Disproportionation of an Element in a Zeolite. III. Crystal Structure of a High-Temperature Sulfur Sorption Complex of Zeolite LTA Containing Two New Ions: Perthiosulfite, S42–, and the Trisulfur Cation, S32+

Abstract

The structure of a high-temperature sulfur sorption complex of zeolite Na-A (LTA) has been determined by single-crystal crystallography. It was prepared by treating anhydrous Na-A with sulfur vapor at 623 K. Its crystal structure was refined in the space group Pm3m (a = 12.192(1) A) to the error index R1 = 0.075. Upon sorption, sulfur disproportionated fully to give one perthiosulfite anion, S42–, and one trisulfur cation, S32+, per unit cell. The perthiosulfite anion (S–S = 2.16(5) A and S–S–S = 105.4(22)°) is the perthio form of SO32–. It is in the large cavity where it bonds to one 6-ring and three 8-ring Na+ ions (S–Na = 2.83(6) A, 2.80(5) A, and 2.43(5) A). It appears to be the first example of a branched polysulfide ion. The electron-deficient trisulfur cation, S32+ (S–S = 2.11(8) A and S–S–S = 102.0(14)°), bonds to framework oxygen atoms in the sodalite cavity (S–O = 2.64(7) A). Twelve Na+ ions are found per unit cell at five crystallographic sites similar to but different from those in anhydrous ...