A new method to prepare polycrystalline meta-thioboric acid (c-HBS2) has been developed and reported. HBS2 was obtained as a vapor condensate by reacting H2S with B2S3 in the vapor phase, and the optimal conditions for this reaction are reported. The X-ray and spectroscopic characterization suggest that the structure of thioboric acid is monoclinic and made up of hexagonal rings formed by trimer units, (HBS2)3. The present preparation route is facile, faster than other wet routes of thiolysis, and the reaction requires much lower temperatures, thus avoiding contamination by reactor materials.

A new series of anhydrous protonated chalcogenide glasses, xH 2 S + (1x)B 2 S 3 , analogous to alkali-modified glasses, have been prepared. The preparation of these glasses was carried out in multiple steps. First crystalline meta-thioboric acid, c-(HBS 2 ) 3 , was prepared from vitreous boron sulfide, V-B 2 S 3 . c-(HBS 2 ) 3 was then used as a precursor for protonation to prepare a series of xH 2 S + (1x)B 2 S 3 samples with 0.0 e x e 0.5. The glass formation region of this system was found to be 0.0 e x e 0.25. The density and glass-transition temperature (T g ) of the samples were measured. While a substantial decrease in T g of the protonated glasses has been observed, there are insignificant changes in the density of the glasses. The IR and NMR spectra of the samples in the region 0.0 e x e 0.5 suggest that no tetrahedral borons are formed with the incorporation of protons. The characterization shows that these materials are unique and exhibit no borate anomaly as in the alkali-modified glasses.

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Using a combination of neutron diffraction, infrared spectroscopy, and first-principles calculations, we have investigated the structure of hydrated and dehydrated proton conducting alkali thio-hydroxogermanates of general formula M2GeS2(OH)2·yH2O (M = K, Rb, and Cs). The results show that the structure of hydrated and dry materials are basically the same, which confirms previous indications that the main effect of heating these materials is just a loss of water. We suggest that in the hydrated state the structure of these materials is built of dimers of thio-hydroxogermanate anions, with the water molecules acting as bridges between such dimers. In the dehydrated structure, the thio-hydroxogermanate anions instead form an extended network through the formation of interdimer hydrogen bonds through the −OH groups in the structure. The alkali ions are suggested to act as "space-fillers" in voids formed by the thio-hydroxogermanate anion dimers, in both the hydrated and the dehydrated state. Disciplines Inorganic Chemistry | Materials Chemistry | Materials Science and Engineering CommentsReprinted with permission from Chemistry of Materials 20 (2008) Using a combination of neutron diffraction, infrared spectroscopy, and first-principles calculations, we have investigated the structure of hydrated and dehydrated proton conducting alkali thio-hydroxogermanates of general formula M 2 GeS 2 (OH) 2 · yH 2 O (M ) K, Rb, and Cs). The results show that the structure of hydrated and dry materials are basically the same, which confirms previous indications that the main effect of heating these materials is just a loss of water. We suggest that in the hydrated state the structure of these materials is built of dimers of thio-hydroxogermanate anions, with the water molecules acting as bridges between such dimers. In the dehydrated structure, the thio-hydroxogermanate anions instead form an extended network through the formation of interdimer hydrogen bonds through the -OH groups in the structure. The alkali ions are suggested to act as "space-fillers" in voids formed by the thiohydroxogermanate anion dimers, in both the hydrated and the dehydrated state.