| Abstract: | In the crystal structure of the title compond, alternatively called polycalcium(II)‐di‐μ‐carboxymethylphosphonato], Ca(C2H4O5P)2]n or Ca(H2AP)2]n, one of the phosphonate O atoms of the phosphonocarboxylate monoanion lies nearly antiperiplanar (ap) to the carboxylic acid C atom. The phosphonate P atom is located −sc and +ac relative to the carboxylic acid O atoms. The overall structure has a layered architecture. The Ca2+ cations lie on a twofold axis and are bridged by the phosphonate O atoms to form chains along the c axis, giving layers parallel to (100). There are medium‐strength O—H⃛O and C—H⃛O hydrogen‐bonding interactions stabilizing the layers, and O—H⃛O hydrogen bonds connect adjacent layers. |
