A new synthetic method allows isolating fluoride-bridged complexes Bu₄N{[M(3NO₂,5Br-H₃L^1,1,4)]₂(μ-F)} (M = Dy, 1; M = Ho, 2; M = Gd, 3) and Bu₄N{[Dy(3Br,5Cl-H₃L^1,2,4)]₂(μ-F)}·2H₂O, 4·2H₂O. The crystal structures of 1·5CH₃C₆H₅,·2·2H₂O·0.75THF, 3, and 4·2H₂O·2THF show that all of them are dinuclear compounds with linear single fluoride bridges and octacoordinated metal centers. Magnetic susceptibility measurements in the temperature range of 2–300 K reveal that the Gd^III ions in 3 are weakly antiferromagnetically coupled, and this constitutes the first crystallographically and magnetically analyzed gadolinium complex with a fluoride bridge. Variable-temperature magnetization demonstrates a poor magnetocaloric effect for 3. Alternating current magnetic measurements for 1, 2, and 4·2H₂O bring to light that 4·2H₂O is an SMM, 1 shows an SMM-like behavior under a magnetic field of 600 Oe, while 2 does not show relaxation of the magnetization even under an applied magnetic field. In spite of this, 2 is the first fluoride-bridged holmium complex magnetically analyzed. DFT and ab initio calculations support the experimental magnetic results and show that apparently small structural differences between 1 and 4·2H₂O introduce important changes in the dipolar interactions, from antiferromagnetic in 1 to ferromagnetic in 4·2H₂O.

中文翻译：

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作为分子磁体的双核氟化物单桥镧系元素配合物：氟化物桥接钆化合物中前所未有的耦合常数

一种新的合成方法允许分离氟化物桥接配合物 Bu ₄ N{[M(3NO ₂ ,5Br-H ₃ L ^1,1,4 )] ₂ (μ-F)} (M = Dy, 1 ; M = Ho, 2 ; M = Gd, 3 ) 和 Bu ₄ N{[Dy(3Br,5Cl-H ₃ L ^1,2,4 )] ₂ (μ-F)}·2H ₂ O, 4 ·2H ₂ O.晶体1 ·5CH 3 _C 6 _H 5 _, · 2 ·2H ₂ O·0.75THF, 3 , 4的结构·2H ₂ O·2THF表明它们都是具有线性单氟桥和八配位金属中心的双核化合物。在 2-300 K 温度范围内的磁化率测量表明，3中的 Gd ^III离子是弱反铁磁耦合的，这构成了第一个经晶体学和磁学分析的具有氟化物桥的钆配合物。变温磁化表明3的磁热效应较差。1、2和4 ·2H ₂ O的交流磁测量表明4 ·2H ₂ O 是 SMM，图1显示了在 600 Oe 的磁场下类似 SMM 的行为，而图2即使在施加的磁场下也没有显示出磁化的弛豫。尽管如此，2是第一个经过磁分析的氟桥钬络合物。DFT 和从头算计算支持实验磁性结果，并表明1和4 ·2H ₂ O 之间明显小的结构差异引入了偶极相互作用的重要变化，从1中的反铁磁性到4 ·2H ₂ O中的铁磁性。