Nachweis innermolekularer beweglichkeit durch NMR-spektroskopie-XXV. Planare stickstoffinversion in iminokohlensäureestern und iminodithiokohlensäureestern. Einfluss der substitution am iminokohlenstoff auf die inversionsgeschwindigkeit am stickstoff

Linear Hammett-correlations (with σ^-) have been found for the rates of thesyn-anti-topomerization in substituted N-aryliminocarbonates(1;ρ{variant} = 1·44) and N-aryl-iminodithiocarbonates(2;ρ{variant} = 1·30). Large substituents in the aryl ring in the ortho-position to the imino nitrogen increase the topomerization rate. From these results the conclusion has been drawn that planar inversion of nitrogen is the rate determining step for syn-anti-topomerization in 1 and 2. This is further supported by the solvent effects : no influence of solvent polarity but influence of protic solvents on barriers. The influence of substitution of the imino-carbon on planar inversion rate in imines is shortly discussed.