Vibrational normal modes of diazo-dimedone: A comparative study by Fourier infrared/Raman spectroscopies and conformational analysis by MM/QM

The 2-diazo-5,5-dimethyl-cyclohexane-1,3-dione ( 3) was synthesized and the FT-IR/Raman spectra were measured with the purpose of obtain a full assignment of the vibrational modes. Singular aspects concerning the –C N N oscillator are discussed in view of two strong bands observed in the region of 2...

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Bibliographic Details
Published in:	Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 67; no. 3; pp. 1080 - 1087
Main Authors:	Téllez Soto, C.A., Ramos, J.M., Rianelli, R.S., de Souza, M.C.B.V., Ferreira, V.F.
Format:	Journal Article
Language:	English
Published:	England Elsevier B.V 01-07-2007
Subjects:	2-Diazo-5,5-dimethyl-cyclohexane-1,3-dione Azo Compounds - chemistry Computer Simulation Cyclohexanes - chemistry DFT:B3LYP/6-31G/BpB86/DN Models, Chemical Molecular Conformation Software Spectroscopy, Fourier Transform Infrared Spectrum Analysis, Raman Vibration Vibrational spectra 2-Diazo-5,5-dimethyl-cyclohexane-1,3-dione Vibrational spectra DFT:B3LYP/6-31G/BpB86/DN
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Summary:	The 2-diazo-5,5-dimethyl-cyclohexane-1,3-dione ( 3) was synthesized and the FT-IR/Raman spectra were measured with the purpose of obtain a full assignment of the vibrational modes. Singular aspects concerning the –C N N oscillator are discussed in view of two strong bands observed in the region of 2300–2100 cm −1 in both, Infrared and Raman spectra. The density functional theory (DFT) was used to obtain the geometrical structure and for assisting in the vibrational assignment joint to the traditional normal coordinate analysis (NCA). The observed wavenumbers at 2145 (IR), 2144(R) are assigned as the coupled ν(N N) + ν(C N) vibrational mode with higher participation of the N N stretching. A 2188 cm −1 (IR) and at 2186 cm −1 (R) can be assigned as a overtone of one of ν(CC) normal mode or to a combination band of the fundamentals δ(CCH) found at 1169 cm −1 and the δ (CC N) found at 1017 cm −1 enhanced by Fermi resonance.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1386-1425
DOI:	10.1016/j.saa.2006.09.030