Crystal structure and spectroscopic analysis of a new oxalate-bridged Mn<sup>II</sup>compound:<i>catena</i>-poly[guanidinium [[aquachloridomanganese(II)]-μ<sub>2</sub>-oxalato-κ<sup>4</sup><i>O</i><sup>1</sup>,<i>O</i><sup>2</sup>:<i>O</i><sup>1′</sup>,<i>O</i><sup>2′</sup>] monohydrate]
Acta crystallographica. Section E, Crystallographic communications