Crystal structure of a polymeric calcium levulinate dihydrate: Catena-poly[[diaquacalcium]-bis(μ2-4-oxobutanoato)]

Abstract

In the title calcium levulinate complex, [Ca(C5H7O3)2(H2O)2]n, the Ca2+ ion lies on a twofold rotation axis and is octacoordinated by two aqua ligands and six O atoms from four symmetry-related carboxylate ligands, giving a distorted square-antiprismatic coordination stereochemistry [Ca - O bond-length range = 2.355 (1)-2.599 (1) Å]. The levulinate ligands act both in a bidentate carboxyl O,O′-chelate mode and in a bridging mode through one carboxyl O atom with an inversion-related Ca2+ atom, giving a Ca⋯Ca separation of 4.0326 (7) Å. A coordination polymeric chain structure is generated, extending along the c-axial direction. The coordinating water molecules act as double donors and participate in intra-chain O - H⋯O hydrogen bonds with carboxyl O atoms, and in inter-chain O - H⋯O hydrogen bonds with carbonyl O atoms, thus forming an overall three-dimensional structure.