Intermolecular C-F•••H-C contacts in the molecular packing of three isostructural N-(fluorophenyl) mannopyranosylamines

Among the three compounds reported here, namely N-(4-fluorophenyl)- beta-d-mannopyranosylamine, (I), N-(3-fluorophenyl)-beta-d-mannopyranosylamine, (II), and N-(2-fluorophenyl)-beta-d-mannopyranosylamine, (III), all with chemical formula C12H16FNO5, (I) and (II) are isostructural, whereas (III) assumes the same packing arrangement as the unfluorinated analogue N-phenyl-beta-D-mannopyranosylamine, (IV), which has been reported previously. Similarities with respect to the intermolecular hydrogen-bonding patterns exist across the series (I)-(III). A packing motif that distinguishes the shared packing arrangement of (I) and (II) from that of (III) is a C-F center dot center dot center dot H-C chain of graph set C(4) that is preserved in the formal exchange of F and H atoms at the 4- and 3-positions on the aromatic ring of (I) and (II), but is replaced by a different chain of graph set C(5) when the F atom is located at the 2-position of the aromatic ring in (III). The steric role of the F atom in (I)-(III) is ambiguous but is examined here in detail.