ISSN:
0377-0486
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
IR and Raman spectra (4000-50 cm-1) of caesium hydrogensulphide and also deuterated specimens were recorded in the temperature range 6-520 K. The spectra confirm the presence of SH-…SH- hydrogen bonds in CsSH in contrast to other MSH compounds (M = alkali metal). The temperature evolutions of the wavenumbers and half-widths of the SH stretching and librational modes clearly display the partly second-order phase transitions. These are driven by thermally activated disordering of the SH- ions from the antiferroelectrically ordered low-temperature polymorph (LTM) via a one-dimensionally disordered middle-temperature polymorph (MTM) to the three-dimensionally disordered room-temperature form (RTM) of the CsCl type. The transition temperatures between these polymorphs differ depending on the degree of deuteration, viz. 105 and 115 K and 190 and 210 K for CsSH and CsSD, respectively, owing to the greater strengths of SD-…SD- bonds compared with SH-…SH- hydrogen bonds. In the RTM, the fraction of SH- ions which form hydrogen bonds decreases with increase in temperature. The strength (νSH = 2480-2550 cm-1, rH…S = 275-300 pm) and geometry (H…S—H angle ≈90°) of SH-…SH- hydrogen bonds is also discussed.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jrs.1250250604
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