Ethyl 4-(phenyl­sulfon­yl)piperazine-1-carboxyl­ate

In the title compound, C13H18N2O4S, the piperazine ring adopts a chair conformation. The dihedral angle between the least-squares planes through the piperazine and benzene rings is 73.23 (10)°. In the crystal, there are no classical hydrogen bonds but stabilization is provided by weak C—H⋯π inter­actions

1,3-Benzothia­zole–oxalic acid (2/1)

The asymmetric unit of the title compound, C7H5NS·0.5C2H2O4, contains one benzothia­zole mol­ecule and half an oxalic acid mol­ecule, the complete mol­ecule being generated by inversion symmetry. The benzothia­zole mol­ecule is essentially planar, with a maximum deviation of 0.007 (1) Å. In the crystal, the benzothia­zole mol­ecules inter­act with the oxalic acid mol­ecules via O—H⋯N and C—H⋯O hydrogen bonds generating R 2 2(8) (× 2) and R 4 4(10) motifs, thereby forming supra­molecular ribbons along [101]

Diaqua­bis­(hydrogen tartrato)copper(II) dihydrate

The title complex, [Cu(C4H5O6)2(H2O)2]·2H2O, contains a CuII ion lying on an inversion centre. The coordination geometry of the CuII ion is a distorted octa­hedron with four O atoms from two hydrogen tartrate ions occupying the equatorial positions and two O atoms from two coordinated water mol­ecules occupying the axial positions. In the crystal structure, inter­molecular O—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network