HF, MP2 and DFT calculations and spectroscopic study of the vibrational and conformational properties of N-diethylendiamine.
Spectrochim Acta A Mol Biomol Spectrosc
; 68(3): 942-7, 2007 Nov.
Article
em En
| MEDLINE
| ID: mdl-17317286
ABSTRACT
The conformational stability and vibrational modes of the N-diethylendiamine organic cation (N-DD(2+)) were studied by experimental (Raman) spectroscopy combined with theoretical calculations. Various ab initio theories were used Hartree-Fock (HF) theory, Möller-Plesset second-order perturbation (MP2) theory and density functional theory (DFT). Three stable conformers of N-DD(2+), trans-trans, gauche-gauche and gauche-trans were calculated. A comparison between the computed structural parameters of the conformers at both levels of theory and the X-ray data was made. It is demonstrated that the N-DD(2+) cation adopts more probably the gauche-gauche conformation at room temperature. In order to make a more detailed interpretation of the low temperature phase transition of N-DDHP, the Raman spectra of N-DDHP were recorded at room and low temperature in the 200-3400 cm(-1) region. The vibrational frequencies of the different conformers of N-DD(2+) were also calculated using the DFT/B3LYP (6-31G(d)) level of theory. By comparison between the experimental and theoretical results, the conformational dynamic of the N-DD(2+) organic cation was confirmed. It is shown that the N-DD(2+) cation configuration changes from gauche-gauche conformer to gauche-trans conformer when decreasing the temperature.
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Base de dados:
MEDLINE
Assunto principal:
Análise Espectral Raman
/
Vibração
/
Diaminas
/
Etilenos
/
Modelos Químicos
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article