Synthesis and Characterization of the Trisulfate Pb[S₃O₁₀] and Theoretical Analysis of H₂S₃O₁₀

The reaction of (NH 4 ) 2 PbCl 6 and fuming sulfuric acid (65 % SO 3 ) in a sealed glass tube at 250 °C led to colorless single crystals of Pb[S 3 O 10 ] (orthorhombic, Pbcn , Z = 4, a = 10.9908(4), b = 8.5549(3), c = 8.0130(3) Å, V = 753.42(5) Å 3 ). The compound shows a three‐dimensional linkage of the tenfold oxygen coordinated Pb 2+ ions and exhibits the unusual trisulfate anion, [S 3 O 10 ] 2– , that consists of three vertex connected [SO 4 ] tetrahedra. The distances S–O within the S–O–S bridges of the anion are remarkable asymmetric with distances of 155 and 169 pm, respectively. This structural feature is well reproduced by calculations on a PBE0/cc‐pVTZ and a MP2/cc‐pVTZ level of theory. Similar calculations allow also for an inspection of the yet unknown corresponding acid, H 2 S 3 O 10 . Also for this acid non‐symmetric S–O–S bridges are predicted. The thermal behavior of Pb[S 3 O 10 ] is characterized by the loss of two equivalents of SO 3 at low temperature and the decomposition of intermediate Pb[SO 4 ] at higher temperature.