A one-dimensional iodido-bridged Pt(II)/Pt(IV) mixed-valence complex cation with a hydrogen sulfate counter-anion

The title compound, catena-poly[[[bis­(ethyl­enedi­amine-κ(2) N,N′)platinum(II)]-μ-iodido-[bis­(ethyl­enedi­amine-κ(2) N,N′)platinum(IV)]-μ-iodido] tetra­(hydrogen sulfate) dihydrate], {[Pt(II)(C(2)H(8)N(2))(2)][Pt(IV)I(2)(C(2)H(8)N(2))(2)](HSO(4))(4)·2H(2)O}(n), has a linear chain structure comprising alternating platinum cations with mixed-valent oxidation states of +II/IV. Square-planar [Pt(en)(2)](2+) cations and elongated octa­hedral trans-[PtI(2)(en)(2)](2+) cations (en is ethyl­enedi­amine) are stacked alternately parallel to the b axis, and are bridged by the I ligands. The Pt site of the [Pt(II/IV)(en)(2)] units is located on a twofold rotation axis. The I site, which is located on the same twofold rotation axis, is equally disordered over two positions. The Pt and I sites form a straight ⋯I—Pt(IV)—I⋯Pt(II)⋯ chain, with Pt(IV)—I bond lengths of 2.7202 (6) and 2.6917 (6) Å, and Pt(II)⋯I contacts of 3.2249 (6) and 3.2534 (6) Å. The mixed-valence state of the Pt site is expressed by the structural parameter δ = (Pt(IV)–I)/(Pt(II)⋯I), with values of 0.843 and 0.827 for the two independent I atoms. In the crystal structure, the cationic columnar structure is stabilized by hydrogen bonds of the type N—H⋯O between the amine groups of the Pt complex chains and the disordered hydrogen sulfate counter anions, and between the amine groups and water mol­ecules of crystallization. In addition, O—H⋯O hydrogen bonds between the hydrogen sulfate anions and water mol­ecules of crystallization and between the hydrogen sulfate anions themselves consolidate the crystal packing.