title: Exploring the (Very Flat) Potential Energy Landscape of R-Br⋅⋅⋅π Interactions with Accurate CCSD(T) and SAPT Techniques.
abstract: Halogen bonds involving an aromatic moiety as an acceptor, otherwise known as R-X⋅⋅⋅π interactions, have increasingly been recognized as being important in materials and in protein-ligand complexes. These types of interactions have been the subject of many recent investigations, but little is known about the ways in which the strengths of R-X⋅⋅⋅π interactions vary as a function of the relative geometries of the interacting pairs. Here we use the accurate CCSD(T) and SAPT2+3δMP2 methods to investigate the potential energy landscapes for systems of HBr, HCCBr, and NCBr complexed with benzene. It is found that only the separation between the complexed molecules have a strong effect on interaction strength while other geometric parameters, such as tilting and shifting R-Br⋅⋅⋅π donor relative to the benzene plane, affect these interactions only mildly. Importantly, it is found that the C6v(T-shaped) configuration is not the global minimum for any of the dimers investigated.
authors: Department of Chemistry, Xavier University of Louisiana, 1 Dr. Drexel, New Orleans, LA, 70125, USA.
authors: Kevin E
authors: http://orcid.org/0000-0003-2871-7727
authors: KE
authors: Riley
authors: Department of Chemistry, Texas A&M University, PO Box 30012, College Station, TX, 77842, USA.
authors: Mariela
authors: M
authors: Vazquez
authors: Department of Chemistry, Xavier University of Louisiana, 1 Dr. Drexel, New Orleans, LA, 70125, USA.
authors: Cole
authors: C
authors: Umemura
authors: Department of Chemistry, Xavier University of Louisiana, 1 Dr. Drexel, New Orleans, LA, 70125, USA.
authors: Christopher
authors: C
authors: Miller
authors: Department of Chemistry, Xavier University of Louisiana, 1 Dr. Drexel, New Orleans, LA, 70125, USA.
authors: Khanh-An
authors: KA
authors: Tran
keywords: ab initio calculations; crystal engineering; halogen bonding; noncovalent interactions; protein-ligand complexes