cyclo-Tetra­kis(μ(2)-d-penicillaminato-κ(4) N,S:O,S)tetra­palladium(II) 9.75-hydrate

The asymmetric unit of the title compound, [Pd(4)(C(5)H(9)NO(2)S)(4)]·9.75H(2)O, contains two neutral tetranuclear complex molecules with similar conformations and 19.5 solvent water mol­ecules. Of the 21 independent water molecules, three exhibit an occupancy of one-half. In each tetranuclear complex molecule, the four Pd(II) atoms have a square-planar coordination environment and are spanned by four d-penicillaminate ligands in a κ(4) N,S:S,O coordination mode, forming an eight-membered Pd(4)S(4) metallacycle. In the crystal, two tetra­nuclear mol­ecules are connected to each other through eight N—H⋯O hydrogen bonds between amine and carboxyl­ate groups, constructing a cylindrical dimer. The dimers are further hydrogen-bonded with the solvent water mol­ecules, completing a three-dimensional network.