Vibrational assignment and structure of trifluorobenzoylacetone. A density functional theoretical study.
Molecular structure and vibrational frequencies of 4,4,4-trifluoro-1-phenyl-1,3-butanedione, known as trifluorobenzoylacetone (TFBA), have been investigated by means of density functional theory (DFT) calculations. The results were compared with those of benzoylacetone (BA), acetylacetone (AA), and trifluoroacetylacetone (TFAA). Comparing the calculated and experimental band frequencies and intensities suggests coexisting of both stable cis-enol conformers in comparable proportions in the sample. The energy difference between the two stable chelated enol forms is negligible, 0.96 kcal/mol, calculated at B3LYP/6-311++G** level of theory. The molecular stability and the hydrogen bond strength were investigated by applying the natural bond orbital (NBO) theory and geometry calculations. The theoretical calculations and spectroscopic results indicate that the hydrogen bond strength of TFBA is between those of TFAA and AA, considerably weaker than that of BA.
Tayyari
Sayyed Faramarz
SF
Department of Chemistry, University of Ferdowsi, Mashhad 91775-1436, Iran. Tayyari@ferdowsi.um.ac.ir
Vakili
Mohammad
M
Nekoei
Abdo-Reza
AR
Rahemi
Hedayat
H
Wang
Yan Alexander
YA
D002074:Butanones / Q000737:chemistry*; D004583:Electrons; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D010422:Pentanones / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D055672:Static Electricity; D014732:Vibration
D002074:Butanones; D006845:Hydrocarbons, Fluorinated; D010422:Pentanones; C519063:trifluorobenzoylacetone; C008790:acetylacetone; C035851:benzoylacetone