VIBRATIONAL-SPECTRA OF SOME ARYLALDEHYDE AZINES

Infrared and Raman spectra have been recorded for some symmetric acycl ic azines (2,3-diazabutadienes) derivatives, namely p,p'-di-(N,N dimet hylamino), p,p'-dinitro, p,p'-dihydroxy, and p,p'-dichloro-benzaldazin e, An assignment for nearly all fundamentals are given. Our results co nfirm and complete some previously obtained data concerning the symmet ric and asymmetric stretches of the (-C=N-) bond, nu(s)C=N and nu(alph a)C=N, respectively. The nu(s)C=N can be identified as the most intens e Raman line having the highest half bandwidth. The N-N stretch (nu N- N)is observed only in the Raman spectra in the narrow wavenumber range (1010 -1005 cm(-1)) as the strongest line in the fingerprint region i ndicating an almost C-2h molecular symmetry. The spectra of the parahy droxy derivative show the association of these molecules via intermole cular H-bonding. For this compound, a new band appears at 225 cm(-1) i n the Raman spectra assignable to the out-of-plane deformation mode ga mma C-O of the -OH group.