Exploring Orthogonality between Halogen and Hydrogen Bonding Involving Benzene.

The concept of orthogonality between halogen and hydrogen bonding, brought out by Ho and coworkers some years ago, has become a widely accepted idea within the chemists' community. While the original work was based on a common carbonyl oxygen as acceptor for both interactions, we explore here, by means of M06-2X, M11, B97X, and B97XD/aug-cc-PVTZ DFT calculations, the interdependence of halogen and hydrogen bonding with a shared π-electron system of benzene. The donor groups (specifically NCBr and HO) were placed on either or the same side of the ring, according to a double T-shaped or a perpendicular geometry, respectively.