Crystal structure of poly[[μ2-diaqua-diaqua-μ2-l-proline-κ2O: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.

Keywords

• crystal structure
• proline
• amino acid
• strontium coordination polymer
• N/O—H...Br hydrogen bonds