
TY  - JOUR
A1  - Mishra, A 
A1  - Pullin, ADE 
T1  - Donor-acceptor complexes formed by perfluoro-organo bromides and iodides with nitrogenous and other bases. II. Band shapes and widths in the absorption spectrum of gaseous CF<sub>3</sub>I-N(CH<sub>3</sub>)<sub>3</sub>
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1971
VL  - 24
IS  - 12
SP  - 2493
EP  - 2507
KW  - 
UR  - https://doi.org/10.1071/CH9712493 
N2  - The absorption band centred at c. 77 cm-1 in gaseous mixtures of CF3I and N(CH3)3 previously reported and attributed to the N-I stretching mode of the complex CF3I-N(CH3)3 has been carefully re-examined. This band is of interest as an example of a low frequency ?dissociative type? vibrational mode of a weak molecular complex. The band is asymmetric and apparently structureless with a half intensity width at room temperature of 28-30 cm-1. The width of the band may be accounted for as arising from transitions vi + vi+1 where vi is the vibrational quantum number of the N-I stretching mode with vi up to c. 10 making appreciable contribution to the intensity on the low wave-number side. Centrifugal distortion in the complex is considered. Centrifugal stretching and consequent weakening of the bond may shift the band envelope 2-3 cm-1 to lower wave numbers. Assessment of these and other factors affecting the band shape suggest that the fundamental frequency is probably c. 90 cm-1. The band shape of the vibrational mode of the complex at c. 272 cm-1 is briefly discussed. Many of the considerations presented in this paper should apply to vibration-rotation band shapes in other weak molecular complexes. Some general consequences of anharmonicity for the interpretation of the spectra of weak molecular complexes are discussed. 
ER  -

