Crystal structure of [butane-2,3-dione bis(4-methylthiosemicarbazonato)-κ<sup>4</sup><i>S</i>,<i>N</i><sup>1</sup>,<i>N</i><sup>1′</sup>,<i>S</i>′](pyridine-κ<i>N</i>)zinc(II)
Acta crystallographica. Section E, Crystallographic communications