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

Reaction of hexaazamacrocycle, 1,4,7,10,13,16-hexaazacyclooctadecane (L = [18]aneN6) with boron trifluoride etherate in an aqueous solution of hydrofluoric acid yields the proton-transfer complex of the composition [H6L(F) (BF4)5] · 3H2O (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.

Graphical abstractThe reaction of hexaazamacrocycle, L = [18]aneN6 with boron trifluoride etherate in an aqueous solution of HF resulted in the proton-transfer complex of the composition [H6L(F)(BF4)5] · 3H2O (1). X-ray structure determination revealed an unusual conformation of hexaprotonated macrocycle capable to accommodate the fluoride anion inside and to keep the tetrafluoroborate anions in its close proximity to formulate the 3D supramolecular architecture via diverse system of NH⋯F, NH⋯O and OH⋯F hydrogen bonding.Figure optionsDownload full-size imageDownload as PowerPoint slide