Crystal engineering with short-chained amphiphiles: deca-sodium octa-n-butane-sulfonate di-μ-chlorido-bis-[di-chlorido-palladate(II)] tetra-hydrate, a layered inorganic-organic hybrid material.

In the course of crystal-engineering experiments, crystals of the hydrated title salt, Na(10)[Pd(2)Cl(6)](C(4)H(9)SO(3))(8)·4H(2)O, were obtained from a water/2-propanol solution of sodium n-butane-sulfonate and sodium tetra-chlorido-palladate(II). In the crystal, sodium n-butane-sulfonate anions and water mol-ecules are arranged in an amphiphilic inverse bilayered cationic array represented by the formula {[Na(10)(C(4)H(9)SO(3))(8)(H(2)O)(4)](2+)} (n) . Within this lamellar array: (i) a hydro-philic layer region parallel to the bc plane is established by the Na(+) cations, the H(2)O mol-ecules (as aqua ligands in κNa,κNa'-bridging coordination mode) and the O(3)S- groups of the sulfonate ions, and (ii) hydro-phobic regions are present containing all the n-butyl groups in an almost parallel orientation, with the chain direction approximately perpendicular to the aforementioned hydro-philic layer. Unexpectedly, the flat centrosymmetric [Pd(2)Cl(6)](2-) anion in the structure is placed between the butyl groups, within the hydro-phobic regions, but due to its appropriate length primarily bonded to the hydro-philic 'inorganic' layer regions above and below the hydro-phobic area via Pd-Cl(t)⋯Na- and Pd-Cl(t)⋯H-O(H)-Na-type (Cl(t) is terminal chloride) inter-actions. In addition to these hydrogen-bonding inter-actions, both aqua ligands are engaged in charge-supported S-O⋯H-O hydrogen bonds of a motif characterized by the D (4) (3)(9) graph-set descriptor within the hydro-philic region. The crystal structure of the title compound is the first reported for a metal n-butane-sulfonate.