This paper reports the assignment of the 13C NMR resonances of the Sββ and Sαγ methylenes observed in the spectra of copolymers of propylene with trace amounts of enriched ethylene‐1‐13C. The assignment is achieved by comparing the chemical shifts calculated by an empirical method (at the CH2 stereochemical pseudohexad level), with the experimental spectra of regioregular copolymers with different stereochemical structure. The implications of the observed Sββ and Sαγ resonances on the stereochemical polymerization mechanisms are also discussed.
