Spectroscopy at very high pressures. Part 11. A Raman study of polymorphs of carbon tetrachloride and tetrabromide and their photodecomposition products
- 1 January 1976
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 23,p. 2424-2429
- https://doi.org/10.1039/dt9760002424
Abstract
Raman spectra are reported for all the four solid phases of CCl4, and for three of the four phases of CBr4. All the spectra have been obtained under hydrostatic or near-hydrostatic conditions, and are shown to be compatible with such structural data as are available, except for CBr4(I) for which a pseudo-cubic monoclinic structure is proposed. The phases CBr4(IV) and CCl4(IV) have spectra compatible with predictions on the basis of the SnI4 structure type. Carbon tetrachloride photodecomposes under pressure to yield, principally, C2Cl6 and some chlorine, whereas CBr4 gives much bromine together with other (unidentified) products. The CCl4 photodecomposition can be catalysed by the Cr3+ present in the ruby pressure calibrant: this alters the mode of decomposition yielding, principally, chlorine. The liquid-to-solid transition pressure of chlorine is ca. 7 kbar at 293 K, and that of bromine is 5.26 kbar at 308 K.Keywords
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