title: Chalcogen bonds in complexes of SOXY (X, Y = F, Cl) with nitrogen bases.
abstract: SOF2, SOFCl, and SOCl2 were each paired with a series of N bases. The potential energy surface of the binary complexes were characterized by MP2 calculations with double and triple-ξ basis sets, extrapolated to complete sets. The most stable configurations contained a S···N chalcogen bond with interaction energies as high as 6.8 kcal/mol. These structures are stabilized by a Nlp → σ*(S-Z) electron transfer (Z = O, F, Cl), complemented by Coulombic attraction of N to the σ-hole opposite the Z atom. N···S-F and N···S-Cl chalcogen bonds are stronger than N···S═O interactions. Formation of each chalcogen bond elongates all of the internal covalent bonds within SOXY, especially the S-Cl bond. Halogen-bonded (N···Cl-S) complexes were also observed, but these are more weakly bound, by less than 3 kcal/mol.
authors.affiliation: Instituto de Química Médica, CSIC , Juan de la Cierva, 3, E-28006 Madrid, Spain.
authors.forename: Luis Miguel
authors.initials: LM
authors.lastname: Azofra
authors.forename: Ibon
authors.initials: I
authors.lastname: Alkorta
authors.forename: Steve
authors.initials: S
authors.lastname: Scheiner