Interplay between the N→C Dative Bond, Intramolecular Chalcogen Bond and π Conjugation in the Complexes Formed by Cyclo[18]carbon and C14 Polyyne with 1,2,5‐Chalcogenadiazoles

The N→C dative bond (DB), intramolecular chalcogen bond and π conjugation play important roles in determining the structures and properties of some molecular carbon materials and organic/polymeric photovoltaic materials. In this work, the interplay between the N→C dative bond, intramolecular chalcogen bond and π conjugation in the complexes formed by cyclo[18]carbon and C14 polyyne with 1,2,5‐chalcogenadiazoles has been investigated in detail by using reliable quantum chemical calculations. This study has made four main findings. First, only the Te‐containing complexes bound by N→C dative bonds are much more stable than their corresponding van der Waals (vdW) complexes. Second, in addition to through‐bond π conjugations, through‐space π conjugations also exist in some Se/Te‐containing complexes bound by N→C dative bonds. Third, the cooperativity between intramolecular chalcogen bond, π conjugation between two monomers and N→C dative bond is not very strong and can be ignored. Fourth, compared to π conjugations, intramolecular Ch···C (Ch = O, S, Se, Te) chalcogen bonds play a secondary role in stabilizing the complexes bound by N→C dative bonds. These findings clearly indicate that the role of “conformational lock”, popular in the field of organic optoelectronic materials, may have been greatly overestimated.