Dynamic 1H NMR along with theoretical study around the carbon-carbon double bond in stable phosphorus ylide derived from triphenylphosphine

Theoretical studies on the basis of rotation around the carbon-carbon double bond in phosphorus ylide namely dimethyl-2-(indolin-2-one-1-yl)-3-(triphenylphosphanylidene) butanedioate was investigated using Ab initio method at HF/6-31G (d,p) and B3LYP/6-31G(d,p) levels of theory. Theoretical activation parameters at 345 K involving ?S?, ?H? and ?G? along with kinetic parameters (Ea) were determined in comparison with the same parameters on the basis of calculated dynamic 1H NMR data. There was a good agreement between theoretical (18±1kcal/mol) and experimental (17.5±1kcal/mol) activation energy.