A Crystallographic Charge Density Study of the Partial Covalent Nature of Strong N⋅⋅⋅Br Halogen Bonds

Eraković, Mihael; Cinčić, Dominik; Molčanov, Krešimir; Stilinović, Vladimir (2019) A Crystallographic Charge Density Study of the Partial Covalent Nature of Strong N⋅⋅⋅Br Halogen Bonds. Angewandte Chemie International edition, 58 (44). pp. 15702-15706. ISSN 1433-7851

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Abstract

The covalent nature of strong N−Br⋅⋅⋅N halogen bonds in a cocrystal (2) of N‐bromosuccinimide (NBS) with 3, 5‐dimethylpyridine (lut) was determined from X‐ray charge density studies and compared to a weak N−Br⋅⋅⋅O halogen bond in pure crystalline NBS (1) and a covalent bond in bis(3‐methylpyridine)bromonium cation (in its perchlorate salt (3). In 2, the donor N−Br bond is elongated by 0.0954 Å, while the Br⋅⋅⋅acceptor distance of 2.3194(4) is 1.08 Å shorter than the sum of the van der Waals radii. A maximum electron density of 0.38 e Å−3 along the Br⋅⋅⋅N halogen bond indicates a considerable covalent contribution to the total interaction. This value is intermediate to 0.067 e Å−3 for the Br⋅⋅⋅O contact in 1, and approximately 0.7 e Å−3 in both N−Br bonds of the bromonium cation in 3. A calculation of the natural bond order charges of the contact atoms, and the σ*(N1−Br) population of NBS as a function of distance between NBS and lut, have shown that charge transfer becomes significant at a Br⋅⋅⋅N distance below about 3 Å.

Item Type:	Article
Additional Information:	This is the accepted version of the following article: M. Eraković, D. Cinčić, K. Molčanov, V. Stilinović, Angew. Chem. Int. Ed. 2019, 58, 15702. which has been published in final form at https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201908875 This article may be used for non-commercial purposes in accordance with the Wiley Self-Archiving Policy [https://authorservices.wiley.com/author- resources/Journal-Authors/licensing/self-archiving.html]
Uncontrolled Keywords:	halogen bond ; covalent bond ; X‐ray charge density
Subjects:	NATURAL SCIENCES > Chemistry > Physical Chemistry NATURAL SCIENCES > Chemistry > Inorganic Chemistry
Divisions:	Division of Physical Chemistry
Projects:	Project title Project leader Project code Project type kristalno inženjerstvo višekomponenti+nih metaloorganksih materijala povezanih halogenoskom vezom: ususret supramolekulskom ugađanju strukture i svojstava-CrystEngMOM Dominik Cinčić IP-2014-09-7367 HRZZ Study of intermolecular interactions by crystallographic charge density analysis UNSPECIFIED UNSPECIFIED Croatian Academy of Sciences and Arts
Depositing User:	Mihael Eraković
Date Deposited:	15 Dec 2020 07:41
URI:	http://fulir.irb.hr/id/eprint/6141
DOI:	10.1002/anie.201908875

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