Allenyl and alkynyl selenols and selenocyanates with gradually increasing distance between the selenium atom and the unsaturated group have been synthesized and studied by photoelectron spectroscopy and quantum chemical calculations. In the triple-bonded derivatives 1, 2, 5, and 6 (1-alkynylselenium derivatives), an enhanced conjugative interaction was observed, which results in a considerable (0.12-0.13 Å) Se - C bond shortening. In the propargyl 3 and 7 and homoallenyl derivatives 10 and 13 a slight but readily well observable hyperconjugation effect could be found. In the case of allenyl selenium derivatives 9 and 12 both effects are in operation, which result in a moderate Se - C bond shortening. With the previously reported study of alkenyl selenium derivatives, the type and extent of the interaction between the SeH or SeCN group and an unsaturated moiety (alkenyl, allenyl, or alkynyl substituent) are now completely clarified.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry