Redetermination of the crystal structure of catena-poly[[[bis-(ethyl-enedi-amine)-platinum(II)]-μ-iodido-[bis-(ethyl-enedi-amine)-platinum(IV)]-μ-iodido] tetra-kis-(octane-1-sulfonate) dihydrate].

The structure of the title compound, which represents a mixed-valence platinum(II,IV) complex, {[Pt(II)Pt(IV)I2(C2H8N2)4][CH3(CH2)7SO3]4·2H2O} n , has been redetermined in a different space group. In contrast to the previously reported determination in the space group P21 cn [Matsushita & Taira (1999 ▸). Synth. Met. 102, 1787-1788], the current model was refined in the centrosymmetric space group Pmcn using the original diffraction data. The title compound has a linear chain structure composed of square-planar [Pt(en)2](2+) and elongated octa-hedral trans-[PtI2(en)2](2+) cations (en is ethyl-enedi-amine) stacked alternately, bridged by the I atoms, parallel to the c axis. Inorganic layers aligned parallel to the bc plane, composed of the Pt-complex columns, the -SO3 (-) part of the octane-1-sulfonate anion, and the water mol-ecule of crystallization, are stacked alternately with organic layers composed of the long-chain alkyl groups along the a axis. The Pt and I sites are located on the same mirror plane whereby the I site is equally disordered over two positions. The Pt and I atoms form a slight zigzag ⋯I-Pt(IV)-I⋯Pt(II)⋯ chain, with Pt(IV)-I bond lengths of 2.6888 (17) and 2.7239 (17) Å, Pt(II)⋯I contacts of 3.2065 (17) and 3.1732 (16) Å, and Pt(IV)-I⋯Pt(II) angles of 178.3 (3) and 176.7 (2)°. The mixed-valence state of the Pt site is expressed by the structural parameter δ = (Pt(IV)-I)/(Pt(II)⋯I), with values of 0.839 and 0.858 for the two independent I atoms. In the crystal, N-H⋯O hydrogen bonds involving the cationic chains, the sulfonate groups and water mol-ecules of crystallization, stabilize the columnar structure.