Synthesis, Spectroscopic, and Structural Characterization of Organyl Disulfanides and a Tetrasulfanide

Various room-temperature-stable monoorganylpolysulfanides of the form [X][RS] (X = [PPh₄]⁺, [PNP]⁺, [NEt₄]⁺; R = Ph, t-Bu, n ≥ 2) were synthesized in a simple and versatile one-step process starting from sodium thiolates and elemental sulfur. The compounds were characterized by X-ray crystal structure analysis, NMR spectroscopy, microelemental analysis, and electrospray mass ionization spectrometry including collision-induced dissociation experiments. While these salts are well-defined species as crystals, they undergo complex equilibria in solution. In one case, compounds ranging from n = 1-8 have been observed in solution. Structural features, dynamics in solution, as well as thermochromic properties of one of the compounds, [PPh₄][PhS₂], are investigated in detail by temperature- and pressure-dependent X-ray crystal structure analysis. The experimental data are complemented by periodic boundary density functional theory calculations on the crystal structures, as well as energy decomposition analyses.