Crystal Structure of a Hydrogen Sulfide Sorption Complex of Dehydrated Partially Cobalt(II)-Exchanged Zeolite A

Abstract

The crystal structure of a hydrogen sulfide sorption complex of partially Co(II)-exchanged zeolite A, Co4Na4-A·11H2S (a = 12.149(2) Å) has been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3̄m at 21(1) °C. The crystal of Co4Na4-A (initially light pink) was dehydrated at 380 °C and 2 × 10-6 Torr for 2 days (deep blue), followed by exposure to ca. 700 Torr of hydrogen sulfide gas at room temperature (black). The structure was refined to the final error indices R1 = 0.055 and Rw = 0.051 with 171 reflections for which I > 3σ(I). Four Co(II) ions are found at 6-oxygen ring sites where each coordinates to three framework oxygens at 2.24(1) Å. Each Co(II) ion is recessed 0.65 Å into the large cavity from the (111) plane of the nearest framework oxygens and coordinates at 2.60(2) Å to one H2S sulfur in the large cavity. Each of four Na+ ions lies between a 4-ring and an 8-ring in the large cavity, where it coordinates to a framework oxygen at 2.75 Å and to an H2S sulfur in the large cavity at 2.87 Å. Each of three additional H2S molecules is near the center of an 8-oxygen ring, where it coordinates to one or two Na+ ions and “hydrogen bonds” with 8-ring oxygens.