Some measures for making a traditional halogen bond be chlorine-shared or ion-pair one in FCl•NH3 complex

The Cl center dot center dot center dot N halogen bond (XB) in FCl center dot NH3 is tuned from a traditional one to a chlorine-shared or an ion-pair one with three methods. The first method is to put this complex into different clusters of (FCl center dot NH3)(H2O)(6). The second method is to add solvents with different dielectric constants around this complex. The third method is to impose a proper external electric field on this complex. The traditional XB has the negative quantity [r(1)(F-Cl) - r(2)(Cl-N)], while the chlorine-shared and ion-pair XBs exhibit the positive r(1) - r(2), both having the ion-pair character of smaller and larger than 85%, respectively. [GRAPHICS] .