Thiosemicarbazid-1-ium Dihydrogenphosphate

Thiosemicarbazid-1-ium dihydrogenphosphate, CH₆N₃S⁺.H₂PO₄^-, unlike the semicarbazide complex compounds, does not exhibit temperature-dependent ferroelectric properties. X-ray structure determination at room temperature has shown that the crystal is centrosymmetric, space group C2/c, and thermal mobility of the structural units is relatively low. This allowed the refinement of all H-atom parameters without any space constraints. The H₂PO₄^- anions, with a distorted tetrahedral configuration, are hydrogen bonded to the thiosemicarbazidium cations. The average observed U_iso value for the H atoms (0.045 Å²) suggests that the protons are well fixed at their sites, and the extensive three-dimensional system of moderately short hydrogen bonds forms a structure in which dynamic disorder by hydrogen `jumping' is not pronounced.

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