Halogen bonds in N-bromosuccinimide and other N-halosuccinimides

Abstract

© 2019, Springer Science+Business Media, LLC, part of Springer Nature. Our crystal data shows marked intermolecular Br interaction with a neighboring O (carbonyl) in the crystal, Br---O(carbonyl) = 2.767(1) Å, well below the sum of the corresponding van der Waals radii, 3.37 Å. This C=O---Br interaction is among the shortest in the CSD (only 8/2185 examples have a similar distance 2.725–2.800 Å). Only one carbonyl group interacts with the halogen atom, thus inducing a helical intermolecular arrangement. The halogen bond was also studied with density functional theory (DFT) methods, based on coordinates of two molecules in the crystal packing, widely modifying the N-Br---O(carbonyl) angle. In each calculation, this angle was fixed, and the corresponding arrangements were analyzed for potential structural correlation. Indeed, the widening of the N-Br---O(carbonyl) angle correlates with a gradual increase of halogen bond interaction Br---O(carbonyl), that is, shorter separation. It is also seen that decreasing the N-Br---O(carbonyl) angle is associated with decreasing Br---Br separation. Isosurface electron density shows the presence of Br sigma-holes in the two-molecule arrangements.