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

Abstract

The title compound, catena-poly[[[bis(ethylenediamine-κ2 N,N′)platinum(II)]-μ-iodido-[bis(ethylenediamine-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 octahedral trans-[PtI2(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 [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 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.