The hindered internal rotations in isomerism forms of a particular phosphorane involving 2-chloro-phenothiazine: Dynamic H-1 NMR study

摘要

The hindered internal rotations around the partial carbon-carbon double bond, nitrogen-carbon and carbon-carbon single bonds within the 2-(2-chloro-phenothiazine-1-yl)-3-(triphenylphosphoranylidene) butandioate has been experimentally studied by the dynamic H-1 NMR spectroscopic in variable temperatures. The activation (Delta H-double dagger, Delta S-double dagger, Delta G(double dagger)) and kinetic (k(c), E-a) parameters have been calculated in a series of separate dynamic H-1 NMR spectra. The energy of activation parameters obtained from classic, Eyring and Arrhenius methods have also been compared for carbon-carbon double bond in this compound. The results from Eyring and Arrhenius plots are in good agreement, but are different from the classical method. For nitrogen-carbon bond and carbon-carbon single bond, activation parameters have been calculated based on the coalescence temperature (classic method). In this study, due to spatial form of the compound, the value of N Delta H-double dagger of the restricted rotation around the partial carbon-carbon double bond and nitrogen-carbon are in close agreement.