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 coupli ng constants (SSCC) in the vinyl group of vinylpyridines studied by th e quantum-chemical INDO-RPA method indicate that the steric closeness of the hydrogen atom to the nitrogen atom causes an increase in the co rresponding direct C-13-H-1 SSCC and a decrease in the analogous const ant of the geminal hydrogen atom. The results obtained qualitatively a gree with the data of ab initio calculations for the simplest systems and the experiment. At the same time, an essential quantitative overes timation of the real effect takes place.