Selective Trapping of Labile S₃ in a Porous Coordination Network and the Direct X‑ray Observation

Abstract

S₃ is one of the basic allotropes of sulfur but is still a mysterious labile species. We selectively trapped S₃ in a pore of a thermally stable coordination network and determined S₃ structure by <i>ab initio</i> X-ray powder diffraction analysis. S₃ in a pore has a <i>C</i>_2<i>v</i> bent structure. The network containing trapped S₃ is remarkably stable under ambient conditions and is inert to photoirradiation. S₃ in the network could be transformed to S₆ by mechanical grinding or heating in the presence of NH₄X (X = Cl or Br). S₆ could be reverse-transformed to S₃ by photoirradiation. We also determined the structure of the network containing S₆ by <i>ab initio</i> X-ray powder diffraction analysis