A one-dimensional bromide-bridged PtII/PtIV mixed-valence complex with a 2-bromoethanesulfonate counter-ion

Abstract

The title salt, catena-poly[[[bis(ethylenediamine)platinum(II)]-μ-bromido-[bis(ethylenediamine)platinum(IV)]-μ-bromido] tetrakis(2-bromoethanesulfonate) dihydrate], {[PtIIPtIV Br2(C2H8N2)4]C2H4BrSO3)4·2H2O}n, crystallizes in the space group P21212. It has a linear chain structure extending parallel to the c axis, composed of square-planar [Pt(en)2]2+ and elongated octahedral trans-[PtBr2(en)2]2+ cations (en is ethylenediamine) stacked alternately and bridged by the Br atoms. The Pt site of the [PtII/IV(en)2] unit is located on a general position. The Br site, which is also located on a general position, is equally disordered over two positions. The Pt and Br atoms form a slight zigzag ⋯Br - PtIV - Br⋯PtII⋯ chain, with PtIV - Br bond lengths of 2.453 (2) and 2.491 (3) Å, PtII⋯Br contacts of 3.069 (2) and 3.032 (3) Å, and PtIV- Br⋯PtIIangles of 178.06 (13) and 177.70 (13)°. The mixed-valence state of the Pt site is expressed by the parameter δ = (PtIV-Br)/(PtII⋯Br), with values of 0.799 and 0.822 for the two independent Br atoms. In the crystal, N - H⋯O and O - H⋯O hydrogen bonds between the amine groups of the Pt complex chains, the sulfonate groups and water molecules of crystallization, stabilize the cationic columnar structure.