Charge-assisted hydrogen bonding in three diaminobenzene salts

Hydrogen-bonding interactions play an important role in the rational design of crystal systems with desirable architectures. The crystal structures of benzene-1,2-diaminium sulfate sesquihydrate, C₆H₂₀N₂ ²⁺·SO₄ ²⁻·1.5H₂O, (1), benzene-1,3-diaminium tetrachloridozincate(II), (C₆H₂₀N₂)[ZnCl₄], (3), and 3-aminoanilinium perchlorate, C₆H₉N₂ ⁺·ClO₄ ⁻, (4), are reported. Hydrated salt (1) is a polymorph (space group C2/c) of a previously reported [Anderson et al. (2011). Cryst. Growth Des. 11, 4904–4919] crystalline modification of salt (2) (space group P2₁/c). The contents of the asymmetric unit of (2) are twice that of (1). In each, the extended structures exhibit hydrogen bonds, resulting in chains of ions and hydrogen-bonded rings with an R ₄ ⁴(8) motif involving water molecules. Hirshfeld surface analysis shows that a significant difference between the two is the degree of C...C interaction. Salt (3) exhibits an extended structure having hydrogen-bonded rings and parallel benzene rings, with a centroid-to-centroid separation of 3.860 (2) Å. Salt (4) displays a three-dimensional superstructure that results from linked planes of ions joined by an extensive hydrogen-bonding network involving N—H...O, N—H...N and C—H...π interactions. The cation–anion and N—H...N interaction energies in (4), determined using density functional theory (DFT), show significantly stronger aminium–perchlorate than amine–perchlorate interactions.