Synthesis, Crystal Structure, and π–π-Stacking Interactions in a Complex of Zinc(II) Chloride with Methylene Blue

The crystal structure of the (MB)2[ZnCl4]·H2O complex (MB is the methylene blue cation) is studied by single crystal XRD. The asymmetric unit of the crystal structure consists of one tetrahedral [ZnCl4]2– anion, two crystallographically independent methylene blue (MB)+ cations, and one molecule of crystallization water. A pair of (MB)+ cations related by an inversion center forms a dimer stabilized by π–π-stacking interactions with molecules orientated in the antiparallel mode. Intermolecular π–π-stacking interactions of (MB)+ cations are analyzed using the Hirshfeld surfaces method. The energies of these interactions are calculated using density functional theory (B3LYP/6-31G) and Hartree–Fock (HF/6-21G) methods.