Abstract: | Temperature dependences of the paramagnetic shifts induced by Eu(fod)3 in 1H NMR spectra of ethylene oxide in carbon disulphide solution are obtained in the temperature range from +40 to ? 100°C at 100 MHz and from +30 to ?60°C at 60 MHz. The influence of chemical exchange leads to a decrease of the observed paramagnetic shifts with decreasing temperature. It is shown that a modified Swift and Connick equation can be used to describe the observed dependences. Upper limits of the mean lifetimes of the Eu(fod)3-ethylene oxide adduct are τp < 1·7 × 10?8 s at 14 °C and τp < 1 × 10?8 s at 20 °C, respectively. The corresponding activation energy is equal to Va = 13·7 kcal/mol. |