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1 Polish Journal of Chemistry

1 2008

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Synthesis, Characterization, Crystal Structure and Quantum Chemical Studies on N-Dimethyl-N'-phenyl-thiocarbamide

Zhao P. S., Qin Y. Q., Zhang J., Jian F. F.

Polish Journal of Chemistry

2008

Vol. 82, nr 11

2153-2165

The title compound of N-dimethyl-Nc-phenyl-thiocarbamide was synthesized and characterized by elemental analysis, IR, NMR, electronic spectra and X-ray single crystal diffraction. Quantum chemical calculations were performed by using B3LYP and HF methods with 6-311G** basis set. Both the methods well simulate the molecular structure. Vibrational frequencies were predicted, assigned and compared with the experimental values, which suggest that both methods can only predict the vibrational frequencies approximatively. The nuclear magnetic shieldings were predicted by using GIAO method and compared with experiment. The results show that, for the title compound, B3LYP/6-311G** method better predicts the 13C NMR spectra than HF/6-311G**, whereas HF/6-311G** better predicts the 1H NMR spectra than B3LYP/6-311G**. Electronic absorption spectra predicted by B3LYP/6-311G** method are closer to the experimental data and natural bond orbital analyses indicate that the absorption bands are mainly from the contribution of n → pi* and pi → pi* transitions. For the system studied here, HF/6-311G** method can not be used to obtain the electronic absorption spectra. On the basis of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between Cp,m 0 , Sm 0 , Hm 0 and temperatures.