九配位，具有扭曲的松饼几何构型。使用直流和交流磁性测量研究了这三个系列配合物的磁性。对于镍 - 钆配合物，直流磁化率测量表明镍和钆离子之间存在预期的铁磁相互作用。由 PHI 软件处理的χT 对 T 数据的拟合为 9 提供了参数 g = 2.08 (J = +0.87 cm)，为 14 提供了参数 g = 2.02 (J = +1.83 cm)。相互作用交换在磁结构上与 Ni - O - Gd 角(α)和 Ni(μ - O)Gd 二面角(β)相关。在施加直流场时，配合物 1 (Tb)、2 (Dy)、7 (Tb)和 12 (Dy)分别表现出单磁弛豫，其单分子磁体参数 U/k 分别为 13.60 K、11.52 K、7.69 K 和 5.14 K。对配合物 2 和 7 的 Cole - Cole 图分析表明，弛豫过程主要涉及单个弛豫过程，α值分别在 0.37 - 0.17 和 0.14 - 0.11 范围内。
