Affiliations: Irkutsk Institute of Organic Chemistry, Siberian Division RAS, Irkutsk 664033, Russia
Note:  Irkutsk Institute of Organic Chemistry, Siberian Division RAS, Irkutsk 664033, Russia
Abstract: The existence of stable rotational isomers of bis-substituted acetylenes has been checked theoretically. The mutual rotation of π-donating or π-accepting substituents having C2v or Cs local symmetry is characterized by the barriers up to 10 kJ mol− and more according to HF SCF MO data (6–31G and 6–31G* basis sets). Two π-donors or two π-acceptors stipulate stable s-gauche conformation while the molecules with π-donating or π-accepting substituents are stable in s-cis or s-trans conformations.