Abstract
Summary: The regiochemical structures of poly(propylene)s obtained in the presence of three single‐site catalysts, Cp*Ti(CH~3~)~3~ + B(C~6~F~5~)~3~ (I + III), CpTi(CH~3~)~3~ + B(C~6~F~5~)~3~ (II + III), and VCl~4~ + anisole + Al(C~2~H~5~)~2~Cl (V + A), are investigated by ^13^C NMR analysis. Polymer 1, obtained in the presence of I + III is, seemingly, fully regioregular, while, surprisingly, polymer 2, obtained in the presence of II + III, appears to be alternating sequence of primary and secondary regioblocks, very much like polymer 3, obtained in the presence of V + A. The stereochemical structure of the polymer obtained in the presence of I + III is in excellent agreement with a Bernoullian statistical model of the stereoselective propagation, while those of the other two polymers possibly require a Coleman‐Fox model.
^13^C NMR spectra of 10%‐enriched poly[(2‐^13^C)propylene], 1′ and 2′, prepared under the conditions reported in Table 1 for the corresponding poly(propylene)s, 1 and 2. The resonances of the tertiary carbons are diagnostic of the regioblock structure of sample 2′.
image^13^C NMR spectra of 10%‐enriched poly[(2‐^13^C)propylene], 1′ and 2′, prepared under the conditions reported in Table 1 for the corresponding poly(propylene)s, 1 and 2. The resonances of the tertiary carbons are diagnostic of the regioblock structure of sample 2′.