Docker Andrew, Kuhn Heike, Beer Paul D
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, U.K.
Chemistry Research Laboratory Oxford Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, U.K.
Angew Chem Int Ed Engl. 2025 Jan 27;64(5):e202417427. doi: 10.1002/anie.202417427. Epub 2024 Nov 14.
Halenium ions (X) are highly reactive electron deficient species that are prevalent transient intermediates in halogenation reactions. The stabilisation of these species is especially challenging, with the most common approach to sequester reactivity through the formation of bis-pyridine (Py) complexes; [(Py)X]. Herein, we present the first example of a macrocyclic stabilisation effect for halenium species. Exploiting a series of bis-pyridine macrocycles, we demonstrate that preorganised macrocyclic ligands stabilise bromenium cations via endotopic complexation, impressively facilitating the isolation of a bench stable 'Br NO ' species. Solid state X-ray crystallographic structural comparison of macrocyclic Br(I) complexes with Ag(I) and Au(I) analogues provides insightful information concerning similarities and stark contrasts in halenium/metal cation coordination behaviors. Furthermore, the first chemical ligand exchange reactions of Br(I) complexes are reported between acyclic [(Py)Br] species and a bis-pyridine macrocyclic donor ligand which importantly highlights a macrocycle effect for halenium cation stabilisation in the solution phase.
卤鎓离子（X）是高活性的缺电子物种，是卤化反应中普遍存在的瞬态中间体。这些物种的稳定化极具挑战性，最常见的方法是通过形成双吡啶（Py）配合物；[(Py)X]来隔离反应活性。在此，我们展示了卤鎓物种大环稳定化效应的首个实例。利用一系列双吡啶大环，我们证明预组织的大环配体通过内配位作用稳定溴鎓阳离子，令人印象深刻地促进了一种易于保存的“Br NO”物种的分离。大环Br（I）配合物与Ag（I）和Au（I）类似物的固态X射线晶体结构比较提供了有关卤鎓/金属阳离子配位行为的相似性和显著差异的有价值信息。此外，还报道了无环[(Py)Br]物种与双吡啶大环供体配体之间Br（I）配合物的首次化学配体交换反应，这重要地突出了溶液相中卤鎓阳离子稳定化的大环效应。
