Hypervalent Iodine(III) Compounds as Biaxial Halogen Bond Donors

Flemming Heinen, Elric Engelage, Christopher J. Cramer, Stefan M. Huber

Research output: Contribution to journalArticlepeer-review

Abstract

"Hypervalent"iodine(III) derivatives have been established as powerful reagents in organic transformations, but so far only a handful of studies have addressed their potential use as halogen-bonding noncovalent Lewis acids. In contrast to "classical"halogen-bond donors based on iodine(I) compounds, iodine(III) salts feature two directional electrophilic axes perpendicular to each other. Herein we present the first systematic investigation on biaxial binding to such Lewis acids in solution. To this end, hindered and unhindered iodolium species were titrated with various substrates, including diesters and diamides, via 1H NMR spectroscopy and isothermal titration calorimetry. Clear evidence for biaxial binding was obtained in two model systems, and the association strengths increased by 2 orders of magnitude. These findings were corroborated by density functional theory calculations (which reproduced the trend well but underestimated the absolute binding constants) and a cocrystal featuring biaxial coordination of a diamide to the unhindered iodolium compound.

Original languageEnglish (US)
Pages (from-to)8633-8640
Number of pages8
JournalJournal of the American Chemical Society
Volume142
Issue number19
DOIs
StatePublished - May 13 2020

Bibliographical note

Funding Information:
This project received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (638337). Funded by the Deutsche Forschungsgemeinschaft (German Research Foundation) under Germany’s Excellence Strategy-EXC 2033-390677874-RESOLV.

Publisher Copyright:
Copyright © 2020 American Chemical Society.

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