Supramolecular arrangement of 3,5-bis[methylene(dihydroxyphosphoryl)]benzoic acid and its complex with calcium

3,5-Bis[methylene(dihydroxyphosphoryl)]benzoic acid and its complex with calcium in the crystalline form were obtained. The 3,5-bis[methylene(dihydroxyphosphoryl)]benzoic acid crystallises as acetone monosolvate (1a) while its calcium complex as methanol disolvate (1b). The solvent molecules in the crystals are disordered. The 3,5-bis[methylene(dihydroxy-phosphoryl)]benzoic acid molecules in crystal 1a are interconnected via OH⋯O hydrogen bonds forming two-dimensional layers parallel to (1 0 0) plane. Within the layers there are present holes that occupied disordered acetone molecules. In 1b the calcium cation is surrounded by six singly deprotonated 3,5-bis[methylene(dihydroxyphosphoryl)]benzoic acid forming distorted octahedral environment. Each singly deprotonated 3,5-bis[methylene(dihydroxyphosphoryl)]benzoic acid links three calcium cations forming two-dimensional coordinating polymers parallel to (0 1 0) plane. The OH···O hydrogen bonds between the singly deprotonated 3,5-bis[methylene(dihydroxyphosphoryl)]benzoic acid ligands stabilize the two-dimensional polymers. Statistically disordered methanol molecules are located in the holes between the two-dimensional coordinating polymers and interact with them via OH···O hydrogen bonds.