Study of stereochemical dependences of the direct C-13-H-1 spin-spin coupling constants in vinylpyridines by the quantum-chemical INDO-RPA method

The stereochemical dependences of the direct C-13-H-1 spin-spin coupling constants (SSCC) in the vinyl group of vinylpyridines studied by the quantum-chemical INDO-RPA method indicate that the steric closeness of the hydrogen atom to the nitrogen atom causes an increase in the corresponding direct C-13-H-1 SSCC and a decrease in the analogous constant of the geminal hydrogen atom. The results obtained qualitatively agree with the data of ab initio calculations for the simplest systems and the experiment. At the same time, an essential quantitative overestimation of the real effect takes place.