Stereoregulated polydideuteroethylene. II. Infrared spectra and normal vibration analysis

Poly‐(trans‐CHDCHD) and poly‐(cis‐CHDCHD) have been obtained with [Al(Et)3 + TiCl4] and with [Al(i‐Bu)3 + TiCl4]. Poly‐(trans‐CHDCHD) and poly‐(cis‐CHDCHD) obtained with [Al(Et)3 + TiCl4] give mutually different infrared spectra. The characteristic absorption bands of the former are found at 1335, 1288, and 594, and 586 cm.−1, and those of the latter at 1306, 597, and 590 cm.−1. In order to interpret these spectra, the normal vibration frequencies of the model structures, namely, erythro‐diisotactic and threo‐diisotactic structures, have been calculated. From the comparison of the observed and calculated frequencies, it has been concluded that poly‐(trans‐CHDCHD) obtained with [Al(Et)3 + TiCl4] consists mainly of the threo‐diisotactic and disyndiotactic portions and poly‐(cis‐CHDCHD) obtained with the same catalyst consists mainly of the erythro‐diisotactic and disyndiotactic portions. The relation between the type of double bond opening and the structure of the resultant polymer has been discussed, and it has been concluded that the cis‐opening of the double bond occurs in the polymerization reaction with [Al(Et)3 + TiCl4]. The spectra of poly‐(trans‐CHDCHD) and poly‐(cis‐CHDCHD) obtained with [Al(i‐Bu)3 + TiCl4] are not so different from each other, but they are different from the spectra of the polymers obtained with [Al(Et)3 + TiCl4]. The polymers obtained with [Al(i‐Bu)3 + TiCl4] show characteristic bands at 2919, 2850, 2176, 2095, 1453, 660, 623, 600, 593, 581, 566, and 545 cm.−1. These bands give evidence of the presence of isolated CH2 and CD2 groups. This fact indicates that the hydrogen–deuterium exchange reaction in monomers as well as the polymerization is promoted by [Al(i‐Bu)3 + TiCl4].