Shortening CN⋯Br–Csp3 halogen bonds via π-stacking

Abstract

The X-ray structure of 2-(dibromomethyl)benzonitrile, featuring unexpectedly short CN⋯Br halogen bond distances between a nitrile group and a C(sp³)-linked bromine atom, is presented. Despite the weak Lewis base nature of the nitrile N atom and absence of strong electron-withdrawing groups on the Br atom, π-stacking significantly enhances both the electron donor and acceptor capability of the interacting partners. As such, and beyond trivial (hetero)aromatic systems, the rationale of CN⋯Br halogen bonding can also be employed in purely aliphatic systems.