Discriminating halogen-bonding from other noncovalent interactions by a combined NOE NMR/DFT approach

Gianluca Ciancaleoni, Roberta Bertani, Luca Rocchigiani, Paolo Sgarbossa, Cristiano Zuccaccia, Alceo Macchioni

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Herein a combined NOE NMR/DFT methodology to discriminate between adducts held together by halogen bonding (XB) and other noncovalent interactions (non‐XB, such as lone pair/π), based on the determination of the XB donors′ and acceptors′ relative orientation, is proposed. In particular, 19F,1H HOESY NMR spectroscopy experiments and DFT calculations on different XB donors, such as perfluorohexyl iodide (I1), iodopentafluorobenzene (I2) and bromopentafluorobenzene (Br), combined with different Lewis bases, such as 1,4‐diazabicyclo[2.2.2]octane (DABCO) and 2,4,6‐trimethylpyridine (Me3Py), were performed. The results clearly show that in the case DABCO/I1 the XB adduct is practically the only one present in solution, whereas for the other pairs a certain amount of non‐XB adduct is present. Combining DFT and HOESY results, the amount of non‐XB adducts can be roughly quantified under our experimental conditions as 4 % for DABCO/I2, between 10 and 20 % for Me3Py/I1 and Me3Py/I2, and 44 % for DABCO/Br.
Original languageEnglish
Pages (from-to)440-447
JournalChemistry - A European Journal
Issue number1
Early online date29 Oct 2014
Publication statusPublished - 2 Jan 2015

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