Unimolecular Reactivity of the [Urea-Sr]2+ Complex, a Metastable Dication in the Gas Phase: An Experimental and Theoretical Perspective

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• 作者：Ane Eizaguirre ; Ot铆lia M贸 ; Manuel Y谩帽ez ; Jeanine Tortajada ; Jean-Yves Salpin
• 刊名：The Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：February 21, 2013
• 年：2013
• 卷：117
• 期：7
• 页码：2088-2095
• 全文大小：341K
• 年卷期：v.117,no.7(February 21, 2013)
• ISSN：1520-5207

文摘

The interactions between urea and Sr²⁺ in the gas phase have been investigated by combining electrospray ionization/mass spectrometry techniques and density functional and high-level ab initio molecular orbital calculations. Our theoretical survey indicates that [Sr(urea)]²⁺ adducts are thermodynamically stable with respect to direct Coulomb explosions. However, after isomerization, some of the local minima of the PES are thermodynamically unstable with respect to the formation of NH₄⁺, but kinetically metastable. The loss of neutral fragments with the concomitant generation of lighter doubly charged fragment ions, namely, [(H₃N)Sr]²⁺ and [(HNCO)]Sr²⁺, compete with the aforementioned Coulomb explosion processes yielding NH₄⁺ + [(NCO)Sr]⁺ and [(H₂N)Sr]⁺ + [H₂NCO]⁺, although the former processes dominate. Hence, both singly and doubly charged species are detected as dissociation products. Quite importantly, the observed eliminations of NH₃ or HNCO lead to the formation of new doubly charged species, which turn out to be thermodynamically stable.