Monomers, Chains and Layers of [Pt₂(SO₄)₄] Units in the Crystal Structures of the Platinum(III) Sulfates (NH₄)₂[Pt₂(SO₄)₄(H₂O)₂], K₄[Pt₂(SO₄)₅] and Cs[Pt₂(SO₄)₃(HSO₄)]

The reaction of Pt(NO 3 ) 2 with concentrated sulfuric acid in sealed glass ampoules at 400 °C causes reduction of the nitrate ion to NH 4 + and leads to single crystals of (NH 4 ) 2 [Pt 2 (SO 4 ) 4 (H 2 O) 2 ] [triclinic, P 1 , Z = 1, a = 749.96(9), b = 754.2(1), c = 765.4(1) pm, α = 102.15 (1)°, β = 110.23(1)°, γ = 100.87(1)°, R all = 0.0677]. In the crystal structure, Pt 2 dumbbells are coordinated by four bidentate‐bridging sulfate ions and two axial H 2 O molecules. The replacement of the axial H 2 O molecules with SO 4 2− , which can be observed in the crystal structure of K 4 [Pt 2 (SO 4 ) 5 ] [triclinic, P 1 , Z = 2, a = 975.6(1), b = 1331.8(1), c = 1491.0(1) pm, α = 101.156(8)°, β = 96.278(8)°, γ = 102.849(8)°, R all = 0.0459], causes a connection of the dumbbells into chains of the composition 1 ∞ [Pt 2 (SO 4 ) 4/1 (SO 4 ) 2/2 ] 4− . K 4 [Pt 2 (SO 4 ) 5 ] has been obtained from the reaction of K 2 [PtCl 4 ] and concentrated H 2 SO 4 at 400 °C in sealed glass tubes. The same reaction with Cs 2 [PtCl 4 ] instead of K 2 [PtCl 4 ] leads to Cs[Pt 2 (SO 4 ) 3 (HSO 4 )] [monoclinic, P 2 1 / c , Z = 4, a = 1724.8(2), b = 881.28(9), c = 935.1(1) pm, β = 100.397(8)°, R all = 0.0458]. In the crystal structure, part of the bidentate‐bridging sulfate ions of the [Pt 2 (SO 4 ) 4 ] core act as monodentate ligands to further Pt 2 dumbbells leading to anionic layers of the composition 2 ∞ [Pt 2 (SO 4 ) 4/2 (SO 4 ) 2/1 ] 2− and neutral units with the formula 2 ∞ [Pt 2 (SO 4 ) 4/2 (HSO 4 ) 2/1 ]. The two types of layers are stacked alternatingly with the ten coordinate Cs + ions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)