Missing Links in the Sulfate Chemistry of Group 15 Elements: As(S2O7)(HS2O7), Sb2(SO4)2(S2O7), and Bi2(S2O7)3 from Reactions in Oleum under Harsh Conditions†

The reactions of As2O3, SbCl3, and (BiO)2CO3 with oleum (65 % SO3) yielded single crystals of As(S2O7)(HS2O7) [monoclinic, P21/c, Z = 4, a = 16.549(1), b = 6.6743(5), c = 9.9498(6) A, β = 102.672(8)°, V = 1072.672(8) A3], Sb2(SO4)2(S2O7) [monoclinic, P21/n, Z = 4, a = 9.1586(2), b = 6.9981(2), c = 17.7956(4) A, β = 100.9690(8)°, V = 1119.73(5) A3], and Bi2(S2O7)3 [triclinic, P, Z = 2, a = 6.5734(1), b = 10.1954(2), c = 11.5121(2) A, α = 90.996(1)°, β = 96.976(1)°, γ = 94.870(1)°, V = 762.75(2) A3]. As(S2O7)(HS2O7) shows the arsenic atoms in a trigonal pyramidal coordination of the oxygen atoms of one chelating S2O72– and one monodentate HS2O7– group. The distinct As(S2O7)(HS2O7) molecules are connected with each other by hydrogen bonds to form layers. Sb2(SO4)2(S2O7) shows the Sb3+ cations in a seesaw-type coordination of oxygen atoms from both anions. In Bi2(S2O7)3 the Bi3+ cations are in a square prismatic oxygen coordination of disulfate units. The antimony and the bismuth compounds exhibit complex three-dimensionally linked structures. The syntheses and the crystal structures, as well as the thermal decomposition of Sb2(SO4)2(S2O7) are presented.