DFT study of sulfur derivatives of cumulenes and their protonated forms of interstellar interest and calculations of dissociation energies of protonated forms (SC(CH)Cn-2S)+ (n = 3-8)

• Published in: Journal of molecular modeling 2014-07, Vol.20 (7), p.1-11, Article 2295
• Main Authors: Benmensour, Mohamed Ali, Djennane-Bousmaha, Sema, Boucekkine, Abdou
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemical Sciences; Chemistry; Chemistry and Materials Science; Computer Appl. in Life Sciences; Computer Applications in Chemistry; Molecular Medicine; or physical chemistry; Original Paper; Theoretical and; Theoretical and Computational Chemistry; Topical Collection QUITEL 2013
• ISSN: 1610-2940; 0948-5023
• DOI: 10.1007/s00894-014-2295-4

A theoretical study of the sulfur cumulenes SC n S (n = 3-8), C n S ( n = 1-8) and of their protonated forms (SC n S)H + and (C n S)H + that might exist in the interstellar environment, has been carried out by means of the standard B3LYP/6-311G** method. The geometries and relative energies of singlet and triplet states according to the number of carbons have been computed. Like neutral species, we have found that the ground state of the most stable protonated forms (SC(CH)C n-2 S) + and ((HC)C n-1 S) + , alternates between a triplet state for the even series and a singlet state for the odd series. We provided the data needed to simulate infrared and microwave spectra (vibration frequencies, dipole moments, and rotational constants) for each protonated species (SC n S)H + and (C n S)H + and for each neutral C n S species. The computing of dissociation energies of the most stable protonated forms (SC(CH)C n-2 S) + (n = 3-8) has shown that the lowest values are obtained for the dissociation of compounds with an even number of carbons, in their triplet state, which produce the observed fragments CS and C 3 S. The dissociation of even protonated forms requires less energy than for the odd protonated forms.