Halogen bonding with carbene bases

Ab initio MP2/aug’-cc-pVTZ calculations have been performed to determine the structures and binding energies of complexes formed from five singlet carbene bases acting as electron-pair donors to four ClX acids. Complexes with ClCCH and ClCN are stabilized by traditional halogen bonds. With one exception, complexes with ClNC and ClF are stabilized by (carbene-Cl)⋯NC and (carbene-Cl)⋯F ion-pair halogen bonds subsequent to chlorine transfer. These complexes have been characterized in terms of their structures, binding energies, charge-transfer energies, bonding properties, and spin-spin coupling constants.This work was carried out with financial support from the Ministerio de Economía y Competitividad – Spain (Project No. CTQ2015-63997-C2-2-P) and Comunidad Autónoma de Madrid (S2013/MIT2841, Fotocarbon). Thanks are also given to the Ohio Supercomputer Center and CTI (CSIC) for their continued computational support.Peer Reviewe