Wydział Chemii

Roman Szostak

2011

Journal of Raman Spectroscopy

42

1185-1192

10.1002/jrs.2808

Naukowa

Angielski

Artykuł

Raman spectra of the Cl3CCHO/CCl4and Cl3CCHO/C6D12binary systems were recorded as a function of the mole fraction.Features originating from self-aggregates of chloral (trichloroethanal, trichloroacetaldehyde – TCAA) molecules were detectedin different spectral regions. The most pronounced changes were observed in the vicinity of theν(CO) andν(C – H) stretchingvibration bands. Using two-dimensional correlation spectroscopy (2D-COS), evolving-factor analysis (EFA) and multivariatecurve resolution (MCR), dimer bands were identified, and their positions were determined. Theν(C – H) stretching vibrationband in dimers was blue-shifted by nearly 18 cm−1, whereas theν(CO) dimer band was red-shifted by more than 5 cm−1.For these bands, the observed shifts were accompanied by an almost twofold change in the bandwidth, from approximately19 and 6 cm−1for dilute solutions (x=0.05) to 36.6 and 11.5 cm−1, respectively, in pure TCAA. The formation of dimers wasconfirmed by multivariate analysis of the Raman spectra of chloral recorded as a function of temperature. Analogous analysisof dichloroacetyl chloride (DCAC) spectra gave an 8.9 cm−1blue shift for theν(C – H) vibration band and−5.5/−10.1cm−1shiftsfor theν(CO) stretching vibrations of the two conformers present. To facilitate the interpretation of experimental findings,the optimized geometries and vibrational wavenumbers of the Cl3CCHO/HCl2CCClO molecules and (Cl3CCHO)2/(HCl2CCClO)2dimers were calculated at the B3LYP/6-311++G(3df,3pd) level. Copyrightc
2010 John Wiley & Sons

blue-shifting hydrogen bond, trichloroethanal, dichloroacetyl chloride, Raman spectra, multivariate analysis, TD DFT calculations

http://dx.doi.org/10.1002/jrs.2808

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