Crystal structure of dipotassium N-carbodi­thio­ato-l-prolinate trihydrate

The mol­ecular and crystal structure of the l-proline-derived di­thio­carbamate–carboxyl­ate compound poly[tri-μ-aqua-(μ-2-carboxyl­atopyrrolidine-1-carbodi­thio­ato)dipotassium], [K(2)(C(6)H(7)NO(2)S(2))(H(2)O)(3)](n) or K(2)(SSC–NC(4)H(7)–COO)·3H(2)O, has been determined. The di­thio­carbamate moiety displays a unique coordination mode, comprising a ‘side-on’ π-coordinated K(+) cation besides a commonly σ-chelated K(+) cation. By bridging coordination of the CSS group, COO group and water mol­ecules, the K(+) cations are linked into a two-dimensional coordination polymer extending parallel to the ab plane. These layers are again inter­connected by O—H⋯S hydrogen bonds.