title: Cooperative and substitution effects in enhancing strengths of halogen bonds in FCl···CNX complexes.
abstract: In this paper, the cooperative effect of halogen bond with hydrogen bond has been used to make a halogen bond in FCl-CNH dimer vary from a chlorine-shared one to an ion-pair one. The halogen bond is strengthened in FCl-CNH-CNH trimer and its maximal interaction energy equals to -76 kJ/mol when the number of CNH in FCl-CNH-(CNH)(n) polymer approaches infinity. Once the free H atom in FCl-CNH-CNH trimer is replaced with alkali metals, the halogen bond becomes strong enough to be an ion-pair one in FCl-CNH-CNLi and FCl-CNH-CNNa trimers. An introduction of a Lewis acid in FCl-CNH dimer has a more prominent effect on the type of halogen bond. A prominent cooperative effect is found for the halogen bond and hydrogen bond in the trimers. FH-FCl-CNH-CNH and FH-FCl-CNH-CNLi tetramers have also been studied and the interaction energy of halogen bonding in FH-FCl-CNH-CNLi tetramer is about 12 times as much as that in the FCl-CNH dimer. The atoms in molecules and natural bond orbital analyses have been carried out for these complexes to understand the nature of halogen bond and the origin of the cooperativity.
authors.affiliation: Laboratory of Theoretical and Computational Chemistry, Chemistry and Chemical Engineering College, Yantai University, Yantai 264005, People's Republic of China.
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Li
authors.forename: Shumin
authors.initials: S
authors.lastname: Ma
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Liu
authors.forename: Wenzuo
authors.initials: W
authors.lastname: Li
authors.forename: Jianbo
authors.initials: J
authors.lastname: Cheng
mesh_terms: D003486:Cyanides / Q000737:chemistry*; D019281:Dimerization; D006219:Halogens / Q000737:chemistry*; D006860:Hydrogen Bonding; D008672:Metals, Alkali / Q000737:chemistry
chemical_list: D003486:Cyanides; D006219:Halogens; D008672:Metals, Alkali