Two Cd and Hg peroxodisulfate complexes with aromatic amines.

The crystal structures of two complexes containing the peroxodisulfate anion are reported, namely mu-peroxodisulfato-1kappaO:2kappaO'-bis[(acetato-kappa2O,O')aqua(2,2':6',2''-terpyridine-kappa3N,N',N'')cadmium(II)] heptahydrate, [Cd2(C2H3O2)2(S2O8)(C15H11N2)2(H2O)2].7H2O, (I), and catena-poly[[[bis(2,2'-bipyridine-kappa2N,N')mercury(II)]-mu-peroxodisulfato-kappa2O:O'] 0.4-hydrate], {[Hg(C10H8N2)2(S2O8)].0.4H2O}n, (II). In both structures, the anion behaves as a bridge, linking neighbouring coordination polyhedra in two different ways, either tightly bound to the heptacoordinated Cd2+ cation forming neatly separated dimeric entities in (I) or across a shorter O-S-O path producing weakly connected chains by way of 'semicoordination' to the Hg2+ cations in (II).