Preparation and properties of H2B2S5 and its decomposition products

Article abstract of DOI:10.1021/ic50175a019

The preparation of solid H₂B₂S₅ and its decomposition product H₂S·xBS₂, x = 4.84 ± 1.75, and observations of their properties by visual and chemical means and by x-ray, infrared, Raman, and mass spectrometry are reported. Metathioboric acid, (HBS₂)₃, was prepared by two methods and heated with sulfur in evacuated, sealed Vycor tubes to yield H₂S·xBS₂. Diiodotrithiadiborolane, I₂B₂S₃, was prepared and treated with H₂S to obtain H₂B₂S₅ in benzene solution. Solid H₂B₂S₅ decomposed and polymerized spontaneously to yield H₂S·xBS₂. X-ray, infrared, and Raman spectrometry revealed polymerization and extensive S-S bonding in the solid. Mass spectrometry of the vapor from the solid products gave predominantly H₂B₂S₅⁺, H₂S⁺, and their fragments at temperatures below 80°C and then high molecular weight ions up to B₈S₁₆⁺ at higher temperatures. Fragmentation of H₂B₂S₅⁺ was shown to yield HBS₃⁺ by identification of the corresponding metastable ion. A relationship of H₂B₂S₅ to (BS₂)_n through polymerization and condensation is proposed.