A one‐dimensional chloride‐bridged Pt II /Pt IV mixed‐valence complex with a 4‐[(4‐hydroxyphenyl)diazenyl]benzenesulfonate counter‐ion

The title compound, catena ‐poly[[[bis(ethylenediamine‐κ 2 N , N ′)platinum(II)]‐ μ‐chlorido‐[bis(ethylenediamine)platinum(IV)]‐μ‐chlorido] tetrakis{4‐[(4‐hydroxyphenyl)diazenyl]benzenesulfonate} dihydrate], {[Pt II Pt IV Cl 2 (C 2 H 8 N 2 ) 4 ](HOC 6 H 4 N=NC 6 H 4 SO 3 ) 4 ·2H 2 O} n , has a linear chain structure composed of square‐planar [Pt(en) 2 ] 2+ (en is ethylenediamine) and elongated octahedral trans ‐[PtCl 2 (en) 2 ] 2+ cations stacked alternately, bridged by Cl atoms, along the b axis. The Pt atoms are located on an inversion centre, while the Cl atoms are disordered over two sites and form a zigzag ...Cl—Pt IV —Cl...Pt II ... chain, with a Pt IV —Cl bond length of 2.3140 (14) Å, an interatomic Pt II ...Cl distance of 3.5969 (15) Å and a Pt IV —Cl...Pt II angle of 170.66 (6)°. The structural parameter indicating the mixed‐valence state of the Pt atom, expressed by δ = (Pt IV —Cl)/(Pt II ...Cl), is 0.643.