Abstract: The temperature dependences of the EPR spectrum of the 2-trifluoromethylnitrobenzene radical anion in DMF:H2O mixtures, caused by the dynamic modulation of the fluorine isotropic hyperfine interaction by the hindered internal rotation of the CF3 group, have been measured and reconstructed numerically. The activation energy of rotation (E (F)) and the dynamic mode depended on the water content in the mixture. For mixtures with a molar fraction of water chi = 0, 0.186, 0.315, 0.409, 0.534, 0.650, 0.810, and 0.910, E (F) = 34.70 kJ/mol, 41.31 kJ/mol, 42.30 kJ/mol, 38.41 kJ/mol, 37.01 kJ/mol, 34.51 kJ/mol, 24.10 kJ/mol, and 21.78 kJ/mol, respectively. For chi = 0.186 in the temperature ranges accessible for measurements, the dynamic exchange is slow; for chi = 0.315, 0.409, 0.534, and 0.650, transitions from slow to intermediate and fast exchange take place; for chi = 0.810 and 0.910 in the temperature ranges under study T a [252, 309]; [254, 297] (K), the exchange is fast. In the range 0.6 < chi < 0.9, E (F) decreased drastically, and the activation energy of rotational diffusion (E (r)) of the radical anion became maximum, which corresponds to the range of the compositions of DMF:H2O with maximum deviations from the ideal state.

Cite: Shundrin L.A. , Melnikov P.V. , Polenov E.A.
Hindered internal rotation of the CF3 group in the 2-trifluoromethylnitrobenzene radical anion in DMF:H2O mixtures
Journal of Structural Chemistry. 2009. V.50. N6. P.1071-1081. DOI: 10.1007/s10947-009-0158-0 WOS Scopus РИНЦ OpenAlex

Original: Шундрин Л.А. , Мельников П.В. , Поленов Е.А.
Внутреннее заторможенное вращение группы CF3 в анион-радикале 2-трифторметилнитробензола в смесях ДМФА:H2O
Журнал структурной химии (J STRUCT CHEM+). 2009. Т.50. №6. С.1121-1131. РИНЦ

Dates:

Published print:	Dec 1, 2009
Published online:	Feb 4, 2010

Identifiers:

Web of science:	WOS:000274300500009
Scopus:	2-s2.0-77949608318
Elibrary:	15313367
OpenAlex:	W1974553683

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