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.

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 redetermination of the structure of the title compound with the original measurement data revealed a centrosymmetric model in space group Pmcn, in contrast to the previous model in space group P2₁cn.

The structure of the title compound, which represents a mixed-valence platinum(II,IV) complex, {[Pt^IIPt^IVI₂(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 P2₁cn [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 octa­hedral trans-[PtI₂(en)₂]²⁺ cations (en is ethyl­enedi­amine) 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 mol­ecule 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 mol­ecules of crystallization, stabilize the columnar structure.