Alkenyl Selenols and Selenocyanates: Synthesis, Spectroscopic Characterization by Photoelectron Spectroscopy, and Quantum Chemical Study

• Published in: Chemistry : a European journal 2004-08, Vol.10 (15), p.3649-3656
• Main Authors: Bajor, Gábor, Veszprémi, Tamás, Riague, El Hassan, Guillemin, Jean-Claude
• Format: Article
• Language: English
• Subjects: ab initio calculations; photoelectron spectroscopy; selenium; selenocyanates; selenols
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200400159

Vinyl, allyl, and homoallyl selenols were easily prepared by a chemoselective reduction of the corresponding selenocyanates with aluminum hydrides. Two stable vinyl and five stable allyl conformers of both series were predicted on the potential‐energy surface. The interaction of SeH or SeCN groups with the vinyl group has been investigated with UV photoelectron spectroscopy and quantum chemical calculations, using the MP2/cc‐pVTZ and B3LYP/cc‐pVTZ levels. In the vinyl derivatives, a surprisingly strong direct conjugation of the selenium lone electron pair and the CC double bond was observed. On the other hand, in allyl position the selenium lone pair is independent on the CC double bond, and the hyperconjugation between the SeC bond and the double bond is the ruling effect. Thus is clarified the type and extent of the interaction between the SeH or SeCN group and the unsaturated moiety. Selenium chemistry: Alkenyl selenols and selenocyanates with increasing distance between the selenium atom and the unsaturated group have been synthesized and investigated by UV photoelectron spectroscopy (see scheme) and quantum chemical calculations. Major differences were observed in the interactions between the SeH or the SeCN group and the unsaturated moiety for vinyl, allyl, and homoallyl derivatives.