Far-infrared and Raman spectra of crystalline ammonium and alkali-metal trichloromercurate(II) salts and some related compounds
- 1 January 1974
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 11,p. 1180-1185
- https://doi.org/10.1039/dt9740001180
Abstract
A complete vibrational assignment has been made for the tetragonal (α) form of the salt NH4[HgCl3] in terms of the known apex-shared octahedral polymeric sheet structure. The assignments have been aided by study of isomorphous ND4 + and Rb+ analogues. An order–disorder phase transition in the NH4 + and ND4 + salts, similar to those in ammonium halides, has been found from observation of a cation librational mode at low temperatures. Another (β) form of the salt NH4[HgCl3] has been characterized as having a double-rutile chain structure; vibrational assignments have been made by comparison with spectra of the isomorphous salts β-ND4[HgCl3] and M[CdCl3](M = NH4, ND4, K, or Rb). The previously described ‘Na[HgCl3]’ has been shown not to exist; dehydration of the compounds NaHgCl3,2H2O or NaHgCl3,2D2O gives a physical mixture NaCl–HgCl2. Vibrational spectra of the salts NH4[HgBr3], K[HgCl3], K2[HgCl4],H2O, and K2[HgCl4],D2O have also been studied.Keywords
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