Crystal structures of (2,2′-bi­pyridyl-κ2N,N′)bis­­[N,N-bis­­(2-hy­droxy­eth­yl)di­thio­carbamato-κ2S,S′]zinc dihydrate and (2,2′-bi­pyridyl-κ2N,N′)bis­­[N-(2-hy­droxy­eth­yl)-N-iso­propyl­di­thio­carbamato-κ2S,S′]zinc

The common feature of the title compounds, [Zn(C5H10NO2S2)2(C10H8N2)]·2H2O, (I), and [Zn(C6H12NOS2)2(C10H8N2)], (II), is the location of the ZnII atoms on a twofold rotation axis. Further, each ZnII atom is chelated by two symmetry-equivalent and symmetrically coordinating di­thio­carbamate ligands and a 2,2′-bi­pyridine ligand. The resulting N2S4 coordination geometry is based on a highly distorted octa­hedron in each case. In the mol­ecular packing of (I), supra­molecular ladders mediated by O—H⋯O hydrogen bonding are found whereby the uprights are defined by {⋯HO(water)⋯HO(hy­droxy)⋯}n chains parallel to the a axis and with the rungs defined by `Zn[S2CN(CH2CH2)2]2'. The water mol­ecules connect the ladders into a supra­molecular layer parallel to the ab plane via water-O—H⋯S and pyridyl-C—H⋯O(water) inter­actions, with the connections between layers being of the type pyridyl-C—H⋯S. In (II), supra­molecular layers parallel to the ab plane are sustained by hy­droxy-O—H⋯S hydrogen bonds with connections between layers being of the type pyridyl-C—H⋯S.