Lesnikov Vladislav K, Golovanov Ivan S, Nelyubina Yulia V, Aksenova Svetlana A, Sukhorukov Alexey Yu
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991, Leninsky prospect, 47, Moscow, Russian Federation.
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991, Vavilova str. 28, Moscow, Russian Federation.
Nat Commun. 2023 Nov 23;14(1):7673. doi: 10.1038/s41467-023-43530-6.
Despite the rich coordination chemistry, hydroxylamines are rarely used as ligands for transition metal coordination compounds. This is partially because of the instability of these complexes that undergo decomposition, disproportionation and oxidation processes involving the hydroxylamine motif. Here, we design macrocyclic poly-N-hydroxylamines (crown-hydroxylamines) that form complexes containing a d-metal ion (Cu(II), Ni(II), Mn(II), and Zn(II)) coordinated by multiple (up to six) hydroxylamine fragments. The stability of these complexes is likely to be due to a macrocycle effect and strong intramolecular H-bonding interactions between the N-OH groups. Crown-hydroxylamine complexes exhibit interesting pH-dependent behavior where the efficiency of metal binding increases upon deprotonation of the hydroxylamine groups. Copper complexes exhibit catalytic activity in aerobic oxidation reactions under ambient conditions, whereas the corresponding complexes with macrocyclic polyamines show poor or no activity. Our results show that crown-hydroxylamines display anomalous structural features and chemical behavior with respect to both organic hydroxylamines and polyaza-crowns.
尽管羟胺具有丰富的配位化学性质，但它们很少被用作过渡金属配位化合物的配体。部分原因是这些配合物不稳定，会发生涉及羟胺基序的分解、歧化和氧化过程。在这里，我们设计了大环聚-N-羟胺（冠醚-羟胺），它们形成的配合物含有由多个（最多六个）羟胺片段配位的d-金属离子（Cu(II)、Ni(II)、Mn(II)和Zn(II)）。这些配合物的稳定性可能归因于大环效应以及N-OH基团之间强烈的分子内氢键相互作用。冠醚-羟胺配合物表现出有趣的pH依赖性行为，其中羟胺基团去质子化后金属结合效率增加。铜配合物在环境条件下的需氧氧化反应中表现出催化活性，而相应的大环多胺配合物则表现出较差的活性或无活性。我们的结果表明，冠醚-羟胺在有机羟胺和多氮冠醚方面都表现出异常的结构特征和化学行为。
