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Trigonal Planar Heteroleptic Lanthanide(III) Bis(silyl)amide Complexes Containing Aminoxyl Radicals and Anions
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2024-11-12 , DOI: 10.1021/acs.inorgchem.4c03281
Gemma K. Gransbury, Hannah M. Nicholas, Siobhan R. Murphy, Jack Emerson-King, Michele Vonci, Conrad A. P. Goodwin, Richard E. P. Winpenny, Nicholas F. Chilton, Marcus J. Giansiracusa, David P. Mills

Modulation of the crystal field (CF) in lanthanide (Ln) complexes can enhance optical and magnetic properties, and large CF splitting can be achieved with low coordination numbers in specific geometries. We previously reported that the homoleptic near-linear Sm2+ complex [SmII{N(SiiPr3)2}2] (1-Sm) is oxidized by the 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) radical to give the heteroleptic, approximately trigonal planar Sm3+ complex, [SmIII{N(SiiPr3)2}2(TEMPO)] (2-Sm). Here, we report the synthesis of homologous [LnIII{N(SiiPr3)2}2(TEMPO)] (2-Ln; Ln = Tm, Yb) complexes by the oxidation of the parent [Ln{N(SiiPr3)2}2] (1-Ln; Ln = Tm, Yb) with TEMPO; complexes 2-Ln all contain TEMPO anions. The homoleptic bent Ln3+ complexes [LnIII{N(SiiPr3)2}2][B(C6F5)4] (3-Ln; Ln = Sm, Tm, Yb) were also treated with TEMPO to yield the heteroleptic, approximately trigonal planar Ln3+ complexes [LnIII{N(SiiPr3)2}2(TEMPO)][B(C6F5)4] (4-Ln; Ln = Sm, Tm, Yb); the cations of 4-Ln all contain TEMPO radicals. We have compared the electronic structures of the two geometrically similar families of Ln3+ complexes with the TEMPO anion (2-Ln) or TEMPO radical (4-Ln) using a combination of UV–vis-NIR and EPR spectroscopy, magnetic measurements, and ab initio calculations. These studies revealed no single-molecule magnet behavior for 2-Yb despite evidence for sizable CF splitting and a high degree of purity of the ground stabilized mJ = |±7/2⟩ state, while the radical TEMPO in 4-Yb did not significantly improve performance.

中文翻译:


含有氨基自由基和阴离子的三角平面异位镧系元素 (III) 双(甲硅烷基)酰胺络合物



镧系元素 (Ln) 配合物中晶场 (CF) 的调制可以增强光学和磁性,并且可以在特定几何形状中以低配位数实现大 CF 分裂。我们之前报道过,同源近线性 Sm2+ 配合物 [SmII{N(SiPr32}2] (1-Sm) 被 2,2,6,6-四甲基哌啶基-1-氧基 (TEMPO) 自由基氧化,得到异质的、近似三角形的平面 Sm3+ 配合物 [SmIII{N(SiPr32}2(TEMPO)] (2-Sm)。在这里,我们报道了同源 [LnIII{N(SiPr32}2(TEMPO)] (2-Ln;Ln = Tm, Yb) 络合物通过母体 [Ln{N(SiPr32}2] (1-Ln;Ln = Tm, Yb) 与 TEMPO;复合物 2-Ln含有 TEMPO– 阴离子。同源弯曲的 Ln3+ 配合物 [LnIII{N(SiPr32}2][B(C6F54] (3-Ln;Ln = Sm、Tm、Yb)也用 TEMPO• 处理,以产生异质的、近似三角形的平面 Ln3+ 复合物 [LnIII{N(SiPr32}2(TEMPO)][B(C6F54] (4-Ln;Ln = Sm, Tm, Yb);4-Ln 的阳离子都含有 TEMPO 自由基。 我们结合使用 UV-vis-NIR 和 EPR 光谱、磁性测量和从头开始计算,将两个几何相似的 Ln3+ 络合物家族的电子结构与 TEMPO 阴离子 (2-Ln) 或 TEMPO 自由基 (4-Ln) 进行了比较。这些研究表明,尽管有证据表明 CF 存在相当大的分裂并且研磨稳定 mJ = |±7/2⟩ 状态的高纯度,但 2-Yb 没有单分子磁体行为,而 4-Yb 中的自由基 TEMPO 并没有显着提高性能。
更新日期:2024-11-12
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