Szell Patrick M J, Grébert Lorraine, Bryce David L
Department of Chemistry and Biomolecular Sciences & Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Private, Ottawa, Ontario, K1N 6N5, Canada.
Angew Chem Int Ed Engl. 2019 Sep 16;58(38):13479-13485. doi: 10.1002/anie.201905788. Epub 2019 Aug 13.
I nuclear quadrupole resonance (NQR) spectroscopy is established as a rapid and robust method to indicate the formation of iodine-nitrogen halogen bonds in co-crystalline powders. Once the relevant spectral frequency range has been established, diagnostic I NQR spectra can be acquired in seconds. The method is demonstrated for a series of co-crystals of 1,4-diiodobenzene. Changes in the I quadrupolar coupling constant (C ) by up to 74.4 MHz correlate with the length of the C-I donor covalent bond and inversely with the I⋅⋅⋅N halogen-bond length. The predictive power of this technique is validated on two previously unknown co-crystalline powders prepared mechanochemically. Single-crystal growth via co-sublimation and structure determination by single-crystal X-ray diffraction cross-validates the findings. Natural localized molecular-orbital analyses provide insight into the origins of the quadrupolar coupling constants.
核磁共振四极共振（NQR）光谱法已成为一种快速且可靠的方法，用于指示共结晶粉末中碘 - 氮卤键的形成。一旦确定了相关的光谱频率范围，即可在数秒内获得诊断性的碘NQR光谱。该方法已针对一系列1,4 - 二碘苯共晶体进行了验证。碘四极耦合常数（C）变化高达74.4 MHz，与C - I供体共价键的长度相关，与I⋅⋅⋅N卤键长度呈反比。该技术的预测能力在通过机械化学方法制备的两种先前未知的共结晶粉末上得到了验证。通过共升华进行单晶生长以及通过单晶X射线衍射进行结构测定对研究结果进行了交叉验证。自然定域分子轨道分析有助于深入了解四极耦合常数的起源。
