Effects of strong hydrogen bonds and weak intermolecular interactions on supramolecular assemblies of 4-fluorobenzylamine

A series of supramolecular salts have been obtained by the self-assembly of 4-fluorobenzylamine and halide ions or metal chloride with 18-crown-6 as the host in the hydrochloric acid medium, i.e. (C₇H₉FN)⁺X^- (X = Cl^-, 1; Br^-, 2), [(C₇H₉FN)₂(18-crown-6)₂]²⁺(MCl₄)^2- (M = Mn, 3; Co, 5; Zn, 7; Cd, 8), [(C₇H₉FN)(18-crown-6)]⁺(FeCl₄)^- (4) and [(C₇H₉FN)(18-crown-6)]⁺1/2(CuCl₄)^2- (6). Structural analyses indicate that 1-2 crystallize in the triclinic space group P-1, 4 in orthorhombic space group Pnma and 3, 5, 6-8 in the monoclinic space group P2₁/c or C2/c. In these compounds, extensive intermolecular interactions have been utilized for the self-assembly of diverse supramolecular architectures, ranging from strong N-H X (X = O, Cl, Br) hydrogen bonds to weak C-H-Y (Y = F, Cl, π) interactions. N-H Cl/Br hydrogen bonds offer the major driving force in the crystal packing of salts 1-2 while N-H O hydrogen bonds are found in salts 3-8.