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Conformational Landscape of the 1/1 Diacetyl/Water Complex Investigated by Infrared Spectroscopy and ab Initio Calculations
journal contribution
posted on 2016-12-13, 00:00 authored by D. Dargent, B. Madebène, P. Soulard, B. Tremblay, E. L. Zins, M. E. Alikhani, P. AsselinThe complexes of diacetyl with water
have been studied experimentally by Fourier transform infrared (FTIR)
spectroscopy coupled to solid neon matrix and supersonic jet, and
anharmonic ab initio calculations. The vibrational analysis of neon
matrix spectra over the 100–7500 cm–1 infrared
range confirms the existence of two nearly isoenergetic one-to-one
(1/1) diacetyl-water S1 and S2 isomers already
evidenced in a previous argon matrix study. A third form (S3) predicted slightly less stable (J. Mol. Mod. 2015, 21, 214) is not observed. The correct agreement
obtained between neon matrix and anharmonic calculated vibrational
frequencies is exploited in several cases to derive band assignments
for the vibrational modes of a specific isomer. Thereafter, theoretical xij anharmonic coupling constants
are used for the attribution of combination bands and overtones relative
to the 1/1 dimer. Finally, the most stable isomer of the one-to-two
(1/2) diacetyl–water complex is identified in the OH stretching
region of water on the grounds of comparison of experimental and calculated
vibrational shifts between water dimer and the three most stable 1/2
isomers.