Cs2K2[Pt12O8(SO4)12]:: A new oxide-sulfate with the cluster anion [Pt12O8(SO4)12]4-

Single crystals Of Cs2K2[Pt12O8(SO4)(12)] (R (3) over bar, Z = 3, a = 1198.9(3), c = 2768.9(9) pm, R-all = 0.1154) were obtained by the reaction Of Cs-2[Pt(NO2)(4)], K-2[Pt(NO2)(4)] and conc. sulfuric acid at 400 degrees C in a sealed glass ampoule. The compound contains the cluster anion [Pt12O8(SO4)(12)](4-). It consists Of Six Pt-2(6+) dumbbell shaped cations that are linked by eight oxide ions and twelve sulfate anions to form a distorted Pt-12 icosahedron. The arrangement of the cluster anions in the crystal structure provides two voids for the cations. The larger one is occupied by the Cs+ ions while the K+ ions reside in the smaller one. For the Cs+ ions the coordination number is 15 while the K+ ions have a coordination number of 13.