Crystal structure of a looped-chain Co<sup>II</sup>coordination polymer:<i>catena</i>-poly[[bis(nitrato-κ<i>O</i>)cobalt(II)]bis[μ-bis(pyridin-3-ylmethyl)sulfane-κ<sup>2</sup><i>N</i>:<i>N</i>′]]
Acta crystallographica. Section E, Crystallographic communications