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首页> 外文期刊>Chemistry: A European journal >Two C3-Symmetric Dy_3~(III) Complexes with Triple Di-m-methoxo-mphenoxo Bridges, Magnetic Ground State, and Single-Molecule Magnetic Behavior
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Two C3-Symmetric Dy_3~(III) Complexes with Triple Di-m-methoxo-mphenoxo Bridges, Magnetic Ground State, and Single-Molecule Magnetic Behavior

机译：具有三重Di-m-甲氧基-mphenoxo桥，磁性基态和单分子磁行为的两个C3对称Dy_3〜（III）配合物

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摘要

Two series of isostructural C_3-symmetric Ln_3 complexes Ln_3·[BPh_4] and Ln_3·0.33[Ln(NO_3)_6] (in which Ln~(III)=Gd and Dy) have been prepared from an amino-bis(phenol) ligand. X-ray studies reveal that Ln~(III) ions are connected by one m2-phenoxo and two m3-methoxo bridges, thus leading to a hexagonal bipyramidal Ln_3O5 bridging core in which Ln~(III) ions exhibit a biaugmented trigonal-prismatic geometry. Magnetic susceptibility studies and ab initio complete active space self-consistent field (CASSCF) calculations indicate that the magnetic coupling between the Dy~(III) ions, which possess a high axial anisotropy in the ground state, is very weakly antiferromagnetic and mainly dipolar in nature. To reduce the electronic repulsion from the coordinating oxygen atom with the shortest Dy-O distance, the local magnetic moments are oriented almost perpendicular to the Dy_3 plane, thus leading to a paramagnetic ground state. CASSCF plus restricted active space state interaction (RASSI) calculations also show that the ground and first excited state of the Dy~(III) ions are separated by approximately 150 and 177 cm~(-1), for Dy_3·[BPh_4] and Dy_3·0.33[Dy(NO_3)_6], respectively. As expected for these large energy gaps, Dy_3·[BPh_4] and Dy_3·0.33[Dy-(NO_3)_6] exhibit, under zero direct-current (dc) field, thermally activated slow relaxation of the magnetization, which overlap with a quantum tunneling relaxation process. Under an applied Hdc field of 1000 Oe, Dy_3·[BPh_4] exhibits two thermally activated processes with U_(eff) values of 34.7 and 19.5 cm~(-1), whereas Dy_3·0.33[Dy(NO_3)_6] shows only one activated process with U_(eff)=19.5 cm~(-1).
机译：由氨基-双（苯酚）配体制备了两个系列的同构C_3对称的Ln_3配合物Ln_3·[BPh_4]和Ln_3·0.33 [Ln（NO_3）_6]（其中Ln〜（III）= Gd和Dy） 。 X射线研究表明，Ln〜（III）离子通过一个m2-phenoxo桥和两个m3-methoxo桥连接，从而形成了一个六边形双锥体Ln_3O5桥接核，其中Ln〜（III）离子呈现出双三角棱柱几何形状。磁化率研究和从头算起的完整活动空间自洽场（CASSCF）计算表明，在基态下具有较高轴向各向异性的Dy〜（III）离子之间的磁耦合非常弱，反铁磁且主要是偶极子。性质。为了减少来自具有最短Dy-O距离的配位氧原子的电子排斥，局部磁矩的取向几乎垂直于Dy_3平面，从而导致顺磁基态。 CASSCF加上受限的活动空间状态相互作用（RASSI）计算还显示，对于Dy_3·[BPh_4]和Dy_3，Dy〜（III）离子的基态和第一激发态之间的距离约为150和177 cm〜（-1）。 ·0.33 [Dy（NO_3）_6]。如对这些大能隙的预期，Dy_3·[BPh_4]和Dy_3·0.33 [Dy-（NO_3）_6]在零直流（dc）场下表现出热激活的磁化慢弛豫，与量子重叠隧道松弛过程。在施加的1000 Oe Hdc磁场下，Dy_3·[BPh_4]表现出两个热激活过程，U_（eff）值分别为34.7和19.5 cm〜（-1），而Dy_3·0.33 [Dy（NO_3）_6]仅显示一个U_（eff）= 19.5 cm〜（-1）激活过程

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