Tetrakis(2-amino-5-methyl-1,3,4-thiadiazole-N3)chlorocopper(II) chloride monohydrate and tetrakis(2-amino-5-ethyl-1,3,4-thiadiazole-N3)chlorocopper(II) chloride.

The structures of the title compounds, [CuCl(C(3)H(5)N(3)S)(4)]Cl.H(2)O, (I), and [CuCl(C(4)H(7)N(3)S)(4)]Cl, (II), comprise square-pyramidal Cu centres with four N-bound organic ligands filling the base positions, a Cl atom in the apical position and a Cl(-) as a free counter-ion. The cation and free chloride ion in (II) have fourfold crystallographic symmetry. Hydrogen-bonding associations from the 2-amino H atoms dominate both structures, with the principal acceptors being the chlorides, although in (I), the N4 atoms are also involved. Furthermore, (I) is a hydrate, with the water molecule participating in the hydrogen-bonding network.