The Role of Intimate Dipole Carbonyl–Carbonyl and Hydrogen–Carbonyl Interactions in the Stereocomplexation and Crystallization: The Case of Poly(Cyclohexene Carbonate)

Enantiopure isotactic poly(cyclohexene carbonate) (PCHC) has been synthesized with chiral Zn‐β‐diiminate catalyst. PCHC crystallizes both as enantiopure polymer (R)‐PCHC and (S)‐PCHC and upon stereocomplexation of the two enantiomers. We report the crystal structures of the enantiopure polymer and of the stereocomplex (R/S)‐PCHC and explain their crystallization based on the establishment of multiple attractive H‐‐‐O═C interactions between oxygen atoms of carbonyl groups and the hydrogen atoms of the cyclohexyl rings and C═O‐‐‐C═O intimate dipole interactions between carbonyl groups of chains of opposite chirality in the stereocomplex. The crystal structure of the enantiopure polymer is characterized by chains in 2/1 helical conformation packed in the orthorhombic unit cell with axes a = 11.55 Å, b = 9.42 Å, and c = 7.36 Å, according to the space group P212121, with steric interdigitation between chains of similar chirality favored by multiple attractive H‐‐‐O═C interactions. The stereocomplex crystallizes in an orthorhombic unit cell with axes a = 10.40 Å, b = 8.41 Å, and c = 7.36 Å, according to the space group Pbc21, driven by establishment of additional C═O‐‐‐C═O dipole interactions between carbonyl groups of chains of opposite chirality, besides of the multiple attractive H‐‐‐O═C interactions.