The role of nitrogen as a halogen bond acceptor: a CSD and theoretical study Harry Nash, J. Grant Hill, Lee Brammer Department of Chemistry, University of Sheffield, UK
Halogen bonds are a class of σ-hole interactions, arising from a charge anisotropy caused by the formation of a σ bond between a halogen and an electron withdrawing group, resulting in an electropositive region localised along the extension of the σ bond[1]. The electropositive σ-hole can interact attractively with many Lewis bases in a highly directional manner with respect to the σ-hole comparable in strength to hydrogen bonding[2][3]. These energetic and geometric characteristics make them of interest pertaining to a wide range of applications in chemistry, from crystal engineering to drug-protein interactions to catalysis[4]. Given the donor-acceptor nature of these interactions, lone-pair possessing nitrogen species are utilised in order to gain insight into the effect the acceptor has on the interaction. The effects of properties such as hybridisation and cyclicity of the nitrogen are considered. In order to better understand the directionality and strength of these noncovalent interactions in the context of solid-state chemistry, this work focuses on searches of the Cambridge Structural Database (CSD) to extract geometric data and utilises high accuracy computational approaches to determine search criteria[5]. It is the aim to use this work as a jumping-off point to study halogen bonding to other lone-pair possessing acceptor species, along with expanding the study to include other classes of σ-hole interactions such as chalcogen bonds, pnictogen bonds, and tetrel bonds. References 1. P. Politzer et al. Halogen bonding and other σ-hole interactions: a perspective, Phys. Chem. Chem. Phys., 2013, 15, 11178, DOI: 10.1039/c3cp00054k 2. G. R. Desiraju, et al. Definition of the halogen bond (IUPAC Recommendations 2013), Pure Appl. Chem., 2013, 85, 8, 1711- 1713. DOI: 10.1351/PAC-REC-12-05-10 3. C. B. Aakeröy, et al. Structural Competition between Hydrogen Bonds and Halogen Bonds, J. Am. Chem. Soc. 2007, 129, 13772-13773, DOI: 10.1021/ja073201 4. L. Brammer, Halogen bonding, chalcogen bonding, pnictogen bonding, tetrel bonding: origins, current status and discussion, Faraday Discuss., 2017, 203, 485, DOI: 10.1039/c7fd00199a 5. C. R. Groom, et al., The Cambridge Structural Database, Acta Cryst., 2016. B72, 171-179, DOI: 10.1107/ S2052520616003954
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