Crystal structure of poly[[μ2-di-aqua-di-aqua-μ2-l-proline-κ(2) O:O'-strontium] dibromide].

In the title coordination polymer, {[Sr(C5H9NO2)(H2O)4]Br2} n , the proline mol-ecule exists in a zwitterionic form with one of the ring C atoms disordered over two sites [site-occupancy factors = 0.57 (6):0.43 (6)]. The Sr(II) ion is nine-coordinated by six water O atoms, two monodentate and two μ2-bridging, and three carboxyl-ate O atoms of the proline ligands, with two bridging [Sr-O range = 2.524 (4)-2.800 (5) Å]. In the crystal, there is no direct inter-action between the proline mol-ecules. However, the proline and water mol-ecules associate with the bromide counter-anions through a number of inter-molecular O-H⋯Br and N-H⋯Br hydrogen-bonding inter-actions, giving a three-dimensional supra-molecular structure.