Theoretical study on the reaction of NbS⁺ (³∑⁻, ¹Γ) with COS in gas phase

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• 作者：Shiwen Yu ; Taohong Li ; Lifeng Yao ; Xiaomei Yang ; Xiaoguang Xie
• 关键词：Niobium sulfide ion ; COS ; Reaction ; B3LYP
• 刊名：Journal of Molecular Structure: THEOCHEM
• 出版年：2009
• 出版时间：15 May 2009
• 年：2009
• 卷：901
• 期：1-3
• 页码：249-257
• 全文大小：615 K

文摘

The reactions of NbS⁺ (³∑⁻, ¹Γ) with COS have been studied using density functional theory at the B3LYP level: the O/S exchange reaction (NbS⁺ + COS → NbO⁺ + CS₂), the S-transfer reaction (NbS⁺ + COS →  + CO) and the O-transfer reaction (NbS⁺ + COS → ONbS⁺ + CS). The different mechanisms on the triplet and singlet surfaces have been identified. It is found that the S-transfer reaction has two parallel reaction paths (path A and path B) with respective to two isomeric products (-1 and -2), which may account, respectively, for the endothermic and the exothermic features of the product cross-section observed in the experiment. The spin-forbidden reaction NbS⁺ (³∑⁻) + COS → (1-A′) + CO was found to be energetically much more favorable than the spin-allowed reaction NbS⁺ (³∑⁻) + COS →  (3-A′) + CO. According to the identified reaction mechanisms, a triplet–singlet surface crossing is suggested. The larger activation barriers (23.7 and 59.5 kcal/mol) and the small probability of the formation of the preceding intermediate ³IM1 result in a much lower efficiency of the O/S exchange reaction and the O-transfer reaction of the ³∑⁻ ground state of NbS⁺ with COS. For the O-transfer reaction, a triplet–singlet surface crossing may also exist.