Anion Cryptates: Synthesis, Crystal Structures, and Complexation Constants of Fluoride and Chloride Inclusion Complexes of Polyammonium Macrobicyclic Ligands

Abstract

Abstract Three macrobicyclic octamines 1–3 and the macrotricyclic hexadecamine 14 have been synthesized. The octamines 1–3 bind anionic substrates when protonated. The stability constants of the complexes between the protonated forms of the macrobicyclic polyamines and halide anions have been determined by pH‐metric measurements. The stability constants in H 2 O are very high; 1 in its hexaprotonated form binds F − with high selectivity (selectivity F − /Cl − > 10 8 ), while 3 exhibits strong stability constants for both F − and Cl − . Three X‐ray structures have been obtained, one where F − is held inside the cavity of 1 · 6H + , one where Cl − is included in 3 · 6H + , and 3 · 6H + where the cavity is empty.