Binding of fluoro-containing anions to hexaazamacrocyclic ligand: Competitive interactions of fluoride and tetrafluoroborate anions with hexaprotonated [18]aneN6

Abstract Reaction of hexaazamacrocycle, 1,4,7,10,13,16-hexaazacyclooctadecane (L = [18]aneN 6 ) with boron trifluoride etherate in an aqueous solution of hydrofluoric acid yields the proton-transfer complex of the composition [H 6 L(F) (BF 4 ) 5 ] · 3H 2 O ( 1 ). X-ray crystallographic analysis shows that the macrocyclic cation adopts an unusual conformation to accommodate the fluoride anion and to keep the tetrafluoroborate anions in a close proximity. The tetrafluoroborate anions and water molecules participate in NH⋯F, NH⋯O and OH⋯F hydrogen bonding responsible for the 3D supramolecular architecture.