No abstract

This paper combines earlier preliminary reports on F2CO, FClCO and Cl2CO into a complete report on the Raman and infrared spectra of these molecules. Details of measurement and handling of the samples are given. The fundamental frequencies observed in both Raman effect (liquid) and infrared (gas) and a large number of overtone and combination frequencies observed in the infrared have been identified and are collected in tables. The observed infrared band envelopes are described and compared with the band envelopes predicted on the basis of the molecular models. Resonance between ν2 and 2ν1 in F2CO and ν2 and ν1+ν4 in FClCO is discussed.

An infrared and Raman spectroscopic study of light and heavy trifluoroacetic acids shows that their vapors at room temperature are composed of a mixture of monomeric and associated molecules. The principal bands corresponding to vibrations of the COOH and COOD groups have been identified for both the monomeric and the associated molecules by means of a comparative study of the two acids (a) in the vapor state at different pressures, (b) in CCl4 solutions at various concentrations, and (c) in the liquid state. The monomeric carbonyl frequencies, influenced by the presence of the perfluoromethyl group, are the highest yet reported in the literature; this is true not only for CF3COOH (1826 cm−1, vapor), CF3COOD (1823 cm−1, vapor), but also for the ethyl ester, CF3COOC2H5 (1802 cm−1, vapor), the sodium salt, CF3COONa (1687 cm−1, solid), and the anhydride (CF3COO)2O (1884 cm−1 and 1818 cm−1, vapor). On the basis of a comparative study of the spectra of all these compounds, as well as of other perfluoromethyl compound spectra reported in the literature, the C–F stretching vibrations for the two acids have been assigned to the strong infrared absorptions at 1244 cm−1 and 1185 cm−1. The corresponding Raman bands are very weak.

The infrared and Raman spectra of SiF4 have been completely reexamined and extended. The Raman spectrum yields four lines at 268 cm−1, 390 cm−1, 800 cm−1, and 1010 cm−1, which have been assigned ν2, ν4, ν1, and ν3 respectively. In the infrared measurements, both prism and grating spectrometers were utilized. Several bands reported in earlier work have been ascribed to impurities and nine new bands have been observed and identified. The long-wave ν4 at 391 cm−1 has been observed with a KRS−5 prism and its envelope determined. Bands involving ν3 appear to have a PR spacing of about 12 cm−1 while those involving ν4 appear to have a PR spacing of about 20 cm−1.

The Raman spectra of aqueous solutions of seventeen different metal perchlorates have been obtained in an effort to collect evidence of possible complex formation. Seven of these, the perchlorates of cadmium( 11), mercury( I), mercury (II), lanthanum(III), thallium( I), magnesium( 11) and manganese( 11) exhibited Rarnan lines in addition to those expected from the perchlorate ion. Of these, only the last three showed Raman lines which could tentatively be attributed to complexes rather than ion-pairs. In all cases these lines were extremely weak and an alternative explanation cannot be excluded with certainty. Even in those cases where extra Raman lines are observed, the association must he very slight.