Vibrational Coupling in trans-Azobenzene and Its Isotopomers (CROSBI ID 465023)
Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija
Podaci o odgovornosti
Meić, Zlatko ; Baranović, Goran ; Smrečki, Vilko ; Novak, Predrag ; Keresztury, Gabor ; Holly, Sandor
engleski
Vibrational Coupling in trans-Azobenzene and Its Isotopomers
In order to clarify the nature of coupling of vibrational coordinates of the azo group with its surrounding, the molecule of trans-azobenzene (tAB) was chosen. It is interesting to compare this coupling with those of isoelectronic compounds containing two phenyl groups connected to a bridging group, such as cis-stilbene (cSB), trans-stilbene (tSB) and trans-N-benzylideneaniline (tBA), already treated by our group. trans-Azobenzene molecule belongs to the C_2h point group with four symmetry species: a_g (Raman active, in-plane), a_u (infrared active, in-plane), b_g (Raman active, out-of-plane) and b_u (infrared active, out-of-plane). In the FT Raman spectrum of powdered tAB a very strong Raman band (a_g) was found at 1440 cm(-1), having no a counterpart in the infrared spectrum. Since it is shifted to 1428 cm(-1) in (N-15)-tAB, it was assigned to the N=N stretching mode. This is a very low value in comparison with 1630 cm(-1) (C=C str.), 1639 cm(-1) (C=C str.) and 1626 cm(-1) (C=N str.) in neat cSB, tSB and tBA, respectively. However, in (D_10)-tAB the strongest Raman band appears at 1466 cm(-1) without any stronger band around. The normal coordinate calculations of tAB, using the AM1 procedure, indicate a substantial contribution to the N=N stretching from the phenyl group mode 19b. In the case of (D_10)-tAB the N=N mode is decoupled, because the light phenyl groups are substituted by the heavy ones, which increases the N=N stretching frequency. Another indication of the strong coupling of azo and phenyl modes in tAB is the appearance of numerous bands in the infrared spectrum of 4-D-tAB (C_S point group) in comparison with tAB itself (C_2h). Such an activation of infrared absorptions was not observed in analogous cSB, tSB and tBA isotopomers.
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Podaci o prilogu
45-x.
1996.
objavljeno
Podaci o matičnoj publikaciji
Book of Abstracts
Mink, J ; Jalsovsky, G ; Keresztury, G.
Budimpešta: Hungarian Academy of Sciences (MTA)
Podaci o skupu
XXIII. European Congress on Molecular Spectroscopy
predavanje
25.08.1996-30.08.1996
Balatonfüred, Mađarska