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首页> 外文期刊>Journal of mass spectrometry: JMS >Gas-phase interactions of organotin compounds with glycine
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Gas-phase interactions of organotin compounds with glycine

机译：有机锡化合物与甘氨酸的气相相互作用

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Gas-phase interactions of organotins with glycine have been studied by combining mass spectrometry experiments and quantum calculations. Positive-ion electrospray spectra show that the interaction of di- and tri-organotins with glycine results in the formation of [(R)_2Sn(Gly)-H]~+and [(R)_3Sn(Gly)]~+ ions, respectively. Di-organotin complexes appear much more reactive than those involving tri-organotins. (MS/MS) spectra of the [(R)_3Sn(Gly)]~+ ions are indeed simple and only show elimination of intact glycine, generating the [(R)_3Sn]~+ carbocation. On the other hand, MS/MS spectra of [(R)_2Sn(Gly)-H]~+complexes are characterized by numerous fragmentation processes. Six of them, associated with elimination of H_2O, CO, H_2O + CO and formation of [(R)_2SnOH]~+ (-57 u),[(R)_2SnNH_2]~+(-58 u) and [(R)2SnH]+ (-73 u), are systematically observed. Use of labeled glycines notably concludes that the hydrogen atoms eliminated in water and H_2O+ CO are labile hydrogens. A similar conclusion can be made for hydrogens of [(R_2)SnOH]~+and [(R_2)SnNH_2]~+ions. Interestingly, formation [(R)_2SnH]~+ ions is characterized by a migration of one the α hydrogen of glycine onto the metallic center. Finally, several dissociation routes are observed and are characteristic of a given organic substituent. Calculations indicated that the interaction between organotins and glycine is mostly electrostatic. For [(R)_2Sn(Gly)-H]~+complexes, a preferable bidentate interaction of the type η~2-O,NH2 is observed, similar to that encountered for other metal ions. [(R)_3Sn]~+ ions strongly stabilize the zwitterionic form of glycine, which is practically degenerate with respect to neutral glycine. In addition, the interconversion between both forms is almost barrierless. Suitable mechanisms are proposed in order to account for the most relevant fragmentation processes.
机译：通过结合质谱实验和量子计算研究了有机锡与甘氨酸的气相相互作用。正离子电喷雾光谱表明，二有机锡和三有机锡与甘氨酸的相互作用导致[（R）_2Sn（Gly）-H]〜+和[（R）_3Sn（Gly）]〜+离子的形成，分别。二有机锡复合物似乎比涉及三有机锡的复合物更具活性。 [（R）_3Sn（Gly）]〜+离子的（MS / MS）光谱确实很简单，仅消除了完整的甘氨酸，产生了[[R] _3Sn]〜+碳正离子化。另一方面，[（R）_2Sn（Gly）-H]〜+配合物的MS / MS光谱具有众多的裂解过程。其中六个与消除H_2O，CO，H_2O + CO和形成[[R] _2SnOH]〜+（-57 u），[[R] _2SnNH_2]〜+（-58 u）和[[R]系统观察到2SnH] +（-73 u）。标记甘氨酸的使用特别得出结论，在水中和H_2O + CO中消除的氢原子是不稳定的氢。对于[（R_2）SnOH]〜+和[（R_2）SnNH_2]〜+离子的氢也可以得出类似的结论。有趣的是，形成[[R] _2SnH]〜+离子的特征是甘氨酸的一个α氢迁移到金属中心。最后，观察到几种解离途径，它们是给定有机取代基的特征。计算表明有机锡和甘氨酸之间的相互作用主要是静电的。对于[（R）_2Sn（Gly）-H]〜+络合物，观察到一种优选的η〜2-O，NH2型二齿相互作用，与其他金属离子相似。 [（R）_3Sn]〜+离子可牢固地稳定两性离子形式的甘氨酸，而实际上这是相对于中性甘氨酸而言简并的。另外，两种形式之间的相互转换几乎是无障碍的。为了解决最相关的碎片过程，提出了适当的机制。

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