On the Use of Mercury Bis(Phenylselenolate) for the Synthesis of Polymeric Clusters: Synthesis and X-ray Structural Characterization of [Hg5Cl3(PhSe)7]n, [Hg7Cl3(PhSe)11]n and [Hg7Br3(PhSe)11]n

(PhSe)2Hg reacts in DMF with HgX2 (X = Cl, Br) in the presence of bis(pyrimidin-2-thio)methane/triphenylphosphine/4,4′-bipyridine, to give the polymeric cages [Hg5Cl3(PhSe)7]n (1), [Hg7Cl3(PhSe)11]n (2) and [Hg7Br3(PhSe)11]n (3). In compound 1 the polymeric chains along the a axis are linked through H···Cl interactions in the c axis, assembling a two-dimensional lattice in the ac plane. The analogue compounds 2 and 3 attain bulky single clusters with the general formula Hg14X6(SePh)22 (X = Cl, Br), accomplished by the symmetrical combination of two asymmetric units [Hg7X3(PhSe)11]. While the polymerization of the single units of 2 along the c axis occurs through 4 selenium atoms, the polymerization of 3 arises through 6 bonds involving Hg and Se atoms. Although 2 and 3 seem to be resultant from the random assembly of asymmetrical rings, both cluster compounds present symmetry centers.