The molecular structure of gaseous 1,2 cyclohexanedione

✍ Scribed by Q. Shen; M. Traetteberg; S. Samdal

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 324 KB
• Volume: 923
• Category: Article
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2009.02.006

✦ Synopsis

The molecular structure of 1,2 cyclohexanedione has been investigated in the vapor at 295 K. The electron diffraction data were consistent with a model of pure enol form (2-hydroxy-2-cyclohexen-1-one) with the six-membered ring in the sofa conformation (with C 5 out of the plane formed by the other carbon atoms). Quantum chemical [HF/MP2/B3LYP 6-311G(d,p)] calculations showed the enol form with hydrogen bond to be lower in energy than the keto form and the enol form without hydrogen bond to be higher in energy than the keto form. HF and B3LYP calculations estimated enol populations of over 99% at 295 K. The principal geometrical parameter values (r g and \ a ) obtained from least squares analysis are:

assumed), sC 3 C 4 C 5 C 6 = 50.8°( 16), sC 4 C 5 C 6 C 1 = 55.3°( 16) and sC 2 C 3 C 4 C 5 = 22.8°(9).