Room-Temperature Stable Ln(II) Complexes Supported by 2,6-Diadamantyl Aryloxide Ligands
Room-Temperature Stable Ln(II) Complexes Supported by 2,6-Diadamantyl Aryloxide Ligands
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DOI：
10.1021/acs.inorgchem.2c02167
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发表时间：
2023-01-03
影响因子：
4.6
通讯作者：
Evans, William J.
中科院分区：
文献类型：
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作者：
Anderson-Sanchez, Lauren M.;Yu, Jason M.;Evans, William J.
空间庞大的芳氧基配体 OAr*（OAr* = -OC6H2-Ad2-2,6tBu-4；Ad = 1-金刚烷基）已用于生成跨镧系元素系列的 Ln(II) 配合物，该配合物比迄今为止报道的 4fnd1 Ln(II) 离子的任何其他配体系统的配合物更热稳定。 Ln(III) 前驱体 Ln(OAr*)3 (1-Ln) 是通过将 1.2 当量的 Ln(NR2)3 (R = SiMe3) 与 3 当量的 HOAr* 反应合成的，其中 Ln = La、Ce、Nd、Gd、Dy、Yb 和 Lu。通过单晶 X 射线衍射研究鉴定了 1-Ce、1-Nd、1-Gd、1-Dy 和 1-Lu。在 2.2.2-穴状配体 (crypt) 存在下，用钾石墨 (KC8) 在四氢呋喃中还原 1-Ln，生成 Ln(II) 配合物 [K(crypt)][Ln(OAr*)3] (2-Ln)。 Ln = Nd、Gd、Dy 和 Lu 的 2-Ln 配合物通过 X 射线晶体学进行了表征，发现其 Ln-O 键距比其 1-Ln 类似物长 0.038-0.087 埃；这与 4fn5d1 电子构型一致。 2-Yb 结构的 Yb-O 距离比 1-Yb 的预测长 0.167 埃，这与 4f14 电子构型一致。虽然 2-La 和 2-Ce 被证明很难分离，但使用 18-crown-6 (18-c-6) 作为钾螯合剂，可以分离 La(II) 和 Ce(II) 与 OAr* 的配合物并进行晶体学表征：[K(18-c-6)][Ln(OAr*)3] (3-Ln)。 Ln(II) 配合物在室温下的分解速度比之前报道的其他 4fn5d1 Ln(II) 配合物慢。例如，在室温下 30 小时后，仅观察到 30% 的 2-Dy 分解，而 [Dy(OAr ')3]- 和 [DyCp ' 3]- 在相似条件下完全分解（OAr ' = OC6H2-2,6-tBu2-4-Me；Cp ' = C5H4SiMe3）。
The sterically bulky aryloxide ligand OAr* (OAr* = -OC6H2-Ad2-2,6tBu-4; Ad = 1-adamantyl) has been used to generate Ln(II) complexes across the lanthanide series that are more thermally stable than complexes of any other ligand system reported to date for 4fnd1 Ln(II) ions. The Ln(III) precursors Ln(OAr*)3 (1-Ln) were synthesized by reacting 1.2 equiv of Ln(NR2)3 (R = SiMe3) with 3 equiv of HOAr* for Ln = La, Ce, Nd, Gd, Dy, Yb, and Lu. 1-Ce, 1-Nd, 1-Gd, 1-Dy, and 1-Lu were identified by single-crystal X-ray diffraction studies. Reductions of 1-Ln with potassium graphite (KC8) in tetrahydrofuran in the presence of 2.2.2-cryptand (crypt) yielded the Ln(II) complexes [K(crypt)][Ln(OAr*)3] (2-Ln). The 2-Ln complexes for Ln = Nd, Gd, Dy, and Lu were characterized by X-ray crystallography and found to have Ln-O bond distances 0.038-0.087 angstrom longer than those of their 1-Ln analogues; this is consistent with 4fn5d1 electron configurations. The structure of 2-Yb has Yb-O distances 0.167 angstrom longer than those predicted for 1-Yb, which is consistent with a 4f14 electron configuration. Although 2-La and 2-Ce proved to be challenging to isolate, with 18-crown-6 (18-c-6) as the potassium chelator, La(II) and Ce(II) complexes with OAr* could be isolated and crystallographically characterized: [K(18-c-6)][Ln(OAr*)3] (3-Ln). The Ln(II) complexes decompose at room temperature more slowly than other previously reported 4fn5d1 Ln(II) complexes. For example, only 30% decomposition of 2-Dy was observed after 30 h at room temperature compared to complete decomposition of [Dy(OAr ')3]- and [DyCp ' 3]- under similar conditions (OAr ' = OC6H2-2,6-tBu2-4-Me; Cp ' = C5H4SiMe3).