Crystallographic Implications for the Design of Halogen Bonding Anion Receptors

X-ray crystallographic analysis has revealed the bis-halogen bond complexation of chloride and iodide by 4-(4-(tert-butyl)phenyl)-5-iodo-3-methyl-1-n-octyl-1H-1,2,3-triazol-3-ium cations in two distinct coordination modes. The chloride complex displays a bent arrangement of the halogen bonding donors around the central anion (147.84(5) and 142.32(5)o), while the iodide salt adopts a structure with an angle closer to orthogonal (78.333(15)o). The X-ray crystal structure of a bromide salt of a halogen bonding rotaxane is also reported. The implications of the angle of halide coordination on the design of interlocked–solution phase halogen bonding anion receptors are discussed.