Crystal structure of the magnesium salt of the herbicide 2,4-D: pentaaqua[(2,4-dichlorophenoxy)acetato-kappa O]magnesium(2,4-dichlorophenoxy)-cetate hemihydrate

In the crystal structure of the title magnesium salt of the phenoxy herbicide (2,4-dichlorophenoxy) acetic acid (2,4-D), [Mg(C8H5Cl2O3)(H2O)(5)](C8H5Cl2O3) center dot 0.5H2O, the discrete cationic MgO6 complex unit comprises a carboxylate O-donor from a monodentate 2,4-D anionic ligand and five water molecules, resulting in a slightly distorted octahedral coordination sphere. The free 2,4-D anions are linked to the complex units through duplex water-carboxylate O-H center dot center dot center dot O hydrogen bonds through the coordinating water molecules. In the crystal, inter-unit O-H center dot center dot center dot O hydrogen-bonding interactions involving coordinating water molecules as well as the solvent water molecule (occupancy 0.5) with carboxylate O-atom acceptors, give a layered structure lying parallel to (001), in which pi-pi ligand-cation interactions [minimum ring centroid separation = 3.6405 (17) angstrom] and a short O-H center dot center dot center dot Cl interaction are also found.