Three zinc(II) complexes presenting a ZnN6 chromophore and with peroxodisulfate as the counter-ion

The crystal structures of three Zn complexes with the peroxodisulfate anion (pds(2-)) acting as counter-ion are reported, namely bis(2,2':6',2"-terpyridine-kappa(3) N)zinc(II) hexaoxo-mu-peroxo-disulfate(VI) dihydrate N,N-dimethylformamide solvate, [Zn(C15H11N3)(2)](S2O8).2H(2)O.C3H7NO or [Zn(tpy)(2)](pds).2H(2)O.DMF, (I), bis[2,4,6-tris(2-pyridyl)-1,3,5-triazine-kappa(2)N(2), N-4]zinc(II) hexaoxo-mu-peroxo-disulfate(VI) dihydrate, [Zn(C18H12N6)(2)](S2O8).2H(2)O or [Zn(tpt)(2)](pds).2H(2)O, (II), and bis[2,6-bis(1H-benzimidazol-2-yl-kappaN(3))-pyridine] zinc(II) hexaoxo-mu-peroxo-disulfate(VI) N, N-dimethylformamide trisolvate, [Zn(C19H13N5)(2)](S2O8).3C(3)H(7)-NO or [Zn(bbp)(2)](pds).3DMF, (III), where tpy is 2,2':6',2"-terpyridine, tpt is 2,4,6-tris(2-pyridyl)-1,3,5-triazine, bbp is 2,6-bis(1H-benzimidazol-2-yl)pyridine and DMF is N, N-dimethylformamide. The three structures are monomeric and present the Zn cation in a distorted octahedral environment, defined by two chelating tricoordinated ligands at almost right angles to each other. These cationic entities interact with an anionic network composed of hydrogen-bonded pds(2-) anions and solvate water and DMF molecules via Coulombic forces, and with each other through a number of pi-pi and C=C ... pi contacts connecting the aromatic rings. The pds(2-) anions stabilize the structures in unprecedented counter-ion behaviour.