ISSN:
0377-0486
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Raman trace scattering intensities are reported for the d0, d3, d6, d8 and d9 deuterated species of trimethylamine. Using normal coordinates from a previous scaled ab initio force field, the data are analysed in terms of seven derivatives ∂α¯∂S in the A1 symmetry species, each of which is well defined. Similar derivatives (dα¯/dr)CH with respect to the stretching of the two kinds of CH bond are shown to be very different from each other, showing a marked effect of the lone pair. Infrared intensities were measured for the d0, d8 and d9 species. These are well reproduced by ab initio calculations at the MP2/6-31G* level. The dipole derivative for the CHS bond trans to the lone pair is much greater than that for the Ha bond in the gauche position. The ab initio atomic polar tensors were used to obtain effective charges and other invariants, and the directions of dμ/dr for the CH bonds were determined. That for the Hs bond lies 23° off the bond direction. The ratio Xa/Xs of the abundances of the Ha and Hs conformers in the d8 isotopomer, required for the above analyses of the spectra, is calculated to be 1.80(4).
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jrs.1250260825
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