Crystal and supramolecular structures of complexes of BF3NH3 and BH3NH3 with 18-crown-6

Abstract

The macrocyclic polyether 18-crown-6 (C₁₂H₂₄O₆) readily forms crystalline 1 : 1 complexes with the adducts BF₃NH₃ and BH₃NH₃. Crystals of the solvates BF₃NH₃·C₁₂H₂₄O₆·CH₂Cl₂ and BH₃NH₃·C₁₂H₂₄O₆·MeOH were suitable for X-ray crystallographic investigation. In both cases, the crystal structures reveal that 18-crown-6 adopts an all-gauche conformation with pseudo D_3d symmetry in which the intermolecular N–H ⋯ O hydrogen-bonding interactions between the macrocyclic polyether and the adducts are associated directly with the triangle of oxygen atoms on the complexing face of the crown.