Crystal structure of poly[[μ2-diaqua-diaqua-μ2-l-proline-κ2 O:O′-strontium] dibromide]

Abstract

In the title coordination polymer, {[Sr(C5H9NO2)(H2O)4]Br2}n, the proline molecule 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 SrII ion is nine-coordinated by six water O atoms, two monodentate and two μ2-bridging, and three carboxylate 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 interaction between the proline molecules. However, the proline and water molecules associate with the bromide counter-anions through a number of intermolecular O - H⋯Br and N - H⋯Br hydrogen-bonding interactions, giving a three-dimensional supramolecular structure.