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首页> 外文期刊>Journal of mass spectrometry: JMS >One electron less or one proton more: how do they differ?
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One electron less or one proton more: how do they differ?

机译：一个电子少或一个质子更多：它们如何不同？

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From the NIST website and the literature, we have collected the Ionisation Energies (IE) of 3,052 and the Proton Affinities (PA) of 1,670 compounds. For 614 of these, both the IE and PA are known; this enables a study of the relationships between these quantities for a wide variety of molecules. From the IE and PA values, the hydrogen atom affinities (HA) of molecular ions M center dot+ may also be assessed. The PA may be equated to the heterolytic bond energy of [MH](+) and HA to the homolytic bond energy. Plots of PA versus IE for these substances show (in agreement with earlier studies) that, for many families of molecules, the slope of the ensuing line is less negative than -1, i.e. changes in the PA are significantly less than the concomitant opposite changes in IE. At one extreme (high PA, low IE) are the metals, their oxides and hydroxides, which show a slope of close to -1, at the other extreme (low PA, high IE) are the hydrogen halides, methyl halides and noble gases, which show a slope of ca. -0.3; other molecular categories show intermediate behaviour. One consequence of a slope less negative than -1 is that the changes in ionic enthalpies of the protonated species more closely follow the changes in the enthalpies of the neutral molecules compared with changes in the ion enthalpies of the corresponding radical cations. This is consistent with findings from ab initio calculations from the literature that the incoming proton, once attached to the molecule, may retain a significant amount of its charge. These collected data allow a comparison of the thermodynamic stability of protonated molecules in terms of their homolytic or heterolytic bond cleavages. Protonated nitriles are particularly stable by virtue of the very large hydrogen atom affinities of their radical cations.
机译：从NIST网站和文献中，我们已经收集了3,052的电离能量（IE）和1,670种化合物的质子亲和力（PA）。对于614，IE和PA都是已知的;这使得能够研究这些数量之间的各种分子之间的关系。从IE和Pa值，也可以评估分子离子M中心点+的氢原子亲缘性（HA）。 PA可以等于[MH]（+）和HA至均解粘合能的异解粘合能。 PA与这些物质的图表（与早期的研究同时）显示，对于许多分子的家庭，随后的线的斜率小于-1，即PA的变化显着低于伴随的相反变化在IE中。在一个极端（高PA，低Ie）是金属，它们的氧化物和氢氧化物，其显示靠近-1的斜率，另一个极端（低PA，高IE）是卤化氢，卤化甲酯和惰性气体，它显示了一个斜坡。 -0.3;其他分子类别显示中间行为。坡度低于-1的一个后果是，与相应的自由基阳离子的离子焓的变化相比，质子化物质的离子焓的变化更接近中性分子的变化。这与来自于附带分子的进入质子的AB初始计算的结果一致，可以保留其电荷大量电荷。这些收集的数据允许在其均透明或异解粘合裂解方面进行质子化分子的热力学稳定性。凭借其自由基阳离子的非常大的氢原子亲缘性，质子化腈尤其稳定。

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