A one-dimensional iodido-bridged PtII/PtIV mixed-valence complex cation with a hydrogen sulfate counter-anion.

The title compound, catena-poly[[[bis-(ethyl-enedi-amine-κ2 N,N')platinum(II)]-μ-iodido-[bis-(ethyl-enedi-amine-κ2 N,N')platinum(IV)]-μ-iodido] tetra-(hydrogen sulfate) dihydrate], {[PtII(C2H8N2)2][PtIVI2(C2H8N2)2](HSO4)4·2H2O} 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 octa-hedral trans-[PtI2(en)2]2+ cations (en is ethyl-enedi-amine) are stacked alternately parallel to the b axis, and are bridged by the I ligands. The Pt site of the [PtII/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-PtIV-I⋯PtII⋯ chain, with PtIV-I bond lengths of 2.7202 (6) and 2.6917 (6) Å, and PtII⋯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 = (PtIV-I)/(PtII⋯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 mol-ecules of crystallization. In addition, O-H⋯O hydrogen bonds between the hydrogen sulfate anions and water mol-ecules of crystallization and between the hydrogen sulfate anions themselves consolidate the crystal packing.