CRYSTAL-STRUCTURE OF A HYDROGEN-SULFIDE SORPTION COMPLEX OF DEHYDRATED PARTIALLY COBALT(II)-EXCHANGED ZEOLITE-A

The crystal structure of a hydrogen sulfide sorption complex of partia lly Co(II)-exchanged zeolite A, Co(4)Na(4)A . 11H(2)S (a = 12.149(2) A ngstrom) has been determined by single-crystal X-ray diffraction techn iques in the cubic space group Pm (3) over bar m at 21(1) degrees C. T he crystal of Co4Na4-A (initially light pink) was dehydrated at 380 de grees C and 2 x 10(-6) Ton for 2 days (deep blue), followed by exposur e to ca. 700 Ton. of hydrogen sulfide gas at room temperature (black). The structure was refined to the final error indices R(1) = 0.055 and R(W) = 0.051 with 171 reflections for which I > 3 sigma(I). Four Co(I I) ions are found at 6-oxygen ring sites where each coordinates to thr ee framework oxygens at 2.24(1) Angstrom. Each Co(II) ion is recessed 0.65 Angstrom into the large cavity from the (111) plane of the neares t framework oxygens and coordinates at 2.60(2) Angstrom to one H2S sul fur in the large cavity. Each of four Na+ ions lies between a 4-ring a nd an 8-ring in the large cavity, where it coordinates to a framework oxygen at 2.75 Angstrom and to an H2S sulfur in the large cavity at 2. 87 Angstrom. 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.