Cracking the Dumbbell – from (NO)4[Pt2(SO4)5] to (NO)2[Pt(S2O7)3] by Oxidation with SO3

Abstract

AbstractThe reaction of elemental platinum, oleum (65 % SO3), and fuming nitric acid in sealed glass ampoules at 350 °C yielded orange single crystals of (NO)4[Pt2(SO4)5] [triclinic, P$\bar{1}$, Z = 4, a = 977.41(3) pm, b = 1318.37(4) pm, c = 1511.47(5) pm, α = 105.218(1)°, β = 95.042(1)°, γ = 102.293(1)°, V = 1814.80(1)·106 pm3]. The crystal structure contains dumbbell shaped [Pt2] moieties surrounded by four chelating sulfate anions, forming the so‐called paddlewheel motif. The paddlewheels are connected via two terminal monodentate sulfate anions to infinite anionic chains. Charge compensation is achieved by nitrosylium cations. The reaction of (NO)4[Pt2(SO4)5] with neat SO3 in sealed glass ampoules at 120 °C yielded yellow single crystals of the tris‐(disulfato)‐platinate(IV) (NO)2[Pt(S2O7)3] [triclinic, P$\bar{1}$, Z = 2, a = 893.20(4) pm, b = 1093.25(4) pm, c = 1098.63(4) pm, α = 62.329(2)°, β = 69.107(2)°, γ = 69.654(2)°, V = 865.88(6)·106 pm3]. In the structure of (NO)2[Pt(S2O7)3] the platinum atoms are coordinated by three bidentate chelating disulfate anions forming an octahedral coordination sphere of oxygen atoms around the platinum atom. Charge compensation is achieved by nitrosylium cations. The thermal behavior of both compounds was monitored by TG/DSC measurements. Magnetic susceptibility measurements on (NO)2[Pt(S2O7)3] revealed diamagnetism, proving the electronic d6 low‐spin configuration of the Pt4+ ion.