Structure of associates in tetramethylurea aqueous solutions from the data of Raman scattering spectroscopy |
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Authors: | V V Lazarev M T Khatmullina L V Rabchuk A S Krauze |
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Institution: | 1.Ufa State Aviation Technical University,Ufa,Russia |
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Abstract: | The results from investigating interactions between tetramethylurea (TMU) and water molecules by means of Raman light scattering
spectroscopy (RS) are presented. It is established that spectroscopic manifestations of association of TMU and H2O molecules are observed for the TMU molecule valence vibration band ν(CO) 1638 cm−1. By means of quantum-chemical calculations, it is shown that the band sensitivity to molecular environment is defined by
the number of 5–6 H2O molecules. It is found that in a pure TMU medium, chain dimers are formed due to the interactions of molecular dipoles arranged
in parallel and hydrogen bonds of the C-H…O type. Ground state geometries of TMU, TMU-TMU, H2O molecules and TMU · (H2O)
n
complexes (n = 1−14) are optimized by the density functional B3LYP procedure, using the 6–31++G(d, p) basis set. The main vibration frequencies are calculated in the harmonic approximation. Associate formation energies are
calculated with allowance for the basis set superposition error (BSSE). |
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