Open-Shell Early Lanthanide Terminal Imides.
Open-Shell Early Lanthanide Terminal Imides.
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DOI：
10.1021/jacs.1c13142
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发表时间：
2022-02
影响因子：
15
通讯作者：
Theresa E Rieser;Renita Thim-Spöring;Dorothea Schädle;Peter Sirsch;Rannveig Litlabø;K. Törnroos;C. Maichle‐Mössmer;R. Anwander
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作者：
Theresa E Rieser;Renita Thim-Spöring;Dorothea Schädle;Peter Sirsch;Rannveig Litlabø;K. Törnroos;C. Maichle‐Mössmer;R. Anwander
第 3 族和第 4f 族元素有机金属化学和反应性由稀土金属/镧系元素 (Ln) 离子大小和相关电负性/离子性/路易斯酸度标准决定性驱动。由于这些原因，较小的闭壳层 Sc(III)、Lu(III)、Y(III) 和日益共价的 Ce(IV) 的末端“无支撑”酰亚胺 [Ln=NR] 的合成涉及不同的反应方案，而“早期”大型 Ln(III) 的衍生物仍然难以捉摸。在此，我们根据新的反应方案报道了开壳层镧系元素阳离子 Ce(III)、Nd(III) 和 Sm(III) 的末端酰亚胺。路易斯酸稳定的亚甲基配合物 [TptBu,MeLn(μ3-CH2){(μ2-Me)MMe2}2] (Ln = Ce, Nd, Sm; M = Al, Ga) 通过消除甲烷与 2,6-二异丙基苯胺 (H2NAriPr) 反应。芳基酰亚胺络合物的形成受 Ln(III) 尺寸、第 13 族金属烷基的路易斯酸度、空间因素、供体溶剂的存在以及芳香胺的空间和酸度 (pKa) 控制。至关重要的是，末端芳基酰亚胺 [TptBu,MeLn(=NAriPr)(THF)2] (Ln = Ce, Nd, Sm) 仅在 M = Ga 时形成，而对于 M = Al，路易斯酸稳定的酰亚胺 [TptBu,MeLn(NAriPr)(AlMe3)] (Ln = Ce, Nd, Sm) 是持久的。与之形成鲜明对比的是，[GaMe3] 稳定的酰亚胺 [TptBu,MeLn(NAriPr)(GaMe3)] (Ln = Nd, Sm) 在非配位溶剂中可逆形成。
Group 3- and 4f-element organometallic chemistry and reactivity are decisively driven by the rare-earth-metal/lanthanide (Ln) ion size and associated electronegativity/ionicity/Lewis acidity criteria. For these reasons, the synthesis of terminal "unsupported" imides [Ln═NR] of the smaller, closed-shell Sc(III), Lu(III), Y(III), and increasingly covalent Ce(IV) has involved distinct reaction protocols while derivatives of the "early" large Ln(III) have remained elusive. Herein, we report such terminal imides of open-shell lanthanide cations Ce(III), Nd(III), and Sm(III) according to a new reaction protocol. Lewis-acid-stabilized methylidene complexes [TptBu,MeLn(μ3-CH2){(μ2-Me)MMe2}2] (Ln = Ce, Nd, Sm; M = Al, Ga) react with 2,6-diisopropylaniline (H2NAriPr) via methane elimination. The formation of arylimide complexes is governed by the Ln(III) size, the Lewis acidity of the group 13 metal alkyl, steric factors, the presence of a donor solvent, and the sterics and acidity (pKa) of the aromatic amine. Crucially, terminal arylimides [TptBu,MeLn(═NAriPr)(THF)2] (Ln = Ce, Nd, Sm) are formed only for M = Ga, and for M = Al, the Lewis-acid-stabilized imides [TptBu,MeLn(NAriPr)(AlMe3)] (Ln = Ce, Nd, Sm) are persistent. In stark contrast, the [GaMe3]-stabilized imide [TptBu,MeLn(NAriPr)(GaMe3)] (Ln = Nd, Sm) is reversibly formed in noncoordinating solvents.